Configuring WRED
Context
Weighted Random Early Detection (WRED) randomly discards packets based on drop parameters to prevent global TCP synchronization. WRED discards packets based on packet colors, so packets with higher priorities are less likely to be discarded. A WRED drop profile defines absolute values of upper and lower drop thresholds, upper and lower drop thresholds in percentage, and maximum drop probability for packets of different colors. For more information about packet colors, see Priority Mapping Configuration.
- After ECN is enabled for the queue where congestion occurs, the device does not randomly discard packets based on the WRED drop profile.
- For the CE12800E equipped with ED-E, EG-E, and EGA-E series cards, after ECN is enabled for a queue, if congestion occurs, the device does not randomly discard packets. Instead, the device randomly marks packets based on the WRED drop profile. When the queue length reaches the upper threshold in the WRED drop profile, the device starts to discard new packets entering the queue. In this case, ECN cannot reset the CE field.
Procedure
- Configure WRED on the CE12800.
- Configure WRED on the CE12800E
- Run color { green | non-tcp | red | yellow } { buffer-size low-limit low-buffer-size high-limit high-buffer-size | buffer-size cell low-limit low-buffer-cell-size high-limit high-buffer-cell-size | low-limit low-limit-percentage high-limit high-limit-percentage } discard-percentage discard-percentage
WRED parameters are set.
By default, the upper drop threshold in percentage, lower drop threshold in percentage, and maximum drop probability of a WRED drop profile are all 100, and absolute values of upper and lower drop thresholds are not configured.
The CE12800E configured with ED-E, EG-E, and EGA-E series cards does not support the non-tcp and buffer-size cell low-limit low-buffer-cell-size high-limit high-buffer-cell-size parameters.
- Run color { green | non-tcp | red | yellow } { buffer-size low-limit low-buffer-size high-limit high-buffer-size | buffer-size cell low-limit low-buffer-cell-size high-limit high-buffer-cell-size | low-limit low-limit-percentage high-limit high-limit-percentage } discard-percentage discard-percentage