LECTURE NOTE

BASIC COMPUTER
NETWORK

(COM 221)
 COURSE CONTENT

1.0. Basic Concept of Computer Networking

1.1 Definition of terms such as computer networks etc
1.2 Advantages and Disadvantages of Computer network
1.3 Types of network such as LAN, MAN, and WAN
1.4 Perimeter Networks addressing VLANS wireless and wireless LAN.
1.5 Leased lines, dial up, ISDN,VPN, T1, T3, E1,E3,DSL, Cable Modem and their
characteristics
1.6 Differentiate between client and server computers
1.7 Differentiate between wired and wireless network
2.0. Hardware components of computer networks and their functions
2.1 Routes, switches, hub, repeater, gateway, and cables
2.2 Differentiate between hub and switch
2.3 Details about repeaters and their functions
2.4 Details about bridges and their functions
2.5 Details about routers and their functions.
2.6 NIC and their functions
3.0. Network planning and design
3.1 Definition of terms such as network planning AND DESIGN
3.2 Importance of network planning
3.3 Steps involved in designing a network
3.4 network topology and access methods
4.0. Different types of network connections
4.1 Point to point, peer to peer
4.2 Types of cable termination and suitable cables for each
4.3 Types of servers such as print, mails e.t.c
4.4 Details of server reliability, availability and data integrity
5.0. Open systems interconnection (OSI) Model and TCP/IP
5.1 Definition of terms OSI models
5.2 Explanation of TCP/IP reference model
5.3 Differentiate between TCP/IP and OSI model
5.4 Function of each layer of the OSI model
6.0. IP addresses of networks using IPV4 and IPV6
6.1 Concept of IP addressing and types
 6.2 Explanation on IPV4
6.3 Classes of IP addresses
6.4 Range of IP address classes
6.5 VLSM/SUBNETING/IPV4
6.6 Explanation of IPV6
6.7 Network functionality test
7.0. Wireless network access
7.1 Differentiate between intranet and extranet
7.2 Various types of internet connectivity
7.3 Wireless networks and types of access
7.4 Differentiate between dialed up/wireless and broadband internet access
7.5 Advantages of broadband over dialed up and wireless access network
7.6 Explanation of wireless network standard
7.7 Types of network security
 BASIC CONCEPT OF COMPUTER NETWORKING

1.1. DEFINITION OF TERMS

A network is a set of devices that generally refers to as nodes connected by communication links.
A node can be a computer, printer or any devices capable of sending and or receiving data
generated by other nodes of the network.
Computer Network:Computer network is simply a connection of autonomous computer
interconnected by single technology. Two computers are said to be interconnected if they are
able to exchange information. Meanwhile the connection need not be through a copper wire,
fibre optics, microwaves, infra-red and communication satellite can also be used. Network comes
in many sizes, shapes and forms but they are usually connected together to make larger networks
with the internet being the most well-known example of a networks.

1.2. ADVANTAGES AND DISADVANTAGES OF COMPUTER NETWORK

ADVANTAGES
1. File sharing: The data stored on a device can be shared with other users and can also be
accessed remotely once they are connected.
2. Data Reliability: Since data in the central server is stored, we are sure that it is reliable
hence, if the information of one the PC gets lost, it is possible to access the data by using
another computer.
3. Improved Communication: Users can easily share information and get across to one
another through various means over the network.
4. Greater Connectivity: Irrespective of where users are located they can easily access
each other as long as they are connected.
5. Reliability: Computer networking ensures information backup for uninterrupted
functioning.
6. Increased Storage Capacity.
7. Better Information Security.
DISAVANTAGES
1. Malware Infection: Virus can be spread easily to the connected computer devices if one
of the computer device is infected.
2. Setup Cost: For installation of a good and effective network, the cost for both the
hardware devices and software to be used is high.
 3. Problem with Independent Usage: There’s little or no privacy for an individual using a
connected device because every information from such device can be accessed by other
connected devices.
4. Security of Computer Network: There is usually a threat to all the nodes on the
network whether the user is online or offline if a node is tampered with.
5. Health Issues: When a user is connected and get every information required at all time,
this may cause such user to spend more time on a computer system with leads to eye
defect, obesity etc.
6. Poor Internet Accessibility

1.3.TYPES OF NETWORK
Networks can be categorized based on size and other factors.
Types of Networks Based On Size
There are three major network categories based on its size, the area it covers and the physical
architecture. These categories are:
1. LAN (Local Area Network)
2. MAN (Metropolitan Area Network)
3. WAN (Wide Area Network)
Meanwhile each network differs in their characteristics such as distance, transition speed, cables
and cost
 Local Area Network (LAN): These are group of interconnected computers within a small
area such as room building or an entire campus. From a LAN, two or more PCs can share
files, folders, printers, applications and other devices. Co-axial cables or CAT5 cables are
normally used for connections and due to short distances errors and noise are minimum.
This network’s data transfer rate is 100Mbps.
 Metropolitan Area Network (MAN): This network is designed to cover a large area and
several LANs connected so that resources can be shared. The network can accumulate up
to 50km invariably. Ilaro town, from FPI east campus can be connected to the LAN at
west campus and can also be linked up with another LAN at Igboora, another LAN from
Yewa College can also be linked up. Data transfer rate is low compared to LAN.
 Wide Area Network (WAN): This is a network that connects all the cities and towns in
Nigeria and worldwide. The data transfer depends on the ISP(Internet Service Provider).
Other types of network include:
4. WLAN(Wireless Local Area Network)
 5. PAN(Personal Area Network)
6. SAN(Storage Area Network)

1.4.PERIMETER NETWORKS
Perimeter Network simply means that assistance or provision that is provided to secure
connectivity between cloud network on premises or physical data center networks and the
internet. Perimeter network is also known as Demilitarized Zones (DMZs). In any effective
computer networks, incoming packet flow through security appliances that are hosted in secure
subnets before the packet can reach the backend server. The security appliances include
firewalls, network virtual appliances and other intrusion detection and prevention system.
Internet band packet from workloads must also flow through security appliances in the perimeter
network before they can leave the network. Usually central IT teams and security teams are
responsible for defining operational requirement for perimeter networks can provide policy
enforcement inspection and auditing.

1.5.DIFFERENCES BETWEEN WIRED AND WIRELESS NETWORKING

A wired network as the name implies refers to any physical medium connected through wires
and cables. These wired cables can be either copper wire, twisted cables and fibre optics.
Wired connectivity is responsible for providing the high security with high bandwidth provision
to the computer for each user. Meanwhile wired connectivity is considered highly reliable incurs
many low delay unlike wireless connectivity.
Wireless Connectivity
It refers to the uses of ‘air’ as a medium to send electromagnetic waves or infrared waves.
Wireless devices have antennas for communication. It provides the major benefit of user
mobility and ease of deployment. Wireless becomes more useful in area where wires cannot be
reached.
 HARDWARE COMPONENTS OF COMPUTER NETWORKS AND THEIR
FUNCTIONS

2.1 THE HARDWARE COMPONENT

2.1.1 ROUTER
A router links two or more local area devices to the Internet. Once devices are interconnected,
this forms a network. Through packet switching, the router transfers Internet data packets from a
central wide area network (WAN) connected to the Internet. The router then pushes the secured
Internet traffic through to devices within the network. This can include computers, tablets,
phones, and smart TVs within range of the router. While a router can broadcast a wireless signal
(Wi-Fi) to connected and enabled devices, it isn’t only for Wi-Fi. Routers also offer hard-wired
connections to the Internet. Once the router connects to Internet data through hard wire or
Ethernet, it can then translate that connection into a transmittable Wi-Fi signal that capable
devices can pick up. You can also hard-wire your computer into the router and use it for a wired
Internet link. You may prefer this if you have security, speed, or reliability concerns.

2.1.2 SWITCHES
A network switch connects devices in a network to each other, enabling them to talk by
exchanging data packets. Switches can be hardware devices that manage physical networks or
software-based virtual devices.A network switch operates on the data-link layer, or Layer 2, of
the Open Systems Interconnection (OSI) model. In a local area network (LAN) using Ethernet, a
network switch determines where to send each incoming message frame by looking at the media
access control (MAC) address. Switches maintain tables that match each MAC address to the
port receiving the MAC address.It takes in packets sent by devices that are connected to its
physical ports, and forwards them to the devices the packets are intended to reach. Switches can
also operate at the Network Layer (Layer 3) where routing occurs.Switches are a common
component of networks based on Ethernet, Fibre Channel, Asynchronous Transfer Mode (ATM),
and InfiniBand, among others. However, most switches today use Ethernet.

2.1.3 REPEATER
A repeater operates at the physical layer. Its job is to regenerate the signal over the same
network before the signal becomes too weak or corrupted to extend the length to which the
signal can be transmitted over the same network. An important point to be noted about
repeaters is that they not only amplify the signal but also regenerate it. When the signal
becomes weak, they copy it bit by bit and regenerate it at its star topology connectors
connecting following the original strength. It is a 2-port device.

FUNCTIONS
 Repeater simply allows to facility for making network interconnection.
 The primary function of repeater is to receive the signals for one LAN terminal cable and
then to regenerate and retransmit the all signals as its original form over other cable
segments.
 A repeater ensures that the amplified signals are not discard or weak before arriving the
destination point.
 Mostly, repeater is capable to regenerate the signal strength but it is done before
broadcasting.
 A repeater works at the physical layer of OSI model and transparent to all protocols which
are operating in the layer above the physical layer.
 With using of repeater, network can be scaled the size limit of a single, physical, cable
segment.
 The number of repeaters that can be used intended is generally limited by a particular LAN
implementation. Using a repeater between two or more LAN cables segment requires that the
same physical layer protocol be used to send signal over all the cable segments.

2.1.4 HUB
A hub is basically multi-port repeater. A hub connects multiple wires coming from different
branches, for example, the connector in star topology which connects different stations. Hubs
cannot filter data, so data packets are sent to all connected devices. In other words,
the collision domain of all hosts connected through Hub remains one. Also, they do not have
the intelligence to find out the best path for data packets which leads to inefficiencies and
wastage.

2.1.5 GATEWAY
A gateway, as the name suggests, is a passage to connect two networks that may work upon
different networking models. They work as messenger agents that take data from one system,
interpret it, and transfer it to another system. Gateways are also called protocol converters and
can operate at any network layer. Gateways are generally more complex than switches or
routers.
2.1.6 CABLES
Communications cables are used to interconnect, connect and transfer data and information
between computers, routers, switches and storage area networks. These cables are essentially the
carrier or media through which data flows.
There are different types of communications cables, and the appropriate type to use will depend
on the structure and topology of the overall architecture of the system. The most commonly used
types of communications cables are dominated by what is referred to as “twisted pair cable”. In
local area network typically office environments, retail and commercial sites, copper
communications cabling, i.e. twisted pair cable is by far the most commonly used type of cable.
Twisted pair cable is used in many Ethernet networks comprising four pairs of thin wires or
conductors, these ‘wires’ or conductors, are contained inside of the insulation or outer sheath of
the cable. Each pair is twisted into several additional twists. These twists are designed to prevent
interference from other devices and indeed from other adjacent cables.
Fibre optic cabling is specified where high bandwidths may be needed; especially in the data
centre environment and where an installation demands high capacity, typically a Hospital,
Airports, Banks etc.We have various number of Fibre optic cables and of course, there is FTTH,
FTTX and much more,Fibre optic cabling is the medium of choice for any installation that is
sending high volumes of data,Of course, there are other types of cables, i.e., coaxial cable, multi-
pair cable and of course, other types of media such as wireless, otherwise known as Wi-Fi.

2.2. DIFFERENCES BETWEEN HUB AND SWITCH

HUB SWITCH
Hub is operated on Physical layer of OSI While switch is operated on Data link layer of
model. OSI Model.
Hub is a broadcast type transmission. While switch is a Unicast, multicast and
broadcast type transmission.
Hub have 4/12 ports. While switch can have 24 to 48 ports.
In hub, there is only one collision domain. While in switch, different ports have own
collision domain.
Hub is a half-duplex transmission mode. While switch is a full duplex transmission
mode.
In hub, Packet filtering is not provided. While in switch, Packet filtering is provided.
Hub cannot be used as a repeater. While switch can be used as a repeater.
Hub is not an intelligent device that sends While switch is an intelligent device that sends
message to all ports hence it is comparatively message to selected destination so it is
inexpensive. expensive.
Hub is simply old type of device and is not While switch is very sophisticated device and
generally used. widely used.
Hacking of systems attached to hub is complex. Hacking of systems attached to switch is little
easy.
Speed of original hub 10Mbps and modern Maximum speed is 10Mbps to 100Mbps.
internet hub is 100Mbps.
Hubs are used in LANs. Switch is used in LANs.
Cheaper as compared to switch. Expensive as compared to HUB.

2.3 DETAILS ABOUT REPEATERS AND THEIR FUNCTION

A repeater is a simple facility used for network interconnection, whose major function is to
receive a network signal from the transmitter and to regenerate the signal in strength and
retransmit the signal while maintaining the data that is transmitted by the signal.
Repeaters are used to increase the range of communication of signals.
A repeater is a simple facility used for network interconnection, whose major function is to
receive a network signal from the transmitter and to regenerate the signal in strength and
retransmit the signal while maintaining the data that is transmitted by the signal. A repeater
regenerates the strength of the signal before transmitting it as without the repeater, the signal
strength will deteriorate as the signal is transmitted.
A repeater is a combination of a receiver and a transmitter. A repeater picks up the signal from
the transmitter, amplifiers and retransmits it to the receiver while maintaining the strength and
data in the signal. A typical example of a repeater station is a repeater used in households to
extend Wi-Fi signals as well as in communication satellites.

Repeater is a network hardware device that is worked at the physical layer of OSI model, and
it helps to amplify or regenerate the signals before retransmitting it. Repeater is also known as
“Signal Boosters”. A repeater has ability to extend the data signal from one network segment
and then pass it to another network segment, thus scaling the size of network.

Repeaters are usually used when the transmitter does not have a direct line of sight with the
receiver. In such cases, we use a repeater to establish a common point between the transmitter
and the receiver such that the repeater is in direct line of sight with the transmitter and the
receiver.

2.4 DETAILS ABOUT BRIDGES AND THEIR FUNCTION

A bridge is a computer network hardware device that works at the data link layer of OSI
model, and it also helps to make interconnection in between multiple networks with using of
same protocol.
Network Bridge divides the large network into small segments, and these segments represent a
separate collision domain, and it also helps to decrease the number of collision over the network.
Every collision domain contains the own individual bandwidth, so its performance is getting to
improve.

A bridge is a kind of networking device that makes the interconnection in between the other
bridge networks, which are getting to use at the same protocol. The main role of bridge in
computer network is to keep store and forwarding frames in between the different segment that
are connected along with bridge.

A bridge in a computer network is a device used to connect multiple LANs together with a
larger Local Area Network (LAN). The mechanism of network aggregation is known as
bridging. The bridge is a physical or hardware device but operates at the OSI model’s data link
layer and is also known as a layer of two switches.
The primary responsibility of a switch is to examine the incoming traffic and determine
whether to filter or forward it. Basically, a bridge in computer networks is used to divide
network connections into sections, now each section has separate bandwidth and a separate
collision domain. Here bridge is used to improve network performance.

FUNCTIONS
Working Activities of Bridge
 The bridge allows to spit the local area network into many small segments.
 It performs the all tasks in data link layer in OSI model.
 Bridge helps to hold the MAC address of all computers in the network.
 It helps to decrease the traffic over the network.
 With using of MAC address, bridge gets to filter the all contents of source and destination
points.
  It is used for making the interconnection two LAN networks along with single and same
protocol.
 Bridge can work as single large LAN with connecting the multiple virtual LANs.
 Bridge has ability to switch any types of data packets like as Apple talk packets or IP
packets over the network layer because in which payload field of the data frame is not
considered. Only MAC address or destination address of the frame is acceptable to block
or forward the data to each node in the computer network.

