NSSA default origination...

[sedhuanand]

Hi,

There are three routers with router id 1.1.1.1 , 2.2.2.2 , 3.3.3.3.

1.1.1.1 is configured as NSSA ABR/ASBR and both 2.2.2.2 , 3.3.3.3 are connected with 1.1.1.1 thru serial link.

I am originating default route for this nssa in 1.1.1.1.

2.2.2.2 is receiving the default from 1.1.1.1 as type 7 LSA with forwarding address as 10.1.1.1 and is installing the default route in the IP Routing table.

3.3.3.3 is also receiving the default from 1.1.1.1 as type 7 LSA with forwarding address as 10.1.1.1 and is not installing the default route in IP Routing table.

3.3.3.3 is recieving the prefix 10.1.1.1/32 as a Type 7 LSA from 2.2.2.2.

If i block the redistribution of 10.1.1.1/32 from 2.2.2.2 , 3.3.3.3 learning the route 10.1.1.0/30 as Intra area route and the default route is also getting installed in the routing table.

Can anyone explain the reason for the above.

Attached the Diagram also.

[sedhuanand]

Please note both 2.2.2.2 and 3.3.3.3 are configured as nssa.

[sundar.palaniappan · Accepted solution]

I am unable to view your topology attachment. Is 1.1.1.1 advertising 10.1.1.1/32 as type 7 LSA to 2.2.2.2. If it is, why is 3.3.3.3 not learning the same LSA from 1.1.1.1. Aren't those two routers directly connected to 1.1.1.1 via serial interface and part of the same NSSA area.

HTH

Sundar

[sedhuanand]

Hi Sundar,

3.3.3.3 is recieving the prefix 10.1.1.1/32 as a Type 7 LSA from 2.2.2.2. 1.1.1.1 originating only default. but the forwarding address in the default orignated is 10.1.1.1 and is being advertised by 2.2.2.2.

[attrgautam]

Anand

Since you see a /32 route, iam assuming it is a PPP link. PPP by default installs a /32 route for the remote IP in the routing table which may be getting redistributed and causing this issue. Suggest you move the link to HDLC or block this route from being generated and let me know if it helps.

no peer neighbor-route

is the command which will do that.