WRED
Weighted Random Early Detection
- Weighted Random Early Detection (WRED) is a congestion avoidance mechanism that addresses packet loss caused by Tail Drop, which occurs when new incoming packets are dropped because a router's queues are too full to accept them
- Tail Drop causes Global TCP Synchronization, where all TCP sources reduce flow with congestion, then increase flow when congestion is reduced and causes congestion again
- When WRED is implemented, you can configure different tail drop thresholds for each IP precedence or DSCP value so that lower-priority traffic is more likely to be dropped than higher priority traffic, thereby avoiding Global TCP Synchronization
- Useful for networks where the majority of traffic uses TCP because TCP packets that are
NOTE: Typically encountered in higher-level certs, such as the CCNP or CCIE, but Boson likes it, so...