Quality of Service
-Guaranteed bandwidth    }__ allocate circuit
-Guaranteed delay/jitter }
-Average bandwidth over time

What we're guaranteeing: (table showing different options)
			   connect | delay | bw | avg bw | bw change
Int serv {        absolute         |       |    |        |
	 {       predicted	   |	   |	|	 |
Diff serv{better than best	   |	   |	|	 |
	 {     best effort	   |	   |	|	 |
	 
Today:
-circuits
-paris metro pricing
  -price determines class of service
    -premium for high quality connectivity
  -over-provision!
  
How much to pay for quality?  (2x ?)

Various types of quality/service:
-fixed(f)/variable(v) rate
-tolerant(t)/intolerant(i) of loss/delay
-adaptive(a)/non-adaptive(na) rate/delay

Applications:
-robot surgery (f, i, na)
-teleconferencing (v, t, a)
-video on demand
-online gaming (v, i, a) (latency/jitter matters)
-internet radio/TV broadcast (delay ok, bw matters)
-online shopping
-web surfing

Mechanism/Cost:
-lightweight circuit provisioning

Is delay adaptation a long term solution?
Ok to shift jitter between users?
con: synchronization of bursts
pro: if well behaved, then better statistical multiplexing

Do we need any special hardware support for QoS?
-different customers will demand different quality

Over-provisioning along is not enough; must distinguish between users:
-synchronized bursts can cause problems
-large flows

Mechanism (5 parts):
-service model (guaranteed, predicted, ...)
-flow specification
-admission control
-reservation protocol
-scheduling

Flow Specification:
-fixed bandwidth, leaky bucket (bandwidth + buffer for bursts), tolerance for loss/delay, latency target

Admission Control:
-strict guarantee - flow spec is met at every hop, rate < capacity
-predicted service (if behavior of others is stable)
  -rate < measured capacity
  -delay (measured delay/jitter of higher priority traffic)
-priorities (in spec/out spec)
  -Over-provisioning for high priority
  
Reservation Protocol:
-RSVP, circuits
-check for reserved bandwidth along path; out of luck if path changes