Principles Digital Communication System & Computer Networks (Charles River Media Computer Engineering)

21.8 LIMITATIONS OF IP VERSION 4

The IP as we know it is running since the late 1970s. During those early days of the Internet, there were no PCs, and computers were either super computers, mainframes, or minis. With the advent of PCs, there has been a tremendous growth in the use of computers and the need to network them, and above all to be on the Internet to access worldwide resources. In the 1990s, the need was felt to revise the IP protocol to deal with the exponential growth of the Internet, to provide new services that require better security, and to provide real-time services for audio and video conferencing. IP Version 4 has the following limitations:

• The main drawback of IP Version 4 is its limited address space due to the address length of 32 bits. Nearly 4 billion addresses are possible with this address length, which appears very high (with a population of 6 billion and a large percentage of the population in the developing world never having seen a computer). But now we want every TV to be connected to the Internet and we want Internet-enabled appliances such as refrigerators, cameras, and so on. This makes the present address length of 32 bits insufficient, and it needs to be expanded.

• The present IP format does not provide the necessary mechanisms to transmit audio and video packets that require priority processing at the routers so that they can be received at the destination with constant delay, not variable delay. The Internet is being used extensively for voice and video communications, and the need for change in the format of the IP datagram is urgent.

• Applications such as e-commerce require high security—both in terms of maintaining secrecy while transmitting and authentication of the sender. IP Version 4 has very limited security features.

• The IP datagram has a fixed header with variable options, because of which each router has to do lots of processing, which calls for high processing power of the routers and also lots of delay in processing.

The drawbacks of IP Version 4 are limited addressing space, inability to support real-time communication services such as voice and video, lack of enough security features, and the need for high-processing power at the routers to analyze the IP datagram header.

Due to these limitations of IP Version 4, IP Version 6 has been developed. IP Version 5 has been used on an experimental basis for some time, but it was not widely deployed.