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Approved by:	glebius (mentor)
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mav 2007-05-16 12:00:22 +00:00
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commit fb7a9f1bb7
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57
share/man/man4/ng_car.4
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@ -36,7 +36,7 @@
.Sh DESCRIPTION
The
.Nm car
node type limits traffic flowing through it using:
node type limits traffic flowing through it using:
.Pp
.Bl -bullet -compact
.It
@ -61,45 +61,52 @@ Traffic flowing from
.Va upper
to
.Va lower
is considered
is considered
.Sy downstream
traffic.
Traffic flowing from
Traffic flowing from
.Va lower
to
.Va upper
is considered
.Sy upstream
.Va upper
is considered
.Sy upstream
traffic.
.Sh MODES OF OPERATION
Each hook can operate in one of modes:
Each hook can operate in one of the following modes:
.Bl -tag -width indent
.It Dv NG_CAR_SINGLE_RATE
Single rate three color marker as described on 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 speed.
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.
.It Dv NG_CAR_DOUBLE_RATE
Two rate three color marker as described on 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 speed at the same time.
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.
.It Dv NG_CAR_RED
Alike 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 alike to RED
active queue management algorithm.
Similar to
.Dv 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.
.Pp
This algorithm is more polite to the TCP traffic then NG_CAR_SINGLE_RATE.
.It Dv 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.
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%.
.Pp
Traffic shaping is much more polite to the TCP traffic then rate limit on links with
bandwidth * delay product less then 6-8 TCP segments, but it consumes additional system
resources for queue processing.
Traffic shaping is much more polite to the TCP traffic then rate limit on
links with bandwidth * delay product less then 6-8 TCP segments, but it
consumes additional system resources for queue processing.
.El
.Sh CONTROL MESSAGES
This node type supports the generic control messages and the following
@ -111,7 +118,7 @@ Set node configuration to the specified at
.It Dv NGM_CAR_GET_CONF Pq Li getconf
Return current node configuration as
.Vt "struct ng_car_bulkconf"
.Bd -literal -offset 4n
.Bd -literal
struct ng_car_hookconf {
u_int64_t cbs; /* Committed burst size (bytes) */
u_int64_t ebs; /* Exceeded/Peak burst size (bytes) */
@ -132,7 +139,7 @@ struct ng_car_bulkconf {
.It Dv NGM_CAR_GET_STATS Pq Li getstats
Return node statistics as
.Vt "struct ng_car_bulkstats"
.Bd -literal -offset 4n
.Bd -literal
struct ng_car_hookstats {
u_int64_t passed_pkts;
u_int64_t droped_pkts;
@ -173,4 +180,4 @@ control message, or when all hooks have been disconnected.
.An Nuno Antunes Aq nuno.antunes@gmail.com
.An Alexander Motin Aq mav@alkar.net
.Sh BUGS
For this moment only DROP and FORWARD actions are implemented.
At this moment only DROP and FORWARD actions are implemented.