Networking: Striving for QoS

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Networking: Striving for QoS

7/21/2005

By Peter GrayBy , Peter Gray

In the new converged network world, achieving true quality of service is our goal.

THINK BACK TO when you were in third grade and class was dismissed for recess. Would the teacher tolerate a mad scramble for the door, with kids forming a logjam, kicking and screaming to get out? Of course not. If nothing else than to avoid being sued, your teacher would ensure that everybody formed a neat and orderly line and filed out in an organized fashion. Occasionally, the teacher might let well-behaved or high-achieving students move to the head of the line, while those who misbehaved (or forgot their homework) got stuck at the end of the line. This is a very basic analogy of how quality of service (QoS) works on a data network.

Why QoS?

With the growth in voice, video, and data traffic on conveged computer networks, establishing QoS is essential. QoS is a set of rules and parameters that determines network traffic prioritization. Think of an Ethernet switch that, like the teacher in the example, is responsible for getting traffic out the door in the correct order and in a timely fashion.

Still, who wants to deal with QoS? Why not just keep voice, video, and data traffic separate? Why introduce more complexity to the network? These may be some of the questions you are asking yourself when considering what a converged network has to offer. Reduction of infrastructure and operation costs is a common goal in converged network implementations, but you may find that user collaboration and increased productivity are the ultimate benefits of a converged network.

In the past, a solution to network congestion and bottlenecks was to throw bandwidth at them. But although a properly designed network with ample bandwidth (and within the campus IT budget) is very important, it d'es not single-handedly ensure that video or voice will work effectively on a converged network. Without QoS, voice and video traffic may break up and arrive at varying intervals, causing delay and jitter, making a conversation or video unintelligible.

QoS and VoIP. Simply put, if you choose to deploy voiceover- IP (VoIP) on your college campus, QoS on the data network is a must. Campus personnel and students have an inherent expectation of service and quality. Campus IT must strive to meet or exceed that expectation, so a VoIP phone should meet the same expectations of a regular land line. Unfortunately, that’s not always the case. In certain situations, VoIP can act just like a cell phone in an area of bad coverage, including problems with echo, dropped or garbled calls, or slight delays, making a conversation intolerable. Yet, a properly designed data network with QoS can alleviate, if not prevent, these problems. (After all, who wants to be the person whose job it is to walk around the campus picking up VoIP handsets and saying, “Can you hear me now?”)

QoS and video-over-IP. In addition to voice, video conferencing and distance education have been moving into the IP world, as well. In the past, college campuses have offered dedicated distance learning in classrooms with closed, fixed telecommunications circuits. Now, college campuses have the opportunity to utilize streaming video over IP and plugtheir portable video conferencing/distance education equipment into any network data port on campus.