From: Cagri Yucel (cyucel@gmail.com)
Date: Fri Oct 13 2006 - 03:38:05 ART
Ok, I remember after watching the diagram for a few minutes :)
The issue is the OSPF default route coming from R3 which is R4's only way to
reach R6. When you aggregate 164.1.0.0/16 is represents a more specific
route to R6 in compate to 0.0.0.0/0. Unfortunately the aggreage as it is
points to null 0 and everything goes down the drain !
Setting internal distance to 255 naturally makes this route unreachable
internally and removes it from the RIB and you again start using the default
from R3.
It was a tricky one !
Hope this helps,
On 10/11/06, msaeed@uaeu.ac.ae <msaeed@uaeu.ac.ae> wrote:
>
> Hello,
>
> R4 in AS100 is sending 164.1.0.0 network using aggregate-address command
> to BB3in AS54, BB3 is accpting it....
>
> R6 in AS200 is sending 164.1.0.0 using aggregate to BB2 in AS254..BB2 is
> accepting that....
>
> now R4 can ping the routes received from BB3, but R6 can not, unless you
> issue the command
>
> bgp distance 20 200 255
>
> and R4 created entry
>
> r> 164.1.0.0 0.0.0.0
>
> then every one in AS200 can ping routes learned from BB3, can any one
> explain whats really happening by preventing 164.1.0.0 to enter RIB of R4
> while I can see that still BB3 and R3 have 164.1.0.0 as normal entry
> in their respective bgp table?
> Or if some one can point me to some document about RIB in BGP....
>
> I appreciate any help.....
>
> Regards,
>
> Mohammad Zahed Saeed
>
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-- -cagri
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