IPv4 Limitations

The Internet became more popular in the late 1970s and start of 1981 and IPv4 was introduced in the RFC 791 during the same time.

IPv4 has been the main addressing scheme since then without any major changes or inventions in it.

When IPv4 was invented, it was not know that the usage of Internet would become so popular and we would have millions of devices using these IP addresses.

Thus the increase in usage of Internet began to cause the exhaustion of the IPv4 addresses. As IPv4 address is 32bit, the total addresses available are approx. 4.3 billion, with many IP addresses being reserved for special purposes not the total useable addresses could be around 3.7 billion.

Also there is use of Private IP addresses which cannot be used on the Internet. Details about those Private IP addresses are mentioned in RFC 1918.

IPv4 addresses are either configured manually or automatically using the DHCP (Dynamic Host Configuration Protocol). These days as almost all devices are IP enabled, we should have simpler means to configure rather have these devices configured automatically without majorly relying on some administration.

Security is another aspect where IPv4 had a push back. With all devices not accessing the Internet, there needs to be some security mechanism to protect the data and perform cryptography services etc. Currently there is a standard for providing security to the IPv4 using IP Sec (Internet Protocol Security)

As the exhaustion of IP addresses are identified, some solutions were thought of which were not permanent but like work around to temporary or short term solutions like:

– CIDR

– NAT

– Private Addressing

Using CIDR, example, a Class A IP address could be used by many more networks based on the concepts of Subnetting etc.

NAT, helped converting private addresses to public so more devices could access the internet using the translation.

Private Addressing, was used as not all device need to be using the Internet so in such scenarios a private IP address can be used and these address can be used in any organization without the worry of IP conflicts, i.e. if there are 10 organizations using a Private IP address 10.1.1.1, it would not cause any disruption in their service and all can use the same IP address in their respective organizations.

There were also some limitation of IPv4 QoS and the proper usage for real time delivery of data. The TOS field in the IPv4 header is used for DSCP that is helpful for prioritizing data. There were other issues like the IPv4 header has a checksum and it is done for each packet which causes some overhead, this has been eliminated in IPv6.

Thus IPv6 is now being popular used and even being made mandatory by some organization and government organization. An IPv6 address is 128 bit and would have approximately 340 trillion addresses.

Thus addressing the issues with IPv4, the IETF (Internet Engineering Task Force) came out with the IPv6.

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