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The decision to select a particular topology for a network does not take place in isolation as the
topology determines the type of media and access methods that would be used on the network.
Therefore, several factors are taken into consideration before selecting a topology which are as
follows:
 Cost: Cost signifies that the network should be cost-effective. For this, it is required to minimize
the installation cost. This can be done by selecting an economical transmission medium (that is,
wires) for data exchange between the network nodes. The network cost can also be minimized
by reducing the distances between the nodes.

 Flexibility: Flexibility signifies that the network must be flexible enough, i.e., it should be easy
to reconfigure. Reconfiguring a network means to rearrange the existing nodes or add new
ones on the network.
 Reliability: It refers to the degree of trust that can be placed on a network. Like any other
system, a network can also encounter failure. A network failure can occur due to the following
causes:
1. When an individual node stops working.

2. When the entire network fails. This is caused by a more serious fault that stops the working
of an individual node.
What is Point-to-Point (P-P) Link

A P-P link, also known as a dedicated link, is used to connect two nodes in a network. The function
of P-P link is to send and receive data over a network. In a P-P network, each workstation receives
data from only one transmitter and each transmitter transmits data only to one receiver. Fig. 8.23
shows a P-P link in a network.
Transmit Receive

A B

Receive Transmit
Fig. 8.24: A Point-to-Point Link

For better performance, the transmit and receive operations can occur over separate cables or
wires, or they can occur in turns over the same wire by using different transmission techniques. A
P-P link can be established in several ways. The simplest way is to install a P-P link between each
pair of computers over a network.

8.12 COMMUNICATION MEDIA

Communication media is also known as transmission media through which data or signal is
transferred between two communicating devices, i.e., from one system to another system, through
wires or without wires. If the data is sent across network through wires, it is called guided media
and if the data is sent without wires, it is called unguided media.
Computer Networks
CTM: Communication media is a transmission media used for sending data or signal across the network.

8.23