A node receives data from one of its two adjacent

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Unformatted text preview: network bandwidth and causes blocking of a packet even when alternative paths are available for its transmission. Hence, static routing schemes are susceptible to component failures. 2. Dynamic routing. In this method, routing tables are updated relatively frequently, reflecting shorter-term changes in the network environment. Dynamic routing strategy is also known as adaptive routing because it has a tendency to adapt to the dynamically changing state of the network, such as the presence of faulty or congested channels. Dynamic routing schemes can use alternative paths for packet transmissions, making more efficient use of network bandwidth and providing resilience to failures. In dynamic routing, however, packets of a message may arrive out of order at the destination node. This problem can be solved by appending a sequence number to each packet and properly reassembling the packets at the destination node. NETWORK TOPOLOGIES A network is a logical extension of a data communication system. In a computer network, two or more computers (often referred to as nodes) are linked together with carriers and data communication devices for the purpose of communicating data and sharing resources. The term network topology refers to the wav in which the nodes of a network are linked together. It determines the data paths that may be used between any pair of nodes in the network. Although the number of possible network topologies is seemingly limitless, the four major ones are the star network, the ring network, the completely connected network, and the multiaccess bus network. The choice of network topology for installing a computer network depends upon a combination of factors such as: 1. The desired performance of the system. 2. The desired reliability of the entire system. 3. Size (number of nodes and their geographical distribution) of the system. 4. Expandability of the system. 5. Cost of the components and services required to implement the network. 6. Availability of communication lines. 7. Delays involved in routing information from one node to another. Star Network Figure 17.19 shows the s...
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This document was uploaded on 04/07/2014.

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