Functions of Bridges in the Network

 The bridge is used to divide LANs into multiple segments.
 To control the traffic in the network.
 It can interconnect two LANs with a similar protocols.
 It can filter the data based on destination/MAC address.

2.3 DETAILS ABOUT ROUTERS AND THEIR FUNCTION

Router has responsible to receives, analyze, and forward the all data packets from
the modem and transfer it to the destination point. After reaching the data packets, the router
monitors the destination address; get to make consultation its routing table that take the decision
which is the best route for transferring the data packets.
A router is a layer three (Network Layer in OSI Reference Model) device used to connect
different networks. For example, if you want to connect two networks one is FDDI and other is
Ethernet, we need a router. It also connects networks with the different network address. To
move information between devices having different network numbers, we need a layer 3 device.
Routers can switch packets on the same interface using VLANs.

Purpose of Router
Router is used for getting to fulfill the following purposes;
 First, to make ensure that data is flowing with correct destination, like as uses sends the
emails to correct internet provider and recipient.
 Second, Routers provide the protection from unwanted data, like as enlarge file is
distributed to each machines over the network and improve the network performance.
 Third, router plays the role as a buffer in between the modem and network, and it also
allows the software security to diminish the risk of viruses or other malware.
Functions of Router
We cannot finish an article about routers without mentioning their functions. The major
functions are:

1. Router Connects Different Network Types

2. It joins networks with different network addresses
3. It finds the shortest path to send packets to the destination
4. It defines logical address schemes
5. Router supports VLANs
6. The router has features like Quality of Service and Filtering
7. It builds routing tables to make layer 3 decisions fast

2.4 DESCRIPTION OF NETWORK INTERFACE CARD (NIC) AND FUNCTIONS

Network interface card is a hardware component (circuit board) that is installed in the computer
system. It helps to make connection with different types of networking devices like
as server and PC to share data over the entire computer network. NIC offers several
functionalities like as Direct Memory Access (DMA) interfaces, partitioning, data transmission,
and I/O interrupt.

2.4.1 What is NIC?

Computers and other devices are very useful in processing, displaying, and printing information.
A computer that is connected to a printer can produce documents, flyers, data spreadsheets, and
other printouts useful to a business. If your office has two or more computers or devices, then
how do we get data from one to the other? What if I need to get the data to a client in another
state or country? Your useful device needs to be able to communicate with other computers and
systems.
The Network Interface Card, or NIC, allows your device to communicate with a network of
other devices utilizing data transfer protocols to ensure the data's integrity. The NIC is the
physical piece of hardware that connects your computer to the network. It can also be known
as network adapter, network interface controller, or as a Local Area Network (LAN)
adapter.
As technology has continued to develop, new devices are now networked with their own NIC,
both wired and wireless. The NIC allows your device to communicate with the network and
networked devices to do everything from viewing monitoring cameras to controlling your air
conditioning. Many new devices are coming every day.

2.4.2 Functions of Network Interface Card

Network interface card (NIC) performs various functions; below list and explain each one –
 It plays role as translator that helps to convert data into digital signal.
 Network card provides both communication methods like as wired and wireless.
 It acts as middleware in between computer and data network. For example, when user sends
the requests for any query on the internet then LAN card receives data from the user system,
and then send them to the server over the internet, then finally it receives the needed data
back from internet for viewing for users.
 This network card uses both OSI model layer such as physical and data link layer. Physical
layer is used for transmitting signal and network layer to transfer data packets.

To transfer the data from your computer to another device, such as a printer or another computer,
the NIC must take the data from your computer and covert it to data packets that can be
interpreted by another NIC for another computer or device. The NIC also converts the received
data packets so that your computer can use the data.
A NIC can connect to the network either through a wired connection or a wireless connection.
How widespread the network is can be defined as a Personal Area Network (PAN), such as
Bluetooth connections, a Local Area Network (LAN) that would be in a local area like an office
building, or, a Wide Area Network (WAN), which could include multiple locations for the same
network. The network is usually the gateway to the Internet. A computer can have multiple
NICs, including both wired and wireless. It is also possible for the different NICs to be
connected to different networks.
Without a NIC, a device is 'air gapped' from the network, and subsequently the Internet, which
enhances its security, but minimizes its potential effectiveness.
 NETWORK PLANING AND DESIGN

3.1 NETWORK PLANNING AND DESIGN

Network planning and design is an iterative process, encompassing topological design, network-
synthesis, and network-realization, and is aimed at ensuring that a new telecommunications
network or service meets the needs of the subscriber and operator.
Computer network planning consists of the following steps:

1. Identifying the applications that you intend to use: Computer networking may be required
diverse environments such as Enterprise Resource Management (ERM), Internet telephony,
Instant Messaging (IM), eMail and others. It is important to discuss the applications that you
intend to use such as the above. These in turn are used for estimating the software, hardware,
and traffic requirements.
2. Traffic Requirements: Computing traffic requirements include several factors. A few points
to consider include the following:
 Identification and documentation of major traffic sources.
 Categorization of traffic as local, distributed, client/server, peer-to-peer, terminal/host or
server/server.
 Estimation of bandwidth requirements for each application.
 Quality of Service (QoS) requirements for each application
 Reliability requirements.

3. Scalability Requirements: Scalability refers to the extent of network growth that should be
supported. For corporate network, scalability is a major consideration. Provision must be
made to add users, applications, additional sites, and external network connections.
4. Geographical considerations: Consider the LAN and WAN links that may be required.
Offices that are separated by large distance (for example one in Delhi and another in New
York) can be linked together by a WAN (Wide Area Network) link. Similarly, building
complexes within a compound can be linked by a LAN (Local Area Network) link.
Typically, the LAN links are high bandwidth (10Mbps and above) and WAN links are of
lower bandwidth (64 Kbps - 2Mbps). Further, the LANs fall within the premises of a
Company whereas WANs are typically leased and maintained by the Telecom. Hence,
WANs are costly in bandwidth terms and need to be planned and designed with utmost care
to minimize resource consumption.
5. Availability: The availability of a network needs to be given careful consideration while
designing a network. It is the amount of time a network is available to users over a period of
time and is often a critical design parameter. Availability has direct relation with the amount
of redundancy required. Another important factor that needs to be considered when
computing availability requirements is the business loss to the Company due to unavailability
of the network for a given amount of time. A right balance needs to be arrived at such that
the profitability is maintained.
6. Security and Accessibility: Security and accessibility are among the important design phase
steps. A security plan needs to be devised that meets the required security specifications. You
must specify:

 a list of network services that will be provided such as FTP, Web, e-mail, etc.
 Who will be administering the security of these services
 How would the people be trained on security policies and procedures
 Recovery plan, in case a security breach does take place.

7. Cost considerations: For LANs, the tendency is to minimize the equipment cost. That is
minimizing the cable cost, minimizing the peer port cost, and the labour cost. For WANs the
primary goal is to minimize the usage of the bandwidth. This is because, the recurring costs
for bandwidth are normally much higher than the equipment or labour cost. Therefore more
weightage is given to reliable equipment, and efficient utilization of bandwidth. Some factors
that optimize cost are:

 Improve efficiency on WAN circuits by using features such as compression,Voice

Activity Detection etc.
 Use technologies such as ATM that dynamically allocate WAN bandwidth.
 Integrate both voice and data circuits
 Optimize or eliminate under-utilized circuits.

3.2 NETWORK DESIGN

Network design is the practice of planning and designing a communications network.
Network design starts with identifying business and technical requirements and continues until
just before the network implementation stage (when you actually do the work to deploy and
configure what was designed). Network design includes things like network analysis, IP
addressing, hardware selection, and implementation planning.
In simple networks, like those found in most homes and small offices, network design is a
straightforward process. In large enterprise networks, the network design process is often very
complex and involves multiple stakeholders.

Understanding PPDIOO & other network lifecycle models

Before we dive into how to design a network, let’s take a moment to review network lifecycle
models. In the context of network design, a network lifecycle model helps explain where and
how network design fits into the broader lifespan of your network’s components and overall
structure.
One of the most popular network lifecycle models is Cisco’s PPDIOO (Prepare, Plan, Design,
Implement, Operate and Optimize) model:

 Prepare. This is where you define high-level requirements and strategy. For example, your
deliverables from this phase may include requirements documentation and current state
surveys.
 Plan. This stage deals with specific network requirements based on information gathered in
the planning stages.
 Design. During the design stage, the information gathered from the previous two stages is
used to create a detailed network design.
 Implement. This is where the work gets done to configure and deploy the network
infrastructure. There is often testing to validate the design in this phase.
 Operate. This is the portion of the lifecycle where the network is in production use. During
this stage, monitoring is an important part of validating that the network is working as
designed and being able to quickly address issues when it isn’t.
 Optimize. At some point in most networks’ lifecycle, tweaks and optimizations are needed.
This is the stage where those changes are identified. For major changes, the cycle begins
again to plan and implement them.

Other network lifecycle models include Cisco’s PBM (plan, build, manage) and
the NDLC (network development life cycle). Regardless of which model you choose, the general
steps — information gathering, design, implementation, and improvement — and cyclical nature
are the same. The important takeaway is understanding any network lifecycle and where network
design fits in.
Designing a network step by step
Now that we understand the basics of a network lifecycle model, let’s take a step-by-step look at
the process of designing a network infrastructure. While the specifics of your network design
will vary based on size and complexity, this general framework can help you make the right
decisions.

1. Identify the requirements

Before you begin any network design project, begin by gathering information and developing
clear business and technical requirements. Without clearly defined targets, the rest of the design
falls apart.
Business requirements help define what you need to do. That means things like:

 Support a new office

 Improve end-user experience
 Cut costs
 Comply with a new regulation
 Improve business continuity
Looking back at the PPDIOO lifecycle model, business requirements align with
the prepare stage. You should work closely with stakeholders when identifying business
requirements.
Once you’ve detailed the business requirements, it’s time to move on to the technical/functional
requirements. Example requirements include:

 Bandwidth
 Security requirements
 Specific protocols the project must implement
 RTO/RPO (recovery time objective/recovery point objective) numbers
 Uptime SLAs (service level agreements)
When you create your requirements, don’t overlook constraints. For example, business
requirements will have a budget constraint. Technical requirements may have constraints such as
the need to continue supporting legacy apps.

2. Assess the current state of the network

Chances are, in most networks you’re not starting with a clean slate. Sometimes that’s a good
thing that makes life easier, other times it can complicate a project. For example, if all the
structured cabling is already in place, that’s one less thing to worry about. However, if all that’s
in place is Cat5 cable and you need Cat6A to support 10GBaseT, the existing cabling now
becomes an issue to deal with.
Whatever the state of the network is, it’s important you know early in the design process. You
need to assess the network’s current state before you make any specific design recommendations.
At the end of this step, you should understand the network layout, performance, data flows,
applications & services on the network, network security, and physical and logical layout.
Some of this can be achieved by reviewing existing network diagrams, policies, and monitoring
tools. In other cases, you’ll need to use automatic network mapping tools and security scanners
to get the full picture.

3. Design your network topology

Once you know your requirements and understand the current state of your network, you can
begin blocking out the functional components of your network. During this step, you’ll need to
consider both the physical and logical aspects of your network.
When it comes to physical network design you’ll need to address things like:
 Running copper and fiber cabling
 Number of switch ports required
 WiFi access point positioning
 Rack layout
 Cooling and power

Logical network design deals with things like:

 IP addressing/subnetting
 VLANs
 Data flows
 Network topology

At the end of this step, you should be able to create a static map of the physical and logical
network you’re designing.
Tip: Don’t forget about cloud workloads and cloud networks. Your network design will need to
account for on-premises and cloud data flows.
Before we move on to the next step, let’s take a look at two key network design concepts:
hierarchical network layers and top-down vs bottom-up design.
Hierarchical network design: What are core, distribution, and access layers?
A traditional hierarchical network design is based on the idea of three basic network layers. Each
layer handles a separate portion of the dataflows on a network. Those layers are:

 Core layer. This is the layer that routes traffic between different geographical sites. In
other words, it’s the network backbone. The core layer is where high-throughput,
expensive core routers shine.
 Distribution layer. The distribution layer sits between the core and access layers. It acts
as a boundary and implements network policies to restrict or allow data flows between
different subnets within the network. Less expensive routers and L3 switches are the
common workhorses of the distribution layer.
 Access layer. The access layer is the layer for endpoint devices like user PCs, printers,
and VoIP phones. Smaller “access switches” are responsible for switching packets and
routing traffic at this layer.
In some cases, you may not need all three of these layers. For example, many networks bypass
the distribution layer altogether.

Top-down vs bottom-up design

Top-down and bottom-up are two approaches to network design based on the OSI model. With a
top-down approach, you start designing your network at the application layer and work your way
down the model finishing with the physical layer. The bottom-up design is exactly the opposite.
Top-down is generally considered a better approach when you start with business requirements
and work your way down. However, top-down is also often more time-consuming. Bottom-up
network design starts with the physical aspect of the network and works upwards.
As a result, bottom-up can be quicker but can often lead to missed requirements or compromises
on desired outcomes, as designing a network from the bottom up locks you into certain outcomes
before you get to the application layer where users get work done.

4. Choose the hardware and software

This step entails identifying the hardware and software you’ll use. In some cases, this will
happen in parallel with step 3. In others, some of the hardware or software may be specified
early in the project. As a rule, selecting the specific hardware and software you’ll use after you
know what the network needs to do gives you the most flexibility.
During this stage, you’ll choose specific cables, racks, network devices, servers, applications,
cloud services, etc. to make your design a reality. For custom parts or large orders, keep in mind
potential supply-chain issues. If you can’t get your structured cabling or access switches in time,
you can slow down project completion.

5. Plan for implementation and beyond

With your network design and hardware/software selections ready, you can now plan for the
implementation and beyond. This step entails creating a plan to deploy, configure, and test the
network. In some cases (usually larger networks) this step may include small-scale test
deployments to validate the design works before scaling out.
Tight project management and keeping stakeholders informed are key parts of getting your plan
right. A network deployment has a lot of moving parts and your plan should account for project
milestones, change management, and key deliverables. Additionally, if the network will be
managed by a different team than those doing the implementation, you’ll need a transition plan.
If you’re responsible for network management going forward, developing a plan for how you’ll
monitor and maintain the network is important as well.

Top 5 network design best practices

Now that we have a framework to follow, let’s take a look at some network design best practices
for making better decisions throughout the process.

1. Integrate security early on

There is a reason the idea of “shifting security left” has become so popular in the DevOps
world: it works. By making security a priority from the beginning of the project, you’re less
likely to have gaps in your security posture. You’re also more likely to improve your overall
network performance because security won’t be inefficiently shoehorned in after most decisions
have been made.
Treat security requirements with just as much priority as performance requirements and spec
them into a project early on. Ideally, we should all have a “security is everyone’s responsibility”
mindset, but in practice that isn’t always the case. It’s usually a great idea to have a security-
focused stakeholder(s) involved in the project end-to-end.

2. Know when to use top-down vs bottom-up

In most cases where you’re starting from scratch, top-down design is the “better” choice. By
designing top-down, you focus on the business requirements and maximize your chances of
getting it right.
However, there are many network design projects where the resource and time investment in
going top-down just doesn’t make sense. For example, if you’re already familiar with an
organization’s overall business requirements and simply need to expand a network or increase
bandwidth, bottom-up can be much more efficient.

