Comparing Integrated IS-IS and OSPF

The increasing popularity of IS-IS has drawn significant attention to its relative merits in camparison with OSPF. The IP networking community has frequently expressed interest in an elaborate comparison between the two protocols, mostly from a practical standpoint. However, very frequently, the IS-IS versus OSPF debate ends up with an academic slantif not religious. Of interest are the similarities and differences between these protocols, as well as any advantages and disadvantages of using one versus the other. The bottom line, however, is that two protocols are so similar, in terms of basic functionality and operation, such that it is really difficult, if not impossible to say, if one is generally better or more efficient than the other. There are many differences, both significant and trivial, that tend to slant advantages toward one over the other for specific applications or in deployment-specific environments.

This section compares Integrated IS-IS and OSPF, identifies major similarities and critical differences as objectively as possible, and tries to refrain from biased comments, such as those frequently witnessed in similar comparisons. The advantages and disadvantages of either protocol are mentioned where possible. The overall goal of this section is to present you with objective facts about each protocol without making any judgments . Network operators seeking to choose IS-IS or OSPF as an IGP should benefit from the following discussions, which should also help clarify any misconceptions or unfounded bias toward either protocol.