Ron, > Ron Grant wrote : > The biggest technical problem with 4-byte ASNs that I'm aware of comes when > propagating BGP communities > - AFAIK even with extended communities, you can't specify two 4-byte ASNs in > a single community. [..] > Recently we ran into this problem when requesting an ASN for the Vancouver > Internet Exchange (VANIX) > - we were told there were no 2-byte ASNs left, so we went back to the drawing > board to see how we could > run our Route Server with a 4-byte ASN, and after wrestling with the problem > for a few weeks, went back > to ARIN and...joy!...someone had returned a 2-byte, which we obtained for the > RS.
Would you have technical specifics about the problems you ran into using a 4-byte-ASN ? Such as the OS / platform / software used for the Route Server and which configurations items / scripts did not work ? I acknowledge that 4-byte-ASN support is not what I expected it to be; it is clear / justified that people will prefer 2-byte ASNs for a while as they require no change to what they are used to. That being said, I think it would be of interest to the ARIN community to have a clear view of the technical issues using 4-byte-ASNs WRT BGP communities. I am in the process of deprecating 65532:666 in favor of RT:4200065532:666. It is a LOT of work. Below is my personal view using Cisco IOS 15.x and the cheat-sheet I use. I would like the cheat-sheet for other platforms. Michel. (config)#ip bgp-community new-format Nothing new about that, we used it on a 2500. What it means is that the format is AS16:value, (16 bits each) instead of being a 32-bit integer. Example : AS 65532, value 666 : the community is 65532:666; one can assign more than one community to a prefix. (config-route-map)#set community 65532:666 65532:667 -> OK (config-route-map)#set community 65532:666 additive -> OK Problem : 4-byte ASNs are 32-bit not 16, duh. Solution, (on paper) : extended communities. Cisco-specific issue : if the desired community is related to the originating AS, one can have only one community per prefix, which possibly is the issue you mentioned in the first place. (config-route-map)#set extcommunity soo 4200065532:666 4200065532:667 ^ % Invalid input detected at '^' marker. (config-route-map)#set extcommunity soo 4200065532:666 additive ^ % Invalid input detected at '^' marker. Way around it : use RT (target AS) instead of SoO. (config-route-map)#set extcommunity rt 4200065532:666 4200065532:667 -> OK (config-route-map)#set extcommunity rt 4200065532:666 additive -> OK #sh ip bgp x.x.x.x BGP routing table entry for x.x.x.x/32, version 4 Paths: (1 available, best #1, table default) Advertised to update-groups: zz Local 192.0.2.1 from y.y.y.y (y.y.y.y) Origin IGP, localpref 100, weight 1, valid, internal, best Community: 65532:666 65532:667 Extended Community: RT:4200065532:666 RT:4200065532:667 It works, and propagates correctly (shows the same on peers). Cheat-sheet for Cisco : +-----------------------------------------+-----------------------------------------------+ | AS 16 bit | AS 32 bit | +-----------------------------------------+-----------------------------------------------+ | set community ASN16:value1 ASN16:value2 | set extcommunity RT ASN32:value1 ASN32:value2 | | set community ASN16:value1 additive | set extcommunity RT ASN32:value1 additive | | match community | match extcommunity | | ip community-list standard | ip extcommunity-list standard | +-----------------------------------------+-----------------------------------------------+ _______________________________________________ PPML You are receiving this message because you are subscribed to the ARIN Public Policy Mailing List (ARIN-PPML@arin.net). Unsubscribe or manage your mailing list subscription at: http://lists.arin.net/mailman/listinfo/arin-ppml Please contact i...@arin.net if you experience any issues.