Everything On The Network

Like it or not, AV and IT increasingly share the same network. For AV pros, that's both a problem and an opportunity. 6/29/2006 5:58 AM Eastern

Everything On The Network

Like it or not, AV and IT increasingly share the same network. For AV pros, that's both a problem and an opportunity.

Hardly a week goes by without another press release announcing a networkable pro AV product, including loudspeakers, displays, and projectors. One reason is the wide availability of hardware, software, and enterprise networks based on Internet protocol (IP) technology. With that installed base, it's not surprising that more AV vendors and integrators are looking to leverage IP.

“Everything is moving to IP networks, and this trend will certainly continue,” says Dave Stoner, president and CEO of ViewCast, a Plano, TX-based maker of networked video products.

Money is a major driver of the convergence trend: It's usually cheaper to run multiple services — in this case, AV and IT — over the same network than it is to build or lease separate ones. Money is also one of at least two reasons why AV pros should care about convergence. The first is that it's already underway and won't be reversed, so it has to be accommodated. The second is that AV pros who learn to work in this new world are less likely to see their business suffer.

“Long-term prospects aren't looking great for custom AV system installers since the inevitable trend is toward everything on an IP network,” says Predrag Filipovic, senior analyst for multimedia and wireless networks at The Diffusion Group, a research firm based in Plano, TX. “That would eventually standardize equipment and communication, thus making AV integration far easier. Equipment can be much ‘smarter,' and thus less business for the integrators —and less appreciated in financial terms.”

Know your networks

One obvious way for AV pros to leverage the convergence trend is by learning at least the basics of networking, such as the various network types and transport technologies.

“An example is being able to understand and configure IP-addressable routers,” says Gene Ornstead, director of advanced TV products at ViewSonic, Walnut, CA. “Some environments utilize Dynamic Host Configuration Protocol (DHCP), while others will require setting up specific static IP addresses.”

Speaking the language also helps build a rapport with the IT staff, improving the chances that you can get something — such as extra bandwidth for a videoconference — when you need it.

Training and certification by major IT vendors such as Cisco Systems and Microsoft are also worth considering — and not just because they add credibility in the eyes of the IT staff you're working with. “Since many of the AV components are based on various versions of Microsoft Windows, it will be necessary for AV pros to be able to manage Windows platforms,” Stoner says. “Microsoft and Cisco certifications will become essential to the AV professional's role.”

Knowing how networks work is also the first step toward managing and troubleshooting them. That expertise means problems get fixed faster than they would if an AV pro has to track down an IT tech to take care of it. “Having integrators use the network to make adjustments to equipment or be able to download control programming to fix a problem saves time for both the integrator and the IT support person,” says John Pfleiderer, video infrastructure and services coordinator at Cornell University in Ithaca, NY.

Integrators who can tinker under the network hood also have the potential to offer more value to their customers — and be able to charge accordingly. For example, not only are they better prepared to fix network-related problems, but they're also able to avoid many of them in the first place.

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Everything On The Network

Like it or not, AV and IT increasingly share the same network. For AV pros, that's both a problem and an opportunity.

“For AV pros, the convergence trend means that they need to become experts in networking technologies,” Stoner says. “Running real-time content across an IP network creates unique challenges and may uncover network design and configuration issues that would otherwise be undetected.”

Quality is priority one

A major concern in any network is quality of service (QoS). For example, suppose that the majority of traffic running over an office's LAN is email, file transfers, and documents headed to the floor's laser printer. Although that traffic is important, it can be categorized as a low priority in the sense that a few seconds of extra time getting across the network won't be noticeable to the sender or recipient.

Audio and video, on the other hand, aren't as tolerant of latency. For them, QoS means ensuring that enough network bandwidth is set aside for their needs. When it's in short supply, the AV traffic takes priority. So even if several other users on the LAN start sending 10-MB PowerPoint files to one another, the network still will provide enough bandwidth for the audio and video traffic — even if it means that PowerPoint files get delayed because there's only so much bandwidth to go around.

