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HomeNews & EventsSIP Forum NewsUncategorizedSIP Forum’s SIP over IPv6 Task Group Achieves Milestone with the Publication of “Interoperability Impacts of IPv6 Interworking with Existing IPv4 SIP Implementations”

SIP Forum’s SIP over IPv6 Task Group Achieves Milestone with the Publication of “Interoperability Impacts of IPv6 Interworking with Existing IPv4 SIP Implementations”

New document details potential impacts to IPv4 SIP implementations when interworking with IPv6 SIP implementations so that SIP application developers can create solutions to handle these cases

NORTH ANDOVER, MA (October 20, 2016) – The SIP Forum announced today its SIP over IPv6 Task Group has achieved a significant milestone in its mission to improve the interoperability of IPv6 Interworking with IPv4 implementations with the publication of a new document entitled “Interoperability Impacts of IPv6 Interworking with Existing IPv4 SIP Implementations“.

The continued proliferation of IPv6 infrastructure deployments has resulted in more IPv6 Session Initiation Protocol (SIP) User Agents (UAs) being turned up on networks around the world. Considering the large installed base of IPv4 SIP UAs deployed prior to the deployment of IPv6, it is a well-known fact that not all IPv4 SIP UAs have taken into account all possible IPv4 SIP-to-IPv6 SIP interoperability considerations at the time of their development.

This new document, co-authored by Carl Klatsky, Comcast; Gonzalo Salgueiro, Cisco Systems; and Olle E. Johansson, Edvina AB, outlines scenarios that emerged from tests conducted at the SIP Forum’s SIPit Interoperability testing events combined with experiences from members of the SIP Forum’s IPv6 Task Group, and are provided as guidance for application developers to help identify and create solutions to resolve the identified interoperability challenges. Gonzalo Salgueiro, a Principal Engineer at Cisco and a co-chair of the IPv6 Task Group, confirms by adding, “Our industry-wide and multi-vendor interoperability testing has repeated surfaced multiple serious IPv4-IPv6 interworking issues in SIP implementations. The intent behind this effort is to offer some measure of coherence and clarity to implementers and operators alike.”

“Even if your SIP implementation only supports the legacy IPv4 protocol, there are things you need to consider in order for the application or server to work in a dual-stack environment. We’ve found issues that cause software crashes because of unexpected data in the protocol messages.” remarks Olle E. Johansson of Edvina AB in Sweden and a co-chair of the IPv6 Task Group. “This document aims to help developers find their bugs early and avoid the known mistakes.”

“As the migration to IPv6 accelerates in SIP, we want to make adoption and implementation as easy and seamless as possible,” said Carl Klatsky, Principal Engineer at Comcast. “We hope this paper provides a helpful roadmap for implementers seeking to navigate an increasingly IPv6-powered environment.”

About the SIP Forum IPv6 Task Group

It is well known that the pool of available IPv4 addresses has been exhausted. At the same time, imminent needs for portable devices and smart devices in the home are continuing to drive a more abundant and available supply of IP addresses for SIP networks. Although resale markets for IPv4 address space are beginning to emerge this is merely a short term solution to the problem. Similarly, the deployments of co-existence technologies (CGN/LSN, 6to4, dual-stack lite, NAT444, etc.) are merely methods to cope with the lack of native IPv6 in the network, or with CE devices that will remain completely reliant on IPv4. CE devices, in particular, have been extremely slow to adopt IPv6.

The SIP Forum’s SIP Over IPv6 Task Group is chartered to evaluate current best practices and enable and promote migration to SIP over IPv6. Migration to native IPv6 will take years to accomplish, due to the costs of transitioning networks from IPv4, as well as consumer products that have not yet widely adopted the IPv6 protocol.

The charter of this Task Group will, therefore, serve to identify issues with SIP over IPv6 as well as to evaluate the impact of transition technologies and dual stack devices on existing SIP networks. The Task Group also seeks to identify solutions to these problems and to ultimately contribute recommendations to official standards bodies, such as the IETF and the ITU.

About the SIP Forum

The SIP Forum is an IP communications industry association that engages in numerous activities that promote and advance SIP-based technology, such as the development of industry recommendations, the SIPit and SIPconnect-IT interoperability and testing events, special workshops, educational seminars, and general promotion of SIP in the industry. The SIP Forum is also the producer of the annual SIPNOC conferences (for SIP Network Operators Conference), focused on the technical requirements of the service provider community. One of the Forum’s notable technical activities is the development of the SIPconnect Technical Recommendation – a standards-based SIP trunking recommendation that provides detailed guidelines for direct IP peering and interoperability between IP PBXs and SIP-based service provider networks. Other important Forum initiatives include work in Fax-over-IP interoperability, User Agent Configuration, VRS interoperability, security, and SIP and IPv6. For more information, please visit:

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