Data Communication and Networking

In: Computers and Technology

Submitted By Ainn
Words 6005
Pages 25
1. Open System Interconnection (OSI) Reference Model.
(a) The OSI model was developed before the Internet and was developed by agreement by the US and European nations (CCITT), yet the Internet and its protocols is by far the dominant network technology on our planet. Why?
The reason behind TCP/IP’s dominance over OSI can be summarized as a result of technical, political and economic reasons:
The reasons for the popularity of TCP/ IP over the OSI are : * TCP/IP answers an immediate, almost desperate need - data communications in heterogeneous networks - very well. * It is relatively simple and robust compared to other alternatives. * TCP/IP is bundled into the Berkeley Software Distribution (BSD) Unix. Hence, TCP/IP became the minimum networking capability for any vendor entering the market for scientific and engineering graphics workstations. * Its available on virtually every hardware and operating system platform and It is often free as its open source. * Thus, it’s the lingua franca of the Internet. * It’s more credible than OSI, making greater utilization of bandwidth at a lower cost. * It supports multiplexing and being connectionless, supports more communication devices. * Existence of Internet layer reduces error handling overhead on the transport layer with the help of intelligent hosts, thus increasing throughput and efficiency at the transport layer.

(b) List the major disadvantages with the layered approach to protocols.
The disadvantages are : 1. Associated with layered protocols is that often higher layers of the protocol stack are unable to optimize data transfers based on the characteristics of underlying layers. 2. Each layer potentially imposes overhead both in terms of processing time and control information stored in protocol headers. 3. Overhead occurring mutually in computation and those headers…...

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