Interactive Connectivity Establishment (ICE): A Protocol for Network Address Translator (NAT) Traversal for Offer/Answer Protocols
RFC 5245
| Document | Type |
RFC - Proposed Standard
(April 2010; Errata)
Obsoleted by RFC 8445
Updated by RFC 6336
|
|
|---|---|---|---|
| Author | Jonathan Rosenberg | ||
| Last updated | 2020-01-21 | ||
| Stream | IETF | ||
| Formats | plain text html pdf htmlized with errata bibtex | ||
| Reviews | |||
| Stream | WG state | WG Document | |
| Document shepherd | No shepherd assigned | ||
| IESG | IESG state | RFC 5245 (Proposed Standard) | |
| Consensus Boilerplate | Unknown | ||
| Telechat date | |||
| Responsible AD | Cullen Jennings | ||
| Send notices to | fluffy@cisco.com, behave-chairs@ietf.org, philip_matthews@magma.ca | ||
Internet Engineering Task Force (IETF) J. Rosenberg
Request for Comments: 5245 jdrosen.net
Obsoletes: 4091, 4092 April 2010
Category: Standards Track
ISSN: 2070-1721
Interactive Connectivity Establishment (ICE):
A Protocol for Network Address Translator (NAT) Traversal for
Offer/Answer Protocols
Abstract
This document describes a protocol for Network Address Translator
(NAT) traversal for UDP-based multimedia sessions established with
the offer/answer model. This protocol is called Interactive
Connectivity Establishment (ICE). ICE makes use of the Session
Traversal Utilities for NAT (STUN) protocol and its extension,
Traversal Using Relay NAT (TURN). ICE can be used by any protocol
utilizing the offer/answer model, such as the Session Initiation
Protocol (SIP).
Status of This Memo
This is an Internet Standards Track document.
This document is a product of the Internet Engineering Task Force
(IETF). It represents the consensus of the IETF community. It has
received public review and has been approved for publication by the
Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of RFC 5741.
Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
http://www.rfc-editor.org/info/rfc5245.
Rosenberg Standards Track [Page 1]
RFC 5245 ICE April 2010
Copyright Notice
Copyright (c) 2010 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
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described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 6
2. Overview of ICE . . . . . . . . . . . . . . . . . . . . . . . 7
2.1. Gathering Candidate Addresses . . . . . . . . . . . . . . 9
2.2. Connectivity Checks . . . . . . . . . . . . . . . . . . . 11
2.3. Sorting Candidates . . . . . . . . . . . . . . . . . . . 12
2.4. Frozen Candidates . . . . . . . . . . . . . . . . . . . . 13
2.5. Security for Checks . . . . . . . . . . . . . . . . . . . 14
2.6. Concluding ICE . . . . . . . . . . . . . . . . . . . . . 14
2.7. Lite Implementations . . . . . . . . . . . . . . . . . . 16
3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 16
4. Sending the Initial Offer . . . . . . . . . . . . . . . . . . 19
4.1. Full Implementation Requirements . . . . . . . . . . . . 19
4.1.1. Gathering Candidates . . . . . . . . . . . . . . . . 19
4.1.1.1. Host Candidates . . . . . . . . . . . . . . . . . 20
4.1.1.2. Server Reflexive and Relayed Candidates . . . . . 20
4.1.1.3. Computing Foundations . . . . . . . . . . . . . . 22
4.1.1.4. Keeping Candidates Alive . . . . . . . . . . . . 22
4.1.2. Prioritizing Candidates . . . . . . . . . . . . . . . 22
4.1.2.1. Recommended Formula . . . . . . . . . . . . . . . 23
4.1.2.2. Guidelines for Choosing Type and Local
Preferences . . . . . . . . . . . . . . . . . . . 23
4.1.3. Eliminating Redundant Candidates . . . . . . . . . . 25
4.1.4. Choosing Default Candidates . . . . . . . . . . . . . 25
4.2. Lite Implementation Requirements . . . . . . . . . . . . 25
4.3. Encoding the SDP . . . . . . . . . . . . . . . . . . . . 26
5. Receiving the Initial Offer . . . . . . . . . . . . . . . . . 28
5.1. Verifying ICE Support . . . . . . . . . . . . . . . . . . 28
5.2. Determining Role . . . . . . . . . . . . . . . . . . . . 29
5.3. Gathering Candidates . . . . . . . . . . . . . . . . . . 30
5.4. Prioritizing Candidates . . . . . . . . . . . . . . . . . 30
5.5. Choosing Default Candidates . . . . . . . . . . . . . . . 31
Rosenberg Standards Track [Page 2]
RFC 5245 ICE April 2010
5.6. Encoding the SDP . . . . . . . . . . . . . . . . . . . . 31
5.7. Forming the Check Lists . . . . . . . . . . . . . . . . . 31
5.7.1. Forming Candidate Pairs . . . . . . . . . . . . . . . 31
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