Optivision sends MPEG-2 over Gig-ethernet..............
October 05, 1998, Issue: 735
Section: ...Yada, Yada, Yada...
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Jerky Video Be Gone: QoS For Ethernet Is Here
Wayne Rash
I was watching the 26-inch monitor on which members of the Mobile Infantry splattered bug-like aliens from elsewhere in the galaxy. On the screen behind me a group of crazed weather scientists chased tornadoes among clumps of swirling cows. Surrounding me were a dozen or so engineers from the University of Hawaii, Lucent Technologies Inc. and Optivision Inc., also watching, straining to see the smallest possible interruption in the flow of video.
This was more than just a Wednesday afternoon at the movies. In fact, this impromptu film festival had a much larger purpose. We were evaluating a group of Gigabit Ethernet switches for our biannual Best of Breed test that will appear in the Comdex issue of InternetWeek. In the past, we had simply tested the switches for their capabilities at the most basic level. Now, it was time for something big-quality of service (QoS).
Until now, most corporate users had been forced to use ATM for their backbone network needs if they planned to guarantee bandwidth for applications such as video feeds that are extremely sensitive to interruption. The reason was that ATM has the ability to handle high-priority traffic such as a video feed, and until recently, Ethernet did not.
Now that's changed. Gigabit Ethernet switch manufacturers are beginning to support the 802.1q standard for QoS, which, if it works right, should ensure that high-priority traffic gets preference over other traffic.
The ability to define high-priority traffic is important on a busy network. Should a portion of the backbone become oversubscribed, the switches on that segment should discard low-priority data packets while ensuring that the higher-priority traffic passes along the network unscathed.
One of the objects of our testing is to ensure that the goals of QoS are actually met. To do this, we used an MPEG-2 codec from Optivision on each end of our backbone, and used the devices to encode and decode video and move it along the network. We used the movies because they're a reliable source of high-resolution, fast-action video. If something happened to interrupt the video, we were certain to see it.
We used the Optivision LiveSystem video encoders and decoders coupled to a Pioneer DVD and Video Disk player on one end (a simulated version of Maui) and high-resolution monitors-located on a rack labeled "Oahu"-on the other. The Optivision LiveSystem takes in the near-broadcast quality video from the Pioneer unit and turns it into high-quality MPEG-2 video and audio (similar to, but higher quality than you'd get from your digital satellite system, and about equal to what comes out of a DVD player), so we felt it would give us bandwidth demands equal to what the most picky of businesses would require.
The reason we selected Optivision for this task was twofold. First, in a moment of weakness, they agreed to actually entrust us with two of their products, and to send engineering and support staff to make sure they worked right. Second, it's a mature product that just happens to support Gigabit Ethernet. This was one instance in which we didn't want the teething problems of beta products.
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