[c-nsp] Propagating a default route...

Jeff Kell jeff-kell at utc.edu
Tue Sep 30 15:56:19 EDT 2008


Having an issue with BGP... 

I have a border router that can't do full feeds (6500/Sup2) so it is
taking partials (upstream customers).  I am trying to make "decisions"
on which upstream to use as a default route.  For traffic shaping
purposes, I have a server that acts as an eBGP peer to get the path
information to different destinations.  With the path information, I can
look at the AS path for the destination and determine which upstream is
the BGP-preferred peer.

This works great when I have the paths, but I need the current "default"
to trickle down to the shaping server.

If I do a straightforward bgp "peer x.x.x.x default-originate" then the
server gets a default with MY AS number, which is not what I want.  I
want the currently selected default upstream's AS.

The border router is getting a default from the upstreams, and the route
shows up properly with the upstream AS path:

>    Network          Next Hop            Metric LocPrf Weight Path
> *> 0.0.0.0          xx.xx.xx.xx              0             0 nnnn i

I want this to propagate down to the shaping server, but it doesn't show
up (unchanged if I remove default-originate).

I'm not doing any outbound filtering to the shaping server.

I'm already doing "no synch" but it doesn't help.  I think I'm missing
another bit or two.

Ring any bells?

Jeff


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