351 lines
8.8 KiB
Groff
351 lines
8.8 KiB
Groff
.\" Copyright 2002 Sandvine Inc.
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.\" All rights reserved.
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.\"
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.\" Subject to the following obligations and disclaimer of warranty, use and
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.\" redistribution of this software, in source or object code forms, with or
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.\" without modifications are expressly permitted by Sandvine Inc.; provided,
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.\" however, that:
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.\" 1. Any and all reproductions of the source or object code must include the
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.\" copyright notice above and the following disclaimer of warranties; and
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.\" 2. No rights are granted, in any manner or form, to use Sandvine Inc.
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.\" trademarks, including the mark "SANDVINE" on advertising, endorsements,
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.\" or otherwise except as such appears in the above copyright notice or in
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.\" the software.
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.\"
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.\" THIS SOFTWARE IS BEING PROVIDED BY SANDVINE "AS IS", AND TO THE MAXIMUM
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.\" EXTENT PERMITTED BY LAW, SANDVINE MAKES NO REPRESENTATIONS OR WARRANTIES,
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.\" EXPRESS OR IMPLIED, REGARDING THIS SOFTWARE, INCLUDING WITHOUT LIMITATION,
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.\" ANY AND ALL IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
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.\" PURPOSE, OR NON-INFRINGEMENT. SANDVINE DOES NOT WARRANT, GUARANTEE, OR
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.\" MAKE ANY REPRESENTATIONS REGARDING THE USE OF, OR THE RESULTS OF THE
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.\" USE OF THIS SOFTWARE IN TERMS OF ITS CORRECTNESS, ACCURACY, RELIABILITY
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.\" OR OTHERWISE. IN NO EVENT SHALL SANDVINE BE LIABLE FOR ANY DAMAGES
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.\" RESULTING FROM OR ARISING OUT OF ANY USE OF THIS SOFTWARE, INCLUDING
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.\" WITHOUT LIMITATION, ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY,
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.\" PUNITIVE, OR CONSEQUENTIAL DAMAGES, PROCUREMENT OF SUBSTITUTE GOODS OR
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.\" SERVICES, LOSS OF USE, DATA OR PROFITS, HOWEVER CAUSED AND UNDER ANY
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.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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.\" THIS SOFTWARE, EVEN IF SANDVINE IS ADVISED OF THE POSSIBILITY OF SUCH
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.\" DAMAGE.
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.\"
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.\" Author: Dave Chapeskie <dchapeskie@sandvine.com>
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.\" $FreeBSD$
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.\"
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.Dd November 1, 2002
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.Dt NG_SOURCE 4
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.Os
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.Sh NAME
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.Nm ng_source
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.Nd netgraph discard node type
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.Sh SYNOPSIS
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.In netgraph/ng_source.h
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.Sh DESCRIPTION
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The
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.Nm source
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node acts as a source of packets according to the parameters set up
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using control messages and input packets.
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The
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.Dv output
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hook must also be connected to a node that responds to the
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.Dv NGM_ETHER_COOKIE Ns / Ns
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.Dv NGM_ETHER_GET_IFINDEX
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message (e.g., an
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.Xr ng_ether 4
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node).
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This type is used for testing and debugging.
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.Pp
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The operation of the node is as follows:
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.Bl -bullet
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.It
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Packets received on the
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.Dv input
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hook are queued internally.
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.It
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On reception of a
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.Dv NGM_SOURCE_START
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message the node starts sending
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the queued packets out the
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.Dv output
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hook on every clock tick as fast
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as the connect interface will take them.
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.It
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While active, on every clock tick the node checks the available space
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in the
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.Va ifqueue
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of the interface connected to the output hook and sends
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that many packets out its
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.Dv output
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hook.
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.It
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Once the number of packets indicated in the start message have been
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sent, or on reception of a stop message, the node stops sending data.
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.El
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.Sh HOOKS
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The
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.Nm source
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node has two hooks:
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.Dv input
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and
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.Dv output .
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The
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.Dv output
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hook must remain connected, its disconnection will shutdown the node.
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.Sh CONTROL MESSAGES
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This node type supports the generic control messages as well as the following,
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which must be sent with the
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.Dv NGM_SOURCE_COOKIE
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attached.
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.Bl -tag -width indent
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.It Dv NGM_SOURCE_GET_STATS Pq Ic getstats
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Returns a structure containing the following fields:
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.Bl -tag -width indent
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.It Va outOctets
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The number of octets/bytes sent out the
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.Dv output
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hook.
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.It Va outFrames
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The number of frames/packets sent out the
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.Dv output
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hook.
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.It Va queueOctets
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The number of octets queued from the
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.Dv input
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hook.
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.It Va queueFrames
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The number of frames queued from the
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.Dv input
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hook.
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.It Va startTime
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The time the last start message was received.
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.It Va endTime
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The time the last end message was received or
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the output packet count was reached.
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.It Va elapsedTime
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Either
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.Va endTime Li \- Va startTime
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or current time
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\-
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.Va startTime .
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.El
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.It Dv NGM_SOURCE_CLR_STATS Pq Ic clrstats
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Clears and resets the statistics returned by
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.Ic getstats
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(except
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.Va queueOctets
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and
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.Va queueFrames ) .
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.It Dv NGM_SOURCE_GETCLR_STATS Pq Ic getclrstats
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As
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.Ic getstats
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but clears the statistics at the same time.
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.It Dv NGM_SOURCE_START Pq Ic start
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.Bl -bullet
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.It
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Takes a single
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.Vt u_int64_t
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parameter which is the number of packets to
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send before stopping.
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.It
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Starts sending the queued packets out the output hook.
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.It
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The output hook must be connected or
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.Er EINVAL
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is returned.