3. Standardize everything
If it can be standardized, standardize it. It will make troubleshooting, patching, maintenance, and
asset management drastically easier in the long run.
Here are some examples of things you can and should standardize:
 Hostnames (e.g. printer5.office2.lan3)
 Hardware models
 IP address schemes
 Cable colors (e.g. one color for VoIP, one for data, etc)
 Security policies

4. Plan for growth

Network bandwidth consumption today isn’t going to be the same a year from now. You have to
consider how much you expect bandwidth consumption to increase over the lifecycle of the
network, and design with that expectation in mind.
One answer is obvious: just build in additional bandwidth based on your expectations. However,
making sure the network is flexible and modular enough to easily accommodate expansion is
arguably more important. After all, you can’t know for certain what your requirements will be in
the future, but you can design with the idea you may need to extend the network in mind.

5. Create and maintain network documentation

Missing, stale, or incomplete network documentation is a major source of tech debt, wasted time,
and added frustration. Do your future self — or your friendly neighborhood network
administrator — a favor and make sure your network design and implementation deliverables
include layer 1-3 network maps. Then, once they’re created, be sure to maintain them going
forward.

Considerations for designing computer networks

Copper vs fiber, logical topologies, IP addressing, VLANs, bandwidth, and WiFi coverage are
some of the most obvious considerations when you’re designing a network. However, that’s far
from an exhaustive list. There is a lot that goes into designing a network, and it can be easy to
overlook things. Here are some key considerations to keep in mind for your next project.

Regulatory requirements
When you’re designing a network, you need to account for legal regulations that impact both the
physical and logical design of your network. For example, local building codes may impact how
you run structured cabling. Similarly, the National Electrical Code in the US has requirements
relevant to the electrical power your network devices will require. From a logical perspective,
regulations like HIPAA, PCI DSS, and GDPR can impact both data in transit and data at rest.
During the network design process, you’ll need to keep these requirements in mind to build a
compliant network.

Network resilience and redundancy

Because of the importance of network availability to business operations, enterprise networks
need some level of fault tolerance. To make that happen, N+1, 2N, or 2N+1 redundancy (or even
higher) is often part of modern network design.
Of course, resilience and redundancy come with a budgetary cost. Your network design will need
to balance resilience and redundancy against the expense. Reliably achieving five-nines
(99.999% uptime) is great if you can do it, but it ain’t cheap!
A good way to frame this tradeoff is: considering your cost of downtime (i.e. how many dollars
per minute/hour will you lose if the network goes down) and balancing that against your
exposure to downtime with your current redundancy plan.

Cloud vs. On-prem

It’s no longer a given that on-premises are the best place to run a given workload. Once you have
your business and technical requirements, you should carefully consider whether or not a cloud
network makes sense as a solution. We won’t rehash the entire cloud vs on-prem debate here, but
make sure you don’t lock yourself into an on-premises solution when the cloud may be a better
fit (or vice versa!).

Cooling and power

It can be easy to overlook the cooling and power requirements of a network. Don’t make this
mistake! If you can’t meet your power requirements, you’ll never get your deployment off the
ground. If you don’t account for all the heat dissipation of your new network equipment, devices
can overheat and prematurely fail. Here are a few points to consider about power and cooling:
  Make sure your electrical panels and electrical outlets can accommodate your new
equipment.
 Make sure to account for power-over-Ethernet (PoE) loads when sizing UPS (battery
backups) and other power equipment.
 Make sure your server room cooling can handle the additional heat generated by your
new network gear or plan to invest in supplemental cooling.
There’s no one size fits all network design. With the right approach, however, you can create a
design that matches your business requirements. Of course, as network lifecycle models like
PPDIOO demonstrate, it doesn’t stop after the design stage!

3.4 NETWORK TOPOLOGY AND ACCESS METHOD

A network topology is the physical and logical arrangement of nodes and connections in a
network. Nodes usually include devices such as switches, routers and software with switch and
router features. Network topologies are often represented as a graph.

Network topologies describe the arrangement of networks and the relative location of traffic
flows. Administrators can use network topology diagrams to determine the best placements for
each node and the optimal path for traffic flow. With a well-defined and planned-out network
topology, an organization can more easily locate faults and fix issues, improving its data transfer
efficiency.

Network geometry can be defined as the physical topology and the logical topology. Network
topology diagrams are shown with devices depicted as network nodes and the connections
between them as lines. The type of network topology differs depending on how the network
needs to be arranged.

 Bus network. In the bus network topology, every node is connected in series along a single
cable. This arrangement is found today primarily in cable broadband distribution networks.

 Star network. In the star network topology, a central device connects to all other nodes
through a central hub. Switches local area networks based on Ethernet switches and most
wired home and office networks have a physical star topology.

 Ring network. In the ring network topology, the nodes are connected in a closed-
loop configuration. Some rings pass data in one direction only, while others are capable of
transmission in both directions. These bidirectional ring networks are more resilient than bus
 networks since traffic can reach a node by moving in either direction. Metro networks based
on Synchronous Optical Network technology are the primary example of ring networks.

 Mesh network. The mesh network topology links nodes with connections so that multiple
paths between at least some points of the network are available. A network is considered to
be fully meshed if all nodes are directly connected to all other nodes and partially meshed if
only some nodes have multiple connections to others. Meshing multiple paths increases
resiliency but also increases cost. However, more space is needed for dedicated links.

 Tree network. The tree network topology consists of one root node, and all other nodes are
connected in a hierarchy. The topology itself is connected in a star configuration. Many
larger Ethernet switch networks, hincluding data center networks, are configured as trees.

 Hybrid network. The hybrid network topology is any combination of two or more
topologies. Hybrid topologies typically provide exceptional flexibility, as they can
accommodate a number of setups. For example, different departments in the same
organization may opt for personalized network topologies that are more adaptable to their
network needs.

Bus Topology

 The bus topology is designed in such a way that all the stations are connected through a
single cable known as a backbone cable.
 Each node is either connected to the backbone cable by drop cable or directly connected
to the backbone cable.
  When a node wants to send a message over the network, it puts a message over the
network. All the stations available in the network will receive the message whether it has
been addressed or not.
 The bus topology is mainly used in 802.3 (ethernet) and 802.4 standard networks.
 The configuration of a bus topology is quite simpler as compared to other topologies.
 The backbone cable is considered as a "single lane" through which the message is
broadcast to all the stations.
 The most common access method of the bus topologies is CSMA (Carrier Sense Multiple
Access).

CSMA: It is a media access control used to control the data flow so that data integrity is
maintained, i.e., the packets do not get lost. There are two alternative ways of handling the
problems that occur when two nodes send the messages simultaneously.
 CSMA CD: CSMA CD (Collision detection) is an access method used to detect the
collision. Once the collision is detected, the sender will stop transmitting the data.
Therefore, it works on "recovery after the collision".
 CSMA CA: CSMA CA (Collision Avoidance) is an access method used to avoid the
collision by checking whether the transmission media is busy or not. If busy, then the
sender waits until the media becomes idle. This technique effectively reduces the
possibility of the collision. It does not work on "recovery after the collision".

Advantages of Bus topology:

 Low-cost cable: In bus topology, nodes are directly connected to the cable without
passing through a hub. Therefore, the initial cost of installation is low.
 Moderate data speeds: Coaxial or twisted pair cables are mainly used in bus-based
networks that support upto 10 Mbps.
 Familiar technology: Bus topology is a familiar technology as the installation and
troubleshooting techniques are well known, and hardware components are easily
available.
 Limited failure: A failure in one node will not have any effect on other nodes.

Disadvantages of Bus topology:

 Extensive cabling: A bus topology is quite simpler, but still it requires a lot of cabling.
  Difficult troubleshooting: It requires specialized test equipment to determine the cable
faults. If any fault occurs in the cable, then it would disrupt the communication for all the
nodes.

 Signal interference: If two nodes send the messages simultaneously, then the signals of
both the nodes collide with each other.

 Reconfiguration difficult: Adding new devices to the network would slow down the
network.

 Attenuation: Attenuation is a loss of signal leads to communication issues. Repeaters are

used to regenerate the signal.

Ring Topology

 Ring topology is like a bus topology, but with connected ends.

 The node that receives the message from the previous computer will retransmit to the
next node.

 The data flows in one direction, i.e., it is unidirectional.

 The data flows in a single loop continuously known as an endless loop.

 It has no terminated ends, i.e., each node is connected to other node and having no
termination point.

 The data in a ring topology flow in a clockwise direction.

 The most common access method of the ring topology is token passing.

 Token passing: It is a network access method in which token is passed from one
node to another node.
  Token: It is a frame that circulates around the network.
Star Topology

 Star topology is an arrangement of the network in which every node is connected to the
central hub, switch or a central computer.
 The central computer is known as a server, and the peripheral devices attached to the
server are known as clients.
 Coaxial cable or RJ-45 cables are used to connect the computers.
 Hubs or Switches are mainly used as connection devices in a physical star topology.
 Star topology is the most popular topology in network implementation.

Advantages of Star topology

 Efficient troubleshooting: Troubleshooting is quite efficient in a star topology as
compared to bus topology. In a bus topology, the manager has to inspect the kilometers
of cable. In a star topology, all the stations are connected to the centralized network.
Therefore, the network administrator has to go to the single station to troubleshoot the
problem.
 Network control: Complex network control features can be easily implemented in the
star topology. Any changes made in the star topology are automatically accommodated.
 Limited failure: As each station is connected to the central hub with its own cable,
therefore failure in one cable will not affect the entire network.
 Familiar technology: Star topology is a familiar technology as its tools are cost-
effective.
  Easily expandable: It is easily expandable as new stations can be added to the open ports
on the hub.
 Cost effective: Star topology networks are cost-effective as it uses inexpensive coaxial
cable.
 High data speeds: It supports a bandwidth of approx 100Mbps. Ethernet 100BaseT is
one of the most popular Star topology networks.

Disadvantages of Star topology

 A Central point of failure: If the central hub or switch goes down, then all the
connected nodes will not be able to communicate with each other.
 Cable: Sometimes cable routing becomes difficult when a significant amount of routing
is required.

Tree topology

 Tree topology combines the characteristics of bus topology and star topology.
 A tree topology is a type of structure in which all the computers are connected with each
other in hierarchical fashion.
 The top-most node in tree topology is known as a root node, and all other nodes are the
descendants of the root node.
 There is only one path exists between two nodes for the data transmission. Thus, it forms
a parent-child hierarchy.
 THE DIFFERENT TYPES OF NETWORK CONNECTIONS

4.1 POINT-TO-POINT
The point-to-point scheme provides separate communication channels for each pair of
computers. When more than two computers need to communicate with one another, the number
of connections grows very quickly as number of computer increases. Above figure illustrates that
two computers need only one connection, three computers need three connections and four
computers need six connections. Point-to-point Connections

The point-to-point scheme provides separate communication channels for each pair of
computers. When more than two computers need to communicate with one another, the number
of connections grows very quickly as number of computer increases. Above figure illustrates that
two computers need only one connection, three computers need three connections and four
computers need six connections.

As the Figure illustrates that the total number of connection grows more rapidly than the total
number of computers. Mathematically, the number of connection needed for N computers is
proportional to the square of N.
Point-to-point connections required = (N2 (N)/2.
Adding the Nth computer requires N·l new connections which becomes a very expensive option.
Moreover, many connections may follow the same physical path. Figure shows a point- to-point
connection for five computers located at two different locations, say, ground and first floor of a
building.
 Point-to-point coneection of Five PC

As there are five PCs, total ten connections will be required for point-to-point connection. Out of
these ten connections six are passing through the same locution and thereby making point-to-
point connection an expensive one. Increasing the PC by one in the above configuration at
location 2 as shown in Figure will increase the total number of connections to fifteen. Out ‘of
these connections eight connections will pass through the same area.

Point to Point Network Topology: In a point-to-point architecture, two nodes (for example,
PCs) in a network communicate directly to each other via a LAN cable or other data transmission
medium. This is the most straightforward and cost-effective method of establishing a computer
network. Because the underlying network is only used by two parties, the connecting link’s
whole capacity is reserved for the two nodes. The network can only have two nodes, which is a
significant disadvantage.
Point to point topology is a method of linking two nodes (a computer, a laptop, a mobile device,
a router, a hub, or a switch) via a common media. A wired cable or a wireless satellite can be
used as the medium. Two nodes are frequently placed near each other in this architecture. A
router or hub can also be a node. A single connection is created between a computer and a router,
hub, or switch in the case of a router or hub.
Simplex, half-duplex, or full-duplex communication between two nodes is possible. Only one
node can transfer data in the simplex form of communication. Both devices (nodes) can
communicate data in half-duplex mode, but only one at a time. Both devices can communicate
data at the same time in full-duplex mode. Microwave, dedicated fibre, or leased line can all be
used to build a connection.
The remote control of the air conditioner in the home is one of the most basic instances. When a
point-to-point connection is used between two points, it is called a point-to-point connection.

Point-to-point network connection utilizing a protocol:

Other networks such as WAN or satellite lines use point-to-point topologies as well. Although
the endpoints (placed at different locations) do not link via a direct cable in WAN, they do
establish a direct tunnel between them. In a conventional WAN, the two distant routers use a
point-to-point protocol to create a tunnel (PPP). According to the OSI model, the connection
operates at the data link layer. Frames are transported directly from source to destination.

Examples of a point-to-point topology:

The link between the TV and the remote control
The link between the air conditioner and the remote control
A LAN (local area network) is a network that connects two computers.
A router’s connection to another router
A router’s and a workstation’s connection.

Point to Point topology advantages and disadvantages:

Following are the advantage and disadvantage of Point to Point topology.
Advantages of Point to Point Topology:
1. Very simple to maintain: if a wire breaks, you can replace it in a matter of seconds.
2. Maximum bandwidth usage of the underlying connected connection
3. In comparison to any other network topology type, this is the simplest.
4. When compared to any other network connection type, there is the least amount of
communication delay.
5. When you simply need to connect two nodes, this is a low-cost solution.
Disadvantages of Point to Point Topology:
1. The network’s performance is solely dependent on a single link. The entire network will stop
working if the common connection goes down.
2. Because a direct connection is required, topology cannot be spread to a vast area. Two
computers, for example, may be far apart if they are in a multistory structure.
3. Because there is just one server or client, if one fails, the entire system will stop working.
The network cluster is not available to you. Any database server will suffer as a result of this.
4. Only when the two devices are close to each other, such as when connecting a printer, is this
method applicable.

4.2 PEER-TO-PEER
In its simplest form, a peer-to-peer (P2P) network is created when two or more PCs are
connected and share resources without going through a separate server computer. A P2P network
can be an ad hoc connection—a couple of computers connected via a Universal Serial Bus to
transfer files. A P2P network also can be a permanent infrastructure that links a half-dozen
computers in a small office over copper wires. Or a P2P network can be a network on a much
grander scale in which special protocols and applications set up direct relationships among users
over the Internet.
The initial use of P2P networks in business followed the deployment in the early 1980s of free-
standing PCs. In contrast to the minimainframes of the day, such as the VS system from Wang
Laboratories Inc., which served up word processing and other applications to dumb terminals
from a central computer and stored files on a central hard drive, the then-new PCs had self-
contained hard drives and built-in CPUs. The smart boxes also had onboard applications, which
meant they could be deployed to desktops and be useful without an umbilical cord linking them
to a mainframe.

