A Brief Historical Tour

A brief historical review of each protocol might be appropriate here to set the stage for the following discussions. Both Integrated IS-IS and OSPF were specified in the latter part of the 1980s. Around 1988, the United States National Science Foundation Network (NSFnet) deployed an interior gateway protocol based on an early IS-IS draft. Around the same time, development work on OSPF was started. OSPF actually evolved from this early version of IS-IS but with IP as its basic premise. OSPF core concepts, such as the flooding of link-state information, the shortest path first algorithm (SPF) for calculating best paths, use of designated router on broadcast links, and so on were all borrowed from this earlier version of ...

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