Introduction:
An internetwork consists of two of more networks connected to each
other. These networks are joined using cables and devices. Several
factors determine the type of network. In each type of network, the
devices are connected in a specific way. For communication between the
networks different models, such as OSI, exist defining the manner in
which the communication between network occurs.
Line configuration
1. Point to Point configuration:
In Point to Point configuration, A dedicated like exists between two
devices. A dedicated Link implies that the full capacity of the channel
is reserved for communication between the two connected devices.
2. Multipoint Configuration:
In multipoint configuration, more than two devices share a link. In
this configuration, several devices are connected on the same link and
hence the capacity of the channel is shared between the device.
Types of Topologies
Topology refers to the configuration of computers and network devices. The two types of topologies are : -
- Physical Topology : – Represents the physical
layout of devices on a network. It refers to the arrangements of the
devices on the network and the way they communicate with each other. The
five basic physical topologies are Bus, Star, Tree, and Mesh.
- Logical Topology : – Represents the way the data
in transferred from one device to the next, irrespective of the
physical interconnection of the devices.
Bus Topology
In
Bus topology, all the devices are connected to a
single cable know as the bus. The devices of the nodes are connected to
the main bus with the help of :
- Drop Line : – Provides connection between the main cable and device.
- Tap : – Creates contact between the drop line and the metallic core of the cable by puncturing the sheath of cable.
Bus Topology is easy to install as the devices need
to be connected only with the bus. Also, it is cost effective, as the
cabling required is less. If one device in the network fails, then the
network in not affected as the communication is not dependent on any
other device in network.
In
Bus Topology the fault isolation is difficult, as
break in the cable is difficult to identify. Also entire network is
affected if the cable breaks.
Star Topology
In
Star Topology all the devices are connected to a
central hub. The devices are not connected to each other directly. In a
star topology, when a device transfers data from one device to another,
the date passes through the hub to reach the destination. The hub is
responsible to manage and control the network.
Star Topology easy to install and manage, as a new
device just requires to be connected to the central hub. It is easier to
detect faults as each device is directly connected to the hub.
Star Topology requires a hub, which makes it
expensive. Also, if the central hub fails then the entire network is
disabled. Also congestion may occur in the network as all the traffic is
routed through the hub
Ring Topology
In
Ring Topology, all the devices are connected in a
closed loop. Each device is connected through point-to-point line
configuration to another device. There are no terminated cables in
Ring Topology as in bus topology.
The fault isolation is easier in
Ring Topology, as you can identify the device through which the data is not transmitted further.
Ring Topology is expensive as a lot of cabling is required. If one device in the network fails, entire networks is affected.
Tree Topology
Tree Topology has a group of star-configured
workstations, which are connected to a linear cable. The difference
between in Tree and Star topology is that in tree topology all the
devices are not directly connected to the central hub. Several secondary
hubs are present, which are connected to the central hub.
In
Tree Topology the distance that a signal can
travel between devices increases as hubs are present. The hub acts as a
repeater, which amplifies the signal if it is weak.
Congestion my occur in
Tree Topology as all the data is router through the hub. If the central hub fails then entire network is affected.
Mesh Topology
In Mesh Topology, every device has a dedicated link to every other
device in the network. The link has to carry the traffic only between
the devices, which it connects. If tere are n devices in the network
then
[n (n-1)]/2 are the number of links needed to connect the device.
In
Mesh Topology the traffic problem is eliminated
as each device has a dedicated link to very other device. This also
ensures security, as the data is directly routed to the destination
devices.
In
Mesh Topology more cabling is required, which makes it expensive to implement.
Type Of Networks
A network is a collection of computers connected to each other with
the help of networking devices. A network is classified on the basis of
its size, ownership, distance covered, and physical architecture. The
different types of network are Local Area Network (
LAN), Man Area Network (
MAN), Wide Area Network (
WAN).
Local Area Network (LAN)
A
Local Area Network is spread over a small
area. LAN s are used when you want to connect the computers in a
building or group of group of buildings. Each computer on a LAN has its
own Central Processing Unit (
CPU), but they can share
expensive devices, such as a printer, and modem. Computers on a LAN can
also share data among themselves. The rate of transferring data over a
lan is vary fast.
Metropolitan Area Network (MAN)
A
Metropolitan Area Network is spread over a larger
geographical area as compared to LAN. MAN is used to connect computers
is a town or a city. MAN provides high speed connectives
using fibre optic cable.
Wide Area Network (WAN)
A
Wide Area Network enables long transmission of
Data, Voice, Image, and Video information. A WAN is larger than a MAN
network. WAN is used to transfer data over large geographical areas,
such as, a country, continent, or the entire world. For Example, the
Internet is the largest WAN.
