Minimising the video monster on your network

Casual video-over-IP use can chew up bandwidth, Kevin Tolly warns

Like so many things, corporate video-over-IP has been heralded as the next big thing for some time now. And, like so many technology breakthroughs before it, IP video is finally entering many companies through the back door — the employee.

With the ranks of employees filling up with younger types accustomed to frequent visits to social networking and related sites like YouTube, the casual checking up on personal items that has gone on since the beginning of the online age can suddenly have resource repercussions as never before.

A single click on a video hyperlink can trigger thousands of packets full of video on a one-way trip through your corporate network. And that happens each and every time a user clicks through.

The issue is so severe that, according to a recent Wall Street Journal story, video is breathing new life into relatively ancient (by internet standards) web-filter solutions. In short, if the employees can’t reach the YouTube or My Space or whatever URL is “offending” the corporation, they can’t trigger the video deluge.

And, while it is easy to understand how accessing such video sites can chew up people’s time, what does it really mean to your network?

To find out, Tolly Group engineers conducted an informal survey and analysis of several popular video sites. After connecting network analysers, they did just what users did and “clicked” to view short videos from a number of sites.

If you are short for time and just want to know whether you should worry or not, here it is. Yes, if you are responsible for providing corporate WAN bandwidth, your video-centric colleagues will eat it up.

Our team selected relatively short, two-minute or so segments from YouTube, Yahoo, Google and Apple’s movie trailer site. Apple’s video was in QuickTime format while the other three were all Flash Video (FLV). The format, though, didn’t seem to make any impact on the network behaviour.

While the “appetite” of the streams varied a bit (tested across a T1, 1.544-Mbps connection), they all put a constant 1Mbit/s load on the network.

Once begun, the video sites machine-gunned down a stream of mostly maximum-size (c. 1500 bytes) packets taking apparently as much bandwidth as desired or that it sensed available. The video is transported as TCP packets right over the existing browser session.

So what about the other, important traffic that needs to traverse the same links? Well, unless you have a QoS appliance in place that throttles down the video or limits a given session, the other traffic just gets pushed out of the way (so to speak).

Latency-sensitive traffic will get delayed while the larger packets are grabbing the line. Timeouts might occur, packets might get dropped, who knows.

To get that video off the wire, though, you might be able to employ another “ancient” technology — caching. While a megabit a second puts a strain on your WAN/broadband connection, it is a trivial load on your campus network.

A cache solution would store a copy of the file locally such that other users calling it up would have it delivered locally.

Given the viral, “check this out” nature of many popular video clips, such an approach could keep employees happy while minimising the load on precious corporate broadband bandwidth.

Short of blocking URLs, your ultimate choice might be to “cache” or “carry” that video traffic.

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Tags networksNetworking & Telecomms IDvideo-over-ip

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