Capacity Allocation in FDDI

• done via two traffic types: synchronous and asynchronous (ie, stream & bursty)

• the allocation algorithm is designed to provide each station with a fixed allocation for synchronous with excess for asynchronous

  • define TTRT >= _ + MFT + TT + _ SAi
  • where TTRT = target token rotation timet = propagation time for 1 circuit
  • MFT = max frame xmit time
  • TT = token xmit time
  • SAi= synchronous allocation for station i
  • TRT, THT = token rotation & holding timers

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