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RE: bgp rib failure problem or not? posted 08/26/2007
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RIB failure has nothing to do with whether BGP likes the route or not.
(obviously it does, otherwise it wouldn't try to give it to the routing
table!)

But it has to do with whether the routing table selected it or not.  If you
think this is a problem, let's look at that a different way. 

Any time you use the network command on a connected route, isn't it in "sh
ip route" via connected and not via OSPF, EIGRP or whatever you used?  You
just don't get an indication of RIB failure although you expect it.  ;)
It's still in the routing protocol's RIB.  So they like it!

HTH,

 
Scott Morris, CCIE4 (R&S/ISP-Dial/Security/Service Provider) #4713, JNCIE
#153, CISSP, et al.
CCSI/JNCI-M/JNCI-J
VP - Technical Training - IPexpert, Inc.
IPexpert Sr. Technical Instructor
 
A Cisco Learning Partner - We Accept Learning Credits!
 
smorris@xxxxxxxxxxxx
 
Telephone: +1.810.326.1444 
Fax: +1.810.454.0130
http://www.ipexpert.com
 

-----Original Message-----
From: nobody@xxxxxxxxxxxxxx [mailto:nobody@xxxxxxxxxxxxxx] On Behalf Of Alex
Steer
Sent: Sunday, August 26, 2007 10:44 AM
To: ccielab@xxxxxxxxxxxxxx
Subject: bgp rib failure problem or not?

Hello everyone,



Just got a quick question with regard to BGP RIB failures on internally
known routes installed into BGP via the network command.  I've noticed quite
a few scenarios where this seems to happen and not sure if I'm missing a
trick.  I was hoping somebody would like to enlighten me slightly as to if
it causes some sort of problem I'm not noticing.



Here is the topology/masterpiece of modern art:-



Network1==R1======R2======R3



AS numbers



R1, R2    = 100

R3           = 300



Network1 is known to R1 and R2 via an IGP (say ospf) and via the network
command on R1.



R1s routing table Network1 is known via connected

R2s routing table Network1 is known via ospf

R3s routing table Network1 is known via eBGP (ad20) next hop R2



Network1 is participating in the OSPF process

Network1 is placed in the BGP table on R1 via "network" command





Great so it all works fine.  So my question is, why does BGP on R2 advertise
the route to R3 when it doesn't like the route itself?  Is there a problem
that the RIB failure is causing and I'm not seeing?  It looks to be working
fine, is there another purpose to informing me of the r?



R2#show ip bgp

Network              Next Hop            Metric   LocPrf   Weight
Path

r>i           Network1/24     Router1                0              100
0                                              i



R3#show ip bgp

Network              Next Hop            Metric   LocPrf   Weight
Path

*>i          Network1/24     Router2                0              100
0                              100         i



By the way I made all of the output up as my lab is off so forgive any
slight mistakes.  It's only to aid in posing my question.

Many thanks for any info on this.



Kind regards



Alex


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