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

2. Review of last lecture

3. Scheduling Mechanisms r Scheduling: choosing the next packet for transmission on a link can be done following a number of policies; r 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 r 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. r Transmit a packet from the highest priority class with a non-empty queue r Preemptive and non-preemptive versions

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

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

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

8. WFQ r 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. WFQ (more) r Worst case traffic arrival: leaky-bucket-policed source r 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. r Simple in terms of having mathematically provable bound on delay, which makes admission control simple. WFQ token rate, r bucket size, b per-flow rate, R D = b/R max arriving traffic

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

11. Admission Control r Session must first declare its QOS requirement and characterize the traffic it will send through the network r R-spec: defines the QOS being requested r T-spec: defines the traffic characteristics r 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 r 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 r Scheduling: m Decide the order of packet transmission r Resource configuration r Admission control