RE: [Idr] RFC 4893 - Question regarding AS-TRANS

How would a NEW speaker know whether the peer is genuinely OLD speaker
or it's NEW speaker pretending to be OLD (peer didn't send AS4 support
capability)?

If the session is established with an OLD speaker w/ AS 23456, there are
chances that peer will wrongly detect AS-PATH loops in the updates it
receives from the NEW peer. If all updates are from a NEW speaker w/
4-octet non-mappable AS, none of them would be installed in OLD
speaker's RIB.

OLD speaker's operator has to be aware of such cases. To avoid
consumption of n/w bandwidth and other resources in cases like above, I
was wondering of having the check on NEW speaker side.

Let me know your comments.

Thanks,
Kalpesh

-----Original Message-----
From: Paul Jakma [mailto:paul@clubi.ie] 
Sent: Tuesday, September 25, 2007 1:00 PM
To: Kalpesh Zinjuwadia
Cc: idr@ietf.org
Subject: RE: [Idr] RFC 4893 - Question regarding AS-TRANS

On Tue, 25 Sep 2007, Kalpesh Zinjuwadia wrote:

> Kalpesh: True. OLD speaker DON'T follow the RFC. I meant having the
> check (for OLD peer's AS) on the NEW speaker.

I wouldn't recommend that.

A 'receiving' NEW speaker can't tell if the other side really is OLD, 
or a NEW speaker pretending to be OLD. E.g. imagine if a NEW speaker 
had an option to administratively configure 4/2 bytes on a per 
session basis (e.g. for testing, or as a short-term workaround for 
some implementation issue).

regards,
-- 
Paul Jakma	paul@clubi.ie	paul@jakma.org	Key ID: 64A2FF6A
Fortune:
crop circles in the corn shell

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