Weighted Random Early Detection (WRED) manages congestion by dropping selected packets before a queue becomes full, reducing tail drop and TCP global synchronization. section 10.6.2
WRED operates by:
- Dropping a percentage of packets as the queue grows beyond a threshold. section 10.6.2
- Providing more control than RED over which packets are dropped. section 10.6.2
- Using packet classifications such as high or low AF drop precedence to influence dropping. section 10.6.2
Early, selective loss encourages affected TCP senders to reduce their windows without forcing every sender to react simultaneously. Avoid WRED for loss-sensitive traffic, including an LLQ priority queue. section 10.6.2
WRED remains a per-hop behavior: each device must be explicitly configured to interpret QoS markings according to the policy; markings alone do not determine treatment. section 10.6.2
