what is computer network topologies
Computer Network Toplogies
A
Network Topology is the arrangement with which computer systems or network
devices are connected to each other. Topologies may define both physical and
logical aspect of the network.
Bus Topology
In Bus
topology, all devices share single communication line or cable.Bus topology may
have problem while multiple hosts sending data at the same time. Therefore, Bus
topology either uses CSMA/CD technology . It is one of the simple forms of
networking where a failure of a device does not affect the other devices. But
failure of the shared communication line can make all other devices stop
functioning.
Star Topology
All
hosts in Star topology are connected to a central device, known as hub device,
using a point-to-point connection. The hub device can be any of the following:
Layer-1
device such as hub or repeater
Layer-2
device such as switch or bridge
Layer-3
device such as router or gateway
Ring
Topology
In ring
topology, each host machine connects to exactly two other machines, creating a
circular network structure. When one host tries to communicate or send message
to a host which is not adjacent to it, the data travels through all intermediate
hosts. To connect one more host in the existing structure, the administrator
may need only one more extra cable.Failure of any host results in failure of
the whole ring.
Mesh Topology
In this
type of topology, a host is connected to one or multiple hosts.This topology
has hosts in point-to-point connection with every other host.Mesh technology
comes into two types:
Full
Mesh: All hosts have a point-to-point connection to every other host in the
network. Thus for every new host n(n-1)/2 connections are required. It provides
the most reliable network structure among all network topologies.
Partially
Mesh: Not all hosts have point-to-point connection to every other host. Hosts
connect to each other in some arbitrarily fashion. This topology exists where
we need to provide reliability to some hosts out of all.
Tree Topology
Also
known as Hierarchical Topology, this is the most common form of network
topology in use presently.This topology divides the network in to multiple
levels/layers of network. Mainly in LANs, a network is bifurcated into three
types of network devices. The lowermost is access-layer where computers are
attached. The middle layer is known as distribution layer, which works as mediator
between upper layer and lower layer. The highest layer is known as core layer,
and is central point of the network, i.e. root of the tree from which all nodes
fork.
Hybrid Topology
A
network structure whose design contains more than one topology is said to be
hybrid topology. Hybrid topology inherits merits and demerits of all the
incorporating topologies