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

if the input rates are low and the queues are long, we recognize the need to reserve
more capacity to drain the queues and allocate rates conservatively till the queues
are controlled. Further, keeping in line with the design principles of ERICA, we use
continuous functions of the queue length, rather than discontinuous functions. Since
feedback to sources is likely to be regular (as long as queues remain), the allocations
due to a continuous function in successive averaging intervals track the behavior of
the queue and re ect it in the rate allocations.
6.15 ERICA+: 100% Utilization and Quick Drain of Queues
ERICA achieves high utilization in the steady state, but utilization is limited
by the target utilization parameter. For expensive links, it is desirable to keep the
steady state utilization at 100%. This is because a link being able to service 5%
more cells can translate into 5% more revenue. The way to get 100% utilization in
steady state, and quick draining of queues is to vary the target ABR rate dynamically.
During steady state, the target ABR rate is 100% while it is lower during transient
overloads. Higher overloads result in even lower target rates (thereby draining the
queues faster). In other words:
Target rate = function (queue length, link rate, VBR rate)
The \function" above has to be a decreasing function of the queue length.
Note that ERICA has a xed target utilization, which means that the drain rate
is independent of the queue size.
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