draft-ietf-l3vpn-as4octet-ext-community-00.txt

[<[e-mail]>]

Yakov, Srihari, Dan,

>From RFC 4893 (BGP Support for Four-octet AS Number Space): "Currently
assigned 2-octet Autonomous System numbers are converted into 4-octet
Autonomous System numbers by setting the two high-order octets of the
4-octet field to zero.  Such a 4-octet AS number is said to be mappable
to a 2-octet AS number."

So it seems that a 2-octet Autonomous System would have two ways to
encode a Route Target or Route Origin:
- using a two-Octet AS Specific Extended Community as defined in rfc4360
(BGP Extended Communities Attribute)
- using a four-octet AS specific extended community as described in
draft-ietf-l3vpn-as4octet-ext-community-00.txt

It looks to me this could create interop issue for BGP/MPLS VPN, even
within a 2 octet AS.

IINM, may I suggest that you add a sentence in the draft to handle such
case? (e.g., mandating the use of *Two*-Octet AS Specific Extended
Community, reserving the "mappable to a 2-octet" AS numbers, ...).

Thanks,
Best regards,
Bruno