Internetworking Devices Used On A Network
Internetworking Devices Used On A Network
Internetworking Devices Used On A Network
NIC: Network Interface Card or NIC are printed circuit boards that are
installed in workstations. It represents the physical connection between
the workstation and network cable. Although NIC operates at the
physical layer of the OSI model, it is also considered as a data link
layer device. Part of the NIC's is to facilitate information between the
workstation and the network. It also controls the transmission of data
onto the wire
Hubs: A hub helps to extend the length of a network cabling system by
amplifying the signal and then re-transmitting it. They are basically
multiport repeaters and not concerned about the data at all. The hub
connects workstations and sends a transmission to all the connected
workstations.
Routers: The aim of using a router is to direct data along the most
efficient and economical route to the destination device. They operate
at Network layer 3, which means they communicate through IP address
and not physical (MAC) address. Routers connect two or more different
networks together, such as an Internet Protocol network. Routers can
link different network types such as Ethernet, FDDI, and Token Ring.
TCP: It is responsible for breaking data down into small packets before
they can be sent on the network. Also, for assembling the packets again
when they arrive.
IP (Internet Protocol): It is responsible for addressing, sending and
receiving the data packets over the internet.
Network Segmentation
Network segmentation implicates splitting the network into smaller networks.
It helps to split the traffic loads and improve the speed of the Internet.
VLAN Segmentation
VLANs enables an administrator to segment networks. Segmentation is done
based on the factors such as project team, function or application, irrespective
of the physical location of the user or device. A group of devices connected
in a VLAN act as if they are on their own independent network, even if they
share a common infrastructure with other VLANs. VLAN is used for data-
link or internet layer while subnet is used for Network/IP layer. Devices
within a VLAN can talk to each other without a Layer-3 switch or router.
The popular device used for segmenting are a switch, router, bridge, etc.
Subnetting
Subnets are more concerned about IP addresses. Subnetting is primarily a
hardware-based, unlike VLAN, which is software based. A subnet is a group
of IP address. It can reach any address without using any routing device if
they belong to the same subnet.
In this CCNA tutorial, we will learn few things to consider while doing
network segmentation
If the receiving and sending devices are connected to the same broadcast
domain, data can be exchanged using a switch and MAC addresses. But if the
sending and receiving devices are connected to a different broadcast domain,
then the use of IP addresses and the router is required.
The node number of the destination node is placed in the MAC header
destination address field.
The node number of the sending node is placed in the MAC header
source address field
The full IPX address of the destination node is placed in the IPX header
destination address fields.
The full IPX address of the sending node is placed in the IPX header
destination address fields.
Layer 3 Packet delivery
To deliver an IP packet across a routed network, it requires several steps.
For instance, if host A wants to send a packet to host B it will send the packet
in this ways
This packet is then broadcast on the local network. The default gateway
router receives the ARP request for MAC address. It responds back
with the Mac address of the default router to Host A.
Now Host A knows the MAC address of the router. It can send an IP
packet with a destination address of Host B.
The packet destined for Host B sent by Host A to the default router will
have the following information,
o Information of a source IP
o Information of a destination IP
o Information of a source Mac address
o Information of a destination Mac address
When the router receives the packet, it will end an ARP request from
host A
Now Host B will receive the ARP request from the default gateway
router for the host B mac address. Host B responds back with ARP
reply indicating the MAC address associated with it.
Now, default router will send a packet to Host B
In the first packet, in the MAC header place the destination number
"20" from the router and its own source field "01". For IPX header
place the destination number "02", source field as "AA" and 01.
While in the second packet, in the MAC header place the destination
number as "02" and source as "21" from the router. For IPX header
place the destination number "02" and source field as "AA" and 01.
WLAN adapter
Access point (AP)
Station adapter
WLAN switch
WLAN router
Security Server
Cable, connectors and so on.
Types of WLAN
Infrastructure
Peer-to-peer
Bridge
Wireless distributed system
WLAN Standards
While to define the standard for these wireless technologies you have another
authority. These include,
The IEEE have defined a various specification for WLAN services( as shown
in table). For instance, 802.11g applies to wireless LANs. It is used for
transmission over short distances at up to 54-Mbps in the 2.4 GHz bands.
Similarly, one can have an extension to 802.11b that applies to wireless
LANS and provides 11 Mbps transmission (with a fallback to 5.5, 2 and 1-
Mbps) in the 2.4 GHz band. It uses only DSSS ( Direct Sequence Spread
Spectrum).
The below table shows different wi-fi protocols and data rates.
Wi-Fi Alliance
Wi-Fi alliance ensures interoperability among 802.11 products offered by
various vendors by providing certification. The certification includes all three
IEEE 802.11 RF technologies, as well as an early adoption of pending IEEE
drafts, such as the one that addresses security.
WLAN Security
Network security remains an important issue in WLANs. As a precaution,
random wireless clients must usually be prohibited from joining the WLAN.
Unauthorized access
MAC and IP spoofing
Eavesdropping
Session Hijacking
DOS ( denial of service) attack
Implementing WLAN
While implementing a WLAN, access point placement can have more effect
on throughput than standards. The efficiency of a WLAN can be affected by
three factors,
Topology
Distance
Access point location.
