RE: Retry: OSPF area LSA blocking

From: Jonathan (nomad@gfoyle.org)
Date: Sun Dec 14 2003 - 16:06:57 GMT-3


you wrote:
Hello!

        I'm trying to validate a simple table for understanding which
ospf
area switches block which types of LSAs. I realzie the some of the
combinations may not be possible. Please add/modify/validate.

area nssa blocks Type-5 into non-backbone area

area stub blocks Type-5 and Type-4 into non-backbone area

no-summary blocks Type-4 and Type-3 into non-backbone area
                        generate default-information as Type-3 LSA (into
non-...)

no-redistribution blocks Type-7 into a non-backbone area

TIA,
Alan

= = =

1. Stub area blocks only type 5 LSAs.

2. Totally stubby areas ("no-summary") block types 3, 4, and 5 LSAs with
the exception
of type 3 LSAs to advertise a default route.

3. NSSA areas are the same as stub areas: they block only type 5 LSAs.

4. You are correct about the "no-redistribution" option for the NSSA.

I recommend reading Chapter 9 of "Routing TCP/IP Volume 1" by Jeff
Doyle.



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