W3C First Public Working Draft,

This version:
Latest published version:
Editor's Draft:
public-webrtc@w3.org with subject line “[webrtc-dscp] … message topic …” (archives)
(Google Inc.)


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

Status of this document

This section describes the status of this document at the time of its publication. Other documents may supersede this document. A list of current W3C publications and the latest revision of this technical report can be found in the W3C technical reports index at https://www.w3.org/TR/.

This document was published by the Web Real-Time Communications Working Group as a Working Draft. This document is intended to become a W3C Recommendation.

If you wish to make comments regarding this document, please send them to public-webrtc@w3.org (subscribe, archives). When sending e-mail, please put the text “webrtc-dscp” in the subject, preferably like this: “[webrtc-dscp] …summary of comment…”. All comments are welcome.

This document is a First Public Working Draft.

Publication as a First Public Working Draft does not imply endorsement by the W3C Membership. This is a draft document and may be updated, replaced or obsoleted by other documents at any time. It is inappropriate to cite this document as other than work in progress.

This document was produced by a group operating under the W3C Patent Policy. W3C maintains a public list of any patent disclosures made in connection with the deliverables of the group; that page also includes instructions for disclosing a patent. An individual who has actual knowledge of a patent which the individual believes contains Essential Claim(s) must disclose the information in accordance with section 6 of the W3C Patent Policy.

This document is governed by the 1 February 2018 W3C Process Document.

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

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. 21 June 2018. 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