When worlds collide

As more audio and video runs over enterprise networks, IT skills become a value-add for AV integrators. Tim Kridel reports.

AV, make way for another acronym: IT, short for information technology. In commercial and enterprise applications, AV control signalling and even content increasingly is running over the client’s IT infrastructure, including local-area networks (LANs) and wide-area networks (WANs).

Although AV and IT currently are cohabiting more than converging, there’s one big reason why that trend most likely will continue: money.

“The cost of installing AV cabling, whether it’s copper or fibre, is very expensive,” says John Lopinto, president and CEO of Communications Specialties, a U.S.-based AV equipment vendor. “It’s not the cable, but [rather] the labour. So people say: ‘We already have this IT network. What can we do to leverage that for AV?’”

Polycom is seeing the same mindset reshaping the market.

“Consolidating networks to a single environment almost always saves administration costs,” says Jim Smith, CTS, CVE, consulting systems engineer for AV channels the videoconferencing equipment vendor. “Many companies are migrating toward a single network for voice communications – voice over Internet Protocol (VoIP) – as well as using that same network for all in-house data traffic. Reduced cost of deployment, elimination of multiple incompatible infrastructures and common management access all combine to improved efficiencies.”

That quest for savings is why basic IT skills are becoming both a value-add and a market differentiator for AV integrators. For example, an integrator that understands basic networking concepts may be able to identify ways to leverage the client’s IT infrastructure and thereby save enough money to make a highly competitive bid.

New variables, new people

As more AV traffic gets routed over LANs and WANs, it becomes more challenging to ensure the quality of service (QoS) and bandwidth that latency-sensitive audio and video require. One reason is because many of those networks originally were engineered for traffic that can tolerate a certain amount of delay. For example, users won’t notice if the packets that carry an e-mail or Web page take a few milliseconds or seconds longer to arrive, but they can tell when audio and video is delayed.

The more IT networks that the AV traffic has to traverse, the more difficult it becomes to avoid delays and bottlenecks. Most AV signals can be highly compressed, which helps AV integrators match them to the bandwidth that each network link can handle. But even that might not help if there are multiple, disparate links, such as a videoconference that originates on an 10 Gigabit LAN and then travels across a third party service provider’s 1.5 Megabit WAN to reach a remote office, where a 10 Gigabit LAN again is available. To make things even more challenging, the videoconference might include telecommuters, whose home offices may be served by a variety of technologies with a variety of bandwidth capabilities.

In that example, one option is to engineer the AV system to make do with whatever the slowest network link can handle. “But when you do that, latency and image quality can suffer,” Lopinto says.

Another, more expensive option is to see if the service provider will guarantee, via a service level agreement (SLA), the minimum amount of bandwidth necessary to provide a consistently good user experience. Some service providers also offer bandwidth on demand, where a certain amount of capacity can be guaranteed for a certain amount of time, such as the duration of a videoconference.

The junctions between different networks also can be a problem area.

“Beware the WAN link bottleneck,” Smith says. “It can be the killer choke point.”

Available bandwidth isn’t the only factor that determines QoS. For example, the network’s router settings also determine whether packets of video arrive when they’re supposed to and whether they get priority over latency-tolerant traffic such as e-mail. The network also may be using multi-protocol label switching (MPLS), where each router labels its packets, and each subsequent router reads that label to determine how to forward them. A relatively new technology, MPLS helps ensure that delay-sensitive IP traffic such as video gets the bandwidth and priority that it needs.

All of those settings typically are controlled by the enterprise’s network administrators, so an AV integrator’s ability to work them and speak their lingo is key. But sometimes that’s easier said than done, especially if the IT staff doesn’t understand AV’s nuances simply because it’s a new world for them.

“My son is an IT consultant, and he’s very good at what he does,” Lopinto says. “But his knowledge of AV signaling is not there.”

Who’s in Control?

The ability to piggyback audio and video on a client’s IT department depends on a variety of factors. One issue is the IT staff’s willingness – or lack thereof – to open the network to applications that are under the domain of a third party: the AV integrator. The decision usually hinges on whether the IT department believes that, for example, videoconferences passing through the corporate firewall will create a back door for hackers.

“[Integrators] prefer to have as much control as possible, but the client doesn’t give them the option most of the time,” Lopinto says. “They rule the roost.”

