draft-ietf-mmusic-sdpng-trans-03.txt

[Ted Hardie <hardie@qualcomm.com>]

DISCUSS

In section 4.1, the document says:

It is RECOMMENDED that implementations recognize the MIME
        multipart/alternative type in SAPv1 announcements, allowing for
        a simple transition to SDPng.


Does this RFC 2119 language echo language in the SAP spec,
or is it introduced here?  In general, are we okay with specs like
this imposing MUST/MAY/SHOULD requirements?  Another
example in this doc is in 4.3.


In section 5, on SDPng and middleboxes it says:

  2)   If entities involved in the respective signaling path use MIDCOM
        protocols (such as STUN) to determine the presence of a NAT and
        its mode of operation, it is up to these entities to include the
        correct addressing information in the SDP or SDPng session
        descriptions.  NATs continue to operate as before and do not
        require any changes because of a migration from SDP to SDPng.


STUN is not a MIDCOM protocol; it was a "pre-MIDCOM" work item
of the working group, and it is not appropriate to call it a MIDCOM
protocol.



Notes:

The draft continually uses TDM, unqualified.  Is this specific to 
SONET/SDH,
or does it apply outside that arena?

In section 3, the draft says


   Additional address families such as ATM or TDM bearers, next
   generation wireless network bearers, DVB channels, etc. can be
   incorporated into SDPng by defining the appropriate extensions for
   the SDPng transports.


This seems to express a design choice that SDPng will have extensions
specific to single-bearer networks.  In many cases (e.g. SIP with 
proxies)
there will be no way to know what the network bearers are.  If these
are limited to specific SDPng use cases, that should be specified.


More nits:

  Finally, RTSP makes special provision to interworking with firewalls
								^to interwork or for interworkin
   by including the crucial transport parameters in a separate RTSP
   header field _in_addition_ to the presentation description.  This
   practice in principle allows to change the presentation description
					  	^missing noun
   format without having to worry about the operation of firewalls and
   similar devices.