A subgroup of the International Multimedia Telecommunications Consortium (IMTC) is developing standards to make videoconferencing systems based on the session initiation protocol (SIP) work better together, and the group’s chair says network managers could play an essential part in this audiovisual evolution.
When videoconferencing vendors started using SIP, the companies followed the standard SIP implementation architecture defined by the Internet Engineering Task Force (IETF). But as sometimes happens with standards, the vendors each interpreted SIP slightly differently. That caused problems. “When you tried to put these videoconferencing systems together, they didn’t interoperate as well as existing H.323 solutions,” explains Charles Eckel, chair of the SIP Parity Activity Group (AG).
In 2009, vendors and other interested parties established the SIP Parity AG within the IMTC to deal with the interoperability challenges. “The idea here was, let’s figure out the key things that have to work well together, and let’s come up with some best practices we can all follow in our implementations and interpretations of the standards,” Eckel says.
The group’s successes to date include a major milestone: improving content sharing via SIP videoconferencing.
Fix for a document-sharing glitch
In the past, users of SIP-based videoconferencing systems would sometimes have trouble sharing content such as slide presentations during audiovisual sessions. The problem stemmed from a glitch associated with the use of the binary floor-control protocol (BFCP) over the transmission control protocol (TCP).
“Firewalls would block the establishment of TCP connections,” Eckel says. “Without those, you wouldn’t be able to conduct the negotiation of tokens that are used to control content sharing.”
To help address the problem, Parity AG developed a set of recommendations indicating the user datagram protocol (UDP) as a transport for BFCP, a token negotiation mechanism to control who is presenting at what time. Matching BFCP with UDP would enable videoconferencing systems to overcome the firewall obstacles that stopped TCP, and the bridge would allow users to share content.
Parity AG has presented its BFCP-over-UDP suggestions to the IETF. Now the task force is extending the BFCP definition based on those pointers.
“We’re 99 percent of the way there, but the actual RFC (request for comments) has not been published yet,” Eckel says. He adds that the extension might be complete by the end of 2014.
According to network-tech industry insiders, SIP parity is an important matter. “Improved SIP interoperability will reduce deployment complexity and enhance management capabilities,” says Allstream unified communications marketing director Dax Nair. “SIP is also emerging as the standard for hosted voice and video systems. Standardization will drive better communications between hosted and premise-based components.”
Network managers called to step up
Eckel says network managers have a significant role to play in Parity AG’s efforts. He suggests managers should “get involved and help the IMTC become aware of any problems they’re facing. The majority of people who are really active in the IMTC come from the developer community. When you have someone who’s an operator of this technology come in to explain the problems, that helps shed light for this group on projects to tackle.” Cooperation between vendors and network managers is key, he says.
Eckel also advises managers who are shopping for videoconferencing systems to take a close look at whether vendors are investing in interoperability. “See if they have participated in forums like the IMTC, to make sure their equipment is interoperable with other vendors’. Because even if it isn’t the case now, at some point in time there’s a good chance you’ll want to use equipment from a different vendor. Don’t build yourself into a corner.”