Cisco AP541N Dual-band Single-radio Access Point Administration ...

4WirelessConfiguring Quality of Service (QoS)Table 24QoS Parameters (Continued)FieldAIFS(Inter-Frame Space)cwMin(MinimumContention Window)cwMax(MaximumContention Window)DescriptionThe Arbitration Inter-Frame Spacing (AIFS) specifies await time for data frames. The wait time is measured inslots. Valid values for AIFS are 1 through 255.This parameter is input to the algorithm that determines theinitial random backoff wait time (window) for retry of atransmission.The value specified for Minimum Contention Window is theupper limit (in milliseconds) of a range from which the initialrandom backoff wait time is determined.The first random number generated will be a numberbetween 0 and the number specified here.If the first random backoff wait time expires before the dataframe is sent, a retry counter is incremented and therandom backoff value (window) is doubled. Doubling willcontinue until the size of the random backoff value reachesthe number defined in the Maximum Contention Window.Valid values for cwMin are 1, 3, 7, 15, 31, 63, 127, 255, 511,or 1023. The value for cwMin must be less than or equal tothe value for cwMax.The value specified for the Maximum Contention Window isthe upper limit (in milliseconds) for the doubling of therandom backoff value. This doubling continues until eitherthe data frame is sent or the Maximum Contention Windowsize is reached.Once the Maximum Contention Window size is reached,retries will continue until a maximum number of retriesallowed is reached.Valid values for cwMax are 1, 3, 7, 15, 31, 63, 127, 255, 511,or 1023. The value for cwMax must be higher than or equalto the value for cwMin.99 Cisco AP 541N Dual-band Single-radio Access Point Quick Start Guide