BGP access-list to match default route

[bfooks]

I'm trying to advertise the default received from eBGP peers to iBGP peers but I do not want the iBGP peers to receive all the other routes. What does an access-list that matches a default route look like? Thanks in adavance for help.

[Harold Ritter]

you can use a prefix-list to achieve this goal.

ip prefix-list default seq 10 permit 0.0.0.0/0

router bgp x

neighbor x.x.x.x prefix-list default out

Hope this helps,

[mdavis]

I am looking to do the same thing, allow only the default route to come in via ebgp.

My question is, would the 0.0.0.0/0 be considered an any/any in this scenerio or d would it be interpreted as only the default route?

TIA

[Harold Ritter]

"ip prefix-list test permit 0.0.0.0/0" only matches the default route.

"ip prefix-list permit 0.0.0.0/0 le 32" matches any routes.

Hope this helps,

[bennettba]

Do a "default-originate" to your iBGP peer... you can do it conditionally with a route-map.. If you're multihomed to providers, you could ask your providers to send a default in addition to 0/0.. Then use a routemap to check for the presence of the upstream route... If the route exists, take the upstream path.. if not, take the other.. You can get very creative with this config...