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Community Member

Regarding NSSA area

                   Hi

Please refer the attachment of the topology and the here why

Only redistributed IGRP routes will appear in Area 1 and advertised via type 7 LSAs   and why not RIP routes will be advertised.

PLease clarify.

Thanks in advance.

Naveen    

1 REPLY
Cisco Employee

Regarding NSSA area

Hi Naveen,

Only redistributed IGRP routes will appear in Area 1 and advertised via type 7 LSAs   and why not RIP routes will be advertised.

This is because Area 1 is an NSSA area. It can import new external routes into OSPF (unlike a stubby area) but it still keeps its stubby-alike status and does not want to learn about other external networks from the backbone (just like a stubby area). Redistributed RIP routes are known in the backbone as LSA-5, but LSA-5 are not translated back to LSA-7 to be reinjected into the Area 1. This is never done.

So while Area 1 can inject new external routes itself, it does not see (and by its definition of Not So Stubby Area does not want to see) external routes in other areas of the OSPF domain.

Best regards,

Peter

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