Questions on qualitative notion of service

Bucket can hold b tokens
Tokens generated at r tokens/sec unless bucket is full
Over an interval of length t, number of admitted packets
Token bucket and WFQ can be combined to provide upper bound on delay
Integrated services
o Provides QoS in IP networks for individual application sessions
o Relies on resource reservation and routers to maintain state and records of allocated resources
o Call admission
Session must first declare QoS requirement and mark the packets
R-spec: defines QoS being requested
T-spec: defines traffic characteristics
A signalling protocol is needed to carry the R-spec and T-spec to the routers where
reservation is required (possibly through RSVP)
Routers will admit calls based on R-Spec and T-Spec and current resource allocation
o Classes
Guaranteed QoS: firm bounds provided on queuing delay at router (for hard real-time)
Controlled load: provides QoS closely approximating an unloaded router
Differentiated services
o Scalability addresses difficulty with maintaining states for large number of flows
o Flexible service models IntServ only has 2 classes, but DiffServ provides qualitative service classes
o Simpler signalling than RSVP for applications wanting a more qualitative notion of service
o Approach