Abstract: Internet has become an integral part of our life, and it is important to have routing protocols that arc effective and stable. IS-IS is a major interior gateway protocol which is applied in some large networks widely. We researched the IS-IS interoperability testing, and established a layered IS-IS protocol interoperability testing interactive model based on the Extended Petri Net. Then we analyzed the Petri net model by using the reachability graph. According to test purpose and generated test sequences, we programed test cases and took some necessary test cases manually as a complement of the test set, Finally, we built the test platform for interoperability testing, and analyzed the test results.

Key words: IS-IS, Interoperability testing, Petri net, GNS3