Best Practices - BGP community to signal transit announces.

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1

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.

[1]http://mailman.nanog.org/pipermail/nanog/2009-November/014767.html

Thanks.

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I am acting as transit for a number of ASNs, and my upstream peers do
filter my announces (as they should as I understand).

Absolutely.

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?

This is a really bad idea, if you tag your customers' prefixes with a 'do transit' community, then the customer leaks, you will tag the extra prefixes, and leak via your transit too.

You must filter your customers based on the data that they put into an agreed RPSL database, and then your transit provider should filter you on the same basis.

Some people shuffle static prefix lists to negotiate their prefix filters. Life is too short for this though. Let computers and databases do the work for you.

Andy Davidson // www.netsumo.com