i) Write a brief report on the evolution of computer networks:
Computer networks networks are the logical result of evolution of computer and communication technologies. They represent particular case distributed computer systems and can be considered a medium for transmitting information over long distances. For later purposes, they implement data encoding and multiplexing methods developed and adopted in various communications systems.
All network can be classified, based on geographical location, in the following categories: wide area network(WANS), local area networks(LAN) and metropolitan area network(MANS).
Chronologically, WANs were the first network to appear. They connect computers distributed over hundred miles. They often based upon existing low quality communication links resulting in low communication speeds compared to LAN, WANs provide a limited set of services mainly file transfer and email in background rather than in real time.
LANs usually cover regions within a radius of no more than 1.5 miles. They are based on expensive high quality connection links that allow simple method of data transmission at a higher speeds of data exchange (about 100mbps) than allowed by WANS usually LANs provide a range of services implemented online.
MANs are intended for serving large cities. Being characterized by rather long distances between network nodes (sometimes 10 miles) they also provide high quality communications links and support high speed of data exchange. MANs ensure economic and efficient connection of LANs providing them accesses to WANs.
The most important stage in the evolution of computer network was the arrival of standard networking technologies. These include Ethernet. FDDI and Token ring these technologies allow different types of computers to connect quickly and efficiently.
During 1980s LANs and WANs were characterized by significant differences between the length and the quality of communication links the complexity of the data transmission methods, data exchange rates the range of provided services and scalability later as a result of the close integration of LANs, WANs, and MANs the convergence of these technologies took place.
The trend of convergence of the different types of networks is characteristic not only for LANs and WANs but also for other types of telecommunications networks including telephone, radio, and tv networks. For now research is aimed at creating universal multiservice capable of efficiently transmitting information of any kind including data, voice and video. ii) compare and contrast OSI reference model vs. TCP\IP model of the network:
I)OSI provides layer functioning and also defines functions of all the layers while TCP/IP model is more based on protocols and protocols are not flexible with other layers. ii) In OSI model the transport layer guarantees the delivery of packets In TCP/IP model the transport layer does not guarantees delivery of packets. iii) OSI model has a separate presentation layer TCP/IP does not have a separate presentation layer. iv) Network layer of OSI model provide both connection oriented and connectionless service. The Network layer in TCP/IP model provides connectionless service
v) OSI model has a problem of fitting the protocols in the model TCP/IP model does not fit any protocol. vi) Protocols are hidden in OSI model and are easily replaced as the technology changes. In TCP/IP replacing protocol is not easy. vii) OSI model defines services, interfaces and protocols very clearly and makes clear distinction between them. In TCP/IP it is not clearly separated its services, interfaces and protocols. viii) Protocols are hidden in OSI model and are easily replaced as the technology changes. In TCP/IP replacing protocol is not easy. ix) OSI model defines services, interfaces and protocols very clearly and makes clear distinction between them. 9. In TCP/IP it is not clearly separated its services, interfaces and protocols.
x) . It has 7 layers It has 4 layers