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Thanks Imed
The flute-sdp 05 version should be public (see earlier email from me
today). After quite a lot of work figuring out a version to suit all
comments, I'm not too keen on late additions.
However, the proposed text isn't that much and doesn't damage the
existing document and it would help for these "common" parts of an ALC
SDP to be specified in the same way as for a FLUTE SDP. So my initial
reaction is this is OK if there's very rapid consensus (so I could
submit an 06 Friday). If there's disagreement or many key unsolved
issues then I would suggest going through the rigmarole of a separate
RFC since it wouldn't have the 3GPP rel.6 dependency tied to it. So
let's see what others think...
Note, earlier comments have been group initiated so 05 is the first
version that would be stable and "satisfying" enough for WGLC. i.e. if
this ALC stuff gets added, it will certainly be subject to WGLC as for
the rest of the flute-sdp.
Cheers, Rod.
>-----Original Message-----
>From: [email protected] [mailto:[email protected]]
>Sent: 30 January, 2006 17:34
>To: [email protected]; [email protected]
>Subject: [Rmt] SDP descriptors for ALC
>
>Hi All,
>
>I was reading the new version of the "SDP Descriptors for
>FLUTE" I-D and figured out that there is no counterpart for
>this specification to describe ALC sessions.
>As most of the parameters and descriptors should be identical
>for ALC and FLUTE transport protocols, my proposal is to
>create a separate section in the proposed I-D to describe SDP
>descriptors for ALC.
>
>I included below a proposal on how to modify the new version
>of the I-D to fulfill this purpose.
>Any comments or alternative proposals?
>
>Best Regards,
>Imed Bouazizi
>
>---------------------------------------------------------------
>---------
>------------------------
>
>
><3rd sentence is new>
>
>Abstract
>
> This document specifies the use of SDP to describe the parameters
> required to begin, join, receive data from, and/or end FLUTE
> sessions. It also provides a Composite Session SDP media grouping
> semantic for grouping media streams into protocol-specific sessions,
> such as multiple-channel FLUTE sessions. General SDP for
>ALC session
> is also specified, mostly by reusing FLUTE descriptors.
>
>-----
>
>1. Introduction
>
><3rd paragraph, 3rd sentence is new>
>
> This document defines a new protocol identifier for File Delivery
> over Unidirectional Transport (FLUTE) protocol [1] and
>other required
> SDP attributes for initiating a FLUTE session. The formal ABNF
> syntax [5] is used for the attributes. A protocol identifier and
> other SDP attributes are also provided for general underspecified
> ALC-based sessions, reusing the majority of syntax specified for
> FLUTE session descriptions. This SDP syntax is
> independent of Any Source Multicast (ASM) or Source Specific
> Multicast (SSM) is used to route the media.
>
>---
>
><new section>
>
>5. ALC Descriptors
>
> The ALC specification [XX] describes the underspecified ALC
>transport
>
>protocol on which FLUTE is based. Many session characteristics
>of ALC are the same as FLUTE, as both originate from LCT
>session semantics [XX].
>Hence,
>to aid the session description of a fully-specified ALC-based
>transport protocol, and ensure the minimum of difference in
>SDP descriptors for similar parameters, the following rules
>apply to ALC-based transport protocols other than FLUTE.
>
>The descriptors for these parameters for ALC sessions SHALL be
>identical to those for FLUTE sessions, as specified in section 3:
> o Source IP Address
> o Session Timing Parameters
> o FEC Object Transmission Information
> o Content Description Pointer
> o Bandwidth Specification
> o Composite Session Semantics
>
>The descriptors for these ALC parameters differs from those of
>FLUTE and are according to the specification of the following
>subsections:
> o Number of channels
> o Transport Session Identifier
> o Protocol Id
>
>5.1. ALC Protocol Identifier
>
> A new value for the "proto" sub-field for ALC media is defined:
>ALC/UDP. The
> ALC/UDP protocol identifier specifies that the session being
> described will use the underspecified ALC [XX] protocol on
>top of a UDP connection.
>
> The remainder of ALC session media line syntax is the same
>as for FLUTE (section >>3.1<<), with respect to: the fmt
>(format) list and the use of a "*"
>character; and, describing more than one ALC session may be
>described by a single SDP using the Composite Session mechanism.
>
>5.2. Transport Session Identifier
>
> The TSI MUST be described by the "alc-tsi" attribute.
>Otherwise, ALC Transport Session Identifier syntax for ALC
>SHALL be the same as for FLUTE as specified in section >>3.4<<.
>
> The syntax for the attribute in ABNF is given below:
>
> alc-tsi-line = "a=alc-tsi:" tsi CRLF
>
>5.3. Channelisation Descriptors
>
> Destination IP address and port number for ALC channels
>shall be according to the same specification as FLUTE (section
>>>3.6<<) with the one exception that the number of channels
>MAY be signalled using an "alc-ch" attribute that behaves
>exactly like the "flute-ch" attribute (section >>3.6.1<<).
>
> The syntax for the attribute in ABNF is given below:
>
> alc-channel-line = "a=alc-ch:" ch CRLF
>
>5.4. Fully-specified ALC-based Protocols other than FLUTE
>
>Specification of fully-specified ALC-based protocols is beyond
>the scope of this document, as is the specification of
>descriptors specific to such protocols, other than FLUTE.
>
>-----
>
>6.2. Attribute Names
>
><snip to new registrations>
>
> SDP Attribute ("att-field"):
> Attribute name: alc-tsi
> Long form: Underspecified ALC Transport Session
>Identifier
> Type of name: att-field
> Type of attribute: Session level or media level
> Subject to charset: No
> Purpose: See this document
> Reference: This document
> Values: See this document
>
> SDP Attribute ("att-field"):
> Attribute name: alc-ch
> Long form: Number of Channels in an Underspecified ALC
>Session
> Type of name: att-field
> Type of attribute: Session level or media level
> Subject to charset: No
> Purpose: See this document
> Reference: This document
> Values: See this document
>
>-----
>
>
>
>
>
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