[c-nsp] Late night BGP puzzler

[Jeff Fitzwater]

I set a MED value for each peer so that I can control which peer is used 
if they have equal paths.


Jeff Fitzwater
OIT Network Systems
Princeton University

Metz, E.T. (Eduard) wrote:
> If I understand correctly, the cost-community is only considered very
> late in the decision process (among others after as-path, med and
> e-bgp/i-bgp): 
> http://www.cisco.com/en/US/tech/tk365/technologies_tech_note09186a008009
> 4431.shtml 
>
> All these should be equal before the cost-community kicks in..
>
> /Eduard
>
>   
>> -----Original Message-----
>> From: cisco-nsp-bounces at puck.nether.net 
>> [mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of Manu Chao
>> Sent: woensdag 1 augustus 2007 12:38
>> To: pkranz at unwiredltd.com
>> Cc: cisco-nsp at puck.nether.net
>> Subject: Re: [c-nsp] Late night BGP puzzler
>>
>> eBGP prefer to iBGP
>>
>> On 8/1/07, Peter Kranz <pkranz at unwiredltd.com> wrote:
>>     
>>> I can't for the life of me figure out why this won't select 
>>>       
>> path #2 as 
>>     
>>> the best path.. can someone unravel what I'm missing.. My 
>>>       
>> goal is to 
>>     
>>> get it to resolve the equal length AS path dispute using 
>>>       
>> the Cost community.
>>     
>>> Path #1 is from a directly connected upsteam provider, no 
>>>       
>> OSPF Path #2 
>>     
>>> is from a directly connected peer router, OSPF cost 10
>>>
>>> gsr-365-backup#sho ip bgp 6.14.0.0/15
>>> BGP routing table entry for 6.14.0.0/15, version 19026850
>>> Paths: (2 available, best #1, table Default-IP-Routing-Table)
>>>   Advertised to update-groups:
>>>      10
>>>   2914 701 668
>>>     128.241.219.33 from 128.241.219.33 (129.250.0.39)
>>>       Origin IGP, metric 11, localpref 10, valid, external, best
>>>       Community: 2914:420 2914:2000 2914:3000 32354:300
>>>       Extended Community: Cost:igp:1:10
>>>   174 701 668
>>>     204.11.106.1 (metric 11) from 204.11.106.1 (204.11.106.1)
>>>       Origin IGP, metric 0, localpref 10, valid, internal
>>>       Community: 174:21000 174:22013 32354:300
>>>       Extended Community: Cost:igp:1:8
>>>
>>> gsr-365-backup#sho ip route 128.241.219.33 Routing entry for 
>>> 128.241.219.32/30
>>>   Known via "connected", distance 0, metric 0 (connected, 
>>>       
>> via interface)
>>     
>>>   Redistributing via bgp 32354
>>>   Advertised by bgp 32354 route-map point-to-point
>>>   Routing Descriptor Blocks:
>>>   * directly connected, via GigabitEthernet4/16
>>>       Route metric is 0, traffic share count is 1
>>>
>>> gsr-365-backup#sho ip route 204.11.106.1 Routing entry for 
>>> 204.11.106.1/32
>>>   Known via "ospf 1", distance 110, metric 11, type intra area
>>>   Last update from 204.11.106.41 on GigabitEthernet5/1, 00:03:19 ago
>>>   Routing Descriptor Blocks:
>>>   * 204.11.106.41, from 204.11.106.1, 00:03:19 ago, via 
>>>       
>> GigabitEthernet5/1
>>     
>>>       Route metric is 11, traffic share count is 1
>>>
>>> gsr-365-backup#
>>>
>>> Peter Kranz
>>> Founder/CEO - Unwired Ltd
>>> www.UnwiredLtd.com
>>> Desk: 510-868-1614 x100
>>> Mobile: 510-207-0000
>>> pkranz at unwiredltd.com
>>>
>>>
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>>>       
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>>     
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