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Manpages TCSection: Linux (8)Updated: 8 December 2001 Index Return to Main Contents NAMEsfq - Stochastic Fairness QueueingSYNOPSIStc qdisc ... perturb seconds quantum bytesDESCRIPTIONStochastic Fairness Queueing is a classless queueing discipline available for traffic control with the tc(8) command. SFQ does not shape traffic but only schedules the transmission of packets, based on 'flows'. The goal is to ensure fairness so that each flow is able to send data in turn, thus preventing any single flow from drowning out the rest. This may in fact have some effect in mitigating a Denial of Service attempt. SFQ is work-conserving and therefore always delivers a packet if it has one available. ALGORITHMOn enqueueing, each packet is assigned to a hash bucket, based on
PARAMETERS
EXAMPLE & USAGETo attach to device ppp0: # tc qdisc add dev ppp0 root sfq perturb 10 Please note that SFQ, like all non-shaping (work-conserving) qdiscs, is only useful if it owns the queue. This is the case when the link speed equals the actually available bandwidth. This holds for regular phone modems, ISDN connections and direct non-switched ethernet links. Most often, cable modems and DSL devices do not fall into this category. The same holds for when connected to a switch and trying to send data to a congested segment also connected to the switch. In this case, the effective queue does not reside within Linux and is therefore not available for scheduling. Embed SFQ in a classful qdisc to make sure it owns the queue. SOURCE
SEE ALSOtc(8)AUTHORAlexey N. Kuznetsov, <kuznet@ms2.inr.ac.ru>. This manpage maintained by bert hubert <ahu@ds9a.nl>
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