Blue (queue management algorithm): Difference between revisions

Revision as of 18:56, 8 June 2013

Revision as of 19:09, 8 June 2013

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{{primary sources|date=June 2011}}

'''Blue''' is an [[active queue management]] algorithm for a [[Router (computing)|router]] or other [[computer network]] device. Like [[random early detection]] (RED), it operates by randomly dropping or marking packet with [[explicit congestion notification]] 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.<ref>{{Cite journal |title=BLUE: A New Class of Active Queue Management Algorithms |author1=Wu-chang Feng |author2=Dilip D. Kandlur |author3=Debanjan Saha |author4=Kang G. Shin |year=1999 |month=April |url=http://www.eecs.umich.edu/techreports/cse/99/CSE-TR-387-99.pdf |journalpublisher=U. University of Michigan |work= Computer Science Technical Report |issue=CSE–TR–387–99 |accessdate= June 8, 2013 }}</ref>

==Operation==

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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===

The main flaw of Blue, which it shares with most single-queue queueing disciplines, is that it does not distinguish between flows, and treats all flows as a single aggregate. Therefore, a single aggressive flow can push out of the queue packets belonging to other, better behaved, flows.

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When a flow's drop/mark probability reaches 1, the flow has been shown to not react to congestion indications from the network. Such an inelastic flow is put in a "[[penalty box]]", and rate-limited.

===Resilient stochastic fair Blue===

Active queue management (AQM) algorithms, including the fairness-aimed ones, are notably vulnerable to spoofing [[distributed denial-of-service]] (DDoS) attacks. A Resilientresilient Stochasticstochastic Fairfair Blue (RSFB) algorithm was proposed in 2009 against spoofing DDoS attacks. The basic idea behind RSFB is to record the responsive normal TCP flows and rescue their dropped packets. RSFB algorithm is effective in preserving the TCP throughput in the presence of spoofing DDoS attacks.<ref name=RSFB>{{Cite journal |author= Changwang Zhang, Jianping Yin, and Zhiping Cai, [|url= http://sites.google.com/site/cwzhangres/home/files/RSFBaResilientStochasticFairBluealgorithmagainstspoofingDDoSattacks.pdf?attredirects |title=0 RSFB: a Resilient Stochastic Fair Blue algorithm against spoofing DDoS attacks], in|work= International Symposium on Communication and Information Technology (ISCIT), |year= 2009. |pages= 1566-1567 |isbn= 978-1-4244-4521-9 }} [http://portal.acm.org/citation.cfm?id=1789954.1790341 RefAbstract]</ref>

===Implementations===

An implementation of Blue is part of [[ALTQ]], the alternative AQM framework for BSD Unix.<ref>[http://www.thefengs.com/wuchang/blue/ BLUE]</ref>

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==References==

<references />

==External links==

* [http://www.thefengs.com/wuchang/blue/ Wu-chang Feng's page about Blue and SFB].

* [http://www.pps.univ-paris-diderot.fr/~jch/software/sfb/ An implementation of SFB for the Linux kernel].

[[Category:Packets (information technology)]]