Advantages of Peer to Peer Network

1. Cost: The overall cost of building and maintaining a peer to peer network is relatively
inexpensive. The setup cost has been greatly reduced due to the fact that there is no central
 configuration. Moreover for the windows server, there is no payment required for each of the
users on the network. The payment should be done only once.
2. Reliability: Peer to Peer network is not dependent on a centralized system. Which means
that the connected computers can function independently with each other? Even if one part of
the network fails, it will not disrupt other parts. Only the user will not be able to access those
files
3. Implementation: It is generally easy to setup a peer to peer network requiring no advanced
knowledge. Only a hub or a switch is needed for the connection. And also since all the
connected computers can manage themselves, there should be no much configurations.
However it needs some specialized software.
4. Scalability: P2P networking has one of the best scalability features. Even if there are extra
clients added, the performance of the network will remain the same. Sometimes more users
tends to share a single file. For this case, the network will increase the availability of
bandwidth.
5. Administration: There is no need for any specialized network administrator since all the
users are given the right to manage their own system. They can choose what type of files they
are willing to share.
6. Server Requirement: In peer to peer networking, each connected computers acts as a server
and a workstation. Therefore, there is no need to use a dedicated server. All the authorized
users can use their respective client computer to access the required files. This can lead to
saving more overhead costs.
7. Resource Sharing: In P2P networking, the resources are shared equally among all the users.
The connected devices can provide and consume resources at the same time. And also this
peer to peer networking can be used for locating and downloading online files easily.
8. Highest Bandwidth because there is only two nodes having entire bandwidth of a link
9. Very fast compared to other network topologies because it can access only two nodes.
10. Very simple connectivity
11. It provides low Latency
12. Easy to handle and maintain
13. Node Can be Replaced in few seconds

Disadvantages of Peer to Peer Networking

1. Decentralization: Peer to Peer networking lacks the feature of centralization. There is no

central server, thus files are stored on individual machines. The entire network accessibility
 is not in the hands of a single person. This makes it more challenging for the users to locate
and find files. If the search is done through each database, the users could waste a lot of
time.
2. Performance: Performance is another issue faced by a peer to peer network. Once the
number of devices connecting the network increases, there will be a performance degrade
since each computer is being accessed by other users. Hence, P2P network doesn't work well
with growing networks.
3. Security: Security for individual files are comparatively less in peer to peer networking.
There is no security other than assigning permissions. Even if the permissions are assigned,
any person with the access to it will be able to log on. Some users don't even require to log
on from their respective workstation.
4. Remote Access: In some cases, there can be unsecured types of codes present on a
particular terminal. If this is the case, there are possibilities where files on a network will be
accessed by remote users without proper permissions. This can lead to a compromised
network.
5. Backup Recovery: Backup is made way difficult in P2P networks, since the data is not
centralized. It is saved on various systems. Therefore, backup needs to be done separately on
each computer. Or else there should be a backup system for every computer.
6. Virus Attacks: Peer to peer networks are more prone to malware and virus attacks since
each connected computers are independent to each other. If one of the computers tends to get
virus infected, it could easily spread to the remaining computers even if they are protected
through an antivirus or a firewall software. Therefore, it is the responsibility of each user to
make sure that their system is protected against viruses.
7. Illegal Content: Most often peer to peer networks are used to transfer copyrighted contents
like movies and music by implementing into torrents. Due to this there is a possibility of
internet ban, notice from content writers or even arrest. That is the reason why P2P networks
are less preferred among some companies and service providers.
8. This topology is only used for small areas where nodes are closely located.
9. The entire network depends on the common channel in case of link broken entire network
will become dead.
10. There is another major drawback of this topology there are only two nodes if any of the node
stops working, data cannot be transfer across the network.
4.3 Client server

Client-server is a relationship in which one program, the client, requests a service or resource
from another program, the server. The label client-server was previously used to distinguish
distributed computing by PCs from the monolithic, centralized computing model used by
mainframes.

Today, computer transactions in which the server fulfills a request made by a client are very
common. The client-server model has become one of the central ideas of network computing. In
this context, the client establishes a connection to the server over a LAN or WAN, such as the
internet.

Once the server fulfils the client's request, the connection terminates. Because multiple client
programs share the services of the same server program, a special server called a daemon might
activate to await client requests.

In the early days of the internet, most network traffic traveled through what is known as north-
south traffic. This is when data moves between remote clients that request web content and data
center servers that provide the content. Today, with the maturity of virtualization and cloud
computing, network traffic is more likely to flow server-to-server -- a pattern known as east-west
traffic.

Advantages of Client Server Network

1. Centralization: The main advantage of client server network is the centralized control that it
is integrated with. All the necessary informations are placed in a single location. This is
especially beneficial for the network administrator since they have the full control over
management and administration. Whatever the problem that occurs in the entire network can
be solved in one place. And also due to this, the work of updating resources and data has
become way more easier.
2. Security: In client server network, the data is well protected due to its centralized
architecture. It can be enforced with access controls such that only authorized users are
granted access. One such method is imposing credentials like username and password.
Moreover if the data were to be lost, the files can be easily recovered from a single backup.
3. Scalability: Client server networks are highly scalable. Whenever the user needs they can
increase the number of resources such as clients and servers. Thus, increasing the size of the
 server without much interruptions. Even if the size gets increased, there is no hesitation about
permission to network resources since the server is centralized. Therefore, very less number
of staffs are required for the configurations.
4. Management: Since all the files are stored in the central server, it is rather easy to manage
files. In client server network has the best management to track and find records of required
files.
5. Accessibility: Irrespective of the location or the platform, every client is provided with the
opportunity to log into the system. By this way all the employees will be able to access their
corporate informations without needing to use a terminal mode or a processor.

Disadvantages of Client Server Network

1. Traffic Congestion: The primary disadvantage of client server network is the traffic
congestion it undergoes. If too many clients make request from the same server, it will result
in crashes or slowing down of the connection. An overloaded server creates many problems
in accessing information.
2. Robustness: As we all know client server networks are centralized. In case if the main server
happens to undergo failure or interference, then the whole network will be disrupted.
Therefore, client server networks lacks on the side of robustness.
3. Cost: The cost involved in setting up and maintaining the server is usually high in client
server network as it does on the network operations. Since the networks are powerful they
can be expensive to purchase. Hence, not all the users will be able to afford them.
4. Maintenance: When the servers are implemented, it is going to work non-stop. Which
means it must be given proper attention. If there are any problems, it must be resolved
immediately without any delay. Hence, there should be a specialized network manager
appointed to maintain the server.
5. Resources: Not all the resources that is present on the server is acquirable. For an example, it
is not possible to print a document on the web directly or edit any informations on the client
hard disk drive.
 OPEN SYSTEMS INTERCONNECTION (OSI) MODEL AND TCP/IP

5.1 CHARACTERISTICS OF OSI MODEL

There are two layers in the OSI model: upper layers and lower layers.
The OSI model’s upper layer mostly deals with application-related difficulties and is only
implemented via software. The application layer is the one that is closest to the user. The
software application is interacted with by both the end user and the application layer. The layer
directly above the other is referred to as an upper layer.
The OSI model’s bottom layer deals with data transit difficulties. Hardware and software are
used to implement the data link and physical layers. The physical layer is the OSI model’s lowest
layer, and it’s the one nearest to the physical media. The physical layer is primarily in charge of
retaining data on the physical medi

5.2 TCP/IP REFERENCE MODEL

TCP/IP Reference Model is a four-layered suite of communication protocols. It was developed
by the DoD (Department of Defence) in the 1960s. It is named after the two main protocols that
are used in the model, namely, TCP and IP. TCP stands for Transmission Control Protocol and
IP stands for Internet Protocol.
The four layers in the TCP/IP protocol suite are −
 Host-to- Network Layer −It is the lowest layer that is concerned with the physical
transmission of data. TCP/IP does not specifically define any protocol here but supports
all the standard protocols.
 Internet Layer −It defines the protocols for logical transmission of data over the
network. The main protocol in this layer is Internet Protocol (IP) and it is supported by the
protocols ICMP, IGMP, RARP, and ARP.
  Transport Layer − It is responsible for error-free end-to-end delivery of data. The
protocols defined here are Transmission Control Protocol (TCP) and User Datagram
Protocol (UDP).
 Application Layer − This is the topmost layer and defines the interface of host programs
with the transport layer services. This layer includes all high-level protocols like Telnet,
DNS, HTTP, FTP, SMTP, etc.
The following diagram shows the layers and the protocols in each of the layers −

5.3 DIFFERENCES AND SIMILARITIES BETWEEN TCP/IP AND OSI MODEL

The difference between TCP/IP and OSI Model seems to be minor but by composition, features,
functions and purpose, the two are extremely different. The difference between the two terms is
also important from the IAS Exam perspective.
The TCP/IP or the Transmission Control Protocol/ Internet Protocol is a communication
protocols suite using which network devices can be connected to the Internet. On the other hand,
the Open Systems Interconnection or OSI Model is a conceptual framework, using which the
functioning of a network can be described.
Given below is a tabulated differences/comparison between the two models of networking, the
TCP/IP and OSI model.

Difference between TCP/IP and OSI Model

TCP/IP OSI Model

The full form of TCP/IP is Transmission The full form of OSI is Open Systems
Control Protocol/ Internet Protocol. Interconnection.
It is a communication protocol that is based It is a structured model which deals which the
on standard protocols and allows the functioning of a network.
connection of hosts over a network.

The most widely used communications The OSI model is a conceptual model that
protocol, TCP/IP prepares and forward data characterizes and standardizes the
packets over a network. communication functions of a computing
system

In 1982, the TCP/IP model became the In 1984, the OSI model was introduced by the
standard language of ARPANET. International Organisation of Standardization
(ISO).

It comprises of four layers: It comprises seven layers:

 Network Interface  Physical

 Internet  Data Link
 Transport  Network
 Application  Transport
 Session
 Presentation
 Application

It follows a horizontal approach. It follows a vertical approach.

The TCP/IP is the implementation of the OSI An OSI Model is a reference model, based on
Model. which a network is created.

It is protocol dependent. It is protocol independent.

It is developed by ARPANET (Advanced It is developed by ISO (International Standard

Research Project Agency Network). Organization)

TCP/IP doesn’t have any clear distinguishing OSI model provides a clear distinction between
points between services, interfaces, and interfaces, services, and protocols.
protocols

TCP refers to Transmission Control Protocol. OSI refers to Open Systems Interconnection.
 OSI uses the network layer to define routing
TCP/IP uses only the Internet layer.
standards and protocols.

TCP/IP follows a horizontal approach. OSI follows a vertical approach.

TCP/IP has four layers. OSI layers have seven layers.

A layer of the TCP/IP model is both In the OSI model, the transport layer is only
connection-oriented and connectionless. connection-oriented.

In TCP, physical and data link are both In the OSI model, the data link layer and
combined as a single host-to-network layer. physical are separate layers.

There is no session and presentation layer in Session and presentation layers are a part of the
the TCP model. OSI model.

It is defined before the advent of the internet. It is defined after the advent of the Internet.

The minimum header size is 20 bytes. The minimum size of the OSI header is 5 bytes.

The above points of comparison display the difference between the TCP/IP and OSI models
efficiently.

However, there are few similarities between the two which are as mentioned below –

Similarities between the TCP/IP and OSI models

 Both the models are based upon layered structuring.

 In both models, data are mainly used to convert raw data into packets and help them
reach their destination node.
 In both models, protocols are defined in a layer-wise manner.
 The layers in the models are compared with each other. The physical layer and the data
link layer of the OSI model correspond to the link layer of the TCP/IP model.
 The session layer, the presentation layer and the application layer of the OSI model
together form the application layer of the TCP/IP model.
 The network layers and the transport layers are the same in both models.
The OSI Model we just looked at is just a reference/logical model. It was designed to describe
the functions of the communication system by dividing the communication procedure into
smaller and simpler components.

TCP/IP was designed and developed by the Department of Defense (DoD) in the 1960s and is
based on standard protocols. It stands for Transmission Control Protocol/Internet Protocol.
The TCP/IP model is a concise version of the OSI model. It contains four layers, unlike the
seven layers in the OSI model.
The number of layers is sometimes referred to as five or four. Here In this article, we’ll study
five layers. The Physical Layer and Data Link Layer are referred to as one single layer as the
‘Physical Layer’ or ‘Network Interface Layer’ in the 4-layer reference.
Functions of OSI Layers:
The OSI model comprises seven layers. Each layer has a distinct purpose. Below is a list of the
seven layers:
1. Physical Layer
2. Data-Link Layer
3. Network Layer
4. Transport Layer
5. Session Layer
6. Presentation Layer
7. Application Layer
 UNDERSTANDING IP ADDRESS IN NEW NETWORKS USING IPV4 AND IPV6

6.1 THE CONCEPT OF IP ADDRESSING AND TYPES

An IP address represents an Internet Protocol address. A unique address that identifies the
device over the network. It is almost like a set of rules governing the structure of data sent over
the Internet or through a local network. An IP address helps the Internet to distinguish between
different routers, computers, and websites. It serves as a specific machine identifier in a
specific network and helps to improve visual communication between source and destination.

IP address structure: IP addresses are displayed as a set of four digits- the default address
may be 192.158.1.38. Each number on the set may range from 0 to 255. Therefore, the total IP
address range ranges from 0.0.0.0 to 255.255.255.255.
IP address is basically divided into two parts: X1. X2. X3. X4
1. [X1. X2. X3] is the Network ID
2. [X4] is the Host ID

1. Network ID–
It is the part of the left-hand IP address that identifies the specific network where the
device is located. In the normal home network, where the device has an IP address
192.168.1.32, the 192.168.1 part of the address will be the network ID. It is customary to
fill in the last part that is not zero, so we can say that the device’s network ID is
192.168.1.0.
2. Hosting ID–
The host ID is part of the IP address that was not taken by the network ID. Identifies a
specific device (in the TCP / IP world, we call devices “host”) in that network. Continuing
with our example of the IP address 192.168.1.32, the host ID will be 32- the unique host ID
on the 192.168.1.0 network.

Versions of IP Address
1. IPV4 (Internet Protocol Version 4): It is the first version of Internet Protocol address.
The address size of IPV4 is 32 bit number. In this Internet Protocol Security (IPSec) with
respect to network security is optional. It is having 4,294,967,296 number of address still
we are seeing a shortage in network addresses as the use of network & virtual devices are
increasing rapidly.
2. IPV6 (Internet Protocol Version 6): It is the recent version of Internet Protocol address.
The address size of IPV6 is 128 bit number. In this Internet Protocol Security (IPSec) with
respect to network security is mandatory. It allows 3.4 x 10^38 unique IP addresses which
seems to be more than sufficient to support trillions of internet devices present now or
coming in future.

IP Address Types:
There are 4 types of IP Addresses- Public, Private, Fixed, and Dynamic. Among them, public
and private addresses are derived from their local network location, which should be used
within the network while public IP is used offline.
1. Public IP address–
A public IP address is an Internet Protocol address, encrypted by various servers/devices.
That’s when you connect these devices with your internet connection. This is the same IP
address we show on our homepage. So why the second page? Well, not all people speak the
IP language. We want to make it as easy as possible for everyone to get the information
they need. Some even call this their external IP address. A public Internet Protocol address
is an Internet Protocol address accessed over the Internet. Like the postal address used to
deliver mail to your home, the public Internet Protocol address is a different international
Internet Protocol address assigned to a computer device. The web server, email server, and
any server device that has direct access to the Internet are those who will enter the public
Internet Protocol address. Internet Address Protocol is unique worldwide and is only
supplied with a unique device.
2. Private IP address–
Everything that connects to your Internet network has a private IP address. This includes
computers, smartphones, and tablets but also any Bluetooth-enabled devices such as
speakers, printers, or smart TVs. With the growing internet of things, the number of private
IP addresses you have at home is likely to increase. Your router needs a way to identify
these things separately, and most things need a way to get to know each other. Therefore,
your router generates private IP addresses that are unique identifiers for each device that
separates the network.
3. Static IP Address–
A static IP address is an invalid IP address. Conversely, a dynamic IP address will be
provided by the Dynamic Host Configuration Protocol (DHCP) server, which can change.
The Static IP address does not change but can be changed as part of normal network
 management.
Static IP addresses are incompatible, given once, remain the same over the years. This type
of IP also helps you get more information about the device.
4. Dynamic IP address–
It means constant change. A dynamic IP address changes from time to time and is not
always the same. If you have a live cable or DSL service, you may have a strong IP
address. Internet Service Providers provide customers with dynamic IP addresses because
they are too expensive. Instead of one permanent IP address, your IP address is taken out of
the address pool and assigned to you. After a few days, weeks, or sometimes even months,
that number is returned to the lake and given a new number. Most ISPs will not provide a
static IP address to customers who live there and when they do, they are usually more
expensive. Dynamic IP addresses are annoying, but with the right software, you can
navigate easily and for free.

