PACKET SWITCHING

The personPacket switching, the fundamental technology behind the Internet, was developed independently in the US and the UK in the mid- 1960s. In the UK, Donald Davies, superintendent of the computing sciences division at the National Physical Laboratory (NPL), was working on the concept of time sharing, and developed a technique for using packets of data rather than the fixed circuit-switched approach of telephony.In 1965, Davies was looking to develop a packet- switched network nationally but, through lack of funding, had to limit the network to a single node at NPL. That was developed in 1969 as the Mark 1, followed in 1973 by the Mark 2, which ran until 1986.MIT researcher Lawrence Roberts first became excited about the idea for use with the US ARPA network and was instrumental in the first network that eventually became the Internet.The technologyThe technology of packet switching was a key step forward in networking. The transmission control protocol (TCP) and the Internet protocol (IP) allow packets of data to be sent out into the network armed only with knowledge of their destination.The packets are forwarded by each node in the network using sophisticated routing algorithms until they reach their destination - and this could be by any number of different routess even for packets in the same message. This makes an incredibly robust network, with the only point of weakness at the multiple domain name servers (DNS) that hold the numbers determining destinations of the packets.The applicationsThe concept of packet switching opened up many market opportunities in the electronics industry. The basic TCP/IP protocol is used not only for the Internet but also for Ethernet lans, although it was first thought that TCP would be too cumbersome to put on a small computer, having been used for the large time-sharing systems.But David Clark and his research group at MIT showed that a compact version of TCP was possible, first for the Xerox Alto (the early personal workstation developed at Xerox Parc) and then for the IBM PC. From that, the multi-billion dollar Ethernet business was built.The idea of a router for handling such packets has made Cisco Systems one of the largest companies in the world. Routers have become more and more complex as the algorithms become more complex to cope with the ever increasing amount of data passing over the Internet each second.And the servers for the nodes on the Internet are the current battleground for the large computer companies such as IBM, Compaq and Dell, which want to sell ever larger, more reliable, PC systems to compete with Sun Microsystems and Silicon Graphics in yet another multi-billion dollar business.All this is not to mention the coming battle of computer companies to run voice over the same TCP/IP protocols and networking infrastructure, with Voice over IP cutting out the circuit switched networks of the telecoms companies. NF