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

exibility of decoupling the enforcement and feedback calculation. This aspect
has since become a standard feature in all schemes developed.
The algorithm quickly adapts to dynamic changes in the network provided the
declared values of the parameters \desired rate" etc are accurate. The algorithm
is shown to be \self-stabilizing" in the sense that it recovers from any past
errors, changes in the set of network users, individual session demands and
session routes.
The algorithm provides fast convergence to max-min rates (within 4k round
trips, where k is the number of bottlenecks).
Charny also shows that the algorithm is \well-behaved" in transience, i.e., given
an upper bound on the round-trip delay, the actual transmission rates can be
kept feasible throughout the transient stages of the algorithm operation while
still providing reasonable throughput to all users. A feasible set of rate alloca-
tions ensures that a rate allocation is such that no link capacity is exceeded. The
arguments assumed synchronization among sources, or a special source policy
which forces synchronization in the asynchronous case.
The drawbacks of the scheme were:
The computation of the fairshare requires order n operations, where n is the
number of VCs. The space requirements of the scheme are also order n:
The feedback procedure is unipolar, i.e., switches only reduce the rates of
sources. As a result, the sources require an extra round trip for increase. This
feature is addressed in the Precise Fair Share Computation option of the OSU
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