A fair traffic conditioner for the assured service in a differentiated services Internet

What is it about?

A research issue under investigation in the context of differentiated services (DiffServ) is the fair distribution of bandwidth between aggregates sharing the same Assured Forwarding (AF) class. Multiplexing both responsive and unresponsive flows, e.g. TCP and UDP respectively, leads to unfair sharing of the available bandwidth in over-provisioned networks. To date, much effort has concentrated on experiments using different methods for mapping TCP and UDP flows of the same AF class to the three possible drop precedences of the AF specification. Although this approach may protect responsive from unresponsive flows, it has not been shown to provide adequate fairness. In this paper we present a traffic conditioner able to provide fairness between responsive and unresponsive flows originating from the same customer network, using a Fair Two-Rate Three-Color Marker. Its capability for fairness is based on the use of the FRED fair active buffer algorithm to control the token allocation of the token buckets residing in the traffic conditioner. We also show that by employing Fair Multiple RED (FMRED) at the DiffServ domain ingress node, the overall fairness of the customer network aggregates is improved when compared to the case where the vanilla MRED algorithm is used.

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