3Com Switch 8800 Family Configuration Guide

198 CHAPTER 22: QOS CONFIGURATION
Configuring WRED parameters
The switch provides four sets of default WRED parameters, respectively numbered
as 0 to 3. Each set includes 80 parameters, 10 parameters for each of the eight
queues. The ten parameters are green-min-threshold, yellow-min-threshold,
red-min-threshold, green-max-threshold, yellow-max-threshold,
red-max-threshold, green-max-prob, yellow-max-prob, red-max-prob and
exponent. Red, yellow and green packets respectively refer to those with drop
precedence levels 2, 1 and 0.
Perform the following configurations in the specified views.
The command restores the parameters of the specified WRED index as the default
setting. The command restores the WRED parameters related to the queue as the
default setting.
The switch provides four sets of WRED parameters by default.
c
CAUTION: When multicast packets are sent through a certain port outbound
queue, it is necessary to use the queue command to increase appropriately the
length parameter of the corresponding queue where packets are all dropped to
ensure the best effect of the replication capability of the egress port.
See the corresponding Command Manual for details of the commands.
Configuring drop algorithm
Please perform the following configurations in Ethernet port view.
By default, tail drop mode is selected.
See the corresponding Command Manual for details of the commands.
Tabl e 172 Configure WRED parameters
Operation Command
Enter WRED index view (system
view)
wred wred-index
Restore the default WRED
parameters (system view)
undo wred wred-index
Configure WRED parameters
(WRED index view)
queue queue-id green-min-threshold green-max-threshold
green-max-prob yellow-min-threshold yellow-max-threshold
yellow-max-prob red-min-threshold red-max-threshold
red-max-prob exponent
Restore the default WRED
parameters (WRED index)
undo queue queue-id
Exit WRED index view (WRED
index view)
quit
Tabl e 173 Configure drop algorithm
Operation Command
Configure drop algorithm drop-mode { tail-drop | wred } [ wred-index ]
Restore the default algorithm undo drop-mode