Sizing Router Buffers. Guido Appenzeller Thesis Defense May 24 th , 2004. Routers need Packet Buffers. It’s well known that routers need packet buffers It’s less clear why and how much Goal of this work is to answer the question: How much buffering do routers need?.
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Thesis DefenseMay 24th, 2004
How much buffering do routers need?
send W+1 packets
tSingle TCP FlowRouter with large enough buffers for full link utilization
C’ > C
Flow Completion Time (FCT)
Idea: Find buffer size by modelling queue behaviour
Poisson arrivals offlows
Service time is Lflow, the flow length in packets
Poisson arrivals of bursts
Service time is the lengthof the burst: 2,4,8,16…
P(Q = x)Buffer Requirements for Short Flows
We derived closed-form estimates of the queue
distribution using Effective Bandwidth
No. of flows in CA mode
For buffer sizing, pick n = 100
Flow arrivalson link 1
The old “Rule-of-Thumb”
TCP Reno: requires