Computer network_network devices

COMPUTER NETWORK
NETWORK DEVICES
Presented By
Sweta Kumari Barnwal
Assistant Professor
Arka Jain University
Jamshedpur, Jharkhand

Indexed
 Introduction
 Different network Devices
Router
Hub
Bridge
Switch
Gateway
Brouter
NIC (Network Interface Card)

Network Device
 Devices which are used to provide connectivity between different
kind of devices and network together, so that they can communicate
and able to share the data.
 However, all of the names mean the same but have got different
purposes. Different devices work at different layers of the computer
network.
 Different layers of a computer network are like different zones of a
computer network with specified works, also called as 'network
protocols'.
 Such devices are used to create any size of network having any
number of devices.
 For example: A LAN cable has got the purpose of connecting a
computer to the local/small area network, where as a Wi-Fi router
has got the purpose of sending and receiving data through the world
wide.

Router
 It is a device like a switch that routes data packets based on their IP
addresses. Router is mainly a Network Layer device. Routers normally
connect LANs and WANs together and have a dynamically updating
routing table based on which they make decisions on routing the data
packets. Router divide broadcast domains of hosts connected through
it.
 Functions of a Router: It basically performs two major functions:
• Forwarding – It receives the packets from its input ports, checks it
header, performs some basic functions like checking checksum and
then looks upto the routing table to find the appropriate output port to
dump the packets onto, and forwards the packets onto that output port.
• Routing – It is the process by which the router assign best path to the
packet to reach the destination, It maintains a routing table which is
made using different algorithms by the router only.

Hub
Basically it is a multiport 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, collision domain of all
hosts connected through Hub remains one. Also, they do not have
intelligence to find out best path for data packets which leads to
inefficiencies and wastage.
There are two types of Hub
• Active Hub:- These are the hubs which have their own power supply
and can clean, boost and relay the signal along with the network. It
serves both as a repeater as well as wiring centre. These are used to
extend the maximum distance between nodes.
• Passive Hub :- These are the hubs which collect wiring from nodes
and power supply from active hub. These hubs relay signals onto the
network without cleaning and boosting them and can’t be used to
extend the distance between nodes.

Bridge
 It operates at data link layer. A bridge is a repeater, with add on the
functionality of filtering content by reading the MAC addresses of
source and destination. It is also used for interconnecting two
LANs working on the same protocol. It has a single input and
single output port, thus making it a 2 port device.
 Types of Bridges:
• Transparent Bridges:- These are the bridge in which the stations
are completely unaware of the bridge’s existence i.e. whether or
not a bridge is added or deleted from the network, reconfiguration
of the stations is unnecessary. These bridges make use of two
processes i.e. bridge forwarding and bridge learning. This does not
take part in route discovery or the route selection process. It does
keep track of the location of each workstation on the network by
building a forwarding table of each MAC address and the
corresponding interfaces (ports) associated with each workstation.

Bridge
Source Routing Bridges:- In these bridges, routing operation is
performed by source station and the frame specifies which route to
follow. The hot can discover frame by sending a special frame called
discovery frame, which spreads through the entire network using all
possible paths to destination. SRT bridges are transparent bridges
that combine the capabilities of the source route and the transparent
bridge. When a SRT bridge receives a frame with a RIF, the bridge
handles the frame just as a source route bridge would. If the bridge
receives a frame without a RIF, it handles the frame the same as a
transparent bridge would. Source Route Transparent bridges are com
Spanning Tree algorithm is a protocol developed by the IEEE to
enable bridges to have multiple bridge connections between
networks and reduce problems that occur from redundant links or
loops in LANs. commonly used in small token ring environments.

Switch
It is a multiport bridge with a buffer and a design that can boost
its efficiency(a large number of ports imply less traffic) and
performance. A switch is a data link layer device. The switch can
perform error checking before forwarding data, that makes it very
efficient as it does not forward packets that have errors and
forward good packets selectively to correct port only. In other
words, switch divides collision domain of hosts, but broadcast
domain remains same.
Layer 2 switch work on layer 2 of OSI model i.e. data link layer
and sends a packet to destination port using MAC address table
which stores the mac address of a device associated with that
port.
Layer 3 switch work on layer 3 of OSI model i.e. network layer
where it route packet by using IP address, it is used widely on
VLANs.

Switch
LAYER 2 SWITCH LAYER 3 SWICTH
It 0perates on layer 2 (Data link) of OSI
model.
It operates on layer 3 (Network Layer) of
OSI model.
Send packet to detination on the basis of
MAC address.
Route Packet with help of IP address
Work with MAC address only
Can perform functioning of both 2 layer
and 3 layer switch
Used to reduce traffic on local network.
Mostly Used to implement VLAN
(Virtual Local area network)
Quite fast as they do not look at the Layer
3 portion of the data packets.
Takes time to examine data packets before
sending them to their destination
It has single broadcast domain It has multiple broadcast domain.
Can communicate within a network only.
Can communicate within or outside
network.

Repeaters
 It operates at the physical layer used to regenerate the signal over the same
network before the signal becomes too weak or corrupted so as to extend
the length to which the signal can be transmitted over the same network.
 Repeaters is that they do not amplify the signal. When the signal becomes
weak, they copy the signal bit by bit and regenerate it at the original
strength. It is a 2 port device.

Gateway
A gateway, as the name suggests, is a passage to connect two networks
together that may work upon different networking models. They basically
work as the 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
switch or router.

Brouter
It is also known as bridging router is a device which combines features of both
bridge and router. It can work either at data link layer or at network layer.
Working as router, it is capable of routing packets across networks and
working as bridge, it is capable of filtering local area network traffic.

NIC ( Network Interface Card)
It is an important hardware component used to provide network connections. With
its wide applications, there are various types of network interface cards emerging
in the market like PCIe card and server network card. NIC card can transmit
signals at the physical layer and deliver data packets at the network layer. No
matter what layer the network interface controller lies, it acts as a middleman
between a computer/server and a data network. When a user requests a web page,
the LAN card gets data from the user device, and sends them to the server on the
internet, then receives the required data back from the Internet to display for users.

Computer network_network devices

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