Although it sometimes isn’t possible to convince the IT department to allow audio and video on its network, it certainly helps to have at least a basic understanding of networking concepts and IT terminology. That knowledge lets an integrator talk the talk, which can help build credibility in the IT staff’s eyes – ideally to the point that the staff believes that the integrator knows enough not to create security risks.

At the same time, it’s important to recognise that IT staff often don’t understand basic AV concepts. That can create a learning opportunity, which may lead to a realisation that it’s okay to piggyback on the company’s LAN or WAN. “Both have to learn something about the other’s area of expertise,” Lopinto says.

Going separate ways

In some cases, it’s preferable to run AV traffic over a separate network – albeit an IP-based one – rather than piggybacking on an existing infrastructure. That could be because the IT department requires it, but it also could be the integrator’s preference. For example, just as the IT department may be concerned about creating back doors into its network, the integrator also might be concerned about unauthorised access to AV traffic, such as a confidential videoconference.

“An argument can be made that it should not be a network that can be bridged to the existing, non-AV network for fear of it either loading down or having unauthorised control of the AV equipment,” Lopinto says.

“Separate” has a couple of definitions. One is physically separate, with AV traffic running over its own cables, perhaps pulled through the same conduit that carries copper for the enterprise’s LAN. Separate also can involve partitioning the LAN infrastructure so that even though all of the traffic traverses the same cables, routers and switches, the AV and enterprise applications never mix, like trains on parallel tracks that never meet.

The type of client also can determine whether separate networks are the only way to go.

“In environments of extreme network security, [such as] certain government agencies, having dedicated AV versus IT networks makes good sense, as the AV integrator may not be allowed access to the secure network,” Smith says.

Another potential reason for using separate networks is if adding AV traffic to a LAN or WAN would risk overloading that infrastructure.

“If the data can be handled nicely with a single E-1 WAN link, and the AV burden would exceed the rule-of-thumb 30% traffic load threshold, then it makes sense to add a second E-1 and dedicate it to the AV traffic,” Smith says.

Knowledge is power

Although piggybacking audio, video or AV control signals over enterprise LANs is still the exception rather than the rule, an understanding of IT is already valuable.

“The really good system integrator is the one who understands all of the different distribution technologies – coax, fibre, twisted pair – and can apply them either on a mixed basis for whatever the application is, and be able to speak to on an intelligent basis with the technologists who are good with these areas,” Lopinto says. “The ability to implement the distribution through the IP network is just another tool. To the extent that you understand all of these different things, you’re going to be of much greater value to your clients.”

Just how much IT knowledge integrators should have is a matter of opinion. Some vendors and integrators recommend going so far as to acquire Cisco or Microsoft certification. Others say that that’s overkill or even irrelevant.

“Many of the IT certifications are relevant to typical office network deployments, and not to managing a network that is hosting streaming or conferencing traffic,” Smith says. “So the end result is a technical team certified for e-mail and print-job support, yet unable to correlate the subtleties of continuous data-stream interactions in that same network.”

One helpful skill is an understanding of security systems such as firewalls, which can block audio and video streams. Indeed, some AV vendors have spent the past few years developing solutions to make firewall traversal easier. For example, in 2004, Tandberg acquired Ridgeway Systems & Software and began incorporating its firewall-traversal into some Tandberg IP-video products.

Another useful skill is understanding of Dynamic Host Configuration Protocol (DHCP), which is a framework that lets servers assign IP addresses to computers and other hardware.

“[Suppose that] a network is set to use DHCP instead of static addressing – most convenient and typical – and there is a control system along with AV gear on that network,” Smith says. “If the network refreshes the addresses, which can happen on a reboot or after a certain period of time, then the addresses of those attached devices may change, effectively breaking the control paths. Also, if conferencing equipment ‘lives’ on that same DHCP network, there must be active address translation available on the network; otherwise no site could communicate with any other site.”

For newcomers to IT, that sounds like a lot to learn. The good news is that IT staffs also have a lot to learn.

“This is all new territory for everybody,” Lopinto says. “So we all need to gain some experience with it.”

Tim Kridel

Tim Kridel is a freelance writer who covers technology and telecoms for a variety of publications and analyst firms. He’s based in the United States and can be reached at inavate@imlgroup.co.uk

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