Re: Sh IP BGP Sum - T/S the BGP neighbors.

From: James (james@towardex.com)
Date: Wed Jun 23 2004 - 03:04:16 GMT-3

if i am thinking correctly, the bgp session is managed by the Finite State
Machine (FSM), which transitions following states until bgp TCP connection is
established between the peers, in following order:

1. Idle - router waits random time before attempting TCP connect
2. Connect - attempting tcp connection to remote peer
3. Active - connection timedout? wait random time, then go back to step 2.
4. OpenSent - connection is opening.
5. Established - session is up
6. Any Number - session is established and number of bgp prefixes received.

i don't exactly renumber all steps of the FSM, so above may not be 100%
accurate, but you get the idea..

so speaking in english, ifyou see Active, your session is down. most likely
b/c connection is being rejected at one of the routers, or connection is being
timed out or other fatal errors preventing the peering to start.

hope this helps! :)

-James 

-- 
James Jun                                            TowardEX Technologies, Inc.
Technical Lead                        Network Design, Consulting, IT Outsourcing
james@towardex.com                  Boston-based Colocation & Bandwidth Services
cell: 1(978)-394-2867           web: http://www.towardex.com , noc: www.twdx.net

On Wed, Jun 23, 2004 at 03:47:42PM +1000, Devi Mallampalli wrote:
> As part of trouble shooting BGP neighbor relationship problems , Am I
> safe to think that when ever I do not see any "number" under last column
> of "State/PfxRcd" (with sh ip bgp sum command) and that section shows me
> that peer is under ,
> "Active" state , it means that I do not have IP reachability problem
> between peers.
> &
> "Idle" state , it means that I do have IP reachability , but I have some
> sort of configuration problem  under BGP process , i.e. with my
> remote-peer N/W prefix mentioning under BGP process or specifying a
> wrong AS number.
> Thanks for any verification.
> Devi.
> 
> 
> 
> 
> 
> 
> 
> 
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