DSCP Control API

Draft Community Group Report,

This version:
Issue Tracking:


This API defines a control surface for manipulating the network control bits (DSCP bits) of outgoing WebRTC packets.

Status of this document

This specification was published by the Web Platform Incubator Community Group. It is not a W3C Standard nor is it on the W3C Standards Track. Please note that under the W3C Community Contributor License Agreement (CLA) there is a limited opt-out and other conditions apply. Learn more about W3C Community and Business Groups.

1. Introduction

The [WEBRTC] spec defines a "priority" field as part of its RTCRtpEncodingParameters structure, with the possible values "very-low", "low", "medium" and "high".

This specification adds a field to RTCRtpEncodingParameters that allows control over the DSCP markings without affecting local prioritization.

2. IDL specification

partial dictionary RTCRtpEncodingParameters {
    RTCPriorityType networkPriority;  // Note: No default

2.1. networkPriority definition

networkPriority has the same effect as priority, except that it only affects the DSCP markings of the generated packets, as described in [RTCWEB-TRANSPORT] section 4.2.

If networkPriority is unset, the DSCP markings of the generated packets are controlled by the priority member.


Conformance requirements are expressed with a combination of descriptive assertions and RFC 2119 terminology. The key words “MUST”, “MUST NOT”, “REQUIRED”, “SHALL”, “SHALL NOT”, “SHOULD”, “SHOULD NOT”, “RECOMMENDED”, “MAY”, and “OPTIONAL” in the normative parts of this document are to be interpreted as described in RFC 2119. However, for readability, these words do not appear in all uppercase letters in this specification.

All of the text of this specification is normative except sections explicitly marked as non-normative, examples, and notes. [RFC2119]

Examples in this specification are introduced with the words “for example” or are set apart from the normative text with class="example", like this:

This is an example of an informative example.

Informative notes begin with the word “Note” and are set apart from the normative text with class="note", like this:

Note, this is an informative note.


Terms defined by this specification

Terms defined by reference


Normative References

Simon Pieters; Glenn Adams. CSS Object Model (CSSOM). 17 March 2016. WD. URL: https://www.w3.org/TR/cssom-1/
S. Bradner. Key words for use in RFCs to Indicate Requirement Levels. March 1997. Best Current Practice. URL: https://tools.ietf.org/html/rfc2119
Adam Bergkvist; et al. WebRTC 1.0: Real-time Communication Between Browsers. 2 November 2017. CR. URL: https://www.w3.org/TR/webrtc/

Informative References

H. Alvestrand. Transports for RTCWEB. 31 October 2016. Active Internet-Draft. URL: https://tools.ietf.org/html/draft-ietf-rtcweb-transports

IDL Index

partial dictionary RTCRtpEncodingParameters {
    RTCPriorityType networkPriority;  // Note: No default