RFC 6947 · INFORMATIONAL · 2013

The Session Description Protocol Alternate Connectivity Attribute

Overview

RFC 6947, “The Session Description Protocol Alternate Connectivity Attribute”, is an Informational document published in May 2013 by M. Boucadair, H. Kaplan, R. Gilman, S. Veikkolainen. The canonical text is published by the RFC Editor.

Abstract

This document proposes a mechanism that allows the same SDP offer to carry multiple IP addresses of different address families (e.g., IPv4 and IPv6). The proposed attribute, the "altc" attribute, solves the backward-compatibility problem that plagued Alternative Network Address Types (ANAT) due to their syntax.

The proposed solution is applicable to scenarios where connectivity checks are not required. If connectivity checks are required, Interactive Connectivity Establishment (ICE), as specified in RFC 5245, provides such a solution.

Abstract as published in the RFC, via rfc-editor.org.

What “Informational” means

Published for the general information of the community. It does not define an IETF standard and carries no standards-track status.

Read this RFC

The canonical text of RFC 6947 is hosted at rfc-editor.org. Available in TXT,HTML.

Other RFCs from 2013

Who Is Online

In total there are 77 users online: 0 registered, 69 guests and 8 bots.

Most users ever online was 5,555 on 17 Jul 2026, 3:23 am.

Bots: AhrefsBot Applebot Baiduspider Bingbot Googlebot Other Bot PetalBot SemrushBot

Users active in the past 15 minutes. Total registered members: 372