Which queue-type is recommended for congested environments but performs poorly with UDP?

In congested environments, Random Early Detection (RED) queues are utilized to manage network traffic efficiently. This queue type functions by monitoring the average queue length and proactively dropping packets before the queue becomes completely full. This strategy helps prevent congestion collapse by signaling to the sender to reduce transmission rates.

While RED can effectively manage traffic during congestion and promote fair usage of bandwidth by minimizing queue overflow, it is not suitable for UDP traffic due to the nature of UDP's operation. Unlike TCP, UDP does not have built-in mechanisms for retransmission or flow control. If packets are dropped in a RED queue, there is no way for UDP applications to recover those packets, leading to potential issues with performance and reliability. This contrasts with TCP, which can adjust its transmission rate based on feedback about packet loss.

The importance of RED lies in its ability to work in high-traffic environments, providing a method to avoid excessive queuing and maintain a level of service, yet it struggles with UDP because of the absence of error recovery, which can result in loss of packets without any retransmission efforts.