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.It
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The node connected to the output hook must respond to
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.Dv NGM_ETHER_GET_IFINDEX
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which is used to get the
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.Va ifqueue
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of the attached interface.
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.It
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.Dv NGM_ETHER_SET_AUTOSRC
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is sent to the node connected to the
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.Dv output
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hook
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to turn off automatic ethernet source address overwriting (any errors
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from this message are ignored).
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.El
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.It Dv NGM_SOURCE_STOP Pq Ic stop
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Stops the node if it is active.
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.It Dv NGM_SOURCE_CLR_DATA Pq Ic clrdata
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Clears the packets queued from the
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.Dv input
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hook.
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.El
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.Sh SHUTDOWN
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This node shuts down upon receipt of a
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.Dv NGM_SHUTDOWN
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control message, or when the
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.Dv output
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hook has been disconnected.
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.Sh EXAMPLES
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Attach the node to an
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.Xr ng_ether 4
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node for an interface.
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If
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.Nm ng_ether
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is
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not already loaded you will need to do so.
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For example, these commands
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load the
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.Nm ng_ether
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module and attach the
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.Dv output
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hook of a new
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.Nm source
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node to
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.Dv orphans
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hook of the
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.Li bge0:
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.Nm ng_ether
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node.
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.Bd -literal -offset indent
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kldload ng_ether
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ngctl mkpeer bge0: source orphans output
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.Ed
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.Pp
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At this point the new node can be referred to as
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.Dq Li bge0:orphans .
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The
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node can be given its own name like this:
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.Pp
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.Dl "ngctl name bge0:orphans src0"
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.Pp
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After which it can be referred to as
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.Dq Li src0: .
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.Pp
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Once created, packets need to be sent to the node, the TCL net package
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can be used to generate these packets:
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.Pp
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[Sandvine specific TCL code example omitted]
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.Pp
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To feed the output of the above TCL script to the
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.Nm source
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node's
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.Dv input
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hook via
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.Xr nghook 8 :
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.Pp
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.Dl "tcl genPacket | nghook bge0:orphans input"
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.Pp
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To check that the node has queued these packets you can get the node
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statistics:
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.Bd -literal -offset indent
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ngctl msg bge0:orphans getstats
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Args: { queueOctets=64 queueFrames=1 }
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.Ed
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.Pp
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Send as many packets as required out the
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.Dv output
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hook:
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.Pp
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.Dl "ngctl msg bge0:orphans start 16"
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.Pp
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Either wait for them to be sent (periodically fetching stats if desired)
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or send the stop message:
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.Pp
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.Dl "ngctl msg bge0:orphans stop"
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.Pp
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Check the statistics (here we use
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.Ic getclrstats
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to also clear the statistics):
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.Bd -literal -offset indent
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ngctl msg bge0:orphans getclrstats
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Args: { outOctets=1024 outFrames=16 queueOctets=64 queueFrames=1
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startTime={ tv_sec=1035305880 tv_usec=758036 } endTime={ tv_sec=1035305880
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tv_usec=759041 } elapsedTime={ tv_usec=1005 } }
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.Ed
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.Pp
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The times are from
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.Vt "struct timeval" Ns s ,
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the
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.Va tv_sec
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field is seconds since
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the Epoch and can be converted into a date string via TCL's [clock
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format] or via the
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.Xr date 1
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command:
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.Bd -literal -offset indent
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date -r 1035305880
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Tue Oct 22 12:58:00 EDT 2002
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.Ed
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.Sh IMPLEMENTATION NOTES
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.No ( Fx 4.4
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version)
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.Pp
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The use of
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.Xr splimp 9
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around the
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.Dv NG_SEND_DATA
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loop is important.
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Without it,
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the time taken by a single invocation of
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.Fn ng_source_intr
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becomes too
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large and the packet rate drops.
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Probably due to the NIC starting to
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send the packets right away.
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.Pp
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Copying all the packets in one loop and sending them in another inside
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of
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.Fn ng_source_send
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is done to limit how long we are at
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.Xr splimp 9
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and gave
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minor packet rate increases (~5% at 256 byte packets).
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However note
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that if there are errors in the send loop, the remaining copied packets
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are simply freed and discarded; thus we skip those packets, and ordering
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of the input queue to the output is not maintained.
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.Pp
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Calling
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.Xr timeout 9
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at the end of
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.Fn ng_source_intr
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instead of near the
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beginning is done to help avoid CPU starvation if
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.Fn ng_source_intr
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takes a long time to run.
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.Pp
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The use of
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.Xr splnet 9
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may be sub-optimal.
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It is used for synchronization
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within the node (e.g., data received on the
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.Dv input
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hook while
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.Fn ng_source_send
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is active) but we do not want to hold it too long and risk
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starving the NIC.
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.Pp
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For clarity and simplicity, debugging messages and instrumentation code
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has been removed.
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On i386 one can include
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.Aq Pa machine/cpufunc.h
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to have access to the
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.Fn rdtsc
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function to read the instruction counter at the
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start and end of
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.Fn ng_source_intr .
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Also useful is the packet count returned by
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.Fn ng_source_send .
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Do not try to report such things from within
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.Fn ng_source_intr ,
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instead include the values in
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.Va sc->stats .
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.Sh SEE ALSO
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.Xr netgraph 4 ,
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.Xr ng_echo 4 ,
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.Xr ng_hole 4 ,
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.Xr ng_tee 4 ,
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.Xr ngctl 8 ,
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.Xr nghook 8
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.Sh HISTORY
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The
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.Nm
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node type was implemented in
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.Fx 4.8 .
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.Sh AUTHORS
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.An Dave Chapeskie Aq dchapeskie@SANDVINE.com
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