Types of Website IP address:

Website IP address is of two types- Dedicated IP Address and Shared IP Address. Let us
discuss the two.
1. Dedicated IP address–
A dedicated IP address is one that is unique for each website. This address is not used by
any other domain. A dedicated IP address is beneficial in many ways. It provides increased
speed when the traffic load is high and brings in increased security. But dedicated IPs are
costly as compared to shared IPs.
2. Shared IP address–
A shared IP address is one that is not unique. It is shared between multiple domains. A
shared IP address is enough for most users because common configurations don’t require a
dedicated IP.

IP Address Classification Based on Operational Characteristics:

According to operational characteristics, IP address is classified as follows:
1. Broadcast addressing–
The term ‘Broadcast’ means to transmit audio or video over a network. A broadcast packet
is sent to all users of a local network at once. They do not have to be explicitly named as
recipients. The users of a network can open the data packets and then interpret the
 information, carry out the instructions or discard it. This service is available in IPv4. The
IP address commonly used for broadcasting is 255.255.255.255
2. Unicast addressing–
This address identifies a unique node on the network. Unicast is nothing but one-to-one
data transmission from one point in the network to another. It is the most common form of
IP addressing. This method can be used for both sending and receiving data. It is available
in IPv4 and IPv6.
3. Multicast IP addresses–
These IP addresses mainly help to establish one-to-many communication. Multicast IP
routing protocols are used to distribute data to multiple recipients. The class D addresses
(224.0.0.0 to 239.255.255.255) define the multicast group.
4. Anycast addressing–
In anycast addressing the data, a packet is not transmitted to all the receivers on the
network. When a data packet is allocated to an anycast address, it is delivered to the closest
interface that has this anycast address.

6.2 INTERNET PROTOCOL VERSION 4

Meaning of Internet Protocol Version 4
Internet Protocol Version 4 (IPv4) is the fourth revision of the Internet Protocol and a widely
used protocol in data communication over different kinds of networks. IPv4 is a connectionless
protocol used in packet-switched layer networks, such as Ethernet. It provides the logical
connection between network devices by providing identification for each device. There are many
ways to configure IPv4 with all kinds of devices – including manual and automatic
configurations – depending on the network type.
IPv4 is based on the best-effort model. This model guarantees neither delivery nor avoidance of
duplicate delivery; these aspects are handled by the upper layer transport.
IPv4 is defined and specified in IETF publication RFC 791. It is used in the packet-switched link
layer in the OSI model.
IPv4 uses 32-bit addresses for Ethernet communication in five classes: A, B, C, D and E. Classes
A, B and C have a different bit length for addressing the network host. Class D addresses are
reserved for multicasting, while class E addresses are reserved for future use.
Class A has subnet mask 255.0.0.0 or /8, B has subnet mask 255.255.0.0 or /16 and class C has
subnet mask 255.255.255.0 or /24. For example, with a /16 subnet mask, the network
192.168.0.0 may use the address range of 192.168.0.0 to 192.168.255.255. Network hosts can
take any address from this range; however, address 192.168.255.255 is reserved for broadcast
within the network. The maximum number of host addresses IPv4 can assign to end users is 232.
IPv6 presents a standardized solution to overcome IPv4’s limiations. Because of its 128-bit
address length, it can define up to 2,128 addresses.

6.3 Classes and Range of IP addresses

IP Header Classes:

Class Address Subnet Example IP Leading bits Max number Application

Range masking of networks
IP Class A 1 to 126 255.0.0.0 1.1.1.1 8 128 Used for large
number of
hosts.
IP Class B 128 to 191 255.255.0.0 128.1.1.1 16 16384 Used for
medium size
network.
IP Class C 192 to 223 255.255.255.0 192.1.11. 24 2097157 Used for
local area
network.
IP Class D 224 to 239 NA NA NA NA Reserve for
multi-
tasking.
IP Class E 240 to 254 NA NA NA NA This class is
reserved for
research and
Development
Purposes.
Here, classes A, B, C offers addresses for networks of three distinct network sizes. Class D is
only used for multicast, and class E reserved exclusively for experimental purposes.
Let’s see each of the network classes in detail:

Class A Network
This IP address class is used when there are a large number of hosts. In a Class A type of
network, the first 8 bits (also called the first octet) identify the network, and the remaining have
24 bits for the host into that network.
An example of a Class A address is 102.168.212.226. Here, “102” helps you identify the network
and 168.212.226 identify the host.
Class A addresses 127.0.0.0 to 127.255.255.255 cannot be used and is reserved for loopback and
diagnostic functions.

Class B Network
In a B class IP address, the binary addresses start with 10. In this IP address, the class decimal
number that can be between 128 to 191. The number 127 is reserved for loopback, which is used
for internal testing on the local machine. The first 16 bits (known as two octets) help you identify
the network. The other remaining 16 bits indicate the host within the network.
An example of Class B IP address is 168.212.226.204, where *168 212* identifies the network
and *226.204* helps you identify the Hut network host.

Class C Network
Class C is a type of IP address that is used for the small network. In this class, three octets are
used to indent the network. This IP ranges between 192 to 223.
In this type of network addressing method, the first two bits are set to be 1, and the third bit is set
to 0, which makes the first 24 bits of the address them and the remaining bit as the host address.
Mostly local area network used Class C IP address to connect with the network.
Example for a Class C IP address:
192.168.178.1

Class D Network
Class D addresses are only used for multicasting applications. Class D is never used for regular
networking operations. This class addresses the first three bits set to “1” and their fourth bit set to
use for “0”. Class D addresses are 32-bit network addresses. All the values within the range are
used to identify multicast groups uniquely.
Therefore, there is no requirement to extract the host address from the IP address, so Class D
does not have any subnet mask.
Example for a Class D IP address:
227.21.6.173

Class E Network
Class E IP address is defined by including the starting four network address bits as 1, which
allows you two to incorporate addresses from 240.0.0.0 to 255.255.255.255. However, E class is
reserved, and its usage is never defined. Therefore, many network implementations discard these
addresses as undefined or illegal.
Example for a Class E IP address:
243.164.89.28
Limitations of classful IP addressing
Here are the drawbacks/ cons of the classful IP addressing method:

 Risk of running out of address space soon

 Class boundaries did not encourage efficient allocation of address spa

6.4 VLSM/SUBNETTING IPV4

Variable Length Subnet Mask (VLSM) is a subnet -- a segmented piece of a larger network --
design strategy where all subnet masks can have varying sizes. This process of "subnetting
subnets" enables network engineers to use multiple masks for different subnets of a single class
A, B or C network.

With VLSM, an IP address space can be divided into a well-defined hierarchy of subnets with
different sizes. This helps enhance the usability of subnets because subnets can include masks of
varying sizes.
A subnet mask helps define the size of the subnet and create subnets with very
different host counts without wasting large numbers of addresses.

VLSM fundamentals

To fully understand VLSM, it's important to be familiar with several fundamental terms: subnet
mask, subnetting and supernetting.

Subnet mask

Every device on a network has an IP address. A subnet mask splits this IP address into the host
and network addresses. This helps define which part of the IP address belongs to the network,
and which part belongs to the device.
The subnet mask is a 32-bit number, where all the host bits are set to 0, and the network bits are
set to 1. So, the subnet mask consists of a sequence of 1s followed by a block of 0s, where the 1s
represent the network prefix and the 0s mark the host identifier.
Subnetting
In subnetting (or subnetworking), a large network is logically or physically divided into multiple
small networks or "subnets." The reason for subnetting a large network is to address network
congestion and its negative impact on speed and productivity.
Subnetting also improves efficiency due to the way an address space is utilized in a small
network. Finally, the divisions between subnets allow organizations to enforce access controls,
which improves network security, and helps contain security incidents.

6.5 IPV6 (INTERNET PROTOCOL VERSION 6)

IPv6 is the newest version of internet protocol formulated by the Internet Engineering Task
Force (IETF), which helps identify and local endpoint systems on a computer network and route
online traffic while addressing the problem of IPv4 address depletion due to prolonged internet
use worldwide.

Internet protocol version 6 (IPv6) is a network layer protocol that allows communication to take
place over the network. Each device on the internet has a unique IP address used to identify it
and figure out where it is. At the time of the digital revolution of the 1990s, it became apparent
that the IP addresses that Internet Protocol version 4 (IPv4) used to connect devices would not be
enough to meet demand.

Therefore, the IETF set on developing the next-generation internet protocol. IPv6 became a draft
standard for the IETF in December 1998, and on July 14, 2017, it was approved as an internet
standard for global rollout.

Limitations of IPv4 and the need for IPv6

IPv4 addresses were getting depleted due to the rapid growth of internet users, high usage of
devices such as mobiles, laptops, and computers, inefficient address use, and always-on devices
like cable modems. To mitigate the problem of address depletion in IPv4, technologies such as
classful networks, classless inter-domain routing, and network address translation were
developed. These technologies contributed to the solution by implementing improvements in the
backbone of the web’s address allocation and routing systems.
The IPv6 packet is built with 40 extended octets so that users can scale the protocol for the future
without disrupting its core structure. The packet has two parts: the header and the payload. IPv6
introduced jumbograms that enabled the packet to handle over 2^32. Jumbograms enhance
performance over high maximum transmission unit (MTU) links and tackle the payload.

Further, IPv6 has a 128-bit address and has a larger address space available for future allocation.
The 128-bit address is broken into 8 groups, each containing 16 bits. Four hexadecimal numbers
represent each group, and colons are used to divide each group from the others. IPv6 provides a
host connected to the network with a unique identifier specific to the subnet.

The addressing structure of IPv6, which is established in RFC 4291, makes it possible for three
distinct kinds of communications to take place — i.e., the unicast, anycast, and multicast
communication methods.

Advantages of using IPv6

 The technology provides internet users with several advantages:
 IPv6 provides a solution to address the global issue of depleting address spaces due to
increased demand for IP addresses due to technological advancements.
 It offers reliability and faster speeds. IPv6 supports multicast addresses, meaning bandwidth-
intensive packet flows like media streams can reach many destinations simultaneously.
 It enforces more robust network security than IPv4. IPv6 has IPSecurity, which ensures data
privacy and data integrity. It also reinforces routing efficiency.
 It supports stateless and stateful address configuration regardless of the presence or absence
of a Dynamic Host Configuration Protocol (DHCP) server.
 It has a larger address space and can handle packets more efficiently.
Disadvantages of using IPv6
However, it also comes with a few constraints. For example, IPv6 is not backward compatible
with IPv4. Communication between a device and a network with different internet protocols is
difficult.

Despite IPv4 being of inferior quality, offering lower performances, and having its address
spaces nearly depleted, it is still more popular than IPv6. Full migration to IPv6 will take an
exceptionally long time due to the incompatibilities between the two protocols and the
significant expenses associated with transitioning to IPv6 infrastructure.

How IPv6 Work

The working of IPv6 relies on the following key concepts:
1. IPv6 addresses
An IPv6 address uses 128 bits, four times more than the IPv4 address, which uses only 32 bits.
IPv6 addresses are written using hexadecimal rather than dotted decimal, as in IPv4. An IPv6
address consists of 32 hexadecimal numbers since a hexadecimal number uses 4 bits. These
numbers are grouped into eight groups of 4’s and are written with a colon (:) as a separator. For
instance, group6:, group7:, group8:, etc.
An IPv6 address may be shortened using various techniques due to its length. For instance,
2001:0db8:0000:0000: 0000:7a6e: 0680:9668 may be shortened to 2001:db8::7a6e: 680:9668.
The main technique employed is the removal of leading zeros. Additionally, consecutive sections
of zeros can be replaced with two colons (::), even though you may only use this approach once
in a given address to avoid making the address indeterminate or ambiguous.

2. Network and node addresses

In IPv4, address classes were used to split an address into two components: a network
component and a node component. This was later replaced by subnet masking. Similarly, in
IPv6, an address is split into two parts. The address is divided into two 64-bit segments. The top
64-bit segment is the network component, and the lower 64-bit component is the node
component.
The top 64-bit segment (network component) is used for routing. The lower 64-bit element (node
component) identifies the address of the interface or node. The node component is derived from
the actual physical or Mac address using IEEE’s extended unique identifier (EUI-64) format.
The computer network component is split into two blocks of 48 and 16 bits, respectively. The
lower 16-bits are controlled by a network administrator and are used for subnets on an internal
network. The upper 48-bits are for routing over the internet and are used for the global network
addresses.
3. IPv6 address types and scope
There are three types of IPv6 addresses:
 Global unicast addresses: They are routable on the internet and start with 2001:. The prefix
for international unicast addresses comes from what routers convey in their network
announcements. They are the same thing as the IPv4 public addresses. SLAAC, which stands
for “stateless address autoconfiguration,” needs a block of 64 addresses. Internet authorities
give address blocks to Internet service providers (ISPs) so that they can give them to their
customers. Currently, the advice is to provide home sites with more than one 64.
 Unique local addresses: These addresses are meant to be used inside an internal network
like a local area network. They are routable on the internal network but not on the internet.
The address allocation space is segmented into two /8 spaces – fd00::/8 for those globally
assigned and fd00::/8 for locally assigned addresses. Organizations can manually set
addresses using the prefix fd00.
 Link-local addresses: These addresses are meant to be used as an internal network. They are
routable on the internal network but not on the internet. Further, they are analogous to the
IPv4 address 169.254.0.0/16, allocated on the IPv4 network without a DHCP server. The
link-local addresses start with the prefix fe80. Even if there is no routing, each IPv6 interface
has to have a link-local address configured. This is essential.

4. Using IPv6 addresses in uniform resource locators (URLs)

Using an IPv4 network, a user can access a network resource such as a web page using
HTTP://192.168.121/webpageOpens a new window . Webpages can also be accessed via IPv6,
albeit with a tweak in the format. IPv6 addresses contain a colon as a separator and must be
enclosed in square brackets. For instance, HTTP://[2001:db8:4531:674::100e]/webpage.
5. IPv6 loopback
The loopback address represents the same interface as a computer. The TCP/IP protocol stack
loops the packets back on the same interface both in IPv4 and IPv6. In IPv4, 127.0.0.0/8 network
is reserved for loopback addresses. In IPv6, the loopback address is
0000:0000:0000:0000:0000:0000:0000:0001/128. It can be simplified to::1/128. Not only in
IPv4 but also IPv6, routers will not forward packets that have an undefined address. The
unspecified address of IPv6 is::/0.

