Traffic Management for the Available Bit Rate (ABR) Service in ...

utilization) with no oscillations and minimal queues. Please note that the simulation
graphs, though introduced periodically, are at the end of the chapter.
6.22.3 Minimal Delay and Queue Lengths
Figure 6.8: Two source con guration
To test for minimal delays and short queue lengths, we use a multiple source
con guration. The simplest such con guration is the two source con guration, where
two sources share a link as illustrated in gure 6.8. Each source must converge to
almost half of the link rate (1/2 Target Utilization), which is the max-min optimal
allocation.
Figure 6.13 shows that the convergence is fast, the queue lengths are small (hence,
the delay is minimal) and steady state performance is good. For ERICA+, the
two sources rapidly converge to their optimal rates as seen in gure 6.14, and the
queue length rises to reach the limit corresponding to its target delay parameter (100
microseconds corresponds to approximately 30 cells at 155.52 Mbps). There is a slight
rate oscillation seen in gure 6.14(a) to allow the queues to reach the target value,
but the steady state has no rate oscillations and 100% link utilization ( gure 6.14(c)).
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