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New Member

ABR/ASBR ?

Hi,

I have attached a F/R topology diagram and configs with output from 'sh ip ospf data asbr-routers' command at the end of each config.

I cannot understand why 'Top' & 'Middle' have become ASBR's and not ABR as is the case with 'bottom'.

Also note the metric of 16777215 which suggests to me that the ASBR is light years away !!!

Any help would be appreciated.

PS: I have reloaded the 3 routers giving the same result.

Cheers,

Phil.

6 REPLIES
New Member

Re: ABR/ASBR ?

Can you attach a copy of show ip route of each router?

Hall of Fame Super Gold

Re: ABR/ASBR ?

Phil

I note a couple of things from having looked at the material that you posted. Some of which probably bears on your problem and some of which may not.

My first observation is that the different behavior you are seeing is most likely a reflection of different code that you are running on each router. You did not provide much information about the code versions but top and middle state that they are running some variant of 11.2 and bottom states that it is running some variant of 11.1.

Secondly, as configured, none of the routers are really ASBRs. I wonder if what they are reporting is something that was in the config at some point in the past, that was removed, and which left some vestige in the OSPF data base. Especially when they report:

Length: 28

Network Mask: /0

I wonder if this is some kind of left-over. I wonder if you rebooted all the routers if the behavior would change.

Also I note that the routers are connected by Frame Relay which is configured on the physical serial interface of the router and not on subinterfaces. I note that top has a frame relay map for bottom but not for middle. And I note that middle has a frame relay map for top but not for middle. And middle has no frame relay map for either neighbor. The inconsistency is likely to be problematic.

HTH

Rick

New Member

Re: ABR/ASBR ?

Rick,

Agreed that none of the routers are configured as ASBR's which was really my question, I think they should all be ABR's as is the case with bottom.

I don't think the 'length 28, Netmask: /0' is a remnant from a previous config as I have rebooted on several occasions now generating the same results.

I have standardised the configs to eliminate inverse-arp issues and made all links static mapping and get the same result after cold-start.

I think your first observation will possibly be the issue with the different versions of IOS.

I'm going to copy the 11.1 code that is on bottom over to top and middle to see if that cracks it.

New Member

Re: ABR/ASBR ?

Rick,

Success. I standardised the IOS images to match with 'bottom' i.e the router that hadn't got the ASBR issue and all is working now.

If you stick a quick reply in to this post I will rate your post.

Thanks for your observations.

Phil.

Hall of Fame Super Gold

Re: ABR/ASBR ?

Phil

I am glad that we were able to help find an explanation for your problem.

I hope that you will continue to be active in the NetPro forums.

HTH

Rick

Re: ABR/ASBR ?

Phil,

Can you post the following output from all 3 devices.

1. show ip ospf nei

2. show ip ospf border-routers

Sundar

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