Skip site navigation (1)Skip section navigation (2)

FreeBSD Man Pages

Man Page or Keyword Search:
Man Architecture
Apropos Keyword Search (all sections) Output format
home | help
NG_CAR(4)	       FreeBSD Kernel Interfaces Manual		     NG_CAR(4)

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:

     +o	 Single	rate three color marker	as described in	RFC 2697,
     +o	 Two rate three	color marker as	described in RFC 2698,
     +o	 RED-like rate limit algorithm used by Cisco,
     +o	 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.  Commit-
	     ted 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.  Com-
	     mitted 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_SIN-
	     GLE_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.

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 (bytes) */
		     u_int64_t ebs;	     /*	Exceeded/Peak burst size (bytes) */
		     u_int64_t cir;	     /*	Committed information rate (bits/s) */
		     u_int64_t pir;	     /*	Peak information rate (bits/s) */
		     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;	     /*	single/double rate, ...	*/
		     u_int8_t opt;	     /*	color-aware or color-blind */
	     };

	     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.

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.

FreeBSD	9.3			March 11, 2007			   FreeBSD 9.3

NAME | SYNOPSIS | DESCRIPTION | HOOKS | MODES OF OPERATION | CONTROL MESSAGES | SHUTDOWN | SEE ALSO | AUTHORS | BUGS

Want to link to this manual page? Use this URL:
<http://www.freebsd.org/cgi/man.cgi?query=ng_car&sektion=4&manpath=FreeBSD+7.0-RELEASE>

home | help