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

control problem was also simpler. Speci cally, the ABR service needs to provide
good performance given that the variation in both the demand and capacity is
high. Demand is usually variable because of the bursty nature of data tra c.
Capacity varies because of the presence of higher priority CBRor VBR tra c
classes. Further, the scheme must be robust to adapt to conditions like delayed
or lost feedback.
Implementation Cost/Performance tradeo s: The scheme should provide sev-
eral tradeo points for implementation incurring di erent costs. The basic ver-
sion of the scheme should not require expensive implementation (for example,
per-VC queuing as in the case of credit-based schemes). The scheme should be
exible enough to perform well for the target workload scenario, at an accept-
able cost.
Scalability: The scheme should not be limited to a particular range of speed, dis-
tance, number of switches, or number of VCs. Typical parameters which have
scalability implications are: the amount of bu ers required, the bu er alloca-
tion, queuing and scheduling policy required, the number of switch algorithm
operations required per-control cell, and the convergence time (time taken to
reach a steady state) of the switch algorithm.
Implementation, Space and Time Complexity: The scheme should be simple
to implement - it should not require measurements or logic which are expensive.
Further, the amount of memory required for the scheme should be minimal.
The best possibility is to have a constant space (or O(1) space complexity)
algorithm which utilizes constant space irrespective ofthenumber of VCs setup
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