30
V. Liberatore
Pervasive Computing
Quality-of-Service (QoS)
Best-effort model
nPrevalent
in the Internet
nNo
end-to-end circuit
nPackets
can be delayed
nDelay is often unpredictable
nNo
bandwidth reservation
QoS
nAmeliorate best-effort model
nE.g.,
packet priorities
Impact on control
nDelays
E.g., forces small feedback
gains
nPacket
drop-outs
Infinite delays
nJitter
Delay variability
Often more critical than average
delays
nBandwidth
Relevance?