The Internet Protocol: IPV4 Address Allocation
Explore how IPv4 address allocation evolved to support internet scalability through classless interdomain routing and variable-length subnets. Learn about address block distribution, longest prefix matching for routing decisions, and special reserved IPv4 addresses to understand modern network layer protocols.
Allocating Blocks of Addresses to Organizations
A second issue concerning the addresses of the network layer is how to allocate blocks of addresses to organizations.
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The first allocation scheme was to allocate class address blocks on a first come, first served basis.
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Large organizations such as IBM, BBN, as well as Stanford or MIT were able to obtain one class A address block each.
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However, most organizations requested class B address blocks consisting of addresses, which was suitable for their size. Unfortunately, there were only 16,384 different class B address blocks. This address space was being consumed quickly. Since a disproportionate number of class B address blocks were being used, the number of entries for class B blocks increased. So the routing tables maintained by the routers were also growing quickly, and some routers had difficulties maintaining all these routes in their limited memory. Hence, the purpose ...