[c-nsp] IBGP Routing Trouble on 6509

[Oliver Boehmer (oboehmer)]

Richard J. Sears <> wrote on Tuesday, June 27, 2006 3:53 AM:

[..]
> So lets assume that the performance routing hardware says to send
> 4.36.116.0/24 to AS7911.
> 
> When I issue a sh ip ro 4.36.116.0 I get this:
> 
> AR01#sh ip ro 4.36.116.0
> Routing entry for 4.36.116.0/24
>   Known via "bgp 6130", distance 200, metric 0
>   Tag 7911, type internal
>   Last update from 206.71.160.254 01:11:36 ago
>   Routing Descriptor Blocks:
>   * 206.71.160.254, from 206.251.233.245, 01:11:36 ago
>       Route metric is 0, traffic share count is 1
>       AS Hops 3
>       Route tag 7911
> 
> And a sh ip bg 4.36.116.0:
> 
> AR01#sh ip bg | i 4.36.116.0
> * i4.36.116.0/24    206.71.160.254                140      0 7911 174
> 21889 i 
>
> the route appears correctly in the routing table, and doing a sh ip
> bgp shows the correct local_pref, netblock and nethop IPs.

Can you post "show ip bgp 4.36.116.0" in total? Wonder why there is no
">" in front of the prefix.. possibly received from multiple neighbors?

> 
> Now the real weird part - if I traceroute to that netblock from the
> 6509, it goes the correct path, if I traceroute from a machine
connected to
> the 6509, it fails, bouncing between my 6509 and one of my backbone
> routers.

This is strange. You can check
http://www.cisco.rw/en/US/products/hw/switches/ps700/products_tech_note0
9186a00804c5472.shtml for some info to troubleshoot CEF/MLS on the 6509
to see the forwarding plane. I.e. "show ip cef 4.36.116.0", "show mls
cef 4.36.116.0", etc.

	oli