Hi, At first I thought this was because you were seeing the pre-policy routes, but that’s not the case if you’re asking for advertised routes under a neighbour - when I look at advertised routes on ASR9k neighbours where I have prepends in the policy, I see those prepends. You don’t see them if you ask for “route-policy <blah>” though, weirdly.
I can’t see anything wrong with your config - perhaps you can paste the relevant unmodified config, I wonder if your modifications have hidden bugs or something. Note that you left your ASN in anyway, despite doing the MY-AS thing in some places, so, may as well just include it rather than potentially obscuring things ;) -- Nathan Ward > On 20/04/2016, at 16:50, Brian Knight <[email protected]> wrote: > > 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. > > This is our first time configuring these types of MPLS VPNs on IOS XR. > > I've got a config that looks a little something like this: > > -------- > > route-policy BACKUP-IN > apply IPV4-RESERVED-DENY > apply IPV4-DEFAULT-DENY > # For backup, localpref = 350 > # > set local-preference 350 > set community BGP-SITECODE additive > end-policy > > route-policy BACKUP-OUT > # For backup, prepend = 2 > # > # Announce only default route > if destination in (0.0.0.0/0) then > prepend as-path MY-AS 2 > set community BGP-SITECODE > else > drop > endif > end-policy > > router bgp 53828 > neighbor THEIR-IP > remote-as THEIR-AS > address-family ipv4 unicast > default-originate > route-policy BACKUP-IN in > route-policy BACKUP-OUT out > send-community-ebgp > send-extended-community-ebgp > soft-reconfig inbound > maximum-prefix 500 80 restart 1 > > -------- > > The config originates a default route towards THEIR-IP, which is expected. > But the default route that is generated is apparently not influenced by the > BACKUP-OUT policy (prepend MY-AS 2 times). > > RP/0/8/CPU0:AR1.ATL1#sh bgp ipv4 u nei THEIR-IP adv > Wed Apr 20 01:00:39.545 CDT > Network Next Hop From AS Path > 0.0.0.0/0 0.0.0.0 Local i > > What's the simplest way to prepend AS path on a default route advertised to > a single peer? > > A few sources suggest adding a default route to Null0 in our Internet > routing table and advertising it through redistribution, or enter a > "network 0.0.0.0/0" command in the BGP address-family, both of which can be > influenced by route policies. Neither of those options sound particularly > simple to me. > > I have also tried the following to no avail: > > --------- > > route-policy DEFAULT-BACKUP-OUT > prepend as-path 53828 2 > set community BGP-SITECODE > end-policy > > router bgp 53828 > neighbor THEIR-IP > address-family ipv4 unicast > default-originate route-policy DEFAULT-BACKUP-OUT > > --------- > > I'd be grateful for any insight. > > Thanks, > > -Brian Knight > _______________________________________________ > cisco-nsp mailing list [email protected] > https://puck.nether.net/mailman/listinfo/cisco-nsp > archive at http://puck.nether.net/pipermail/cisco-nsp/ _______________________________________________ cisco-nsp mailing list [email protected] https://puck.nether.net/mailman/listinfo/cisco-nsp archive at http://puck.nether.net/pipermail/cisco-nsp/
