ng_source(4)

NAME

ng_source - netgraph node for traffic generation

SYNOPSIS

#include <sys/types.h>
#include <netgraph/ng_source.h>

DESCRIPTION

The source node acts as a source of packets according to the

parameters
set up using control messages and input packets. The

ng_source node type
is used primarily for testing and benchmarking.

HOOKS

The source node has two hooks: input and output. The output

hook must
remain connected, its disconnection will shutdown the node.

OPERATION

The operation of the node is as follows. Packets received

on the input
hook are queued internally. When output hook is connected,

ng_source
node assumes that its neighbour node is of ng_ether(4) node

type. The
neighbour is queried for its interface name. The ng_source

node then
uses queue of the interface for its evil purposes. The

ng_source node
also disables autosrc option on neighbour ng_ether(4) node.

If interface
name cannot be obtained automatically, it should be config

ured explicitly
with the NGM_SOURCE_SETIFACE control message, and autosrc

should be
turned off on ng_ether(4) node manually.

Once interface is configured, upon receipt of a

NGM_SOURCE_START control
message the node starts sending the previously queued pack

ets out the
output hook on every clock tick as fast as the connected in

terface will
take them. While active, on every clock tick the node

checks the available space in the interface queue and sends that many pack

ets out its
output hook. Once the number of packets indicated in the

start message
has been sent, or upon receipt of a NGM_SOURCE_STOP message,

the node
stops sending data.

CONTROL MESSAGES

This node type supports the generic control messages as well

as the following, which must be sent with the NGM_SOURCE_COOKIE at

tached.

NGM_SOURCE_GET_STATS (getstats)

Returns a structure containing the following fields:

outOctets

The number of octets/bytes sent out the

output hook.

outFrames

The number of frames/packets sent out the

output hook.

queueOctets

The number of octets queued from the input

hook.

queueFrames

The number of frames queued from the input

hook.

startTime

The time the last start message was re

ceived.

endTime

The time the last end message was received

or the output
packet count was reached.

elapsedTime

Either endTime - startTime or current time

startTime.

NGM_SOURCE_CLR_STATS (clrstats)

Clears and resets the statistics returned by

getstats (except
queueOctets and queueFrames).

NGM_SOURCE_GETCLR_STATS (getclrstats)

As getstats but clears the statistics at the same

time.

NGM_SOURCE_START (start)

This message requires a single uint64_t parameter

which is the
number of packets to send before stopping. Node

starts sending
the queued packets out the output hook. The output

hook must be
connected and node must have interface configured.

NGM_SOURCE_STOP (stop)

Stops the node if it is active.

NGM_SOURCE_CLR_DATA (clrdata)

Clears the packets queued from the input hook.

NGM_SOURCE_SETIFACE (setiface)

This message requires the name of the interface to

be configured
as an argument.

NGM_SOURCE_SETPPS (setpps)

This message requires a single uint32_t parameter

which puts
upper limit on the amount of packets sent per sec

ond.

SHUTDOWN

This node shuts down upon receipt of a NGM_SHUTDOWN control

message, when
all hooks have been disconnected, or when the output hook

has been disconnected.

EXAMPLES

Attach the node to an ng_ether(4) node for an interface. If

ng_ether is
not already loaded you will need to do so. For example,

these commands
load the ng_ether module and attach the output hook of a new

source node
to orphans hook of the bge0: ng_ether node.

kldload ng_ether
ngctl mkpeer bge0: source orphans output

At this point the new node can be referred to as ``bge0:or

phans''. The
node can be given its own name like this:

ngctl name bge0:orphans src0

After which it can be referred to as ``src0:''.

Once created, packets need to be sent to the node, the TCL

net package
can be used to generate these packets:

[Sandvine specific TCL code example omitted]

To feed the output of the above TCL script to the source

node's input
hook via nghook(8):

tcl genPacket | nghook bge0:orphans input

To check that the node has queued these packets you can get

the node
statistics:

ngctl msg bge0:orphans getstats
Args: { queueOctets=64 queueFrames=1 }

Send as many packets as required out the output hook:

ngctl msg bge0:orphans start 16

Either wait for them to be sent (periodically fetching stats

if desired)
or send the stop message:

ngctl msg bge0:orphans stop

Check the statistics (here we use getclrstats to also clear

the statistics):

ngctl msg bge0:orphans getclrstats
Args: { outOctets=1024 outFrames=16 queueOctets=64

queueFrames=1
startTime={ tv_sec=1035305880 tv_usec=758036 } end

Time={ tv_sec=1035305880
tv_usec=759041 } elapsedTime={ tv_usec=1005 } }

The times are from struct timevals, the tv_sec field is sec

onds since the
Epoch and can be converted into a date string via TCL's

[clock format] or
via the date(1) command:

date -r 1035305880
Tue Oct 22 12:58:00 EDT 2002

SEE ALSO

netgraph(4), ng_echo(4), ng_hole(4), ng_tee(4), ngctl(8),

nghook(8)

HISTORY

The ng_source node type was implemented in FreeBSD 4.8.

AUTHORS

Dave Chapeskie <dchapeskie@SANDVINE.com>

BSD December 5, 2005

BSD