IP version 4 (IPv4) has been a core part of the TCP/IP protocol suite and has served well during tremendous growth of the Internet. IPv4, mostly called just IP, defines addressing and routing for most corporate networks that use TCP/IP as well as the public Internet. Though IPv4 has been a long-time companion, it has its shortcomings that created the need for a protocol that could replace IPv4. That protocol is Internet Protocol version 6 or IPv6 for short. IPv6 defines the same general functions that are defined by IPv4. However, there are differences in detail that we will explore in this chapter.
IP version 6 (IPv6) serves as the protocol that will eventually replace IP version 4 (IPv4). The most obvious reason for migrating TCP/IP networks from IPv4 to IPv6 is growth. IPv4 uses a 32-bit address, which allows for a little over four billion addresses. It may seem like a pretty large number of addresses but the immense growth of networks and the Internet has almost exhausted our stock of available IPv4 addresses for new deployments. IPv6 uses 128-bit addresses and increases the number of available addresses to 2^128, a number so large that we don’t have a word for it.
The change from IPv4 to IPv6 is not just about one protocol being replaced by another; it impacts many other protocols as well. In this super-sized chapter, we start by introducing IPv6 addressing and routing, also discussing troubleshooting of the same. We then cover OSPFv3 (Open Shortest Path First Version 3) and EIGRPv6 (Enhanced Interior Gateway Routing Protocol for IPv6), in detail.