User guide

Understanding Bandwidth Management Link Characteristics
84
pmp-0229 (Mar 2013)
For each token, the SM can send toward the network in the uplink (or the AP can send toward the
SM in the downlink) an equivalent number of kilobits. Two buckets determine the permitted
throughput: one in the SM for uplink and one in the AP for downlink.
The applicable set of Uplink Burst Allocation and Downlink Burst Allocation parameters
determine the number of tokens that can fill each bucket. When the SM transmits (or the AP
transmits) a packet, the equivalent number of tokens is removed from the uplink (or downlink)
bucket.
Except when full, the bucket is continuously being refilled with tokens at rates that the applicable
set of Sustained Uplink Data Rate and Sustained Downlink Data Rate parameters specify. The
bucket often drains at a rate that is much faster than the sustained data rate but can refill at only the
sustained data rate. Thus, the effects of the allocation and rate parameters on packet delay are as
follows:
• the burst allocation affects how many kilobits are processed before packet delay is imposed.
• the sustained data rate affects the packet delay that is imposed.
Which set of these MIR parameters are applicable depends on the interactions of other parameter
values. These interactions are described under Setting the Configuration Source on Page 324.
Also, where the Configuration Source parameter setting in the AP specifies that BAM values
should be used, they are used only if Prizm is configured to send the values that it stores for the
MIR parameters.
MIR Data Entry Checking
Uplink and downlink MIR is enforced as shown in Figure 25.
NOTE:
In these figures, entry refers to the setting in the data rate parameter, not the
burst allocation parameter.
Figure 25: Uplink and downlink rate caps adjusted to apply aggregate cap
uplink cap enforced =
uplink entry x aggregate cap for the SM
uplink entry + downlink entry
downlink cap enforced =
downlink entry x aggregate cap for the SM
uplink entry + downlink entry