Speed is not enough

Video in the enterprise used to mean costly videoconferencing rooms that were beyond the reach of many organizations, had to be booked by the hour, transmitted images over dedicated Integrated Services Digital Network (ISDN) lines and weren’t used very much. With the arrival of video over Internet

Protocol (IP), video is now available at the desktop and is well on its way to the mobile user. Not just videoconferencing, but streaming video and other video applications are attracting more interest.

“”I think IP is going to provide a platform for a whole bunch of things that people have been wondering about,”” says Roberta Fox, president and senior partner of Fox Group Consulting in Markham, Ont.

That’s all good news, except of course that it means more headaches for those responsible for the network.

There’s no question that video requires more bandwidth than voice. Best-quality voice over IP requires a 64-kilobit-per-second connection, says Ralph Santitoro, director of the office of the chief technology officer at Nortel Networks Corp. By comparison, a basic videoconference linkup needs 384Kbps. Rick Perkins, product manager for videoconferencing at Toronto-based Sony of Canada Ltd., suggests allowing half a megabit per second, though he notes that the H.264 video standard, launched about a year ago, allows for better quality than ever before at lower bandwidths.

Half-duplex is suitable for data but not for video

If you want to run video over a network, Santitoro says, “”you have to be careful when you engineer your network, because you have to know how many video sessions (I am) going to do simultaneously.””

This is not to say enterprise networks typically lack the bandwidth to handle video. With 100 Mbps pipes commonplace and even gigabit speeds in some areas, the capacity is there to handle plenty of video — depending on what else the network is being asked to do. There is the catch, though — some enterprise networks, even though they boast considerable bandwidth, are already over-utilized.

“”The first thing is to have a good understanding of what exactly is going into your network,”” advises Zeus Kerravala, senior analyst at the Boston-based Yankee Group Inc. For instance, even though voice is not as bandwidth-hungry as video, extensive VoIP use will reduce the amount of bandwidth available for video, as will other network applications.

Santitoro says two things other than bandwidth are crucial to successful video services — and for that matter to voice as well. The first is a simple thing but one that still trips up some organizations when they first tackle video. Ethernet networks can be configured to run either in half duplex or full duplex. Half duplex means data travels in one direction at a time — the network is like a narrow bridge with traffic lights at both ends, allowing traffic to flow first in one direction and then in the other.

In full duplex, data can travel in both directions at once. Many networks are configured to run in half duplex, Santitoro says, and that works well enough for data, but is disastrous for either voice or video transmission. The good news is that fixing it is just a matter of changing the setting.

The second issue is quality of service (QoS). In a network context, this is the ability to prioritize traffic. If a packet of data is delayed in transmission, it matters little to users, but if a packet of voice or video traffic is delayed, the distortion in an audio or video signal is noticeable. The answer is simple enough – give priority to the voice or video packets. QoS technology in a network can recognize which packets are which and direct traffic accordingly. To transmit video successfully, says Santitoro, “”you really have to support some form of quality of service in your network.””

Newer networking equipment supports QoS, but existing networks might not be configured to use it, Santitoro says. It could be simply a matter of adjusting settings. In some cases, older equipment might have to be replaced. Some older routers, for instance, support QoS but do so in software rather than in hardware, which is slow and will degrade the performance of the network.

Besides the network issues, Fox observes, there may be another point to consider if you are looking at streaming video for purposes such as training or if you want to archive videoconferences. Video takes plenty of storage, and Fox says ambitious video use may mean adding storage capacity.

The local-area network is one thing; the wide-area network is another. Long-haul connections tend to have less bandwidth, and network managers generally have less control over them, so the headaches multiply.

“”You can go through the public Internet,”” Perkins says, “”but as soon as you do you’ve got issues of quality of service.”” He recommends setting up a virtual private network to insulate video traffic from some of the vagaries of the public network.

“”When I started to implement video in the company I was running it over the same lines that I used for data,”” says Matthew Smith, information and communications systems co-ordinator at Toronto-based Norshield Financial Group, “”and what you’ll notice when you try to do that is that you can’t get a business-quality video session to last on the public Internet.””

Voice is more complicated than video

Smith resolved the problem by turning to BCS Global Networks Inc. of Mississauga, Ont., which provided Norshield with video-over-IP links between its Toronto and Chicago offices that incorporate quality of service provisions to ensure satisfactory video quality. BCS’ service also bridges from Norshield’s IP-based system to outside videoconferencing participants using Integrated Services Digital Network (ISDN) lines — the usual way of doing videoconferencing until recently.

Norshield expanded its videoconferencing network to its Barbados office in December and plans to bring an office in Montreal online this year.

Now that the video network is in place, Smith adds, Norshield has begun using spare capacity for voice over IP connections among its offices as well. He says VoIP is actually more complicated than video, because of the need to interconnect with the traditional telephone network.

Don’t let the firewall get in the way

One other issue with IP videoconferencing over wide-area networks, Perkins notes, is firewalls. Either the videoconferencing hardware needs to be outside the firewall, or an open port must be provided. “”If you don’t address it,”” Perkins says, “”(the firewall will) stop it dead.””

Sadly for harried networking specialists, wide-area connections are only going to get more important, because the new frontier for video services appears to be mobility. Cell phones with still cameras built in are already becoming popular, and pocket-sized devices with video capabilities are the logical next step.

In Britain, mobile phones with video capabilities are available now, notes Mike Hollier, chief technology officer of Psytechnics Ltd., an Ipswich, U.K.-based maker of voice and video quality assessment software.

The early adopters are not likely to be business users, Hollier predicts.

“”What they ought to be seeing in their minds is teenagers pulling funny faces at each other over their latest 3G phone thing,”” Hollier notes. But as mobile video becomes more common, it may interest business users too.

Mobility is “”really adding a new dimension”” to videoconferencing, Santitoro says. More and more workers are telecommuting, and mobile videoconferencing will let them participate in meetings from wherever they are. Digital subscriber line (DSL) connections are now “”just about good enough”” for videoconferencing, making video much more accessible.

And while videoconferencing is still what most people think of first when video is mentioned, there are other applications. Streaming video is seeing increasing use, both over the Web and within organizations — it is especially useful for training, Santitoro notes. With video security systems increasingly moving from analog to digital, delivering security video over IP networks is an interesting option. Like it or not, networks will have to get the picture.

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Grant Buckler
Grant Buckler
Freelance journalist specializing in information technology, telecommunications, energy & clean tech. Theatre-lover & trainee hobby farmer.

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