SA Components- Forwarding o Classifier and route selection Incoming packets mapped to classes Single flow or set of flows with same Qos E.g. all video flows Based on ip header fields Determines next hop ◆ Packet scheduler Manages one or more queues for each output Order queued packets sent Based on class, traffic control database, current and past activity on outgoing port a Policing
11 ISA Components – Forwarding Classifier and route selection ◼ Incoming packets mapped to classes Single flow or set of flows with same QoS ◼ E.g. all video flows Based on IP header fields ◼ Determines next hop Packet scheduler ◼ Manages one or more queues for each output ◼ Order queued packets sent Based on class, traffic control database, current and past activity on outgoing port ◼ Policing
61. 4 ISA Services o Traffic specification(TSpec) defined as service for flow On two levels l General categories of service Guaranteed ◆ Controlled load ◆ Best effort( default) a Particular flow within category TSpec is part of contract 12
12 6.1.4 ISA Services Traffic specification (TSpec) defined as service for flow On two levels ◼ General categories of service Guaranteed Controlled load Best effort (default) ◼ Particular flow within category TSpec is part of contract
Token Bucket o Many traffic sources can be defined by token bucket scheme o Provides concise description of load imposed by flow Easy to determine resource requirements o Provides input parameters to policing function 13
13 Token Bucket Many traffic sources can be defined by token bucket scheme Provides concise description of load imposed by flow ◼ Easy to determine resource requirements Provides input parameters to policing function
Token Bucket Diagram token rate= R IP octets per second bucket size B。 ctets current bucket occu pancy arriving departing data data
14 Token Bucket Diagram
ISA Services-Guaranteed service o Assured capacity level or data rate o Specific upper bound on queuing delay through network l Must be added to propagation delay or latency to get total delay I Set high to accommodate rare long queue delays ◆ No queuing losses Ie, no buffer overflow O E. g. Real time play back of incoming signal can use delay buffer for incoming signal but will not tolerate packet loss 15
15 ISA Services –Guaranteed Service Assured capacity level or data rate Specific upper bound on queuing delay through network ◼ Must be added to propagation delay or latency to get total delay ◼ Set high to accommodate rare long queue delays No queuing losses ◼ I.e. no buffer overflow E.g. Real time play back of incoming signal can use delay buffer for incoming signal but will not tolerate packet loss