Blue (queue management algorithm): Difference between revisions

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'''Blue'''<ref>W. Feng, D. Kandlur, D. Saha, K. Shin. ''Blue: A New Class of Active Queue Management Algorithms.'' U. Michigan CSE-TR-387-99, April 1999.</ref> is an [[Active Queue Management]] algorithm. Like [[Random early detection|RED]], it operates by randomly dropping or [[Explicit Congestion Notification|ECN]]-marking packets in a router's queue before it overflows. Unlike RED, however, it requires little or no tuning on the part of the network administrator.

==Operation of Blue==

A Blue queue maintains a drop/mark probability ''p'', and drops/marks packets with probability ''p'' as they enter the queue. Whenever the queue overflows, ''p'' is increased by a small constant ''p_d'', and whenever the queue is empty, ''p'' is decreased by a constant ''p_i<p_d''.

Assuming the mix of traffic on the interface doesn't change, ''p'' will slowly converge to a value that keeps the queue within its bounds with full link utilisation.

==Stochastic Fair Blue==