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Smokeping_probes_IRTT(3)	   SmokePing	      Smokeping_probes_IRTT(3)

NAME
       Smokeping::probes::IRTT - a SmokePing Probe for IRTT
       <https://github.com/peteheist/irtt>

SYNOPSIS
	*** Probes ***

	+IRTT

	binary = /usr/local/bin/irtt # mandatory
	forks =	5
	offset = 50%
	step = 300
	timeout	= 15
	tmpdir = /tmp/smokeping-irtt

	# The following	variables can be overridden in each target section
	/^influx_.+/ = influx_location = In the	basement
	dscp = 46
	extraargs = --ttl=32
	fill = rand
	hmac = opensesame
	interval = 1.5
	ipversion = 6
	length = 172
	localaddr = 192.168.1.10:63814
	metric = rtt
	pings =	5
	readfrom = irtt1
	readfrompollinterval = 2
	serverfill = rand
	sleep =	0.5
	writeto	= irtt1

	# [...]

	*** Targets ***

	probe =	IRTT # if this should be the default probe

	# [...]

	+ mytarget
	# probe	= IRTT # if the	default	probe is something else
	host = my.host
	/^influx_.+/ = influx_location = In the	basement
	dscp = 46
	extraargs = --ttl=32
	fill = rand
	hmac = opensesame
	interval = 1.5
	ipversion = 6
	length = 172
	localaddr = 192.168.1.10:63814
	metric = rtt
	pings =	5
	readfrom = irtt1
	readfrompollinterval = 2
	serverfill = rand
	sleep =	0.5
	writeto	= irtt1

DESCRIPTION
       This SmokePing probe uses IRTT <https://github.com/peteheist/irtt> to
       record network round-trip time <https://en.wikipedia.org/wiki/Round-
       trip_delay_time>, one-way delay <https://en.wikipedia.org/wiki/End-to-
       end_delay> or IPDV
       <https://en.wikipedia.org/wiki/Packet_delay_variation> (jitter),	based
       on the value of the metric variable.

       Additionally, the probe provides	a results sharing feature, which
       allows using results from a single IRTT run to record multiple metrics
       for a given host	at the same time. One target is	defined	with the
       writeto variable	set, which selects the name of a temporary file	to
       save the	IRTT output to.	Additional targets are defined with the
       readfrom	variable set to	the same value,	which, instead of running
       IRTT, wait for the main target's	output to become available, then parse
       it to record the	chosen metric from the same data. See the writeto and
       readfrom	variables for more information.

   WARNING
       The results sharing feature (writeto and	readfrom variables) requires
       the number of forks for the IRTT	probe to be at least the total number
       of IRTT targets defined (regardless of whether they have	writeto	and
       readfrom	set). Otherwise, there can be a	deadlock while readfrom
       targets wait for	their corresponding writeto target to complete,	which
       may never start.

VARIABLES
       Supported probe-specific	variables:

       binary
	   The location	of your	irtt binary.

	   Example value: /usr/local/bin/irtt

	   Default value: /usr/bin/irtt

	   This	setting	is mandatory.

       forks
	   Run this many concurrent processes at maximum

	   Example value: 5

	   Default value: 5

       offset
	   If you run many probes concurrently you may want to prevent them
	   from	hitting	your network all at the	same time. Using the
	   probe-specific offset parameter you can change the point in time
	   when	each probe will	be run.	Offset is specified in % of total
	   interval, or	alternatively as 'random', and the offset from the
	   'General' section is	used if	nothing	is specified here. Note	that
	   this	does NOT influence the rrds itself, it is just a matter	of
	   when	data acquisition is initiated.	(This variable is only
	   applicable if the variable 'concurrentprobes' is set	in the
	   'General' section.)

	   Example value: 50%

       step
	   Duration of the base	interval that this probe should	use, if
	   different from the one specified in the 'Database' section. Note
	   that	the step in the	RRD files is fixed when	they are originally
	   generated, and if you change	the step parameter afterwards, you'll
	   have	to delete the old RRD files or somehow convert them. (This
	   variable is only applicable if the variable 'concurrentprobes' is
	   set in the 'General'	section.)

	   Example value: 300

       timeout
	   How long a single 'ping' takes at maximum

	   Example value: 15

	   Default value: 5

       tmpdir
	   A temporary directory in which to place files for writeto/readfrom.

	   Default value: /tmp/smokeping-irtt

       Supported target-specific variables:

       /^influx_.+/
	   This	is a tag that will be sent to influxdb and has no impact on
	   the probe measurement. The tag name will be sent without the
	   "influx_" prefix, which will	be replaced with "tag_"	instead. Tags
	   can be used for filtering.

	   Example value: influx_location = In the basement

       dscp
	   The packet DSCP
	   <https://en.wikipedia.org/wiki/Differentiated_services> value to
	   use ("irtt client --dscp"). This is the same	as the classic one
	   byte	IP ToS field, but on the modern	Internet, typically only the
	   lower 6 bits	are used, and this is called the DSCP value. The upper
	   two bits are	reserved for ECN
	   <https://en.wikipedia.org/wiki/Explicit_Congestion_Notification>.
	   Hex may be used if prefixed by "0x".

