Digi TransPort - Page 487

Queue Profiles parameters
Digi TransPort User Guide 487
WRED Queue Length Weight factor
A weighting factor used in the WRED algorithm when calculating the weighted queue length.
The weighted queue length is based on the previous queue length and has a weighting factor
that may be adjusted to provide different transmit characteristics. The actual formula used is:
new_length = (old_length * (1-1/2^n)) + (current_length * 1/2^n)
Small weighting factor values result in a weighted queue length that moves quickly and more
closely matches the actual queue length. Larger weighting factor values result in a queue
length that adjusts more slowly. If a weighted queue length moves too quickly (small
weighting factor), it can result in dropped packets if the transmit rate rises quickly, but will also
recover quickly after the transmit rate tails off. If a weighted queue length moves too slowly
(large weighting factor), it allows a burst of traffic through without dropping packets, but may
result in dropped packets for some time after the actual transmit rate drops off. Therefore,
use care in selecting the weighting factor to suit the type of traffic using the queue.
Related CLI commands
Examples
• To display a queue profile, enter the following command:
gqprof <instance> ?
Where <instance> is the number of the queue profile to be displayed.
•To change the value of a parameter, use the following command:
qprof <instance> <parameter> <value>
• To set the maximum throughput for queue profile 5 to 10kbps, enter the following command:
qprof 5 maxkbps 10
Entity Instance Parameter Values Equivalent Web Parameter
qprof n minkbps 0-2147483647 Minimum kbps
qprof n maxkbps 0-2147483647 Maximum kbps
qprof n qlen 0-2147483647 Maximum Packet Queue Length
qprof n minth 0-2147483647 WRED Minimum Threshold
qprof n maxth 0-2147483647 WRED Maximum Threshold
qprof n mprob 0-100 WRED Maximum Drop
Probability (%)
qprof n wfact 0-2147483647 WRED Queue Length Weight
factor