Which option is a congestion avoidance mechanism?
- QPM
- WRED
- LFI
- MRF
Explanation: WRED (Weighted Random Early Detection) is a congestion avoidance mechanism that manages network resources by selectively dropping packets before a queue becomes completely full. While standard "tail drop" mechanisms only discard packets when a buffer is already overflowed, WRED monitors the buffer depth and performs early discards on random packets once a minimum defined threshold is exceeded.
This proactive dropping is primarily used to prevent TCP global synchronization, which occurs when multiple TCP senders simultaneously reduce their transmission rates due to a tail drop, leading to suboptimal bandwidth utilization. By using WRED, the switch can skew the randomness of these drops based on traffic weights, meaning more important traffic is less likely to be dropped than less important traffic during periods of congestion.
Related exam: Modules 1 – 7: Checkpoint Exam: Network Switching Answers (CCNP ENCOR v9)
