5A Data transport

24.3713GPPProtocol specificationRelease 17Stage 3TSWeb Real-Time Communications (WebRTC) access to the IP Multimedia (IM) Core Network (CN) subsystem (IMS)

Tools: ARFCN - Frequency Conversion for 5G NR/LTE/UMTS/GSM

5A.1 General

Data transport is the support of TCP, UDP and the means to securely set up connections between entities, as well as the functions for deciding when to send data: Congestion management, bandwidth estimation and so on.

5A.2 UE

A UE supporting WebRTC shall support the WebRTC non-browser functionality as specified in RFC 8825 [30] clause 4, excluding requirements, if any, relating to specific audio and video codecs that are indirectly referenced within RFC 8825 [30] clause 4.

5A.3 WWSF (WebRTC Web Server Function)

There are no data transport requirements for the WWSF.

NOTE: Any application downloaded from the WWSF that requires data transport is expected to use it in accordance with WebRTC non-browser support of data transport.

5A.4 eP-CSCF (P-CSCF enhanced for WebRTC)

The eP-CSCF and eIMS-AGW in conjunction shall support the WebRTC gateway functionality as specified in RFC 8825 [30] clause 4, excluding requirements, if any, relating to specific audio and video codecs that are indirectly referenced within RFC 8825 [30] clause 4.

The eP-CSCF and eIMS-AGW in conjunction which is expected to be deployed where it can be reached with a static IP address (as seen from the client) do not need to support full ICE; and therefore the eP-CSCF and eIMS-AGW in conjunction may implement ICE-Lite only (specified in RFC 8445 [45]). ICE-Lite implementations do not send consent checks, so the eP-CSCF and eIMS-AGW in conjunction may choose not to send consent checks too, but shall respond to the received consent checks. The eP-CSCF and eIMS-AGW in conjunction with a static IP address is expected to not need to hide its location, so the eP-CSCF and eIMS-AGW in conjunction do not need to support functionality for operating only via a TURN server (specified in RFC 8656 [47]); instead the eP-CSCF and eIMS-AGW in conjunction may choose to produce Host ICE candidates only.

If the eP-CSCF and eIMS-AGW in conjunction serve as a media relay into another RTP domain, the eP-CSCF and eIMS-AGW may choose to support only features available in that network. The eP-CSCF and eIMS-AGW in conjunction do not need to support Trickle Ice (specified in RFC 8838 [43]). However, the eP-CSCF and eIMS-AGW in conjunction shall support DTLS-SRTP (specified in RFC 5764 [6]), since this is required for interworking with WebRTC endpoints.