Case study: ATM ABR congestion control

• two-byte ER (explicit rate) field in RM cell

  • congested switch may lower ER value in cell
  • sender’ send rate thus minimum supportable rate on path

• EFCI bit in data cells: set to 1 in congested switch

  • if data cell preceding RM cell has EFCI set, sender sets CI bit in returned RM cell

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