04-24-2008 08:38 AM - edited 03-03-2019 09:41 PM
I have a issue here currently I have a BGP connection one in Dallas and the other in Ft. Worth. The way it is set up is that Ft. Worth is the primary and Dallas is the back. So I have local preference set up on the Dallas router so that traffic will go out Ft. Worth and if Ft. Worth is gone then traffic will reroute through Dallas. The issue is on the Dallas router I have set up another BGP connection but due to the local preference that is already there I can see that my routing table for this particular ip address 205.248.197.209 bounce between Ft. Worth and Dallas. I thought I could remedy this by using a route filter but it still isn't working is there any way I can over ride this?
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04-25-2008 07:16 AM
Warren
The additional information does show that you are receiving an advertisement for the /32 route from that neighbor (among others). And it does not show the weight being applied. In thinking about why it does not show with weight I wonder if it was learned before you applied the weight. Would you do a reset on that neighbor to relearn the prefixes advertised by the neighbor and then do sh ip bgp 205.248.197.209 and post the output.
HTH
Rick
04-24-2008 09:31 AM
Warren
In general I would think that if you were to configure weight on the new BGP connection in Dallas then Dallas would be able to use those routes since weight is earlier in the BGP decision process than local preference.
If that does not seem to solve your issue then perhaps you could provide some additional details of how BGP is configured on both routers.
HTH
Rick
04-24-2008 10:59 AM
Warren:
Weight is a Cisco-proprietary BGP attribute, so if you're working in a multivendor environment you should work with another attribute to influence path selection.
Victor
04-24-2008 11:04 AM
Thanks guys for the info but the other end is a cisco as well I tried using weight but I think I'm doing it wrong as it didn't work. Trying to find some docs on it now.
04-24-2008 11:40 AM
Warren
Weight should work. Perhaps you can post what you have configured and we can suggest how to improve it.
HTH
Rick
04-24-2008 11:52 AM
Thank you for the help, the one in blue is the new BGP connection I've added today. Sorry I took off the weight statement as when
I did it it didn't work so I removed it.
04-24-2008 12:00 PM
Warren
I looked at what you posted. But without seeing how you had attempted to configure weight, we can not know why it did not work.
It might also be helpful to see the prefix list that is applied to these neighbors.
HTH
Rick
04-24-2008 12:18 PM
ok I think all I did for the weight statement was add:
neighbor 168.162.60.209 weight 200
here is everything....
04-25-2008 04:30 AM
Warren
Thanks for the additional information. This looks reasonable. The routes learned from that neighbor should have weight applied. And the prefix list does permit 205.248.197.209/32. Are you sure that the neighbor is advertising this as a /32?
It would be helpful if you have the weight command in the config to post the output of show ip bgp 205.248.197.209 and of show ip route 205.248.197.209.
HTH
Rick
04-25-2008 05:41 AM
Hi Rick thank you for taking the time to look into this here are the show commands as requested. For the weight command it is already in there unless I did it wrong. Please see attached for the output commands
as a work around I have added static routes till we figure this out.
04-25-2008 07:16 AM
Warren
The additional information does show that you are receiving an advertisement for the /32 route from that neighbor (among others). And it does not show the weight being applied. In thinking about why it does not show with weight I wonder if it was learned before you applied the weight. Would you do a reset on that neighbor to relearn the prefixes advertised by the neighbor and then do sh ip bgp 205.248.197.209 and post the output.
HTH
Rick
04-25-2008 07:31 AM
Hi Guys;
Thank you all for your help!!!! I don't know what the difference is between now and yesterday but I reset the routes again and now I its going over the right way. Thank you agian for all your help....here is the output after I reset BGP:
sfschirt4#sh ip bgp 205.248.197.209
BGP routing table entry for 205.248.197.209/32, version 92997
Paths: (4 available, best #2, table Default-IP-Routing-Table, Advertisements suppressed by an aggregate.)
Not advertised to any peer
Local
172.19.200.4 (metric 5) from 172.19.103.30 (172.19.103.30)
Origin incomplete, metric 1, localpref 100, valid, internal
64940
168.162.60.209 from 168.162.60.209 (168.162.60.209)
Origin IGP, localpref 100, weight 500, valid, external, best
Extended Community: RT:7381:4169
64940, (received-only)
168.162.60.209 from 168.162.60.209 (168.162.60.209)
Origin IGP, localpref 100, valid, external
Extended Community: RT:7381:4169
64940, (received & used)
168.162.60.213 from 168.162.60.213 (168.162.60.213)
Origin IGP, localpref 100, valid, external
Extended Community: RT:7381:4169
04-25-2008 07:20 AM
What's the origin of this host route? OSPF, right? Can you sh ip route and sh ip bgp for your other router? It looks like eBGP feeds back the route back to you..it should not as AS PATH should prevent that...
serg
04-25-2008 07:57 AM
Thanks Serg for chiming in as well I appreciate your assistance
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