TC(8) Linux TC(8) (NAME) tc-sfq - (Stochastic Fairness Queueing) (SYNOPSIS) tc qdisc ... [ divisor hashtablesize ] [ limit packets ] [ perturb seconds ] [ quantum bytes ] [ flows number ] [ depth number ] [ headdrop ] [ redflowlimit bytes ] [ min bytes ] [ max bytes ] [ avpkt bytes ] [ burst packets ] [ probability P ] [ ecn ] [ harddrop ] (DESCRIPTION) (Stochastic Fairness Queueing SFQ) (qdisc) tc(8) . SFQ <<>> (flows) . . (DoS) . SFQ (work- conserving) . (ALGORITHM) (enqueueing) () (hash bucket) . ( tc filter ) . sfq : (i) (ii) (iii) . SFQ ipv4 ipv6 UDP TCP ESP . . TCP/IP . . sfq (perturbation) . . linux-3.3 ( ) . (dequeuing) (round robin) . linux-3.3 SFQ . (tail-drop) . linux-3.3 SFQ (divisor) . (tail-drop) headdrop . (PARAMETERS) divisor 2.6.39 . . : . limit SFQ. . linux-3.3 . depth ( linux-3.3). . perturb ( ) . 0 . . : 60. . divisor . quantum . MTU . flows linux-3.3 . . headdrop SFQ (tail-drop) . headdrop ( ) TCP . redflowlimit RED SFQ . (Random Early Detection) . ( RED tc-red(8) ). redflowlimit ( ) SFQ . min . max /3 . max . redflowlimit /4 . probability 0.0 1.0 . 0.02 . avpkt . burst . 1000 . burst . : (2 * min + max) / (3 * avpkt) ecn RED <<>> (mark) <<>> (drop) . (Explicit Congestion Notification ECN) RED . ECN . ECN depth . harddrop max ecn (drop) . (EXAMPLE & USAGE) ppp0: # tc qdisc add dev ppp0 root sfq SFQ qdisc ( work- conserving) . ISDN . DSL . . . SFQ qdisc . sfq IP /: # tc filter add ... flow hash keys src,dst perturb 30 divisor 1024 divisor sfq . sfq flow hash . sfq RED: # tc qdisc add dev eth0 parent 1:1 handle 10: sfq limit 3000 flows 512 divisor 16384 redflowlimit 100000 min 8000 max 60000 probability 0.20 ecn headdrop (SOURCE) o Paul E. McKenney "Stochastic Fairness Queuing", IEEE INFOCOMM'90 Proceedings, San Francisco, 1990. o Paul E. McKenney "Stochastic Fairness Queuing", "Interworking: Research and Experience", v.2, 1991, p.113-131. o : M. Shreedhar and George Varghese "Efficient Fair Queuing using Deficit Round Robin", Proc. SIGCOMM 95. (SEE ALSO) tc(8), tc-red(8) (AUTHORS) Alexey N. Kuznetsov, , Eric Dumazet . bert hubert . iproute2 24 January 2012 TC(8)