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Unformatted text preview: computer of such a
network has a direct dedicated link, called a point-to-point link, with all other
computers in the network. The control is distributed with each computer deciding
its communication priorities.
1. This type of network is very reliable, as any link breakdown will affect only
communication between the connected computers. 2. Each node of the network need not have individual routing capability.
3. Communication is very fast between any two nodes.
1. It is the most expensive network from the point of view of link cost. If there are
n nodes in the network, then (n-l)/2 links are required. Thus, the cost of linking the
system grows with the square of the number of nodes.
Multi-access Bus Network
Figure 17.22 shows a multi-access bus network. In this type of network, a single
transmission medium is shared by all nodes. That is, all the computers are attached
to the same communication line (channel). When a particular computer wants to
send a message to another computer, it appends the destination address to the
message and checks whether the communication line is free. As soon as the line
becomes free, it broadcasts (place) the message on the line. As the message travels
on the line, each computer checks whether it is addressed to it. The message is
picked up by the addressee computer, which sends an acknowledgement to the
source computer and frees the line. This type of network is also known as
'multipoint' or 'multidrop' or 'broadcasting' network. It is appropriate for use in a
local area network where a high-speed communication channel is used and
computers are confined to a small area. It is also appropriate when satellite
communication is used as one satellite channel may be shared by many computers
at a number of geographical locations. Advantages
1. The main advantage of a multi-access bus network is the reduction in physical
The failure of a computer in the network does not affect the network
functioning for other computers.
3. Addition of new computers to the network...
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- Spring '14