Subject: [dispatch] A comment on draft-kaplan-dispatch-b2bua-loop-detection

From: Gonzalo Camarillo <[email-masked]>
Date: Thu, 23 Feb 2012 12:57:01 +0200

Hi,

Section 4 of the draft says:

http://tools.ietf.org/html/draft-kaplan-dispatch-b2bua-loop-detection-00#section-4

> 4. B2BUA Loop-Detection Behavior
> 
> 
>    A Proxy-B2BUA, as defined in [draft-b2bua-taxonomy], MUST implement
>    the loop-detection mechanism for the Via header field, as defined
>    for a Proxy in [RFC5393].
> 
>    [Note: should we require all B2BUAs to perform Via-header loop-
>    detection as well, even if they themselves don't forward on the Via
>    headers?]

This requirement needs to go beyond Proxy-B2BUAs. For example, a
Signaling-only B2BUA that happens to inspect message bodies needs to be
required to do loop detection as well.

A better way to scope this requirement could be to say that all B2BUAs
need to perform loop detection and then think of exceptions to the rule
and specify them explicitly if needed. For example, the draft could say
that all B2BUAs MUST perform loop detection *unless* they do not forward
Via headers on. Or using positive language, the draft could say that all
B2BUAs that forward Via headers on MUST perform loop detection.

Cheers,

Gonzalo