Provided by: freebsd-manpages_8.2-1_all bug

NAME

     ng_car — Commited Access Rate netgraph node type

SYNOPSIS

     #include <netgraph/ng_car.h>

DESCRIPTION

     The car node type limits traffic flowing through it using:

     ·   Single rate three color marker as described in RFC 2697,
     ·   Two rate three color marker as described in RFC 2698,
     ·   RED-like rate limit algorithm used by Cisco,
     ·   Traffic shaping with RED.

HOOKS

     This node type supports the following hooks:

     upper   Hook leading to upper layer protocols.

     lower   Hook leading to lower layer protocols.

     Traffic flowing from upper to lower is considered downstream traffic.  Traffic flowing from
     lower to upper is considered upstream traffic.

MODES OF OPERATION

     Each hook can operate in one of the following modes:

     NG_CAR_SINGLE_RATE
             Single rate three color marker as described in RFC 2697.  Committed burst packets
             are counted as green, extended burst packets are counted as yellow and exceeding
             packets are counted as red.  Committed burst getting refilled with CIR (Committed
             Information Rate) speed.  When it is full, exceeded burst getting refilled.

     NG_CAR_DOUBLE_RATE
             Two rate three color marker as described in RFC 2698.  Committed burst packets are
             counted as green, peak burst packets are counted as yellow and exceeding packets are
             counted as red.  Committed burst getting refilled with CIR speed.  Peak burst
             getting refilled with PIR (Peak Information Rate) speed at the same time.

     NG_CAR_RED
             Similar to NG_CAR_SINGLE_RATE, but with different understanding of extended burst.
             When normal burst exceeded and extended burst is used, packets are counted red with
             probability equal to part of extended burst consumed.  Extended burst getting
             refilled first.  When it is full, committed burst getting refilled.  This behavior
             is similar to RED active queue management algorithm.

             This algorithm is more polite to the TCP traffic than NG_CAR_SINGLE_RATE.

     NG_CAR_SHAPE
             Committed burst packets are counted as green, exceeding packets are delayed by queue
             with RED management and counted as yellow.  Packets dropped by queue counted as red.
             Queue parameters are hardcoded: length 99 packets, min_th 8 packets, max_p 100%.

             Traffic shaping is much more polite to the TCP traffic than rate limit on links with
             bandwidth * delay product less than 6-8 TCP segments, but it consumes additional
             system resources for queue processing.
     By default, all information rates are measured in bits per second and bursts are measured in
     bytes. But when NG_CAR_COUNT_PACKETS option is enabled, rates are measured in packets per
     second and bursts are in packets.

CONTROL MESSAGES

     This node type supports the generic control messages and the following specific messages.

     NGM_CAR_SET_CONF (setconf)
             Set node configuration to the specified at struct ng_car_bulkconf

     NGM_CAR_GET_CONF (getconf)
             Return current node configuration as struct ng_car_bulkconf

             struct ng_car_hookconf {
                     u_int64_t cbs;          /* Committed burst size */
                     u_int64_t ebs;          /* Exceeded/Peak burst size */
                     u_int64_t cir;          /* Committed information rate */
                     u_int64_t pir;          /* Peak information rate */
                     u_int8_t green_action;  /* Action for green packets */
                     u_int8_t yellow_action; /* Action for yellow packets */
                     u_int8_t red_action;    /* Action for red packets */
                     u_int8_t mode;          /* operation mode */
                     u_int8_t opt;           /* mode options */
             };

             /* possible actions (..._action) */
             enum {
                 NG_CAR_ACTION_FORWARD = 1,
                 NG_CAR_ACTION_DROP
             };

             /* operation modes (mode) */
             enum {
                 NG_CAR_SINGLE_RATE = 0,
                 NG_CAR_DOUBLE_RATE,
                 NG_CAR_RED,
                 NG_CAR_SHAPE
             };

             /* mode options (opt) */
             #define NG_CAR_COUNT_PACKETS    2

             struct ng_car_bulkconf {
                     struct ng_car_hookconf upstream;
                     struct ng_car_hookconf downstream;
             };

     NGM_CAR_GET_STATS (getstats)
             Return node statistics as struct ng_car_bulkstats

             struct ng_car_hookstats {
                     u_int64_t passed_pkts;
                     u_int64_t droped_pkts;
                     u_int64_t green_pkts;
                     u_int64_t yellow_pkts;
                     u_int64_t red_pkts;
                     u_int64_t errors;
             };

             struct ng_car_bulkstats {
                     struct ng_car_hookstats upstream;
                     struct ng_car_hookstats downstream;
             };

     NGM_CAR_CLR_STATS (clrstats)
             Clear node statistics.

     NGM_CAR_GETCLR_STATS (getclrstats)
             Atomically return and clear node statistics.

SHUTDOWN

     This node shuts down upon receipt of a NGM_SHUTDOWN control message, or when all hooks have
     been disconnected.

EXAMPLES

     Limit outgoing data rate over fxp0 Ethernet interface to 20Mbit/s and incoming packet rate
     to 5000pps.

           /usr/sbin/ngctl -f- <<-SEQ
                   mkpeer fxp0: car lower lower
                   name fxp0:lower fxp0_car
                   connect fxp0: fxp0_car: upper upper
                   msg fxp0_car: setconf { downstream={ cir=20000000 cbs=2500000 ebs=2500000 greenAction=1 yellowAction=1 redAction=2 mode=2 } upstream={ cir=5000 cbs=100 ebs=100 greenAction=1 yellowAction=1 redAction=2 mode=2 opt=2 } }
           SEQ

SEE ALSO

     netgraph(4), ngctl(8)

     J. Heinanen, A Single Rate Three Color Marker, RFC 2697.

     J. Heinanen, A Two Rate Three Color Marker, RFC 2698.

AUTHORS

     Nuno Antunes <nuno.antunes@gmail.com>
     Alexander Motin <mav@FreeBSD.org>

BUGS

     At this moment only DROP and FORWARD actions are implemented.