Weighted Random Early Detection

Random early detection (RED) is a congestion avoidance algorithm that is most useful when a majority of the traffic is adaptive, such as TCP. TCP uses packet drops as implicit signals of network congestion, reducing the rate at which traffic is sent (or backing off) when a packet is missed.

When a majority of the traffic on a congested link consists of TCP streams from various senders, FIFO queuing tail drops when the queue fills, causing all the TCP senders to back off at the same time. Over a period of time (t), the TCP senders ramp up the sending rate, and when the link gets congested again, the TCP senders all back off at the same time. This oscillating behavior is called global synchronization, as charted ...

Get Inside Cisco IOS Software Architecture (CCIE Professional Development) now with the O’Reilly learning platform.

O’Reilly members experience live online training, plus books, videos, and digital content from nearly 200 publishers.