7.7 Two Ways of Directing Traffic to the Internet

CCNP RS 300-101, Optimizing OSPF Behavior, Uncategorized

… and here they are.

Method 1 – default-information originate

The default-information originate command is configured on an ASBR to inject a default route into the OSPF process, which is flooded as a Type 5 LSA with the route pointed back to the ASBR where it was configured.

Method 2 – Stub Area

A stub area has the following characteristics.

  • Its ABR automatically injects a default route as a Type 3 LSA into the stub area
  • It does not propagate Type 5 LSAs received from an ASBR; it blocks all Type 5 LSAs

Both methods generate a default route. Default routes are the most efficient means of summarization because a single statement can represent many route statements.

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