Re: Strange behavior in a VRF switch with redistribution

Christopher,

Yes, the tag gets set from the AS number. See RFC 1403 for some interesting
history. I don't know if it's considered some sort of standard but I think
it is the default on most recent Cisco routers, although I normally don't
see BGP redistributed into OSPF. You can always set the tag to 0 with a
route-map.

On Wed, Mar 31, 2010 at 2:22 PM, Christopher Copley
<copley.chris_at_gmail.com>wrote:

> Experts,
>
> I am seeing a strange behavior and it has me purplexed. I have a 6500
> that
> I am running 2 VRF's on (no mpls) to isolate a guest network. On this same
> switch I have BGP running to another site and mutual redist between OSPF
> and
> BGP. No where on the core am I setting any route tags to any routes, but
> when I look at the other side of the WAN circuit I am seeing routes come
> across with the BGP AS# for a route tag.
>
> -D1-WS2#sho ip route 207.16.70.0
> Routing entry for 207.16.70.0/24
> Known via "ospf 1", distance 110, metric 17
> Tag 65534, type extern 1
> Last update from 10.218.80.186 on TenGigabitEthernet1/1, 02:15:42 ago
> Routing Descriptor Blocks:
> * 10.218.80.186, from 10.173.0.194, 02:15:42 ago, via
> TenGigabitEthernet1/1
> Route metric is 17, traffic share count is 1
> Route tag 65534
>
> And if I look at the site with the VRF installed I see the info below
>
> D1-CS1#sho ip route 207.16.70.0
> Routing entry for 207.16.70.0/24
> Known via "bgp 65002", distance 120, metric 27
> Tag 65001, type external
> Redistributing via ospf 1
> Advertised by ospf 1 subnets
> Last update from 1.1.1.1 3d06h ago
> Routing Descriptor Blocks:
> * 1.1.1.1, from 1.1.1.1, 3d06h ago
> Route metric is 27, traffic share count is 1
> AS Hops 1
> Route tag 65001
> MPLS label: none
>
>
> I can only guess this is happening b/c of the VRF's on the 6500. On the
> 6500
> I can also see it has a place for the MPLS label (guess it is b/c of the
> VRF's also? Can any one confirm this type of behavior?
>
> Thanks
> Christopher
>
>
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-- 
Bryan Bartik
CCIE #23707 (R&S, SP), CCNP
Sr. Support Engineer - IPexpert, Inc.
URL: http://www.IPexpert.com
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