| Internet-Draft | RoQ Candidates for ICE | January 2026 |
| Dawkins | Expires 26 July 2026 | [Page] |
This document describes the use of Interactive Connectivity Establishment (ICE) procedures to select candidate paths for use with RTP over QUIC (RoQ).¶
This note is to be removed before publishing as an RFC.¶
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This document describes the use of Interactive Connectivity Establishment (ICE) procedures ([RFC8445]) to select candidate paths for use with RTP over QUIC (RoQ) ([I-D.ietf-avtcore-rtp-over-quic]).¶
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all capitals, as shown here.¶
(Note to RFC Editor: if this document ever reaches you, please remove this section)¶
SDP for RoQ is defined in a separate document [I-D.draft-ietf-avtcore-sdp-roq], which mentions use of ICE with RoQ. This document describes how RoQ implementations would use ICE candidates as part of RoQ RTP session setup. That description might reasonably be folded back into [I-D.draft-ietf-avtcore-sdp-roq] at some point, but is currently separated to allow QUIC experts and ICE experts to review the description without having to excavate it as part of a larger specification.¶
This document has not yet been adopted by any IETF working group, so does not carry any special status within the IETF.¶
The QUIC transport protocol ([RFC9000]) is encapsulated in UDP ([RFC768] and [RFC2460]), so in theory, a RoQ endpoint could use the ICE procedures described in [RFC8445] to identify candidate endpoint addresses and choose among them, and then attempt to open a QUIC connection allowing use of RoQ to carry RTP media.¶
While that would work in theory, in practice, the potential for confusion between an RTP endpoint expecting to use UDP encapsulation and an RTP endpoint expecting to use RoQ encapsulation make this a bad idea.¶
This specification defines a new ICE Transport Protocol (Section 6), so that RTP endpoints can distinguish between non-RoQ flows and RoQ flows, and provides additional application considerations (Section 4) when ICE is used for RoQ flows.¶
The intention for ICE usage to identify RoQ candidates is that it should be as similar as possible to ICE usage to identify UDP candidates ([RFC8445]). "As similar as possible" does not mean "identical", so the relevant differences are described in Section 4.¶
The reason for defining a new ICE Transport Protocol identifier is to allow ICE endpoints to distiguish between candidates for RTP media flows encapsulated in UDP and candidates for RTP media flows encapsulated in RoQ. Without a new ICE Transport Identifier, it is difficult to tell the difference, because RoQ is encapsulated in QUIC, and then in UDP.¶
Because UDP is very close to a null transport protocol (allowing port multiplexing, but not much more), and QUIC is a modern transport protocol, there are differences that application developers need to be aware of, in ICE candidate selection. These differences are described in this section.¶
Editor's Note: The following subsections are very much works in progress!¶
The description for gathering candidates in Section 4.1 of [RFC6544] includes a number of helpful considerations that would also apply to RoQ endpoints, including, for instance, deciding whether it is preferable to have no media at all, rather than to have media over TCP. Wise implementors will study those considerations carefully.¶
The recommended formula for candidate type preferences, referenced in Section 4.2 of [RFC6544] and described in Section 5.1.2.1 of [RFC8445] SHOULD also be used for RoQ candidates.¶
Editor's Note: Section 4.2 of [RFC6544] suggests recommended candidate type preferences for NAT-assisted candidates (105) and UDP-tunneled candidates (75). Are RECOMMENDED candidate type preferences useful for RoQ candidates?¶
Editor's Note: Section 5 of [RFC6544] provides a helpful outline for techniques that can be used to obtain candidates for use with ICE RoQ, but we still need to go through the details (for example, do we need to make recommendations about use of TURN-IPv6, Teredo, or SOCKS IPv4-IPv6 gatewaying for obtaining IPv6 RoQ candidates? The recommendations for ICE-TCP date from 2012!)¶
The procedure described in Section 6 of [RFC6544] for receiving the initial offer and answer also apply for RoQ, except that RoQ candidates are encoded as described in Section 3 and Section 4 of [I-D.draft-ietf-avtcore-sdp-roq].¶
Because RoQ is also connection-oriented, the possibility described in Section 6.1 of [RFC6544] for an ICE offerer to initiate a QUIC connection to carry RoQ media sessions on a selected candidate pair in parallel with ICE-lite operation also applies, if the offerer is using the a=setup:active attribute. When this is the case, the requirements that the answerer accept that offer and repspond to it while keeping the already-created connectionin that section also apply to RoQ.¶
Editor's Note: Harald Alvestrand notes that QUIC doesn't have peer-to-peer extensions specified, so the client end of the connection will have to specify port 9 (discard), meaning that it can do outgoing QUIC but not incoming QUIC over this UDP port pair. What other implications follow from this limitation?¶
The Security Considerations contained in [RFC8445], [RFC6445], [RFC9000], and ([I-D.ietf-avtcore-rtp-over-quic]) are included here by reference.¶
IANA has created a sub-registry "ICE Transport Protocols" in the "Interactive Connectivity Establishment (ICE)" registry for ICE candidate-attribute transport extensions. This specification adds the "RoQ" token to that registry.¶
| Token | Reference |
|---|---|
| RoQ | (This Specification Section 6) |
This draft builds on considerable previous work that resulted in the base "Interactive Connectivity Establishment (ICE)" specification ([RFC8445]) and the related "TCP Candidates with Interactive Connectivity Establishment (ICE)" specification [RFC6544]. The author of this specification owes those authors many thanks.¶