Subject: Re: [GROW] New Version Notification for draft-ymbk-grow-bgp-collector-communities-01.txt

From: Emile Aben <[email-masked]>
Date: Mon, 5 Oct 2015 13:17:14 +0200

On 08/09/15 17:15, Job Snijders wrote:
> On Tue, Sep 08, 2015 at 05:05:48PM +0200, Randy Bush wrote:
>>>> I do not feel comfortable overloading locally administrated bits with
>>>> something that represents global significance. The 64xxx communites
>>>> come dangerously close to codepoints we use internally. I'd prefer
>>>> that the local portion of BGP Communities remains truely local.
>>>
>>> only problem is that completely blows the purpose of the exercise, a
>>> global tagging to help ops and researchers be more sure of what they
>>> are seeing in the collectors.
>>
>> i think i misunderstood you.  you are suggesting using 42-44 or
>> whatever, not 65000 space.  sure.  i do not care what the numbers
>> are.
> 
> I suggest to take the codepoint(s) from 0xFFFF0000 - 0xFFFFFFFF
> http://www.iana.org/assignments/bgp-well-known-communities/bgp-well-known-communities.xhtml
> as we then at least have made the most effort to avoid clashes with
> locally significant values.
> 
> At the very least I see operational value in having a well-known
> community to tag "customer" prefixes with, this is something I'd use
> internally, in public documentation and BCOPs/guides how to set up a BGP
> transit network. A "CUSTOMER" community could benefit a group braoder
> then the research community.

Proposal specifically is about 16-bit (not 32-bit) values, because it's
useful to have the first half be the (16 bit) ASN to which this
information applies, ie. <asn>:<color>. This allows route-collectors to
also collect this type of information from networks other then their
direct peers (modulo bgp selection process, community-stripping).

Also if you'd go 32-bit community, because BGP communities are optional
transitive, they can easily leak, simple scenario:
- 32bit community for tagging customer cone becomes standard
- your peer decided to put the 32bit community on all of their customer cone
- you receive this feed from your peer
- you don't strip the 32bit community either on entrance or exit
- result: your competitors customer cone appears tagged as your customer
cone to a route collector

cheers,
Emile