Features of IPv6
IPv6 has been rethought to overcome the shortcomings of its predecessor, IPv4 while preserving
the fundamental capabilities of Internet Protocol (IP) addressing. The following are features of
IPv6:
1. Larger address space: The main reason IPv6 was developed was to provide a solution for
the eventual exhaustion of addresses in IPv4. Unlike its predecessor, IPv6 uses four times
more bits to address devices on the internet. These extra bits provide an address space for
approximately 3.4 x 10^ 38 devices. Every square meter of our planet has the potential to
have around 1564 addresses allocated to it.

Therefore, the larger address spaces provided by IPv6 can meet the aggressive requirements
for allocating addresses for almost everything on the planet. More addresses make address
conservation techniques such as network address translation (NATs) redundant.
2. Simplified header: The IPv6 header has a new simplified header format designed to be less
complex and easier to process than IPv4. The new structure is achieved by moving both
optional and non-essential fields of the headers to extension headers appearing after the IPv6
header. The header of the IPv6 is, therefore, only twice more extensive than that of IPv4,
even though IPv6 addresses are four times larger.
3. End-to-end connectivity: With IPV6, every machine now has a unique IP address and may
traverse the internet without requiring NATs or other translating elements. After the full
implementation of IPv6, every host can directly reach other hosts on the internet, but there
will be some restrictions in the form of firewalls and organizational policies.
4. Auto-configuration: Auto-configuration not only ensures verification of the uniqueness of a
link but also determines the information that should be auto-configured. IPv6 allows stateless
address configuration (or no dynamic host configuration protocol DHCP server) and stateful
address configuration to ease host setup (as in the presence of a DHCP server).

Hosts on a connection automatically manage IPv6 addresses meant for the link, using
addresses generated via prefixes that local routers announce during stateless address settings.
Hosts on the same connection may set up themselves using link-local addresses and interact
without human configuration in the absence of a router. This ensures that inter-
communication goes on regardless of the presence of a server.
5. Faster forwarding or routing: IPv6 features a streamlined header that places all extra
information at the end. The information in the front part of the header is enough for quick
routing decisions, which makes the routing decision-making process as fast as looking at the
mandatory header section.
6. Stronger security through IPSec: Internet protocol security (IPSec) is currently an optional
feature of IPv6. However, the IETF initially decided that IPSec security had to be there to
 make IPv6 more secure than IPv4. IPSec is used at the network processing layer to secure the
network.
7. No broadcast: IPv6 uses a multicast address to communicate with multiple hosts since it
does not have any broadcast address support. For one-to-many communication, a multicast
address is utilized. It is allocated to a collection of interfaces belonging to several nodes.
When IPv6 transmits a payload to a multicast group, it is sent to all interfaces associated with
that address. The value of a multicast address begins with “FF” making it easy to identify.
8. Anycast support: The anycast feature provided by IPv6 is the mode of packet routing. It is
used for one-to-one-of-many communications. Anycast addresses are allocated to a
collection of interfaces belonging to various nodes. Only a single member interface is
reached when a packet is transmitted via an anycast address. The member is usually the
closest one according to the routing protocol choice of distance.
9. Greater mobility: The mobility feature allows hosts such as mobile devices to remain
connected to the same IP address even when roaming in different locations. This is made
possible by taking advantage of automatic IP configuration and extension headers.
10. Enhanced priority support: IPv6 uses traffic class and flow label data to inform the
underlying router how to process and route the packet efficiently. Routers use flow label
fields in the IPv6 header to identify and provide distinct management for packets belonging
to a flow. Quality of service (QOS) can be supported even when the packet is encrypted
through IPSec because the IPV6 header is the one that identifies the traffic.
11. Smooth transition: IPv6 offers an extensive address system that enables the assignment of
universally distinct IP addresses to devices, allowing the devices to communicate and receive
data. Routers may also make quicker forwarding choices due to a lighter header.
12. Extensibility: IPv6 can be easily scaled simply by adding extension headers after the
existing header. In contrast to IPv4, which could only allow 40 bytes, IPv6 extension headers
are restricted solely by the capacity of the IPv6 packet.

Challenges of IPv6
By 1998, the IETF had formalized the development of IPv6 due to the rapidly decreasing number
of IP addresses that IPv4 provided. A couple of decades later, in 2017, the IETF ratified IPv6 as
an Internet standard.
The transition from IPv4 to IPv6 is yet to be realized entirely in 2022. With increasing
technological advancements, the number of global IPv4 addresses available is nearly depleted,
and the need to migrate to IPv6 has become critical. The primary problem with transitioning
from IPv6 is that it is not backward compatible with IPv4. Routing and domain name system
(DNS) problems occur when using an IPv6 address with a network that only uses IPv4.
The challenges of IPv6 include:
1. Security issues
IPv6 offers many more performance improvements than its predecessor, yet it is still vulnerable.
The main security concerns in IPv6 revolve around:
 Header manipulation: Attacks can be based on manipulating headers. Users can minimize
them by using IP security or IPSec and extension headers. Nevertheless, these solutions do
not always work as specific nodes like firewalls can still be overwhelmed.
 Dual-stacking: When using both IPv4 and IPv6, individual security concerns of the two
protocols can be amplified.
 Flooding: With the address of IPv6 being four times bigger than that of IPv4, it takes much
more time to scan it. Due to this, smurf-type attacks can be a problem; thus, it is
recommended to filter out unnecessary traffic.
 Mobility: The mobility feature in IPv6 exposes it to security concerns such as spoofing
attacks. Network administrators can minimize spoof attacks by implementing special security
measures to resolve them before they appear.

2. High costs
Due to their incompatibilities, the migration from IPv4 to IPv6 has not been smooth sailing for
both organizations and ISPs. Despite being feature-rich, fully upgrading to IPv6 does not have a
sufficient return on investment (ROI) to justify the upgrade; hence several ISPs and
organizations have opted out. A complete migration requires that all stakeholders put in the
necessary infrastructure to keep up with internet best practices, which are impossible due to the
high costs involved.
It is expensive to purchase the necessary infrastructure, and organizations and ISPs have to
retrain their personnel or hire external experts to bridge the gap. This leads to additional costs.
3. DNS issues
Network connection requires the most basic information, which is the DNS data. With IPv6, this
can be a challenge. Configuring a DNS server in an IPv6 network can be complex. This issue is
more likely to persist until a consensus is reached on the best way to convey DNS information.
4. Challenges in network adaptation
Although IPv6 is considered the future, many internet service providers (ISPs) don’t yet offer
IPv6 services or provide any monitoring support. This is a significant concern as organizations
that use IPv6 must seek alternative ISPs that can support IPv6 addressing services. Alternatively,
they can get virtual ISPs or use a 6to4 router.

Takeaway
While IPv6 has been around for a while, it is yet to gain total momentum. IDG, in a recent
opinion piece published in August 2022, noted that IPv6 was facing a skills gap with significant
differences between adoption regions. Yet, IPv6 is instrumental to the growth of the internet and
will play a vital role in emerging use cases like peer-to-peer data transfer and web3. To gain
from these technologies, organizations must recognize the importance of IPv6 and prepare for its
adoption.

IP address is your digital identity. It’s a network address for your computer so the Internet
knows where to send you emails, data, etc.
IP address determines who and where you are in the network of billions of digital devices that
are connected to the Internet.

IPv4 vs IPv6
The common type of IP address (is known as IPv4, for “version 4”). Here’s an example of
what an IP address might look like: 25.59.209.224
An IPv4 address consists of four numbers, each of which contains one to three digits, with a
single dot (.) separating each number or set of digits. Each of the four numbers can range from
0 to 255. This group of separated numbers creates the addresses that let you and everyone
around the globe to send and retrieve data over our Internet connections. The IPv4 uses a 32-
bit address scheme allowing to store 2^32 addresses which is more than 4 billion addresses. To
date, it is considered the primary Internet Protocol and carries 94% of Internet traffic. Initially,
it was assumed it would never run out of addresses but the present situation paves a new way
to IPv6, let’s see why?
An IPv6 address consists of eight groups of four hexadecimal digits. Here’s an example IPv6
address: 3001:0da8:75a3:0000:0000:8a2e:0370:7334
This new IP address version is being deployed to fulfil the need for more Internet addresses. It
was aimed to resolve issues which are associated with IPv4. With 128-bit address space, it
allows 340 undecillion unique address space. IPv6 also called IPng (Internet Protocol next
generation).
IPv6 support a theoretical maximum of 340, 282, 366, 920, 938, 463, 463, 374, 607, 431, 768,
211, 456. To keep it straightforward, we will never run out of IP addresses again.

Types of IPv6 Address

Now that we know about what is IPv6 address let’s take a look at its different types.
 Unicast addresses It identifies a unique node on a network and usually refers to a single
sender or a single receiver.
 Multicast addresses It represents a group of IP devices and can only be used as the
destination of a datagram.
 Anycast addresses It is assigned to a set of interfaces that typically belong to different
nodes.

Advantages of IPv6
 Reliability
 Faster Speeds: IPv6 supports multicast rather than broadcast in IPv4.This feature allows
bandwidth-intensive packet flows (like multimedia streams) to be sent to multiple
destinations all at once.
 Stronger Security: IPSecurity, which provides confidentiality, and data integrity, is
embedded into IPv6.
 Routing efficiency
 Most importantly it’s the final solution for growing nodes in Global-network.

Disadvantages of IPv6
 Conversion: Due to widespread present usage of IPv4 it will take a long period to
completely shift to IPv6.
 Communication: IPv4 and IPv6 machines cannot communicate directly with each other.
They need an intermediate technology to make that possible.
6.7 NETWORK FUNCTIONALITY TEST
Network Testing (or network performance testing), similar to Software Testing, is the process of
analyzing and testing your network using a network performance test to identify bugs and
performance issues, evaluate large network changes, and measure network performance.

Even the most robust networks experience network problems.

That’s why before and after every new service migration or deployment, every new application
or network device, and honestly - just as a continuous practice, perform a network performance
test using Network Monitoring to detect and troubleshoot problems as soon as they happen.

Benefits of Network Testing?

Network testing can help you ensure that your network is functioning properly, secure, and able
to handle the needs of your organization, while also saving you time and money in the process.

There are several benefits of network testing. Here are some of the key ones:

 Identify and resolve issues: Network testing can help identify problems with the network
before they become major issues. By detecting and addressing issues early on, you can
prevent downtime, reduce the risk of security breaches, and ensure that the network is
operating at optimal levels.
 Optimize network performance: Network testing can help you identify bottlenecks and
other performance issues that may be slowing down the network. By optimizing the
network's performance, you can ensure that it is able to handle the traffic and data transfer
needs of your organization.
 Ensure network security: Network testing can help you identify security vulnerabilities in
your network, such as open ports or weak passwords, that could be exploited by attackers. By
addressing these vulnerabilities, you can reduce the risk of a security breach.
 Improve user experience: By optimizing the network's performance and ensuring that it is
functioning properly, you can improve the user experience for employees, customers, and
other stakeholders who rely on the network to access applications and data.
 Save time and money: Network testing can help you identify issues and make
improvements more efficiently, which can save time and money in the long run. By
 preventing downtime and improving performance, you can also avoid the costs associated
with lost productivity and revenue.

A network functionality test is a process used to evaluate and verify the operational capabilities
of a computer network. It aims to ensure that the network components, devices, and services
function correctly and meet the desired performance criteria. This type of testing is crucial for
maintaining network reliability, performance, and security.
Here are some key aspects and steps involved in a network functionality test:
1. Test Scope Definition: Determine the specific aspects of the network that need to be tested,
such as hardware devices, network protocols, security measures, or specific services like
email or file sharing.
2. Test Planning: Develop a comprehensive plan that outlines the test objectives,
methodologies, test scenarios, and success criteria. Define the network environment,
including the types of devices, operating systems, network topology, and traffic patterns.
3. Test Execution: Implement the test plan by performing various tests to validate different
aspects of network functionality. Some common types of tests include:
a. Connectivity Testing: Verify the ability of devices to communicate with each other by
sending and receiving data packets.
b. Performance Testing: Evaluate the network's performance metrics, such as latency,
throughput, and bandwidth, under different loads and conditions.
c. Protocol Testing: Ensure that network protocols (e.g., TCP/IP, HTTP, FTP) are properly
implemented and functioning as expected.
d. Security Testing: Assess the network's security measures, including firewalls, intrusion
detection systems, and encryption protocols, to identify vulnerabilities or weaknesses.
e. Service Testing: Test specific network services, such as DNS resolution, email delivery,
web browsing, or file sharing, to verify their functionality and performance.
4. Test Result Analysis: Collect and analyze the test results to determine if the network meets
the defined criteria and performance benchmarks. Identify any issues, errors, or deviations
from expected behavior.
5. Troubleshooting and Issue Resolution: If problems or inconsistencies are identified during
the test, troubleshoot the network components or configurations to resolve the issues. This
may involve debugging network devices, adjusting settings, or applying patches or updates.
6. Documentation and Reporting: Document the test process, including the test plan, test
results, analysis, and any recommended actions or improvements. Generate a comprehensive
 report summarizing the findings, including any areas that need further attention or
optimization.

Regular network functionality testing is crucial for ensuring network reliability, performance,
and security. It helps network administrators and IT teams identify and address issues before
they impact users or disrupt critical business operations. By conducting these tests, organizations
can maintain a stable and efficient network infrastructure that meets the needs of their users and
supports their overall business objectives.
 WIRELESS NETWORKS ACCESS

Internet
An Internet is a public network and it is not owned by anyone. Since, it is a public network
therefore anyone can access it without a valid username and password. Internet is the largest
network in the case of number of connected devices. In this, there are numerous users and it
provides lots of information to users. It acts as a tool for sharing information all over the
world.
Extranet
Extranet is a private network and it is owned by a single or multiple organization. Since, it is a
private network therefore no one can access it without a valid username and password. It acts
as a medium to share the information between the internal and external members. It is more
secure network and managed by numerous organizations.

Differences between Internet and Extranet:

S.NO Internet Extranet
1. It is used as public network. Whereas it is used as private network.
2. An internet is less secure because it has zero While the extranet is more secure than
security level in the firewall. the Internet.
3. In the case of the Internet, anyone can access Whereas in the case of extranet, no one
it without a valid username and password. can access it without a valid username
and password.
4. A large number of users can access the Whereas here, a limited number of users
 Internet. can access the extranet.
5. An internet acts as a tool for sharing Whereas it acts as a medium to share the
information all over the world. information between the internal and
external members.
6. An internet is not owned by anyone. Whereas extranet is owned by a single or
multiple organization.
7. An Internet is not managed by either Unlike the internet, it is managed by
authority. numerous organizations.
8. An internet is the largest network in the case Whereas in the case of extranet, it is
of number of connected devices. small in terms of connected devices as
compared to the internet.
9. An internet is less costly than extranet. Whereas in the case of extranet, it is more
costly.
10. It’s users are the general public. It’s users are the employees of the
organization which are connected.
11. It is not owned by anyone. It is owned by single or multiple
organization.
12. There is no regulating authority for Internet. It is regulated by multiple organizations.
13. It is maintained by ISP. It is maintained by CIO, HR or
communication department of an
organization.
14. It is the network of networks. It is derived from Intranet.
15. Example: What we are normally using is Example: DELL and Intel using network
Internet. for business related operations.
16. The Internet is a global network that The Internet is a global network that
connects millions of devices and computers connects millions of devices and
worldwide. computers worldwide.
17. The Internet is a global network that The Internet is a global network that
connects millions of devices and computers connects millions of devices and
worldwide. computers worldwide.
18. It is open to everyone and allows access to An extranet is a closed network that
public information, such as websites and requires authentication to access.
online services.
19. Extranets are used primarily for
It is used for communication, sharing of
collaboration, sharing of confidential
information, e-commerce, education,
information, and conducting business
entertainment, and other purposes.
between organizations.
20. Users can access the Internet from any Access to an extranet is restricted to
location with an Internet connection and a authorized users and is typically limited
compatible device. to specific devices and locations.
21. Security measures, such as firewalls, Extranets employ similar security
encryption, and secure sockets layer (SSL) measures to protect against unauthorized
protocols, are used to protect against threats access and ensure the privacy and
like hacking, viruses, and malware. integrity of shared data.
22. The Internet is a public network that is not Extranets are private networks that are
owned by any particular organization or owned and managed by the organizations
group. that use them.
23. Examples of extranet-based services
Examples of Internet-based services include
include supply chain management,
email, social media, search engines, and
customer relationship management
online shopping sites.
(CRM), and project collaboration tools.
24. The Internet is a global network that The Internet is a global network that
connects millions of devices and computers connects millions of devices and
worldwide. computers worldwide.
26. An extranet is a closed network that
It is open to everyone and allows access to requires authentication to access.
public information, such as websites and
online services.

