> > What happens, if the IXP uses a 4-byte ASN? RFC5668 (4-Octet AS Specific > BGP Extended Community) defines <Global Admin,4bytes>:<Local Admin, > 2bytes>. > > I have been asking some IXP operators, about their practice and their > reply was "4-byte ASNs are supported by our RS". What's your experience? > Did you see IXPs, that do not support them? Do you think, the IXP > operators are aware of this limitation? Have you seen IXPs with 4-byte > ASNs or do RIRs reserve 2-byte ASNs for future IXPs? What other > operational problems did you experience while using 4-byte ASNs? >
Do you see an issue with future IXP or future IXP members ? You can see at this list of members of one IXP that there are both 2-byte and 4-byte ASNs living in harmony, with a large number of 4-byte ones: http://ptt.br/particip/sp The IXP itself is using a 2-byte public ASN, so if at some point communities are used (although there are route-servers capable of granular policy without communities), they could use standard 2-byte community format. And with a bit coordination, 2-byte private ASNs and communities could be used to overcome limitations in member routers support of 4-byte ASNs. Rubens telnet lg.sp.ptt.br Trying 200.160.1.3... Connected to lg.sp.ptt.br. Escape character is '^]'. ============================================== = PTTMetro SP = = Contact: e...@ptt.br = = +55 11 5509-3550 = = inoc-dba: 22548*100 = = = = Looking Glass Server = = All connections and keystrokes logged = ============================================== lg.sp.ptt.br> show ip bgp summary BGP router identifier 187.16.218.252, local AS number 20121 RIB entries 32868, using 3081 KiB of memory Peers 4, using 18 KiB of memory Neighbor V AS MsgRcvd MsgSent TblVer InQ OutQ Up/Down State/PfxRcd 187.16.216.253 4 26162 3294906 1619885 0 0 0 05w0d23h 19247 187.16.216.254 4 26162 3468468 1617924 0 0 0 01w5d06h 19227 Total number of neighbors 2
