Introduction to QoS | Rick Gallahers MPLS Training Guide: Building Multi Protocol Label Switching Networks

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Let's take a trip down memory lane. Imagine walking into a restaurant in your hometown and being greeted by the owner, who shakes your hand. He knows both your name and your favorite meal. You know that you will experience true quality service, for the owner consistently checks speed of delivery, taste and presentation of the food, and staff performance to ensure that you have a worthwhile dining experience.

In the telephone industry, Quality of Service (QoS) has always been an issue. Technicians consistently monitor telephone lines to ensure that every word can be heard with a high degree of accuracy. The 'pin-drop' company is so sure of its quality that it advertises that you can hear the dropping of a pin across one of its connections.

In data communications, QoS has been an issue since the possibility of running Voice over IP (VoIP) first aired. In order to achieve voice 'toll' quality, call-voice datagrams had to arrive in a timely manner, dropping hardly any packets on the path. VoIP is now a reality that has been implemented around the world with a good success rate. Contrary to predictions, however, a sharp drop in QoS awareness has taken place as VoIP has increased in market share.

Two years ago, QoS was a real concern. There was a dedicated web site called the QoS Forum; it is no longer in service. The web keywords 'QoS' and 'Quality of Service' score very few hits on Google. More networks are being designed with massive excesses in bandwidth as a means of controlling Quality of Service issues.

I suggest not only that problems Quality of Service have not disappeared, but also that they assume a new dimension with each emerging technology. Over-provisioning and over-engineering do not solve existing QoS problems. The current industry myth is that it is more cost effective to 'buy' 200% more bandwidth than a network requires than it is to worry about QoS. However, contrary to popular belief, bandwidth alone cannot solve QoS problems. In this chapter, we will discuss the three primary elements of QoS, explain why bandwidth alone cannot solve QoS issues, examine how a combination of measures can effectively address QoS challenges, and explore genuine QoS solutions.

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