27. Extranets are used primarily for

It is used for communication, sharing of
collaboration, sharing of confidential
information, e-commerce, education,
information, and conducting business
entertainment, and other purposes.
between organizations.
28. Users can access the Internet from any Access to an extranet is restricted to
location with an Internet connection and a authorized users and is typically limited
compatible device. to specific devices and locations.
29. Security measures, such as firewalls, Extranets employ similar security
 encryption, and secure sockets layer (SSL) measures to protect against unauthorized
protocols, are used to protect against threats access and ensure the privacy and
like hacking, viruses, and malware. integrity of shared data.
30. The Internet is a public network that is not Extranets are private networks that are
owned by any particular organization or owned and managed by the organizations
group. that use them.
31. Examples of extranet-based services
Examples of Internet-based services include
include supply chain management,
email, social media, search engines, and
customer relationship management
online shopping sites.
(CRM), and project collaboration tools.

7.2 Various Types Of Internet Connectivity

There are many connections that can be used for internet access. All the connections have their
own speed range that can be used for different purposes like for home, or for personal use.
In this article, we will discuss different types of internet connections.

 Dial-Up Connection
A dial-up connection is established between your computer and the ISP server using a modem.
A dial-Up Connection is a cheap and traditional connection that is not preferred these days as
this type of connection is very slow.
To access the internet connection in the dial-up connection we need to dial a phone number on
the computer and that’s why it requires a telephone connection. It requires a modem to set up a
dial-up connection, which works as interference between your computer and the telephone line.
In this connection, we can use either an internet connection or telephone at a time.
 Broadband Connection
Broadband refers to high-speed internet access that is faster than traditional dial-up access. It is
provided through either cable or telephone composition. It does not require any telephone
connection that’s why here we can use telephone and internet connection simultaneously. In
this connection, more than one person can access the internet connection simultaneously.
It is a wide bandwidth data transmission that transports several signals and traffic types. In this
connection, the medium used is coaxial cable, optical fiber cable, radio, or twisted pair cable.

 DSL
DSL stands for Digital Subscriber Line. It provides an internet connection through the telephone
line(network). DSL is a form of broadband communication that is always on, there is no need to
dial a phone number to connect. DSL connection uses a router to transport data and the speed of
this connection range between 128k to 8Mbps depending on the service offered. A DSL
connection can translate data at 5 million bytes per second, or 5mbps.
DSL service can be delivered simultaneously with wired telephone service on the same
telephone line due to high-frequency bands for data.
 Cable
It is a form of broadband access cable modem that can provide extremely fast access to the
internet. The speed of this connection varies which can be different for uploading data
transmission or downloading.
It uses a cable modem to provide an internet connection and operates over cable TV lines. The
speed of cable connection ranges from 512k to 20Mbps.h

 Satellite Connection
This type of connection is provided mainly in rural areas where a broadband connection is not
yet offered. It accesses the internet via a satellite that is in Earth’s orbit.
The signal travels from a long distance that is from earth to satellite and back again which
provides a delayed connection. Satellite connection speeds range from 512k to 2.0Mbps.
 Wireless Connection
As the name suggests wireless connection does not use telephone lines or cables to connect to the
internet. The wireless connection uses a radio frequency band to connect to the internet. It is also
an always-on connection and this connection can be accessed from anywhere and speed may
vary for different locations. It ranges from 5Mbps to 20Mbps.

 Cellular
Cellular technology provides wireless Internet access through cell phones. Speed may vary
depending on the service provider. The most common are 3G and 4G which means from 3rd
generation and 4th generation respectively. The speed of the 3G cellular network is around
2.0Mbps and the 4G cellular network is around 21Mbps the goal of the 4G network is to achieve
peak mobile speeds of 100Mbps but the current speed of the 4G network is about 21Mbps.

 ISDN
ISDN stands for Integrated Service Digital Network and it is a circuit-switched telephone
network system, but it also provides access to packet-switched networks that transmits both
voice and data over a digital line. It provides a packet-switched connection for data in increments
of 64 kilobit/s.
ISDN connection provides better speeds and higher quality than traditional connections. It
provided a maximum of 128kbit/s bandwidth in both upstream and downstream directions.
7.3 WIRELESS NETWORK AND TYPES OF ACCESS
A wireless network refers to a computer network that makes use of Radio Frequency (RF)
connections between nodes in the network. Wireless networks are a popular solution for homes,
businesses, and telecommunications networks.
It is common for people to wonder “what is a wireless network” because while they exist nearly
everywhere people live and work, how they work is often a mystery. Similarly, people often
assume that all wireless is Wi-Fi, and many would be surprised to discover that the two are not
synonymous. Both use RF, but there are many different types of wireless networks across a
range of technologies (Bluetooth, ZigBee, LTE, 5G), while Wi-Fi is specific to the wireless
protocol defined by the Institute of Electrical and Electronic Engineers (IEEE) in the 802.11
specification and it’s amendments.

Differences between Wired vs. Wireless Network

At the most obvious, a wireless network keeps devices connected to a network while still
allowing them the freedom to move about, unencumbered by wires. A wired network, on the
other hand, makes use of cables that connect devices to the network. These devices are often
desktop or laptop computers but can also include scanners and point-of-sale machines.

There are more subtle technology differences that come in to play between wired and wireless.
Most modern wired networks are now “full duplex”, meaning that they can be
transmitting/receiving packets in both directions simultaneously. In addition, most wired
networks have a dedicated cable that runs to each end user device.

In a Wi-Fi network, the medium (the radio frequency being used for the network) is a shared
resource, not just for the users of the network, but often for other technologies as well (Wi-Fi
operates in what are called ‘shared’ bands, where many different electronic devices are approved
to operate). This has several implications: 1) unlike a wired network, wireless can’t both talk
and listen at the same time, it is “half duplex” 2) All users are sharing the same space must take
turns to talk 3) everyone can ‘hear’ all traffic going on. This has forced Wi-Fi networks to
implement various security measures over the years to protect the confidentiality of information
passed wirelessly.

Types of Wireless Network Connections

In addition to a LAN, there are a few other types of common wireless networks: personal-area
network (PAN), metropolitan-area network (MAN), and wide-area network (WAN).
1. LAN: A local-area network is a computer network that exists at a single site, such as an
office building. It can be used to connect a variety of components, such as computers,
printers, and data storage devices. LANs consist of components like switches, access points,
routers, firewalls, and Ethernet cables to tie it all together. Wi-Fi is the most commonly
known wireless LAN.
2. PAN: A personal-area network consists of a network centralized around the devices of a
single person in a single location. A PAN could have computers, phones, video game
consoles, or other peripheral devices. They are common inside homes and small office
buildings. Bluetooth is the most commonly known wireless PAN.
3. MAN: A metropolitan-area network is a computer network that spans across a city, small
geographical area, or business or college campus. One feature that differentiates a MAN
from a LAN is its size. A LAN usually consists of a solitary building or area. A MAN can
cover several square miles, depending on the needs of the organization.
Large companies, for example, may use a MAN if they have a spacious campus and need to
manage key components, such as HVAC and electrical systems.
4. WAN: A wide-area network covers a very large area, like an entire city, state, or country. In
fact, the internet is a WAN. Like the internet, a WAN can contain smaller networks,
including LANs or MANs. Cellular services are the most commonly known wireless WANs.
Wireless networking uses radio frequency connections to connect network nodes. This type of
networking enables devices to connect to the network while roaming within its coverage area.
Wireless networks are a famous home, business, and telecommunications network solution.

7.4 ADVANTAGES OF BROADBAND OVER DIAL-UP, WIRELESS INTERNET

ACCESS

1. Cost: A broadband connection typically costs more than a dial-up connection. The charges
involved in a broadband is from monthly rental, irrespective of whether using the connection
or not. Even though this solution looks great for people who are always online, it is certainly
not for those who use less.
2. Speed: Although a broadband connection posses extreme speed capabilities, it cannot be
guaranteed always. It also relies on the servers of a Internet Service Provider (ISP). Any
downfalls in the ISP will definitely impact the broadband speed.
3. Security: Computers in a broadband connection is always made available which makes
them vulnerable to security threats. Especially for wireless broadband connections. There is
high possibility of hackers and other unauthorized people to access your broadband
connection without your knowledge. Therefore, a personal protection such as a firewall is
needed to make it secure.
4. Accessibility: Some people who are residing in rural areas have a problem accessing the
broadband connection. Especially for ADSL and Fibre connections. This is because all the
phonelines that is been used in a broadband connection is not supported by a DSL service.
 7.5 WIRELESS NETWORK
What Does Wireless Network Mean?
Wireless networks are computer networks that are not connected by cables of any kind. The use
of a wireless network enables enterprises to avoid the costly process of introducing cables into
buildings or as a connection between different equipment locations. The basis of wireless
systems are radio waves, an implementation that takes place at the physical level of network
structure.
Wireless networks use radio waves to connect devices such as laptops to the Internet, the
business network and applications. When laptops are connected to Wi-Fi hot spots in public
places, the connection is established to that business’s wireless network.
There are four main types of wireless networks:

 Wireless Local Area Network (LAN): Links two or more devices using a wireless
distribution method, providing a connection through access points to the wider Internet.
 Wireless Metropolitan Area Networks (MAN): Connects several wireless LANs.
 Wireless Wide Area Network (WAN): Covers large areas such as neighboring towns and
cities.
 Wireless Personal Area Network (PAN): Interconnects devices in a short span, generally
within a person’s reach.

Types of Wireless Networks

There are mainly four types of standard wireless networks such as wireless local-area network
(WLAN), wireless personal area network (WPAN), wireless metropolitan-area network
(WMAN), and wireless wide-area network (WWAN).

 Wireless Local-Area Network: A wireless local area network (WLAN) is a group of devices
connected in a fixed location, such as an office or home. A LAN can be large or small, varying
from a home network consisting of a single user to an enterprise network in an office or school
with tens of users and devices. A LAN’s defining feature is connecting devices in a single,
limited area regardless of size. You can use LANs, commonly in-home WiFi networks and
small business networks.
 Wireless Personal Area Network: A wireless personal area network (WPAN) links
electronic devices in a user’s immediate vicinity. A PAN can range in size from a few
 centimeters to ten meters. The connection between a Bluetooth earpiece and a smartphone is
one of the most common real-world examples of a PAN.

 Wireless Metropolitan Area Network: A wireless metropolitan-area network (WMAN) is a

computer network that spans a city, a small geographical area, a business or college campus,
or both. The size of a MAN is one feature that distinguishes it from a LAN. A LAN typically
covers a single building or area, whereas a MAN can cover several square miles depending on
the organization’s needs. A MAN is a portion of a telephone company network that can
provide a city’s cable TV network.
 Wireless Wide-Area Network: A wireless wide-area (WWAN) network spans a large
geographic area, such as an entire city, state, or country. Smaller networks, such as LANs or
MANs, can be contained within a WAN. Because WANs are not bonded to a particular
location, they enable localized networks to communicate across long distances. The Internet
and cellular services are excellent examples of wide-area networks.

What is Wireless Networking?

Wireless Networking refers to a method by which homes, telecommunications networks, and
business installations avoid the costly process of introducing cables into a building, or as a
connection between various equipment locations, using radio waves and/or microwaves to
maintain communication channels.

In a wireless network, data is transmitted and received over the air, eliminating the need for
wired connections. This allows devices, such as personal computers, laptops, smartphones, and
tablets, to connect to the internet and each other without physical wires, providing a high level of
mobility and flexibility.
 Advantages of Wireless Networking
There are various advantages of wireless networking, such as:
 Increased efficiency: Improved data communications facilitate faster information transfer
between partners and customers. While on a sales call, for example, sales representatives can
remotely confirm stock levels and prices.
 Connectivity and availability: Because wireless technology allows users to communicate on
the go, you are rarely disconnected.
 Flexibility: Office workers can continue to do productive work while away from the office.
This has resulted in new working styles, such as work-from-home (WFH).
 Savings: Wireless networks can be easier and less expensive to install, as the use of cables is
minimum. It comes in handy, especially in buildings where the landlord does not allow you to
install cables.
 Adding devices: You can easily connect a new device to the existing setup since the
connection doesn’t rely on wires or cables. You can also add or remove the number of
equipment without worry since there is no cable capacity limit.
 New possibilities: Wireless networking may enable you to introduce new products or
services—many airport departure lounges, train stations, and hotels, for example.

What is Wireless Transmission?

Wireless transmission is said to use unguided media, as opposed to the guided media of copper
cabling and fiber-optic cabling used in traditional wired networks. Wireless networking is
typically used for:

 Communication with mobile stations, which precludes the use of fixed cabling, or for
mobile users who roam over large distances, such as sales reps with laptops that have
cellular modems.
 Work areas in which it is impractical or expensive to run cabling, such as older buildings
that are costly to renovate. In this case, two solutions are possible:
 Create a wireless LAN (WLAN) that uses no cabling between stations.
 Create a combination of traditional wired local area networks (LANs) and as
many wireless stations as needed.
 Networking buildings on a campus using a wireless bridge or router. You can typically
use wireless bridges or routers over distances up to 25 miles. They might support point-
 to-point or multipoint connections and often support Internet Protocol
(IP) or Internetwork Packet Exchange (IPX) routing using static routing or the Routing
Information Protocol (RIP).

The 802.11ac standard, often referred to as Gigabit Wi-Fi, has the following characteristics:

 Maximum theoretical speed of 1.3 Gbps

 Operates in the 5-GHz band
 Connects up to four devices simultaneously using Multi-User, Multi-Input, Multi-Output
(MU-MIMO) technology

WiFi near future

The next wireless communications standard is 802.11ax, and it is expected to be officially
certified by the IEEE in late 2019. It will be much faster than the 802.11ac standard and able to
function even when the signal encounters heavy interference. Additionally, 802.11ax routers will
be MU-MIMO enabled, and they will be able to send data to multiple devices – rumored to be up
to 12 devices – at the same time. Most older routers send data to only one device at a time while
switching back and forth between devices so quickly the switch isn’t noticed.

Factors Limiting Wi-Fi Connection Speeds

The disparity between theoretical and practical Wi-Fi performance comes from network
protocol overhead, radio interference, physical obstructions on the line of sight between devices,
and the distance between devices.
In addition, as more devices communicate on the network simultaneously, performance
decreases due not only to how bandwidth works but also the limitations of the network hardware.
A Wi-Fi network connection operates at the highest possible speed that both devices, often
referred to as endpoints, can support. An 802.11g laptop connected to an 802.11n router, for
example, networks at the lower speed of the 802.11g laptop. Both devices must support the same
standard to operate at the higher speed.

