Method and apparatus for guaranteeing data transfer rates and delays in data packet networks using generalized discrete data transfer rate approach
View Patent ↗A scheduler and method for use in packet communication systems apply a generalized discrete-rate scheduling technique which removes the limitation of the linear increase in sorting complexity with the number of supported service rates. The set of supported service rates may be increased without increasing the number of timestamps that need to be sorted. Conversely, the generalized discrete-rate scheduler supports a given number of service rates using a smaller number of rate FIFO queues, thus further reducing complexity. Such improved performance is achieved by splitting, for scheduling purposes only, a connection or session into multiple sub-connections or sub-sessions. The technique can be applied to per-connection-timestamp and no-per-connection-timestamp discrete-rate schedulers, as well as to any other discrete-rate scheduler.
1. A method for processing a session in a packet-processing system the session having a service rate, the method comprising the steps of:
determining whether the service rate matches one of a plurality of basic rates R i , with each basic rate associated with a respective one of a plurality of rate-specific queues; and
splitting the session, in response to a non-match of the service rate with any one of the plurality of basic rates, into a plurality of N subsessions for queuing into one of the plurality of rate-specific queues, where a subsession rate is selected and the session is split into the plurality of N subsessions such that every subsession is restricted to have an identical subsession rate r i,j satisfied by dividing the service rate by N to equal one of the plurality of basic rates R i .
2. The method of claim 1 , wherein the subsession rate matches one of the plurality of basic rates.
3. The method of claim 1 , further comprising the step of:
queuing the subsessions into a corresponding rate-specific queue having an associated basic rate matching the subsession rate.
4. The method of claim 1 , wherein the steps of determining and splitting are performed by a queue controller.
5. The method of claim 1 , further comprising the step of:
processing the session and subsessions using a per-connection-timestamp procedure.
6. The method of claim 1 , further comprising the step of:
processing the session and subsessions using a no-per-connection-timestamp procedure.
7. The method of claim 1 , wherein the rate-specific queues are rate first-in-first-out (FIFO) queues.