From: Pierre-Alex (pierreg@planetkc.com)
Date: Thu Oct 02 2003 - 10:57:01 GMT-3
Daniel,
The 172.16.151.0 route is not self generated by r2
Here is an example of route self generated by r2, you can see than the
weight is 32768 and notice the keyword "sourced", "local",
R2>sh ip bgp 172.16.121.0
BGP routing table entry for 172.16.121.0/24, version 2
Paths: (1 available, best #1, table Default-IP-Routing-Table)
Advertised to non peer-group peers:
10.5.2.1 172.16.1.11
Local
0.0.0.0 from 0.0.0.0 (2.2.2.2)
Origin IGP, metric 0, localpref 100, weight 32768, valid, sourced,
local, be
st
Cheers,
Pierre-Alex
----- Original Message -----
From: "Daniel Sheedy" <dansheedy@gmx.net>
To: <ccielab@groupstudy.com>
Cc: "Pierre-Alex" <pierreg@planetkc.com>
Sent: Thursday, October 02, 2003 12:22 PM
Subject: Re: BGP confederation metric rule
> Hi Pierre,
>
> I will be the first to put my hand up for the "not too sure on BGP club"
and
> am in the middle of getting up to speed on it, But form this page,
> http://www.cisco.com/univercd/cc/td/doc/cisintwk/ito_doc/bgp.htm
>
> I noticed there were a few other things that it checked before it got to
the
> external/internal comparison.
>
> If the path specifies a next hop that is inaccessible, drop the update.
> Prefer the path with the largest weight.
> If the weights are the same, prefer the path with the largest local
> preference.
> If the local preferences are the same, prefer the path that was originated
> by BGP running on this router.
> If no route was originated, prefer the route that has the shortest
AS_path.
> If all paths have the same AS_path length, prefer the path with the lowest
> origin type (where IGP is lower than EGP, and EGP is lower than
incomplete).
> If the origin codes are the same, prefer the path with the lowest MED
> attribute.
> If the paths have the same MED, prefer the external path over the internal
> path.
> If the paths are still the same, prefer the path through the closest IGP
> neighbor.
> Prefer the path with the lowest IP address, as specified by the BGP router
> ID.
>
> Was one of the paths originated from this router? Or, do they have
> different MEDs? (excuse my ignorance if i am looking at it and cant see
it).
>
> Daniel Sheedy
>
>
>
> ----- Original Message -----
> From: "Pierre-Alex" <pierreg@planetkc.com>
> To: <ccielab@groupstudy.com>
> Sent: Thursday, October 02, 2003 12:39 PM
> Subject: BGP confederation metric rule
>
>
> > BGP metric rules says to prefer BGP confed-external routes over IBGP
> routes.
> > I am getting the contrary.
> >
> > Can anyone put me back on track?
> >
> > Thank you,
> > Pierre-Alex
> >
> > ------------------------------------------------
> >
> > R2>sh ip bgp 172.16.151.0
> > BGP routing table entry for 172.16.151.0/24, version 9
> > Paths: (2 available, best #1, table Default-IP-Routing-Table)
> > Advertised to non peer-group peers:
> > 10.5.2.1
> > (65030)
> > 10.5.1.1 (metric 2185984) from 172.16.1.11 (1.1.1.1)
> > Origin IGP, metric 0, localpref 100, valid, internal, best <-----
> the
> > IBGP route was chosen. Violation of the rule!
> > (65030)
> > 10.5.1.1 (metric 2185984) from 10.5.2.1 (5.5.5.5)
> > Origin IGP, metric 0, localpref 100, valid, confed-external <-----
> > this should have been chosen
> >
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