[c-nsp] IOS XR BGP default route - prepending AS

Adam Vitkovsky Adam.Vitkovsky at gamma.co.uk
Fri Apr 22 08:57:12 EDT 2016

> Brian Knight
> Sent: Wednesday, April 20, 2016 7:51 AM
> At $DAYJOB we use MPLS VPNs from other carriers to provide Internet
> access to customers connected to these VPNs.  There is always a primary
> path for outbound access, plus one or more backup paths.  I am trying to
> configure a backup path, but can't seem to set AS path prepending on the
> default route we announce to the MPLS VPN.
Hi Brian,

Hmm interesting I'm just thinking if it's some weird corner case.
-but you do see the route in BGP table so the policy applied on neighbour out attach point should match on it.

Do you see the default route matching if you do "show bgp route-policy BACKUP-OUT" please?

> default-originate route-policy DEFAULT-BACKUP-OUT
This won't work as the attach point for default-originate is very limited and allows the "set" operation to modify only the MED parameter also the only valid "match" operation is rib-has-route.

Anyways I'd try introducing the default route into BGP via network cmd (would require defining a static default route to null0).


        Adam Vitkovsky
        IP Engineer

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