Approximating Rate - Based work Conserving Schedulers with limited state buffer Management

We present an active queue management policy that can be used to approximate a large class of scheduling disciplines called rate-based work-conserving schedulers. We call this policy Discard Based on Queue state (DBQ). DBQ only uses the state information pertaining to packets currently in the queue in order to make a decision to accept or reject an incoming packet. As a result of this decision, DBQ can closely approximate the underlying scheduling discipline. We show simulation results to corroborate this.

DBQ has a distinct advantage over scheduling approaches in networks like the Internet, where flows are highly dynamic and short-lived. It requires state limited to only the packets that are currently in the queue. It does not need any complicated setup or tear-down procedure for flow state. It requires constant number of (O (1)) very simple operations to make a drop decision.

Many well-known schedulers such as WFQ and static priorities belong to the class of rate-based work-conserving schedulers. We also give simple composition rules that can be used to define newer rate-based work conserving schedulers.

By: Rahul Garg Abhinav Kamra

Published in: RI03009 in 2003


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