Illustrated TCP/IP by Matthew G. Naugle Wiley Computer Publishing, John Wiley & Sons, Inc. ISBN: 0471196568   Pub Date: 11/01/98

Chapter 172
IPv6 Routing

Routing in IPv6 is almost identical to IPv4 routing under CIDR except that the addresses are 128-bit IPv6 addresses instead of 32-bit IPv4 addresses. With very straightforward extensions, all of IPv4’s routing algorithms (OSPF, RIP, IDRP, ISIS, etc.) can used to route IPv6.

IPv6 also includes simple routing extensions that support powerful new routing functionality. These capabilities include:

•  Provider selection (based on policy, performance, cost, etc.)

•  Host mobility (route to current location)

•  Auto-readdressing (route to new address)

The new routing functionality is obtained by creating sequences of IPv6 addresses using the IPv6 Routing option. The Routing option is used by an IPv6 source to list one or more intermediate nodes (or topological group) to be “visited” on the way to a packet’s destination. This function is very similar in function to IPv4’s Loose Source and Record Route option.

OSPFv6 for IPv6, like IPv4, will run directly on top of IPv6. OSPFv6 will run as a separate protocol just like any other “ships in the night” type of protocol in a multiprotocol router. It will have a separate link-state database than OSPFv4. In short, nothing will be shared between OSPFv4 and OSPFv6 (in the router, that is). Each will not know the other exists.

However, in order to make IPv6 operate with OSPFv6, some changes are necessary. Most notably will be the 128-bit address. Router IDs, links, and areas will be associated with an 128-bit number.

RIP made it through as well. How could we forget good old RIP? Hey, it’s still a good, decent protocol for small networks and is very easy to implement. And, with the advent of RIP2, RIP is alive and well. As with the advantage of VLSM with RIP2, the dominance of RIP continues and extensions for 128 bit addressing have been provided.