From: Bit Gossip (bit.gossip@chello.nl)
Date: Sun Jun 24 2007 - 16:03:19 ART
This is true; but how can this influence the selction?
AFAIK: the router running the selection prefers locally originated routes
over learned routes, with locally meaning on the same router performing the
selection.
In this case none of the prefixes is local and both are learned !
Bit.
----- Original Message -----
From: "Edison Ortiz" <edisonmortiz@gmail.com>
To: "Bit Gossip" <bit.gossip@chello.nl>; <ccielab@groupstudy.com>
Sent: Sunday, June 24, 2007 8:34 PM
Subject: Re: BGP Best path selection
>I should've read the whole message before replying :)
>
> 28.119.16.0/24 was locally originated from 204.12.1.254
> while
> 112.0.0.0/8 was locally originated from 54.1.3.254
>
> __
>
> Edison Ortiz
> (Routing & Switching, CCIE # 17943)
>
>
>
> ----- Original Message -----
> From: "Bit Gossip" <bit.gossip@chello.nl>
> To: <ccielab@groupstudy.com>
> Sent: Sunday, June 24, 2007 11:41 AM
> Subject: BGP Best path selection
>
>
>> maybe I should take a break....
>> I can not understand the BGP selection process for these 2 prefixes:
>> -for 28.119.16.0/24 the best next-hop is 204.12.1.254
>> -for 112.0.0.0 instead it is 54.1.3.254
>> Any idea why? The difference seems to be that the path with MED=0 is
>> preferred
>> over the path with missing MED, but I have NOT configured 'bgp bestpath
>> med
>> missing-as-worst' and so missing MED should be treated as MED=0
>>
>> Rack1R6#show ip bgp 28.119.16.0/24
>> BGP routing table entry for 28.119.16.0/24, version 17
>> Paths: (2 available, best #2, table Default-IP-Routing-Table)
>> Flag: 0x820
>> Advertised to update-groups:
>> 1 2
>> 54
>> 54.1.3.254 from 54.1.3.254 (212.18.3.1)
>> Origin IGP, localpref 100, valid, external
>> 54
>> 204.12.1.254 from 204.12.1.254 (31.3.0.1)
>> Origin IGP, metric 0, localpref 100, valid, external, best
>>
>>
>>
>> Rack1R6#show ip bgp 112.0.0.0
>> BGP routing table entry for 112.0.0.0/8, version 4
>> Paths: (2 available, best #2, table Default-IP-Routing-Table)
>> Advertised to update-groups:
>> 1 2
>> 54 50 60
>> 204.12.1.254 from 204.12.1.254 (31.3.0.1)
>> Origin IGP, localpref 100, valid, external
>> 54 50 60
>> 54.1.3.254 from 54.1.3.254 (212.18.3.1)
>> Origin IGP, metric 0, localpref 100, valid, external, best
>>
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