[c-nsp] IBGP Routing Trouble on 6509

[Richard J. Sears]

Hi Oli - 


Here is the sh ip bg on that address space - I just cut it to save a bit
of space...


AR01#show ip bgp 4.36.116.0
BGP routing table entry for 4.36.116.0/24, version 11742246
Paths: (3 available, best #2, table Default-IP-Routing-Table)
  Advertised to update-groups:
     5          8         
  7911 174 21889, (received & used)
    206.71.160.254 (metric 11) from 206.251.233.253 (206.251.233.253)
      Origin IGP, localpref 140, valid, internal
      Community: 6130:17159
      Originator: 206.251.233.42, Cluster list: 206.251.233.0
  7911 174 21889, (received & used)
    206.71.160.254 (metric 11) from 206.251.233.245 (209.112.240.1)
      Origin IGP, localpref 140, valid, internal, best
      Community: 6130:17159
      Originator: 206.251.233.42, Cluster list: 206.251.233.0
  7911 174 21889, (received & used)
    206.71.160.254 (metric 11) from 206.251.233.249 (206.251.233.249)
      Origin IGP, localpref 140, valid, internal
      Community: 6130:17159
      Originator: 206.251.233.42, Cluster list: 206.251.233.0



So my question is that if I show the route in the bgp table and in the
ip routing table and its all correct yet the switch is sending traffic
to someplace its not supposed to, then could there be an issue with the
RIB or FIB tables..?

Could this be an issue of running out of FIB TCAM max routes..? (Mine
still set to default)..?

Thanks



On Tue, 27 Jun 2006 09:05:47 +0200
"Oliver Boehmer \(oboehmer\)" <oboehmer at cisco.com> wrote:

> 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


******************************************
Richard J. Sears
CCNP/CCDP/F5SE
Vice President & CTO         
American Internet Services                          
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http://www.americanis.net
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