From: Brett Tate <brett@broadsoft.com>
To: "Ali C. Begen (abegen)" <abegen@cisco.com>,
 "mmusic@ietf.org" <mmusic@ietf.org>
Date: Wed, 8 Aug 2012 04:53:41 -0700
Thread-Topic: Draft-ietf-mmusic-rfc4566bis-05: session-level attributes
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Subject: Re: [MMUSIC] Draft-ietf-mmusic-rfc4566bis-05: session-level attributes
Precedence: list

> > Draft-ietf-mmusic-rfc4566bis-05 section 5 indicates the=20
> > following.
> >
> > "In general, session-level values are the default for all=20
> > media unless overridden by an equivalent media-level value."
> >
> > "The connection ("c=3D") and attribute ("a=3D") information=20
> > in the session-level section applies to all the media of=20
> > that session unless overridden by connection information=20
> > or an attribute of the same name in the media description.
> > For instance, in the example below, each media behaves=20
> > as if it were given a "recvonly" attribute."
> >
> > If the attributes are related but with different names=20
> > (such as "inactive" and "sendrecv"), does the attribute=20
> > at the media-level have precedence over the value at the=20
> > session-level?  If so, I recommend that the draft be=20
> > updated to clarify the topic.
>=20
> I believe so. at least that is my understanding from the=20
> text. Does it really need clarification? Thoughts?

I think that it should be clarified because it is unclear if "an attribute =
of the same name" indicates the typical situation or only situation concern=
ing application of "unless overridden by an equivalent media-level value". =
 For instance if I sent "a=3Dinactive" at session-level and "a=3Dsendrecv" =
at media-level, I'd be concerned that the receiver may interpret the SDP as=
 being abnormal (such as including both values at media-level) instead of a=
llowing "a=3Dsendrecv" to override "a=3Dinactive".

In case it matters from an extendibility perspective, requiring the same na=
me might make it easier to recognize the override.  However since section 6=
 already introduces complications with defaulting to "sendrecv" if a new op=
tion is defined/used and unknown, allowing the override even when the names=
 are not the same doesn't make things too much worse; it actually allows co=
mmunication of a backup attribute (such as "a=3Dinactive") if they don't un=
derstand the preferred new attribute (such as "a=3Dfoo").

"If none of the attributes "sendonly", "recvonly", "inactive",=20
and "sendrecv" is present, "sendrecv" SHOULD be assumed as the
default for sessions that are not of the conference type
"broadcast" or "H332" (see below)."

Thanks for the response,
Brett