Re: [MMUSIC] WGLC on draft-ietf-mmusic-msrp-usage-data-channel-16

[Christer Holmberg <[e-mail]>]

Hi,
    >>>- Added text to make more clear the scope of path and MSRP URI:
    >> 
    >>>Data channels are negotiated independently of the value of the "path" 
    >> attribute. This means that when MSRP messages are transported on a data 
    >> channel, the "path" attribute
    >> 
    >>>is not used for transport negotiation or routing of the messages. MSRP 
    >> endpoints using data channels can set the value of the "path" attribute, 
    >> including the MSRP URI, and use it as described in RFC4975
    >> 
    >> I think we need to be a little more explicit, so I suggest something like:
    >> 
    >> "When MSRP messages are transported on a data channel, the "path" 
    >> attribute is not used for routing of the messages. The MSRP data channel 
    >> is established using the SDP offer/answer procedures defined in 
    >> [I-D.ietf-rtcweb-data-channel], and the MSRP messages are then 
    >> transported on that data channel. Because of that an MSRP endpoint can 
    >> set the MSRP-URI authority value of the "path" attribute at its own 
    >> discretion, following the syntax and rules in [RFC4975]."
    >
    > I'm concerned that this might imply that an msrp(s) URI is not 
    > sufficient information to establish communication. (That some additional 
    > information, received out-of-band, might be a prerequisite.)
    >
    > Do you intend that to be a possible situation?
    >
    > I would hope that it is not - that an msrp(s) URI is sufficient. In that 
    > case, both the transport setup and the path attribute would be derived 
    > from the same source.

    I am not sure I understand....

    The MSRP URI is *not* enough to establish the SCTP association and the data channel. The procedures for establishing a data channel are defined in [I-D.ietf-rtcweb-data-channel], and then each usage have some specific attribute values etc.

   We are not modifying the procedures how to establish a data channel - we are defining how to send MSRP messages over a data channel.

    Regards,

    Christer