Q&A: Cisco's Steve Collen on Convergence and Video Bandwidth

Collen explains what IT departments are asking for in physical security projects


Collen: The customers I'm speaking to say they do want to run it [the security system] over the existing network. We get questions along the lines of "Is the bandwidth going to be sufficient for video surveillance, and can I protect the video surveillance system in terms of good security?" The answer to both of those questions is a resounding "Yes, the bandwidth is sufficient and the network protection will be there." So that tends to diffuse any questions of people who would be contemplating a second network.

SIW: Steve, that brings up a question that many users are likely to ask. What is realistic in bandwidth volume for IP-based video?

Collen: From a wired network perspective, there isn't an issue with bandwidth. With MPEG-4 or H.264, you're talking about a 2 to 4 megabits per second bandwidth stream and that -- in corporate networks -- is definitely not an issue. So the bandwidth in a switched environment is going to be there. When you're going across a wireless network or a WAN, then the bandwidth becomes more of a factor and that is when you have to carefully plan what you do and what you send.

We're seeing customers come to us and ask questions like, "What video traffic really is appropriate to send over the WAN, and should I be only sending certain portions of my traffic, and only then, perhaps, at the end of the day?" So, for example, they could only send event traffic across the WAN -- in other words, the "interesting" traffic.

Wireless video is an interesting challenge. There certainly are a lot of questions about wireless video right now. We're actually testing that ourselves, finding out what is and what is not possible to do on a wireless network, but you definitely have to be more sensitive to the bandwidth issues there. In a nutshell, on the corporate LAN network, full-motion video, 24 by 7, should not be a problem. But when it comes to WAN and wireless, you actually have to be a lot more selective about what traffic you exchange.

SIW: But even with a corporate LAN, are they still not experiencing problems with bandwidth and congestion?

Collen: We haven't seen video significantly impact the bandwidth of the corporate network. We're talking about a 100 megabits per second bandwidth stream being pretty standard, and the video traffic is only taking a fraction of that. We are seeing, however, a lot of customer interest in the implementation of quality of service (QOS) mechanisms on the video traffic such that if congestion became a factor, there is a solution for that. Or conversely, you may want to prioritize your video traffic to make sure it gets through. So customers are asking us a lot about Quality of Service mechanisms for doing those things, using type-of-service or precedence bits to mark traffic, and then various queuing mechanisms that you apply based around that marking of traffic.