11/10/2005 -- Microsoft and Cisco have announced they plan to support Interactive Connectivity Establishment (ICE), a method for delivering Voice over Internet Protocol (VoIP) and streaming media through Network Address Translation (NAT) filters on firewalls.

Using the Internet to make voice calls has finally begun to take off with companies like Skype and Vonage -- as has video streaming. However, because of issues caused by inherent characteristics of NATs, which randomly assign addresses to devices inside the firewall, it is difficult to reliably route those packets in real-time to the proper receivers.

ICE is an approach using existing protocols to verify actual versus assigned network addresses so that traffic can be routed efficiently in real-time. The approach uses protocols such as Simple Traversal of UDP Through NAT (STUN) and Traversal Using Relay NAT (TURN), working with Session Initiation Protocol (SIP).

“Finding a way for VoIP to work better across NATs and firewalls is a problem that is faced across the industry,” said Gurdeep Singh Pall, corporate vice president of the Office Real-Time Collaboration Group at Microsoft, in a statement regarding the announcement. “Microsoft and Cisco are encouraging our industry partners to utilize the ICE methodology to ensure more consistent, reliable experiences for our customers, and to improve SIP-based VoIP interoperability across networks.”

NATs are designed to enhance security for both home and enterprise users, but they also inherently create barriers to penetration of other packets that are not malicious. Thus, the same functionality that prevents network intrusion also often results in voice and video streams being blocked from outside the network, the statement adds.

Work on ICE is overseen by the Internet Engineering Task Force (IETF). The goal is to address the impact of NATs on peer-to-peer media connectivity. “Many proprietary media services traverse NATs by tunneling using HTTP or Port 80, but this approach is not as security-enhanced, robust or scalable as the ICE methodology,” according to the statement. -Stuart Johnston (courtesy of ENTmag.com)