Chapter 12. Extensions for IPv6

One of the more significant differences between OSPF and IS-ISa difference that you have already observed in the previous three chaptersis that IS-IS is much easier to extend to support new features and capabilities than is OSPF. This difference is nowhere more striking than in the two protocols' support for IP version 6. IS-IS is extended to support this "next generation" of IP through the simple definition of two new TLVs. OSPF, on the other hand, requires an entirely new version: OSPFv3.