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

other words, a di erent set of parameters are required if round trip times change
by an order of magnitude, with the link capacities being constant.
The performance of the scheme in the presence of variable ABR demand and
capacity is unclear. Also, the side e ects (if any) of the resetting the MAX
variable will become more clearer under such conditions.
Arithmetic mean (or exponential averaging) is not the correct method for aver-
aging ratios where the denominator is not constant [49]. Further, the running
average assumes that the successive values averaged are close to each other.
The technique cannot e ectively average (or track) sequence of values which
are uncorrelated.
4.11 FMMRA Scheme
The \Fast Max-Min Rate Allocation (FMMRA)" scheme [6] was developed by
researchers Arulambalam, Chen, Ansari at NJIT and Bell Labs.
4.11.1 Key Techniques
The algorithm combines ideas from the ERICA scheme (described in this disserta-
tion) and the UCSC scheme described in section 4.9. It is based on the measurement
of available capacity and the exact calculation of fair rates, while not being sensitive
to inaccuracies in CCR values.
It uses the concept of an advertised rate, , a rate which isgiven to unconstrained
connections. The advertised rate is updated upon receipt of a BRM cell of a session,
using its previous value, the change in the bottleneck bandwidth of the session and
the change in the bottleneck status of the session. A connection which cannot use
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