As I understand, in case ISP-A would like to peer with ISP-B, the ISP-A usually specifies it's AS-set it will announce to ISP-B? For example in case XS4ALL(xs4all.nl) would like to set up a peering with some other ISP, it will announce AS-ACCESSFORALL, which contains all XS4ALL ASN's. ISP-B should be able to find all those ASN's which are under the AS-set called AS-ACCESSFORAL by:
$ whois AS-ACCESSFORALL | grep member members: AS3265 members: AS1200 members: AS5417 members: AS8283 members: AS20689 members: AS33955 $ Now if ISP-B is interested in all the prefixes which are under those ASN's it could do "whois -h whois.ripe.net -i origin <ASN>" with every ASN under the AS-ACCESSFORAL and manually write the addresses down or do: peval AS-ACCESSFORALL | sed 's/({//;s/})//;s/, /\n/g' | aggregate -q This last command would give: $ peval AS-ACCESSFORALL | sed 's/({//;s/})//;s/, /\n/g' | aggregate -q 46.21.224.0/20 46.23.80.0/20 62.216.0.0/19 62.251.0.0/17 77.73.16.0/21 80.100.0.0/15 80.126.0.0/15 81.24.0.0/20 82.92.0.0/14 82.161.0.0/16 83.68.0.0/19 83.160.0.0/14 91.200.16.0/22 91.208.34.0/24 94.142.240.0/21 95.129.120.0/21 193.104.193.0/24 193.110.157.0/24 193.111.228.0/24 194.109.0.0/16 194.159.72.0/23 194.159.224.0/21 194.217.220.0/22 195.11.224.0/19 195.64.80.0/20 195.69.144.0/22 195.95.150.0/24 195.173.224.0/19 212.238.0.0/16 213.84.0.0/16 213.222.0.0/19 217.194.16.0/21 $ So in case XS4ALL announces it's AS-set AS-ACCESSFORALL(it seems to be the only AS-set for company XS4ALL) to ISP-B, the latter would receive all those prefixes above over the established BGP session. Have I understood this whole concept correctly? Any additional notes/corrections are most welcome! It's not directly Cisco-related question, but hopefully not off-topic as well :) regards, martin _______________________________________________ cisco-nsp mailing list cisco-nsp@puck.nether.net https://puck.nether.net/mailman/listinfo/cisco-nsp archive at http://puck.nether.net/pipermail/cisco-nsp/