WRR Scheduling: End-to-End Delay Bound

• Messages take at most e(i)/wt(i) rounds to complete

• Implies delay through first switch = (e(i)/wt(i))RL

• At each subsequent switch, each round of packets arriving is sent
in the next round

– Implies one round delay at each hop

• Therefore, end-to-end delay for connection i with message size ei assigned weight wt(i) passing through r switches is bounded by:

W(i) ≤ (e(i)/wt(i) + r – 1)RL

• Can also be shown that jitter can be bounded by jitter < p(i) – e(i) + (r – 1)(RL – 1)  for messages of size ei with inter-arrival time of p(i)


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