Internet Engineering Task Force (IETF) J. Rosenberg
Request for Comments: 6544 jdrosen.net
Category: Standards Track A. Keranen
ISSN: 2070-1721 Ericsson
B. B. Lowekamp
Skype
A. B. Roach
Tekelec
March 2012
TCP Candidates with Interactive Connectivity Establishment (ICE)
Abstract
Interactive Connectivity Establishment (ICE) defines a mechanism for
NAT traversal for multimedia communication protocols based on the
offer/answer model of session negotiation. ICE works by providing a
set of candidate transport addresses for each media stream, which are
then validated with peer-to-peer connectivity checks based on Session
Traversal Utilities for NAT (STUN). ICE provides a general framework
for describing candidates but only defines UDP-based media streams.
This specification extends ICE to TCP-based media, including the
ability to offer a mix of TCP and UDP-based candidates for a single
stream.
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/rfc6544.
Rosenberg, et al. Standards Track [Page 1]RFC 6544 ICE TCP March 2012Copyright Notice
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Rosenberg, et al. Standards Track [Page 2]RFC 6544 ICE TCP March 2012Table of Contents
1. Introduction ....................................................4
2. Terminology .....................................................5
3. Overview of Operation ...........................................5
4. Sending the Initial Offer .......................................7
4.1. Gathering Candidates .......................................7
4.2. Prioritization .............................................8
4.3. Choosing Default Candidates ...............................10
4.4. Lite Implementation Requirements ..........................10
4.5. Encoding the SDP ..........................................11
5. Candidate Collection Techniques ................................12
5.1. Host Candidates ...........................................12
5.2. Server Reflexive Candidates ...............................13
5.3. NAT-Assisted Candidates ...................................13
5.4. UDP-Tunneled Candidates ...................................14
5.5. Relayed Candidates ........................................15
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