"show bgp command" result?

[fedorafan]

Hi guys, first post here, thank you.

I have the following bgp output which I really don't understand, notice path1 and path2 both have same Origin, metric, localperf, and "AS paths", and path1 learned the path from confed-internal, while path2 are from confed-external, so why path1 (not path2) is the best path?

What else could possible affects the path selection in this case? what should I look for in the router configuration?

routerL#sh ip bgp a.a.a.a

Path #1: Received by speaker 0
(xx53) 6xx 15xx
b.b.b.b (metric 31020) from c.c.c.1 (c.c.m.1)
Origin IGP, metric 0, localpref 100, valid, confed-internal, best
Community: blah blah
Path #2: Received by speaker 0
(xx53) 6xx 15xx
b.b.b.b (metric 31020) from c.c.c.2 (c.c.n.2)
Origin IGP, metric 0, localpref 100, valid, confed-external
Community: blah blah

 

[lerdalt]

I'm a little rusty on some of this, but would need to better understand the confed-internal and confed-external pieces before I make a guess.

 

[unclerico]

Do you know if the Weight attribute has been configured? A sh run of this router would be a good place to start.

I hate all Uppercase... I don't want my groups to seem angry at me all the time! =)
- ColdFlame (vbscript forum)

 

[fedorafan]

i am pretty sure the weight are same, sh ip bgp show the same weight value, anything else I should check?

 

[Belushi]

The BGP decision making process is going farther down the road than what you are seeing in the sh ip bgp command output.

Check out this BGP best path selection algorithm here:

http://www.cisco.com/en/US/tech/tk365/technologies_tech_note09186a0080094431.shtml

You don't see too may people using confederations. Personally I prefer route reflectors to acheive an iBGP full mesh.