Best Practices - BGP community to signal transit announces.

Patrick Tracanelli eksffa at
Sat Jan 23 17:51:23 UTC 2010

Hello Nanogers,

I am acting as transit for a number of ASNs, and my upstream peers do 
filter my announces (as they should as I understand). Therefore I am in 
the way to set up a community agreement with 'em asking 'em to allow my 
transit announces for a certain community I wil signal 'em up.

Therefore, I have two doubts which I would like to share and hear out 
your opinions.

Is there any best practices or RFC which shall suggest how this 
community should be set up? Say, while I do standardize this community 
to be MY-ASN:1 or MY-ASN:65501, is there a difference? Which community 
numbers should be used for this purpose, if there are any best practice 
for this?

Other than that, I remember Randi Bush's thread on signaling the 
upstream provider with communities, where a "use with caution" warn was 
issued[1]. Therefore, is my scenario a "dont" in the "dos and donts" 
list of practices on signaling the upstreams? If for some reason I 
should avoid setting up a community for that, whats the other better way 
to solve it, instead of asking for all upstream providers, one-by-one to 
allow the transit prefix to be announced via me?

I have searched for their own existing communities and, while some up 
peers do have an adequated community already in place for that, they 
wont allow me to announce prefixes in their communities, and not 
everyone will have a comm for that purpose.



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