NG_SOURCE(4) MidnightBSD Kernel Interfaces Manual 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 configured 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 packets out the output hook on every clock tick as fast as the connected interface will take them. While active, on every clock tick the node checks the available space in the interface queue and sends that many packets 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 attached.

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 received.

endTime

The time the last end message was received or the output packet count was reached.

elapsedTime

Either endTimestartTime 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 second.

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:orphans’’. 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 } endTime={ tv_sec=1035305880
tv_usec=759041 } elapsedTime={ tv_usec=1005 } }

The times are from struct timevals, the tv_sec field is seconds 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〉

MidnightBSD 0.3 December 5, 2005 MidnightBSD 0.3