QoS can be maintained via QoS profiles, where each traffic type is tagged with a priority level that network nodes such as servers read in order to know how to handle it. “It can be assigned on a time-of-day basis, by LAN segment, or by user basis,” says Jim Smith, a systems engineer with Polycom, a Pleasanton, CA-based maker of conferencing equipment. “Most network hardware is capable of supporting QoS.”

Bandwidth bottlenecks

The big catch is that depending on what the network is carrying, it may be difficult to reserve enough bandwidth for AV traffic or ensure that it always gets priority. For example, if the network also carries voice calls — known as voice over IP (VoIP) — then they also must be given priority. An increasing number of enterprises now use VoIP, especially between offices, because it's cheaper than regular telephony. So if a company's wide-area network (WAN) routinely carries VoIP calls between multiple offices, and a videoconferencing session needs to share those links, it becomes tricky to ensure that both types of traffic aren't delayed by each other or by other uses.

“You want to maintain your streaming traffic below about 30 percent of network capacity,” Smith says. “A good rule of thumb is that you don't want to exceed 70 percent of your network's rated capacity for total traffic burden.”

That leaves breathing room in case traffic unexpectedly spikes, or if part of the network goes down, and the other links have to shoulder the whole traffic load. These types of issues highlight the importance of being able to work with the IT staff or even configure parts of the network yourself. “You can manage — or have the network operations center manage it for you — the QoS and provision network switches to be video friendly for distribution across the LAN,” says Cornell's Pfleiderer. “However, going off campus, there's much less control, and it's much more difficult to manage the bandwidth needed for video distribution.”

When the network includes links that are owned and operated by a third party, such as the phone company, it may be difficult to maintain the control that some AV applications require. Many telecom providers offer service level agreements (SLAs), where the contract specifies minimum benchmarks, such as how many megabits of bandwidth will always be available to the customer and its applications. If an SLA isn't available, or if it's too expensive to justify, one option is to package the AV traffic in a way that makes it more likely to zip through the WAN with no delays.

“Sometimes you have to seek technologies that work better under unmanaged circumstances,” Pfleiderer says. “For example, the use of MPEG-2 on the LAN can be managed, but in a WAN environment it might be better to employ MPEG-4 to reduce the amount of bandwidth needed to transmit the video.”

If you're working with a network or combination of networks where you don't have a guaranteed amount of bandwidth, it's worth running a few tests to see what they can support. These “Internet speedometers” aren't 100 percent accurate, but they can provide a helpful ballpark estimate.

Everything On The Network

Like it or not, AV and IT increasingly share the same network. For AV pros, that's both a problem and an opportunity.

“This allows you to see how much bandwidth is available to upload and download from your connection,” Pfleiderer says. “It's pretty handy to see how much bandwidth is actually on a connection. Speakeasy is one I like to use.”

Another variable to be aware of is that some networks, such as consumer-class cable and digital subscriber line (DSL), are asymmetrical: Their download speeds are much faster than their upload throughput. That's something to consider if the flow of AV traffic goes in both directions, or if some of the users are telecommuters on a cable or DSL connection.

Even on an enterprise-grade LAN or WAN, bandwidth-intensive AV traffic can quickly take its toll. The typical HD (MPEG-4) video stream requires 18 to 20 MB/sec throughput rates,” says ViewSonic's Ornstead. “While this seems low compared to the 100-MB rate of standard Ethernet, multiple data streams may cause the video transmission to be interrupted.”

The budget factor

A major reason for the increase in networkable pro AV gear is that it's usually cheaper to piggyback the audio and video traffic on the existing IT infrastructure than it is to install and maintain a separate network. Even so, there are additional costs to consider. An obvious one is extending the LAN so that there's a jack next to the projector, loudspeaker, or display.

If the AV traffic pushes the LAN or WAN to its limits, the network may need to be upgraded. If the network is leased from a third party, the upgrade could mean paying for a bigger chunk of bandwidth.

