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Network Traffic Management Essentials

Comprehensive overview of scheduling mechanisms, resource configuration, and admission control in network traffic management. Learn about various scheduling policies, including FIFO, priority queuing, round robin, and weighted fair queuing (WFQ). Understand the complexities and simplicities of different scheduling approaches, such as priority-driven scheduling and worst-case traffic arrival scenarios. Explore resource configuration aspects like traffic engineering, QoS routing, and network planning, along with admission control procedures and signaling protocols.

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Network Traffic Management Essentials

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  1. CIS679: Scheduling, Resource Configuration and Admission Control • Review of Last lecture • Scheduling • Resource configuration • Admission control

  2. Review of last lecture

  3. Scheduling Mechanisms • Scheduling: choosing the next packet for transmission on a link can be done following a number of policies; • FIFO: in order of arrival to the queue; packets that arrive to a full buffer are either discarded, or a discard policy is used to determine which packet to discard among the arrival and those already queued

  4. Scheduling Policies • Priority Queuing: classes have different priorities; class may depend on explicit marking or other header info, eg IP source or destination, TCP Port numbers, etc. • Transmit a packet from the highest priority class with a non-empty queue • Preemptive and non-preemptive versions

  5. Scheduling • Scheduling: • FIFO • Priority Scheduling (static priority) • Round Robin • Weight Fair Queuing (WFQ)

  6. packets are transmitted according to their priorities; within the same priority, packets are served in FIFO order. Complex in terms of no provable bounded delay due to no flow isolation Simple in terms of no per-flow management: SP make it possible to decouple QoS control from the core-router. D = ?? max Priority-driven Scheduler

  7. Round Robin • Round Robin: scan class queues serving one from each class that has a non-empty queue

  8. WFQ • Weighted Fair Queuing: is a generalized Round Robin in which an attempt is made to provide a class with a differentiated amount of service over a given period of time

  9. Worst case traffic arrival: leaky-bucket-policed source Complex in terms of having per-flow isolation mechanism, hence needing per-flow state maintenance and resource reservation at per-element: WFQ couple QoS control to the core-router. Simple in terms of having mathematically provable bound on delay, which makes admission control simple. D = b/R max WFQ (more) token rate, r arriving traffic bucket size, b per-flow rate, R WFQ

  10. Resource Configuration • Traffic engineering • QoS routing • Resource provisioning • Network planning • Network design

  11. Admission Control • Session must first declare its QOS requirement and characterize the traffic it will send through the network • R-spec: defines the QOS being requested • T-spec: defines the traffic characteristics • A signaling protocol is needed to carry the R-spec and T-spec to the routers where reservation is required; RSVP is a leading candidate for such signaling protocol

  12. Admission Control • Call Admission: routers will admit calls based on their R-spec and T-spec and base on the current resource allocated at the routers to other calls.

  13. Conclusion • Scheduling: • Decide the order of packet transmission • Resource configuration • Admission control

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