7.6 Summarization on ASBRs

CCNP RS 300-101, Optimizing OSPF Behavior, Uncategorized

Summarization on ASBRs affects Type 5 LSAs. Here are some characteristics of summarization on an ASBR:

  1. The summary will be entered into the ASBRs routing table with a route to null; the null interface ensures that traffic is not forwarded to any subnets that are not defined within the summary range.
  2. Only the summary range will be advertised to OSPF neighbors as a Type 5 LSA.

The command to summarize routes injected from external sources (example):

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