Sunday, January 30, 2011

Doubts about quality of service over IP

Gary Bachula, Vice President for External Affairs for Internet2, asserts that specific QoS protocols are unnecessary in the core network as long as the core network links are "over-provisioned" to the point that network traffic never encounters delay. In "quality of service" engineering, this formulation is guaranteed by the admission control feature. It is important to note that this only refers to core networks and not end-to-end connections. Recent studies point to a relatively low end-to-end bandwidth availability even on Internet2.

The Internet2 QoS Working Group concluded that increasing bandwidth is probably more practical than implementing QoS.[7][8]

The Internet2 project found, in 2001, that the QoS protocols were probably not deployable inside its Abilene network with equipment available at that time. While newer routers are capable of following QoS protocols with no loss of performance, equipment available at the time relied on software to implement QoS. The Internet2 Abilene network group also predicted that "logistical, financial, and organizational barriers will block the way toward any bandwidth guarantees" by protocol modifications aimed at QoS.[9][10] In essence, they believe that the economics would be likely to make the network providers deliberately erode the quality of best effort traffic as a way to push customers to higher priced QoS services.

The Abilene network study was the basis for the testimony of Gary Bachula to the Senate Commerce Committee's Hearing on Network Neutrality in early 2006. He expressed the opinion that adding more bandwidth was more effective than any of the various schemes for accomplishing QoS they examined.[11]

Bachula's testimony has been cited by proponents of a law banning quality of service as proof that no legitimate purpose is served by such an offering. This argument is dependent on the assumption that over-provisioning isn't a form of QoS and that it is always possible. Cost and other factors affect the ability of carriers to build and maintain permanently over-provisioned networks.

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