OSPF ASBR issue

[kondratev]

The scheme of the network is on the picture. Router A supposes that router D is ABR/ASBR (review show ip ospf border-routers). And router A doesn't see router H as ASBR.

I've checked OSPF databases on routers A and D. Router D doesn't sent LSA type 4 into area 0.

Why router A doesn't suppose that ASBR is router H?

[Harold Ritter]

Andrew,

I looks like router D is redistributing external routes in OSPF, or at least is configured to do so.

As to why router H is not being seen as an ASBR, we would need to see the configuration to find out. Can you please post the ospf configuration for router D and H.

Regards,

[kondratev]

Router D isn't configured to do redistribution. You can find some more 'show' commands in attachements.

[sdoremus33]

Frm rtrD to rtrH issue the following commands

1) Sh ip ospf interface

2) Sh ip ospf data

3) Sh ip ospf neighbor

Could you post some of the output to further investigate. Thanks

[paul.matthews]

Bear in mind your use of areas - you will not see detail from within area 20 in area 0. H is in area 20, D is the ABR between 20 & 0, A is in the backbone.

[kondratev]

You're right. You've described my situation correctly.

I've attached some more 'show' commands to gain a better understanding.

[Harold Ritter]

Andrew,

The reason router D is being seen as both an ABR and an ASBR is that you configured area 20 as NSSA. Router D does the type 7 to type 5 translation and is therefore considered as the ASBR for these external routes.

It is also normal in this case that router H is not seen as an ASBR outside of area 20.

Regards,

[kondratev]

I think that ABR (router D) must send LSA type 4 about ASBRs situated in his area (area 20). But router A doesn't see any LSA type 4. Why? Please correct me, if I'm not right.