“For streaming a lot of video and audio, the costs could be higher if the campus meters bandwidth consumption,” Pfleiderer says. “Storage costs for storage area networks (SANs), or for video files stored on the server and delivered via downloads, could result in additional licenses or costs per download. This would depend on how much the campus has to recover costs for large downloads or live streaming. If you need to stream globally, then costs for commercially provided edge servers might become part of the costs for overall network use.”

According to one systems integrator, content distribution network space storage runs about $40/GB, and delivery ranges from $3 to $10/GB, depending on contract and volume.

Worlds apart

In some cases, it may make sense to maintain separate networks for AV and IT traffic, such as when there's no practical or cost-effective way to accommodate their bandwidth and latency needs within the same pipe. However, using separate networks doesn't necessarily mean two physically different sets of infrastructure. For example, one alternative is subnets, which are networks within networks, just as the Internet is a collection of multiple networks. The boundaries are maintained via separate IP addresses for different devices on the network.

Subnets also can be shared — as was the case at Cornell, where the AV department was on the same subnet as the help desk and some general computer users. At certain times of the day, there wasn't much elbow room. “We found that it was much more manageable to set up a smaller subnet and put all of the videoconferencing and streaming equipment on it,” Pfleiderer says. “We not only gained better control of the bandwidth, but it added stability to the video signals. I suppose that just having less competition for available bandwidth on the smaller net did the trick. Besides, the smaller subnet was easier to manage because we knew who or what was on the dedicated subnet, so if there are problems, it's much easier to troubleshoot and identify where the difficulties are.”

Indeed, ease of management is one reason why it may make sense for AV to carve out its own corner of the world. “We can provision the network switches for optimal delivery of video, which might not be easy in a larger, more dynamic subnet that's chiefly concerned with general computing and not video distribution,” Pfleiderer says.

Everything On The Network

Like it or not, AV and IT increasingly share the same network. For AV pros, that's both a problem and an opportunity.

One potential drawback to subnets — and the convergence trend in general — is that it places all of the eggs in one basket. If the network goes down, so do the AV sessions running over it. That concern is one reason why some IT departments are reluctant to put everything on a single network. “It's a basic fear of the AV overlay,” says Polycom's Smith. “They don't know what's in it. They're afraid of the technology. They don't want it on their network. It's more about fear than about reality.”


According to, an online magazine for certified IT professionals, the top 10 hottest industry certifications for 2006 are:

1. Red Hat Certified Engineer

2. Microsoft Certified Technical Specialist: SQL & .NET

3. Microsoft Certified Architect

4-5 Cisco Certified Security Professional (tie). (CCSP), Project Management Professional (PMP)

6. Cisco Certified Internetwork Expert

7. Cisco Certified Network Professional

8. MCSE: Security (Microsoft)

9. Systems Security Certified Practitioner (SSCP)

Everything On The Network

Like it or not, AV and IT increasingly share the same network. For AV pros, that's both a problem and an opportunity.

10. Linux Professional Institute Certification, Level 2 (LPIC 2)



For more information about how AV and IT are converging, check out the following:

  • Loudspeakers Join The Network — Another piece falls into place in the IT integration puzzle, March 2006
  • What's Wrong With Wireless? – Unreasonable expectations, technical hurdles, and security issues have prevented wireless projection from going mainstream. Are we any closer to a solution? May 2005
  • Navigating LANs, MANs, and WANs – How prepared are you to deliver projects across IP and ISDN networks? Connecting multiple endpoints, troubleshooting the installation, and providing on-site logistics are all a part of balancing quality of service and security, February 2005
  • Convergence Complete on Many Campuses – While other market segments are just beginning to struggle with convergence issues, the merger of AV and IT is nearing completion in the higher education market, September 2003
  • Speakeasy – This free website tests your Internet connection's upload and download speeds. Visit
  • Tim Kridel is a freelance writer and analyst who covers telecom and technology. He's based in Kansas City and can be reached at

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