Configuring Wred Parameters - H3C S9500 Series Operation Manual

Operation Manual – QoS/ACL
H3C S9500 Series Routing Switches
Table 2-13 Configure queue scheduling
Configuring
scheduling
Restore the default setting
By default, the switch uses all-SP mode, so those queues not configured with WRR
algorithm are SP mode.
See the corresponding Command Manual for details of the commands.

2.2.7 Configuring WRED Parameters

In the case of network congestion, the switch drops packets to release system
resources. And then no packets are put into long-delay queues.
The switch allocates drop precedence for it when receiving a packet (also called
coloring the packet). The drop precedence values range from 0 to 2, with 2 for red, 1 for
yellow and 0 for green. In congestion, red packets will be first dropped, and green
packets last.
You can configure drop parameters and thresholds by queue or drop precedence.
The following two drop modes are available:
1) Tail drop mode: Different queues (red, yellow and red) are allocated with different
drop thresholds. When these thresholds are exceeded respectively, excessive
packets will be dropped.
2) WRED drop mode: Drop precedence is taken into account in drop action. When
only min-thresholds of red, yellow and green packets are exceeded, excessive
packets are dropped randomly at given probability. But when max-thresholds of
red, yellow and green packets are exceeded, all excessive packets will be
dropped.
You must first configure WRED parameters for every outbound queue in defining drop
precedence.
I. 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.
You can use the following commands to configure WRED parameters.
Operation
queue-scheduler
queue
queue-weight }
queue-weight } &<1-8> }*
undo queue-scheduler [ queue-id ] &<1-8>
Command
wrr
&<1-8>
2-18
Chapter 2 QoS Configuration
{ group1 { queue-id
| group2 { queue-id