Data Networks
Data Networks
Data Networks
Networking Devices
Equipment that connects directly to a network
segment is referred to as a device.
These devices are broken up into two classifications.
end-user devices
network devices
End-user devices include computers, printers,
scanners, and other devices that provide services
directly to the user.
Network devices include all the devices that connect
the end-user devices together to allow them to
communicate.
Networking Device
Icons
Repeater
A repeater is a network device used to regenerate a
signal.
Repeaters regenerate analog or digital signals
distorted by transmission loss due to attenuation. A
repeater does not perform intelligent routing.
Hub
Hubs concentrate
connections. In other
words, they take a group
of hosts and allow the
network to see them as a
single unit.
This is done passively,
without any other effect
on the data transmission.
Active hubs not only
concentrate hosts, but
they also regenerate
Bridge
Bridges convert network transmission data formats as
well as perform basic data transmission management.
Bridges, as the name implies, provide connections
between LANs. Not only do bridges connect LANs, but
they also perform a check on the data to determine
whether it should cross the bridge or not. This makes
each part of the network more efficient.
Workgroup Switch
Workgroup switches add
more intelligence to data
transfer management.
Switches can determine
whether data should
remain on a LAN or not,
and they can transfer
the data to the
connection that needs
that data.
Router
Routers have all capabilities of the previous devices.
Routers can regenerate signals, concentrate multiple
connections, convert data transmission formats, and
manage data transfers.They can also connect to a
WAN, which allows them to connect LANs that are
separated by great distances.
The Cloud
The cloud is used in diagrams to represent where the
connection to the internet is.
It also represents all of the devices on the internet.
Network Topologies
Network topology defines the structure of the network.
One part of the topology definition is the physical
topology, which is the actual layout of the wire or
media.
The other part is the logical topology,which defines
how the media is accessed by the hosts for sending
data.
Physical Topologies
Bus Topology
A bus topology uses a single backbone cable that is
terminated at both ends.
All the hosts connect directly to this backbone.
Ring Topology
A ring topology connects one host to the next and the
last host to the first.
This creates a physical ring of cable.
Star Topology
A star topology connects all cables to a central point
of concentration.
Extended Star
Topology
An extended star topology links individual stars
together by connecting the hubs and/or switches.This
topology can extend the scope and coverage of the
network.
Hierarchical
Topology
A hierarchical topology is similar to an extended
star.
Mesh Topology
A mesh topology is implemented to provide as
much protection as possible from interruption of
service.
Each host has its own connections to all other
hosts. Although the Internet has multiple paths to
any one location, it does not adopt the full mesh
topology.
Examples of Data
Networks
LANs
Wireless LAN
Organizations and
Standards
In cabled networks, IEEE is the prime issuer of standards
for wireless networks. The standards have been created
within the framework of the regulations created by the
Federal Communications Commission (FCC).
A key technology contained within the 802.11 standard
is Direct Sequence Spread Spectrum (DSSS).
WANs
SANs
A SAN is a dedicated,
high-performance
network used to move
data between servers and
storage resources.
Because it is a separate,
dedicated network, it
avoids any traffic conflict
between clients and
servers.
Virtual Private
Network
A VPN is a private network that is constructed within a public
network infrastructure such as the global Internet. Using VPN,
a telecommuter can access the network of the company
headquarters through the Internet by building a secure tunnel
between the telecommuters PC and a VPN router in the
headquarters.
Bandwidth
Measuring
Bandwidth
4 Transport
3 Network
2 Data Link
1 Physical
Memorize
it!
4 Transport
Examples:
Email
Web browsers
3 Network
2 Data Link
1 Physical
This layer is
responsible for
presenting the data in
the required format
which may include:
Encryption
Compression
PDU - Formatted Data
Sometimes referred to
as the Cisco Layer.
Makes Best Path
Determination
decisions based on
logical addresses
(usually IP addresses).
PDU - Packets
4 Transport
3 Network
2 Data Link
1 Physical
PDU - Frames
Host Layers
7
Application
6
Presentation
5 Session
4 Transport
3 Network
2 Data Link
1 Physical
These layers
only exist in
the source
and
destination
host
computers.
Media Layers
7
Application
6
Presentation
5 Session
4 Transport
3 Network
2 Data Link
1 Physical
These layers
manage the
information out in
the LAN or WAN
between the
source and
destination hosts.