NETWORK TOPOLOGIES• WHAT IS A TOPOLOGY?• The pattern of interconnection of nodes in a

network is called the topology.• FACTORS TO CONSIDER WHILE MAKING A TOPOLOGY CHOICE • Cost• Flexibility• Reliability

First Page :

Point to Point link• A point-to-point link basically relies upon two

functions – transmit and receive.• MAIN CHARACTERISTIC-

each station receives exactly from one transmitter and each transmitter transmits to exactly one receiver.

YYXXTRANSMIT

TRANSMIT

RECIEVE

RECIEVE

Point to Point Network

Types of Network Topologies•STAR TOPOLOGY•BUS TOPOLOGY•RING TOPOLOGY•TREE TOPOLOGY•GRAPH TOPOLOGY•MESH TOPOLOGY

The Star Topology• Consists of a central node to which all the other

nodes are connected by a single path.• Used in most existing information networks

involving data processing or voice communications.

The Bus Topology• Has a single length of transmission medium onto

which the various nodes are attached.• Data is transmitted in small blocks, known as

packets, each of has some data bits, plus a header containing its destination address.

• A destination device in the bus, identifies the address on the packets and copies the data onto the disk.

The Ring Topology• Each node is connected to two and only two

neighboring nodes. • Data is accepted from one of the neighboring

node and is transmitted onwards to another.• After passing through each node, data returns to

the sending node, which removes it.

The Tree Topology• A variation of the bus

topology • Shape of this type of a

network is that of a tree with the central root branching and sub-branching to the extremities of the network.

• No need of removing the packets from the medium because when a signal reaches the end of the medium, it is aborted by the terminators.

The Graph Topology

• The nodes are connected together in an arbitrary fashion.

• A link may or may not connect two or more nodes and can even have multiple links

• If a path has been established in one or two nodes via link(s), then it is known as a connected graph.

A GRAPH TOPOLOGYThe Graph Topology

The Mesh Topology• Each node is

connected to more than one node to provide an alternative route in case the host is either down or too busy.

• Excellent for long distance networking.

• Used in large internetworking environments with stars, rings and buses attached to each node.