qos queue wred
Function
The qos queue wred command applies a Weighted Random Early Detection (WRED) drop profile to the system or an interface queue.
The undo qos queue wred command deletes a WRED drop profile from the system or an interface queue.
By default, no WRED drop profile is applied to the system or an interface queue.
Only the S5720-EI, S5720-HI, S5730-HI, S5731-H, S5731-S, S5731S-H, S5731S-S, S5732-H, S6720-EI, S6720-HI, S6720S-EI, S6730-H, S6730S-H, S6730-S, and S6730S-S support this command.
A WRED drop profile cannot be applied to interfaces 1 to 12 on the S6720-50L-HI-48S, S5732-H48S6Q, S5732-H48UM2CC, and S6730-H48X6C.
Parameters
Parameter |
Description |
Value |
|---|---|---|
queue-index |
Specifies the index of a queue. |
The value is an integer that ranges from 0 to 7. |
drop-profile-name |
Specifies the name of a WRED drop profile. |
The value must be the name of an existing WRED drop profile. |
Views
System view, GE interface view, XGE interface view, MultiGE interface view, 25GE interface view, 40GE interface view, 100GE interface view, port group view
Usage Guidelines
Usage Scenario
Tail drop technology processes all packets in the same manner without classifying the packets. When the queue length reaches its maximum value, the packets that were added last (at the tail of the queue) are discarded. This packet drop policy may cause global TCP synchronization. As a result, TCP connections cannot be set up.
Random Early Detection (RED) and WRED are used to avoid global TCP synchronization.
RED and WRED randomly discard packets to prevent global TCP synchronization. When packets of a TCP connection are discarded, packets of other TCP connections can still be sent at a high rate, ensuring bandwidth use efficiency.
Prerequisites
A WRED drop profile has been created using the drop-profile command.
Precautions
On the switch, you can apply a WRED drop profile to an interface, the system, or a queue on an interface.
If a WRED drop profile is applied to the system and an interface simultaneously, the WRED drop profile applied to the interface takes effect. After a WRED drop profile is applied to the system, it takes effect on all the interfaces.
If you apply a WRED drop profile to an interface and a queue on an interface simultaneously, the system matches the packets with the profiles applied to the queue and interface in sequence. Then the switch performs congestion avoidance on the packets that match the WRED drop profile.
To apply the same WRED drop profile to queues with the same index on multiple interfaces, perform the configuration on a port group to reduce the workload.
Example
# Create a WRED drop profile named wred1 and apply it to queue 1 on the GE0/0/1.
<HUAWEI> system view [HUAWEI] drop-profile wred1 [HUAWEI-drop-wred1] color green low-limit 80 high-limit 100 discard-percentage 10 [HUAWEI-drop-wred1] color yellow low-limit 60 high-limit 80 discard-percentage 20 [HUAWEI-drop-wred1] color red low-limit 40 high-limit 60 discard-percentage 40 [HUAWEI-drop-wred1] quit [HUAWEI] interface gigabitethernet 0/0/1 [HUAWEI-GigabitEthernet0/0/1] qos queue 1 wred wred1