OSPF and IS-IS: Choosing an IGP for Large-Scale Networks

8.1. SPF Enhancements

Chapter 2 gave you an idea of how an SPF algorithm works. And while that overview is enough to give you an understanding of the SPF algorithm, it is too simplistic for a practical link state protocol implementation. In fact, even if you follow the OSPF and IS-IS standards, you will get an implementation that is workable (if naïve) for small networks, but that lacks the stability, scalability, and accuracy necessary to survive in large-scale networks. For router vendors wanting to market to the largest network operators, sophisticated OSPF and ISIS implementations are essential. Demonstrably robust implementations are a competitive advantage, and as a result, many of the enhancements to the SPF algorithm—and in fact the ...