something strange about bgp community

[ML]

Also note there is nothing stopping anyone from adding any community 
they want.
The effect and how long the community stays attached to a route is 
another matter.


On 1/7/2015 8:35 AM, Song Li wrote:
> Hi everyone,
>
> Today when I check one route in Routeviews I find something strange as 
> follows:
>
> route-views>sh ip bgp 176.108.0.0
> BGP routing table entry for 176.108.0.0/19, version 23405621
> Paths: (33 available, best #28, table default)
>   Not advertised to any peer
>   Refresh Epoch 1
>   202018 35320 35320 57800
>     5.101.110.2 from 5.101.110.2 (5.101.110.2)
>       Origin IGP, localpref 100, valid, external
>       Community: 702:120 2914:429 20485:52990 20485:53990 20485:54040 
> 20485:54050 47541:10001
>       rx pathid: 0, tx pathid: 0
>
> the AS-Path is "202018 35320 35320 57800" but the community is 702:120 
> 2914:429 20485:52990 ....
>
> According to RFC 1997, the community format is AA:NN and AA means the 
> AS#. Here, AS702, AS2914 and AS20485 do not appear in the AS-Path and 
> as a result they should not appear in the community. Could anybody 
> tell me what's the reason they do appear in the community of this route?
>
> Thanks!
>