Domain based congestion management

Abstract

The Domain-based Congestion Management method and apparatus detects and regulates congestion in a Diff-serv network. It uses an improvRED method for congestion detection at the core routers and token bucket filters for traffic regulation at the ingress nodes. In addition, improvRED also provides feedback control. ImprovRED uses three thresholds for detecting congestion: a minth, a maxth and a FeedbackThreshold, which takes a value between the minth and the maxth thresholds. Whenever the average queue size is greater than minth and less than Feedback-Threshold, all outgoing packets are marked appropriately to indicate a potential onset of a congestion period. When the average queue size is greater than FeedbackThreshold (but less than maxth) packets are dropped probabilistically and all the outgoing packets are marked appropriately to denote the dropping phase. When the average queue size is greater than the maximum threshold, all incoming packets are dropped. Feedback, in the form of a Local Congestion Notification (LCN) message, is used to notify the ingress nodes of a likely onset of congestion. Ingress nodes immediately respond to the congestion notification by appropriately regulating their respective traffic rates (i.e., the amount of packets they inject into the Diff-serv network). The amount of traffic (or data packets) injected into the core of the Diff-serv domain is controlled by a token bucket filter at each of the ingress nodes.

Description

technical field [0001] The present invention relates to congestion management schemes for controlling the flow of packets on the Internet. Background technique [0002] There are several reasons for possible blocking, such as i) bursty transmissions inherent in nodes and due to statistical multiplexing of nodes on a given path; and ii) non-adaptive monopolizing resource applications, while the above-mentioned congestion results in severe packet loss and affects other sessions sharing network resources. Congestion avoidance and management schemes are necessary for optimal utilization of network resources. [0003] Generally, a congestion control scheme has two parts, i) early congestion detection and avoidance; and ii) a congestion management scheme that starts working when congestion occurs. Several congestion management schemes have been proposed so far. For example, congestion management schemes based on binary feedback rely on terminals returning blocking messages. Si...

AI Technical Summary

Problems solved by technology

However, since bursty traffic can temporarily cause buffer occupancy to be greater than a threshold, simple techniques based on buffer occupancy are insufficient to handle bursty traffic

This leads to frequent use of blocking avoidance / management triggers

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