Re: [Idr] [GROW] Measurements on Regular, Extended, and Large Communities

Colin Petrie <colin@spakka.net> Mon, 27 April 2020 18:42 UTC

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To: Nick Hilliard <nick@foobar.org>, "Sriram, Kotikalapudi (Fed)" <kotikalapudi.sriram=40nist.gov@dmarc.ietf.org>
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From: Colin Petrie <colin@spakka.net>
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Date: Mon, 27 Apr 2020 20:42:39 +0200
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Subject: Re: [Idr] [GROW] Measurements on Regular, Extended, and Large Communities
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If you are analysing Route-Views table dumps (and not updates) then you 
won't see ECs because Quagga/FRR only dumps selected attributes into the 
MRT files [0]. ECs are not on the list of dumped attributes. LCs were 
added to the list as part of the LC implementation patch.

RIPE's RIS implementation records all the received attributes opaquely 
so you will see ECs in there. They are also present within the 
route-views updates files (as these are dumped raw by Quagga).

Cheers,
Colin

[0]: bgp_dump_routes_attr():
https://github.com/FRRouting/frr/blob/master/bgpd/bgp_attr.c#L4146



On 24-04-2020 15:50, Nick Hilliard wrote:
> Sriram, Kotikalapudi (Fed) wrote on 24/04/2020 14:14:
>> ** Question: Any insights why we don't see any ECs at all? **
> 
> possibilities:
> 
> - there are many types of EC and router config grammar is implemented 
> inconsistently across different platforms, and there's no guarantee that 
> the grammar is capable of expressing anything other than the commoner types
> 
> - they can't handle asn32:asn32, so there's no compelling reason to 
> prefer them over rfc1997 communities.
> 
> - the more common EC types already have specific meanings, e.g. RT/SOO/etc
> 
> I've never seen them in the wild used for generic purposes.  It's always 
> rfc1997, or more recently LC.
> 
> Nick
> 
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