How wireless networking Works

In the broadest sense, wireless networking is composed of all forms of network communication
that use electromagnetic waves of any wavelength or frequency, which includes the following
portions of the electromagnetic spectrum:
Infrared (IR): Ranges from frequencies of about 300 GHz to 200 THz and is used primarily in
confined areas where line-of-sight communication is possible. IR cannot penetrate buildings or
structures, but it can reflect off light-colored surfaces.

Microwave: Ranges from 2 GHz to 40 GHz and is used for both point-to-point terrestrial
communication and satellite communication. Microwave suffers from signal degradation when
weather conditions are poor (for example, in fog or rain).

Broadcast radio: Ranges from 30 MHz to 1 GHz, is less affected by poor atmospheric conditions
than microwave, and can travel through most buildings and structures, but suffers from multipath
interference over long distances.

To connect wireless stations to a traditional wired LAN, you need only two components:

One or more access points, which are transceivers connected to the wired LAN. They broadcast
signals to and receive signals from the wireless stations on the LAN, forwarding signals between
the wired network and the wireless stations as needed. The effective reception range from an
access point defines a circular area called a cell, or more properly, a Basic Service Set. When
more than one access point exists on a network and their cells overlap, the access point devices
must also hand off communication as roaming stations move from one cell to another. The
number of wireless stations that an access point can effectively handle is inversely proportional
to the average traffic generated by each station. A typical wireless access point device might
provide up to 3000 square meters of coverage in open areas (or less when obstacles are present)
and support data transmission rates of 1 to 10 Mbps.

A WLAN adapter, which can be an external device called a station adapter that plugs into the
RJ-45 port of a 10BaseT Ethernet card, an external device that connects to an RS-232 serial port,
or a special PCMCIA card. Whatever configuration you use, the wireless adapter turns the
computer in which it is installed into a wireless station on the network. A fixed or detachable
antenna is generally included and gives the station better transmission and reception. For a small-
scale WLAN, the typical power output for an adapter might be 100 mW, resulting in a coverage
range of about 305 meters in open areas (or less when obstacles are present).

Wireless networking
Wireless networking

The existing standard for wireless networking is IEEE 802.11 of Project 802, which specifies the
physical layer (PHY) and media access control (MAC) protocols and characteristics for wireless
communication between networked stations. In particular, 802.11 covers low-power wireless
microwave communication in the Industrial, Scientific, and Medial (ISM) communication band
centering on 2.4 GHz that was set aside by the Federal Communications Commission (FCC) in
the early 1980s for unlicensed wireless communication. 802.11 covers both common spread-
spectrum communication methods (direct sequencing and frequency hopping), includes an
exportable encryption algorithm called wired equivalent privacy (WEP) to prevent
eavesdropping and specifies a maximum data transmission speed of either 1 or 2 Mbps. 802.11
also specifies standards for wireless communication using infrared light. 802.11 is currently
being revised to support transmission speeds of up to 20 Mbps.

NETWORK SECURITY
Network Access Control
With organizations embracing Bring Your Own Device (BYOD) politices, it is critical to have a
solution that provides the visibility, access control, and compliance capabilities that are required
to strengthen your network security infrastructure.

Network Access Control or NAC is a network solution that enables only compliant,
authenticated, and trusted endpoint devices to access network resources and infrastructure.

A NAC system utilizes MAC address control and the SNMP protocol to deny network access to
non-compliant devices, place them in a quarantined area, or give them only restricted access to
computing resources, thus keeping insecure nodes from infecting the network.

A NAC solution can also isolate guests from your internal network, identifying all devices
inserted into network switch ports, and can disable a rogue device from the switch port remotely
without engaging tech support.

Network Security Policies

A network security policy is a set of standardized practices and procedures that outlines rules for
network access, the architecture of the network, and determines how policies are enforced.

Having a network security policy is important because it informs the employees of an

organization the requirements for protecting assets within the infrastructure.

These assets take many forms, such as passwords, documents, or even servers. These policies
also establish guidelines for acquiring, configuring, and auditing computer systems and
networks.
A network security policy that is easily interpreted and enforced can protect the network from
accidental or intentional data loss, lessen the risk of cyber-attacks, and preserve the integrity of
corporate data.

Web Application Penetration Testing - Types Of Penetration Testing

Application Security
Application security is the process of developing, adding, and testing security features within
applications to prevent security vulnerabilities against threats such as unauthorized access and
modifications.

According to Veracode’s State of Software Security report, 83% of the 85,000 applications it
tested had at least one security flaw.

Many had much more, as their research found a total of 10 million flaws, and 20% of all apps
had at least one high severity flaw.

It is important for organizations to perform routine application security testing to identify and
mitigate flaws in code.

This will deter cyber-attackers from compromising or exploiting critical web applications.

Vulnerability Management

Vulnerability management is a continuous process of identifying, prioritizing, remediating, and

reporting on security vulnerabilities in systems.
Assets on the network are discovered, categorized, and reported on to remediate security
vulnerabilities on target systems.

Vulnerability management is critical today because attackers are constantly crawling the internet
looking for vulnerabilities to exploit—and taking advantage of old vulnerabilities that are
unpatched on corporate systems.

Vulnerability patch management lifecycle

Network Penetration Testing

Network penetration testing is an attempt to measure and evaluate the security of an IT

infrastructure by safely trying to exploit vulnerabilities.

These vulnerabilities may exist in operating systems, services and application flaws, improper
firewall configurations or risky end-user behavior.

A primary reason why penetration testing is important to an organization’s cyber security

program is that it helps personnel learn how to handle cyber-attacks from a malicious entity.

Penetration testing also serves to examine whether an organization’s security policies are
functional and effective in deterring attacks.
Network Penetration Test

Data Loss Prevention

Data loss prevention is defined as a strategy that detects potential data breaches or data ex-
filtration transmissions and prevents them by monitoring, detecting and blocking sensitive data
while in use (endpoint actions), in-motion (network traffic), and at rest (data storage).

A primary reason DLP is important because it helps to detect or prevent the exposure of
sensitivity to unintended recipients.

Depending upon the DLP software and policy configuration, DLP can alert the end-user via
popup or email message.

This customization deters the leakage of data whether the activity is accidental or malicious.
Antivirus and antimalware
Antivirus Software
Antivirus software is a type of software used to prevent, scan, detect and delete viruses from a
computer.

Once installed, most antivirus software will run automatically in the background to provide real-
time protection against virus attacks.

An untold number of new viruses are discovered daily, so it is important and critical to have
antivirus software installed and configured to automatically update to the latest detection files to
stay ahead of the tons of malicious code running rampant on the internet.

Malware creators today are truly knowledgeable on how to exploit weaknesses in computer
systems.

Anti-virus software can be deployed as the first layer of defense to prevent computer systems
from becoming infected by a virus.

What Is Endpoint Detection and Response (EDR)

Endpoint Detection and Response (EDR)
Endpoint detection and response technology is defined as a solution that continuously records
system activities and events taking place on endpoints.

EDR provides security teams with the visibility, they need to uncover incidents that would
otherwise remain invisible.
EDR is important because it provides a graphical view of how the attacker gained access to the
system and what they did once they were inside.

EDR can detect malicious activity on an endpoint as a result of zero-day exploits, advanced
persistent threats, fileless or malware-free attacks, which do not leave signatures and can,
therefore, evade legacy anti-virus.

Email Security - Network Security Types

Email Security
Email security is a term that describes different procedures and techniques for protecting email
accounts, content, and communication against unauthorized access, loss or compromise.

Email is often used to spread malware, spam, and phishing attacks.

It is important for an organization to implement email security to protect against the many forms
of cyber-attacks through email, as well as ensure sensitive messages are encrypted as they transit
out of the network to the recipient.

Wireless Penetration Testing - Types Of Penetration Testing

Wireless Security
Wireless security is defined as the protection of unauthorized access and malicious attempts to a
wireless or Wi-Fi network.

Implementing strong wireless security is important today since many organizations allow their
employees to work remotely and connect to the internet over a wireless network.
WiFi is highly susceptible to hacking if weak wireless protocols are enabled. A wireless network
designed with current wireless security protocols, such as WPA2 can deter cyber-attacks.

Intrusion Detection (IDS) VS Intrusion Prevention (IPS) What’s the Difference

Intrusion Prevention System/Intrusion Detection System (IPS/IDS)
An IPS/IDS are network security measures that are deployed in a network to detect and stop
potential incidents. The terms are usually linked together but are distinct in functionality.

The main difference between an intrusion detection system (IDS) and an intrusion prevention
system (IPS) is that an IDS is used to monitor a network, which then sends alerts when
suspicious events on a system or network are detected.

An IPS reacts to attacks in progress with the goal of preventing them from reaching targeted
systems and networks.

An IPS/IDS are critical pieces to the security infrastructure of an organization because one
device can detect and report an attack while the other can stop attacks based on security policies.

In modern networking equipment, it is common for both technologies to be combined into a

single Unified Threat Management appliance.

Network Segmentation - Network Security Types

Network Segmentation
Network segmentation is an architectural approach that divides a network into multiple segments
or micro subnets, each acting as its own small network.

This allows network administrators to control the flow of traffic between subnets based on
granular policies.

Network segmentation is important because it allows organizations to not only improve

monitoring, and performance but most importantly to enhance network security.

Network segmentation can prevent malware from spreading by isolating a network in one area,
while keeping another segment of the network protected.
What is a siem solution - PurpleSec
SIEM
A Security Information and Event Management (SIEM) solution supports threat detection,
compliance and security incident management through the collection and analysis (both near
real-time and historical) of security events, as well as a wide variety of other event and
contextual data sources.

A SIEM has three main core features which make it important for an organization.

These features include the detection of incidents to create an attack timeline, manage incidents,
and is a log source that meets compliance and regulatory requirements.

Web Security
Web Security - Network Security Types
Web security is defined as the protection of a web application that is exposed to the Internet.

The level protection encompasses tools or resources that detect, prevent, and respond to cyber
threats.

It is not uncommon for a business to have a website presence on the Internet.

Many organizations advertise to the public its services, provide a convenient means for accepting
online payments, and exchanging personal information.

Web security is important because it protects an organization’s identity and reputation.

Strategies to deter attacks and strengthen web security include – secure coding techniques,
ensuring web site supports only current SSL/TLS protocols, frequent web application
vulnerability scanning, and penetration testing.

Multifactor authentication - network security types

Multifactor Authentication (MFA)
Multifactor Authentication, or commonly referred to as MFA is an authentication system that
requires more than one distinct authentication factor for successful authentication.

Multifactor authentication can be performed using a multifactor authenticator or by a

combination of authenticators that provide different factors.
The three authentication factors are something you know, something you have, and something
you are.

MFA is important because if your username and password is stolen through a data breach, the
cyber attacker would not have the additional authentication factor to complete the authentication.

Examples of authentication factors are:

 Something you know – Password/PIN.

 Something you have – Hardware/Software Token issued by your organization.
 Something you are – Biometric (Fingerprint, IRIS/Retina Scan).

Virtual private network - network security types

Virtual Private Network (VPN)
A Virtual Private Network, or VPN, is an encrypted connection over the Internet from a device
to a network.

The encrypted connection helps ensure that sensitive data is safely transmitted.

It prevents unauthorized people from eavesdropping on the traffic and allows the user to conduct
work remotely.

Per the definition, VPN’s are important for business and consumers.

An organization may include a standard VPN package for their remote employees to connect to
their office network as if they were in the office.

The VPN provides a secure tunnel between the VPN client and the organization’s VPN server,
which prevents the cyber attacker from seeing sensitive information.

What are the different types of network security devices and tools?
There are quite a few different networking security tools you can incorporate into your line-up of
services. The following list is by no means exhaustive, but available security tools can include:
 Access control: This refers to controlling which users have access to the network or
especially sensitive sections of the network. Using security policies, you can restrict network
access to only recognized users and devices or grant limited access to noncompliant devices
or guest users.
 Antivirus and anti-malware software: Malware, or “malicious software,” is a common
form of cyberattack that comes in many different shapes and sizes. Some variations work
quickly to delete files or corrupt data, while others can lie dormant for long periods of time
and quietly allow hackers a back door into your systems. The best antivirus software
will monitor network traffic in real time for malware, scan activity log files for signs of
suspicious behavior or long-term patterns, and offer threat remediation capabilities.
 Application security: Each device and software product used within your networking
environment offers a potential way in for hackers. For this reason, it is important that all
programs be kept up-to-date and patched to prevent cyberattackers from exploiting
vulnerabilities to access sensitive data. Application security refers to the combination of
hardware, software, and best practices you use to monitor issues and close gaps in your
security coverage.
 Behavioral analytics: In order to identify abnormal behavior, security support personnel
need to establish a baseline of what constitutes normal behavior for a given customer’s users,
applications, and network. Behavioral analytics software is designed to help identify
common indicators of abnormal behavior, which can often be a sign that a security breach
has occurred. By having a better sense of each customer’s baselines, MSPs can more quickly
spot problems and isolate threats.
 Data loss prevention: Data loss prevention (DLP) technologies are those that prevent an
organization’s employees from sharing valuable company information or sensitive data—
whether unwittingly or with ill intent—outside the network. DLP technologies can prevent
actions that could potentially expose data to bad actors outside the networking environment,
such as uploading and downloading files, forwarding messages, or printing.
 Distributed denial of service prevention: Distributed denial of service (DDoS) attacks are
becoming increasingly common. They function by overloading a network with one-sided
connection requests that eventually cause the network to crash. A DDoS prevention tool
scrubs incoming traffic to remove nonlegitimate traffic that could threaten your network, and
may consist of a hardware appliance that works to filter out traffic before it reaches your
firewalls.
 Email security: Email is an especially important factor to consider when implementing
networking security tools. Numerous threat vectors, like scams, phishing, malware, and
suspicious links, can be attached to or incorporated into emails. Because so many of these
threats will often use elements of personal information in order to appear more convincing, it
is important to ensure an organization’s employees undergo sufficient security awareness
 training to detect when an email is suspicious. Email security software works to filter out
incoming threats and can also be configured to prevent outgoing messages from sharing
certain forms of data.
 Firewalls: Firewalls are another common element of a network security model. They
essentially function as a gatekeeper between a network and the wider internet. Firewalls filter
incoming and, in some cases, outgoing traffic by comparing data packets against predefined
rules and policies, thereby preventing threats from accessing the network.
 Mobile device security: The vast majority of us have mobile devices that carry some form
of personal or sensitive data we would like to keep protected. This is a fact that hackers are
aware of and can easily take advantage of. Implementing mobile device security measures
can limit device access to a network, which is a necessary step to ensuring network traffic
stays private and doesn’t leak out through vulnerable mobile connections.
 Network segmentation: Dividing and sorting network traffic based on certain classifications
streamlines the job for security support personnel when it comes to applying policies.
Segmented networks also make it easier to assign or deny authorization credentials for
employees, ensuring no one is accessing information they should not be. Segmentation also
helps to sequester potentially compromised devices or intrusions.
 Security information and event management: These security systems (called SIEMs)
combine host-based and network-based intrusion detection systems that combine real-time
network traffic monitoring with historical data log file scanning to provide administrators
with a comprehensive picture of all activity across the network. SIEMs are similar to
intrusion prevention systems (IPS), which scan network traffic for suspicious activity, policy
violations, unauthorized access, and other signs of potentially malicious behavior in order to
actively block the attempted intrusions. An IPS can also log security events and send
notifications to the necessary players in the interest of keeping network administrators
informed.
 Web security: Web security software serves a few purposes. First, it limits internet access
for employees, with the intention of preventing them from accessing sites that could contain
malware. It also blocks other web-based threats and works to protect a customer’s web
gateway.