Message Session Relay Protocol (MSRP) over Data Channels

This document specifies how a Web Real-Time Communication (WebRTC) data channel can be used as a transport mechanism for the Message Session Relay Protocol (MSRP) and how the Session Description Protocol (SDP) offer/answer mechanism can be used to negotiate such a data channel, referred to as an MSRP data channel. Two network configurations are supported: connecting two MSRP data channel endpoints; and a gateway configuration, connecting an MSRP data channel endpoint with an MSRP over TCP or TLS endpoint. This document updates RFC4975. This document updates RFC4975.