fredrikjj wrote: »
The only somewhat complicated situation is when a non-backbone area has an ASBR, and another non-backbone area wants to reach an external destination advertised by that ASBR.
Area 2's ABR (router C) will need to generated a new type 4 LSA by combining the metric found in the type 4 advertised by router B and its own intra-area cost to reach B.
OfWolfAndMan wrote: »
Forgot to mention that as well. The primary reason for implementing an NSSA/TNSSA area!
Danielh22185 wrote: »
The Type 4 LSA does represent the external routes (in a matter of speaking) but it's representing the path to the ASBR only that contains the external routes (Type 7). So if thinking in terms of the OSPF backbone the ABR is the responsible one that ONLY generates TYPE 4 LSAs.