On S series switches, why cannot inter-area OSPF route summarization take effect

Question: Why cannot inter-area OSPF route summarization take effect?

Answer: As defined in RFC 2328, when an ABR summarizes inter-area routes, it directly generates a Type 3 LSA regardless of the configured range value. When the ABR summarizes intra-area routes, it generates a Type 3 LSA based on the configured range value.
However, route summarization can cause more LSAs being transmitted into the backbone area, making the network unstable.

Scroll to top