In this CCNA tutorial for beginners, we will learn how WLAN can be
implemented in two ways,
1. Ad-hoc mode: In this mode, the access point is not required and can be
connected directly. This setup is preferable for a small office (or home
office). The only drawback is that the security is weak in such mode.
2. Infrastructure mode: In this mode, the client can be connected
through the access point. Infrastructure mode is categorized in two
modes:
WLAN Topologies
BSA: It is referred to as the physical area of RF (Radio Frequency)
coverage provided by an access point in a BSS. It is dependent on the
RF created with variation caused by access point power output, antenna
type, and physical surroundings affecting the RF. Remote devices
cannot communicate directly, they can communicate only through the
access point. An AP start transmitting beacons that advertise the
characteristics of the BSS, such as modulation scheme, channel, and
protocols supported.
ESA: If a single cell fails in giving enough coverage, any number of
cells can be added to extend the coverage. This is known as ESA.
o For remote users to roam without losing RF connections 10 to 15
percent overlap is recommend
o For wireless voice network, an overlap of 15 to 20 percent is
recommended.
Data Rates: Data rates is how quickly information can be transmitted
across electronic devices. It is measured in Mbps. Data rates shifting
can happen on a transmission-by-transmission basis.
Access Point Configuration: Wireless access points can be configured
through a command-line-interface or through a browser GUI. The
features of access point usually allow the adjustment of parameters like
which radio to enable, frequencies to offer, and which IEEE standard to
use on that RF.
Step 1) Validate pre-existing network and Internet access for the wired hosts,
before implementing any wireless network.
Step 2) Implement wireless with a single access point and a single client,
without wireless security
Step 3) Verify that the wireless client has received a DHCP IP address. It can
connect to the local wired default router and browse to the external internet.
Troubleshooting
WLAN may encounter few configuration problems like
Following are the few troubleshooting steps that may help counter above
issues,
For connecting network across the different geographical area, you can use
WAN (Wide Area Network).
In this CCNA tutorial for beginners, we will see how a computer on the
different network communicates with each other.
Introduction to Router
A router is an electronic device used to connect network on LAN. It connects
at least two networks and forwards packets among them. According to the
information in the packet headers and routing tables, the router connects the
network.
It is a primary device required for the operation of the Internet and other
complex networks.
Binary numbers include numbers 1,1,0,0,1,1. But how this number is used in
routing and communicate between networks. Let start with some basic binary
lesson.
You will be familiar with decimals positions like 10, 100, 1000, 10,000 and
so on. Which is nothing but just power to 10. Binary values work in a similar
way but instead of base 10, it will use the base to 2. For instance 2 0 , 21, 22, 23,
….26. The values for the bits ascends from left to right. For this, you will get
values like 1,2,4,….64.
Now since you are familiar with the value of each bit in a byte. The next step
is to understand how these numbers are converted to binary like 01101110
and so on. Each digit "1" in a binary number represents a power of two, and
each "0" represents zero.
In the table above, you can see that the bits with the value 64, 32, 8, 4 and 2
are turned on and represented as binary 1. So for the binary values in the
table 01101110, we add the numbers
These 32 bits are broken into four octets (1 octet = 8 bits). The value in each
octet ranges from 0 to 255 decimal. The right most bit of octet holds a value
of 20 and gradually increases till 27 as shown below.
Let's take another example,
For example, we have an IP address 10.10.16.1, then first the address will be
broken down into the following octet.
.10
.10
.16
.1
The value in each octet ranges from 0 to 255 decimal. Now, if you convert
them into a binary form. It will look something like this,
00001010.00001010.00010000.00000001.
IP address classes
IP address classes are categorized into different types:
Class Categories
Class A 10.0.0.0 – 10.255.255.255
Subnet mask helps you to pinpoint where the end points on the subnet are if
you are provided within that subnet.
Class A- 255.0.0.0
Class B- 255.255.0.0
Class C- 255.255.255.0
Router Security
Secure your router from unauthorized access, tampering, and eavesdropping.
For this use technologies like,
Branch Threat Defense
VPN with highly secure connectivity
VPN Solution
VPN solution protects various types of WAN design (public, private, wired,
wireless, etc.) and the data they carry. Data can be divided into two
categories
Data at rest
Data at transit
Summary:
CCNA full form or CCNA abbreviation is "Cisco Certified Network
Associate"
Internet local area network is a computer network that interconnects
computers within a limited area.
WAN, LAN, and WLAN are the most popular Internet local area
networks
As per the OSI reference model, the layer 3, i.e., the Network layer is
involved in networking
Layer 3 is responsible for packet forwarding, routing through
intermediate routers, recognizing and forwarding local host domain
messages to transport layer (layer 4), etc.
Some of the common devices used for establishing network includes,
o NIC
o Hubs
o Bridges
o Switches
o Routers
TCP is responsible for breaking data down into small packets before
they can be sent on the network.
TCP/IP reference model in the internet layer does two things,
o Transmitting data to the Network Interface layers
o Routing the data to the correct destinations
Packet delivery through TCP is more safe and guaranteed
UDP is used when the amount of data to be transferred is small. It does
not guarantee packet delivery.
Network segmentation implicates splitting the network into smaller
networks
o VLAN Segmentation
o Subnetting
A packet can be delivered in two ways,
o A packet destined for a remote system on a different network
o A packet destined for a system on the same local network