Re: [MMUSIC] [RFC4566] Increment of SDP session version when NO modification is made to the session data

[Brett Tate <[e-mail]>]

Hi,

> >> If session data is NOT made any change, is session-version acceptable
> >> to increase or it is NOT?
> >
> > As far as I know, RFC 4028 section 7.4 provides the only related
mandate.
> > For interoperability reasons, I recommend being lenient when
receiving.
> >
> > Section 7.4:
> >
> > "It is RECOMMENDED that the UPDATE request not contain an offer [4],
> > but a re-INVITE SHOULD contain one, even if the details of the session
> > have not changed.  In that case, the offer MUST indicate that it has
> > not changed.  In the case of SDP, this is accomplished by including
> > the same value for the origin field as did previous SDP messages to
> > its peer.  The same is true for an answer exchanged as a result of a
> > session refresh request; if it has not changed, that MUST be
> > indicated."
>
> Note that 4028 is only concerned with session timers. IMO its language
is
> confusing and possibly deceptive in some regards. It is *not* intended
to
> refine how offer/answer works - only to comment on how standard O/A
rules
> might best be used for signaling triggered by session timer.

I agree that text only applies to devices that support RFC 4028.  However
AFAIK, it does impose related mandates on devices that support RFC 4028
since the working group decided to use MUST instead of SHOULD.