Ericsson

Farogatan 6 SE-164 80 Kista Sweden +46 10 714 82 87 magnus.westerlund@ericsson.com

University of Glasgow

School of Computing Science Glasgow G12 8QQ United Kingdom csp@csperkins.org

It has been identified that Interactive Connectivity Establishment (ICE) RFC5245 is missing a registry for ICE options. This document defines this missing IANA registry and updates RFC5245.

"Interactive Connectivity Establishment (ICE): A Protocol for Network Address Translator (NAT) Traversal for Offer/Answer" defines a concept of ICE Options. However, the ICE RFC fails to create an IANA registry for ICE options. As one ICE option is under specification in , there is now a need to create the registry. RFC 5245 says: "ICE provides for extensibility by allowing an offer or answer to contain a series of tokens that identify the ICE extensions used by that agent. If an agent supports an ICE extension, it MUST include the token defined for that extension in the ice-options attribute." Thus, as future extensions are defined, these ICE options needs to be registered with IANA to ensure non-conflicting identification. The ICE options identifiers are used in signalling between the ICE endpoints to negotiate extension support. RFC 5245 defines one method of signalling these ICE options, using SDP with Offer/Answer. This document updates the ICE specification to define the "Interactive Connectivity Establishment (ICE) Options" registry.

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC 2119.

This document defines a registry "Interactive Connectivity Establishment (ICE) Options" for ICE options that can be used in SDP "ice-options" attribute or other signalling parameters carrying the ICE options.

An ICE option identifier MUST fulfill the ABNF syntax for "ice-option-tag" as specified in . This syntax is reproduced here for simplicity, but the authoritative definition is in the ICE RFC:

ICE options are of unlimited length by the syntax, however they are RECOMMENDED to be no longer than 20 characters. This is to reduce message sizes and allow for efficient parsing. Registration of an ICE option in the "Interactive Connectivity Establishment (ICE) Options" registry is done using the Specification Required policy as defined in "Guidelines for Writing an IANA Considerations Section in RFCs". A registration request MUST include the following information: The ICE option identifier to be registered Name, Email and Address of contact person for the registration Organization or individuals having the change control Short description of the ICE extension to which the option relates Reference(s) to the specification defining the ICE option and the related extensions This document registers no ICE option.

As this document defines an IANA registry for an already existing concept there are no new security considerations.

The authors would like to thank the people having reviewed the draft and provided feedback, Flemming Andreasen, Mykyta Yevstifeyev, Amanda Baber and Brian Carpenter.