Did your transit provider give you a community-string to match - usually their 'AS:arbitrary-number'? Traditionally, what happens is they look for a BGP community string to match and then accept the null route.
So you have a send-community as a neighbor statement with a route-map and prefix-list that is sending your normal traffic: Router bgp (ID) neighbor (IP) send-community neighbor (IP) route-map null-routes out neighbor (IP) prefix-list advertisements out ! route-map null-routes permit 10 match interface Null0 set community (AS):(community-string-to-match) route-map null-routes permit 20 ! ip prefix-list advertisements seq 10 permit (block) ge 32 ! Now, when you add a null route using the following, it will automatically match Null0 and get the BGP-community tag set. It will also allow all other traffic to pass ip route (IP) (Subnet Mask) null0 > Naveen Nathan wrote: >> Hi, >> >> I am new to the list, so please go easy on me. >> >> I'm in need of assistance configuring remote trigger blackhole in >> IOS. This feature is supported by our transit provider. I'm unsure >> if it's working or not, but since the nulled routes don't appear to >> be advertised to the transit peer, I'm assuming not. >> >> I've attached a portion of the cisco-config (substituting sensitive info, >> but it should be easy enough to follow). >> >> Would someone mind suggesting if I'm missing anything of particular >> importance. It would be much appreciated. > > If I understand you correctly, wouldn't one need an extra entry in the > OUTBOUND prefix-list that allows host routes to be advertised to the > transit?: > > ip bgp-community new-format > ! > ip prefix-list NULL seq 5 deny 0.0.0.0/0 le 32 > ! > ip prefix-list OUTBOUND seq 5 permit [BLOCK_B]/22 > ip prefix-list OUTBOUND seq 10 permit [BLOCK_C]/22 > ip prefix-list OUTBOUND seq 15 permit [BLOCK_A]/21 > > ! just an example for illustration... it looks kind of dangerous > ip prefix-list OUTBOUND seq 20 permit 0.0.0.0/0 le 32 > > Steve > -------------- next part -------------- > A non-text attachment was scrubbed... > Name: smime.p7s > Type: application/x-pkcs7-signature > Size: 3233 bytes > Desc: S/MIME Cryptographic Signature > URL: > <https://puck.nether.net/pipermail/cisco-nsp/attachments/20090918/bd4a18be/att > achment-0001.bin> _______________________________________________ cisco-nsp mailing list [email protected] https://puck.nether.net/mailman/listinfo/cisco-nsp archive at http://puck.nether.net/pipermail/cisco-nsp/
