silly question, but why not ask your provider for a default route in with your feed and simply just propagate it downstream??
Dave. Jon Lewis wrote: > I'd like to be able to conditionally advertise a default route to > customers taking just default routes only if my transit BGP sessions > appear to be functional. > > I thought something like this might work: > > neighbor 10.1.0.2 default-originate route-map BGP-UP > > route-map BGP-UP permit 10 > match as-path 100 > > ip as-path access-list 100 permit ^3356_ > ip as-path access-list 100 permit ^4323_ > > But no such luck. Checking the docs at > > http://www.cisco.com/en/US/docs/ios/12_3/iproute/command/reference/ip2_n1g.html#wp1037042 > > > it seems I have to exactly match against a route for the route-map to > work here. That means actually picking a few "canary routes" I expect > to get from my upstreams and hoping they don't go anywhere or change > mask. I'm not really happy with that. Are there better ways to do this? > > Also, while looking at the docs above and experimenting in the GNS3 > simulator (emulated 2600s running c2600-i-mz.123-26.bin), I've found a > few oddities. > > First, there's multiple errors in the docs mentioned above. i.e. From > the URL above: > > In the following example, the last line of the configuration has been > changed to show the use of an extended access list. The local router > injects route 0.0.0.0 to the neighbor 172.16.2.3 only if there is a route > to 192.168.0.0 with a mask of 255.255.0.0: > > router bgp 50000 > network 172.16.0.0 > neighbor 172.16.2.3 remote-as 60000 > neighbor 172.16.2.3 default-originate route-map default-map > ! > route-map default-map 10 permit > match ip address 1 > ! > access-list 100 permit ip host 192.168.0.0 host 255.255.255.0 > > In the above example, they did change the ACL to an extended > access-list, but the route-map wasn't updated to use it (still using 1) > and they say they're looking for 192.168.0.0 with a mask of 255.255.0.0, > but the access-list 100 uses a /24 mask. > > Just above this example, the docs say that > access-list 1 permit 192.168.0.0 > will match a route for 192.168.0.0 with any mask. In my simulator, I > have R1--R2--R3 > R1 advertises 8.0.0.0/16 to R2. R2 is advertising a conditional default > to R3 using the route-map > > route-map BGP-UP permit 10 > match ip address 50 > > access-list 50 permit 8.0.0.0 > > When R2 receives 8.0.0.0/16 from R1, there are no hits on the ACL and > default is not sent ot R3. If I add to access-list 50 > access-list 50 permit 8.0.0.0 0.0.255.255 > > Standard IP access list 50 > 10 permit 8.0.0.0 (973 matches) > 20 permit 8.0.0.0, wildcard bits 0.0.255.255 > > I get hits on the permit 8.0.0.0 line now, and default is sent to R3. > This seems kind of broken. I haven't duplicated the setup with real > hardware to see if it's a simulator screwup...but since the simulator is > running actual IOS, it seems unlikely the simulator is to blame. > > ---------------------------------------------------------------------- > Jon Lewis | I route > Senior Network Engineer | therefore you are > Atlantic Net | > _________ http://www.lewis.org/~jlewis/pgp for PGP public key_________ > _______________________________________________ > 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/