	   Example value: 46

       extraargs
	   Extra arguments to "irtt client" (see irtt-client(1)). Be careful
	   with	extra arguments, as some can corrupt the results.

	   Example value: --ttl=32

       fill
	   The fill to use in the payload for the client to server packet
	   ("irtt client --fill"). The length variable must be large enough so
	   there's a payload to	fill.  Use rand	for random fill, or see
	   irtt-client(1) for more options.

	   Example value: rand

       hmac
	   The HMAC <https://en.wikipedia.org/wiki/Hash-
	   based_message_authentication_code> key to use when sending packets
	   to the server ("irtt	client --hmac").

	   Example value: opensesame

       interval
	   The interval	between	successive requests, in	seconds	("irtt client
	   -i",	but the	unit is	always seconds (s)).

	   WARNING

	   If interval is increased to greater than 5 seconds, the timeout
	   (which defaults to pings * 5	seconds	+ 1) must be modified so that
	   SmokePing doesn't kill the probe prematurely. Additionally,
	   interval must not be	increased such that pings * interval is
	   greater than	step. For example, at step=300 and pings=20, the
	   interval must not be	greater	than 15	seconds, but should preferably
	   be less to account for handshake and	packet wait times.

	   Example value: 1.5

	   Default value: 1

       ipversion
	   The IP version to use for packets (4	or 6, corresponding to "irtt
	   client -4" or "irtt client -6"). By default the IP version is
	   chosen based	on the supplied	host variable.

	   Example value: 6

       length
	   The length (size) of	the packet ("irtt client -l"). The length
	   includes IRTT headers, but not IP or	UDP headers. The actual	packet
	   length is increased to accommodate the IRTT headers,	if necessary.
	   Header size as of IRTT 0.9.0	as used	in SmokePing is	48 bytes when
	   writeto is set (since both monotonic	and wall clock values are
	   requested) and 40 bytes otherwise.

	   Example value: 172

       localaddr
	   The local address to	bind to	when sending packets ("irtt client
	   --local").  See irtt-client(1) Host formats for valid syntax.

	   Example value: 192.168.1.10:63814

       metric
	   The metric to record, one of:

	      rtt: round-trip time <https://en.wikipedia.org/wiki/Round-
	       trip_delay_time>

	      send: one-way send delay	<https://en.wikipedia.org/wiki/End-to-
	       end_delay> (requires external time synchronization)

	      receive:	one-way	receive	delay
	       <https://en.wikipedia.org/wiki/End-to-end_delay>	(requires
	       external	time synchronization)

	      ipdv: IPDV
	       <https://en.wikipedia.org/wiki/Packet_delay_variation>
	       (instantaneous packet delay variation, or jitter)

	      send_ipdv: IPDV for sent	packets

	      receive_ipdv: IPDV for received packets

	   Note	that the "send"	and "receive" metrics require accurate
	   external system clock synchronization, otherwise the	values from
	   one will be abnormally high and the other will be abnormally	low or
	   even	negative, in which case	the value 0 will be given SmokePing.
	   It is recommended to	install	ntp on both the	SmokePing client and
	   IRTT	server.	Properly configured NTP	may be able to synchronize
	   time	to within a few	milliseconds, which is usually enough to
	   provide useful results.  PTP	over a LAN may achieve
	   microsecond-level accuracy. For best	results	between	geographically
	   remote hosts, GPS receivers may be used. Since "send_ipdv" and
	   "receive_ipdv" measure the variation	in times between successive
	   packets, and	since "rtt" and	"ipdv" use monotonic clock values on
	   the client side only, external time synchronization is not required
	   for these metrics.

	   Default value: rtt

       pings
	   How many pings should be sent to each target, if different from the
	   global value	specified in the Database section. Note	that the
	   number of pings in the RRD files is fixed when they are originally
	   generated, and if you change	this parameter afterwards, you'll have
	   to delete the old RRD files or somehow convert them.

	   Example value: 5

       readfrom
	   The name of a file to read results from, instead of running IRTT.
	   Use in combination with writeto to use the results from one IRTT
	   run to record multiple metrics. The value will become the name of a
	   file	in tmpdir, and must be the same	as another target's setting
	   for writeto.	Multiple targets may use the same value	for readfrom,
	   but writeto and readfrom may	not be both set	for a given target.
	   When	readfrom is set, any variables that affect "irtt client" are
	   ignored because IRTT	is not being invoked, including: dscp,
	   extraargs, fill, hmac, interval, ipversion, length, localaddr and
	   serverfill. These values are	only relevant in the corresponding
	   writeto target.

	   Note	that the host variable must still be defined for targets that
	   define readfrom, otherwise the target won't be used.

	   When	using this feature, be sure to have at least as	many forks for
	   the IRTT probe as you have total IRTT targets defined. See the
	   "DESCRIPTION" section for more information.

	   Example value: irtt1

       readfrompollinterval
	   The integer interval	in seconds on which to poll for	results	when
	   readfrom is set. Lower numbers will allow readfrom to see the
	   results a bit sooner, at the	cost of	higher CPU usage. Polling does
	   not begin until the soonest time at which the IRTT client could
	   have	terminated normally.

	   Example value: 2

	   Default value: 5

       serverfill
	   The fill to use in the payload for the server to client packet
	   ("irtt client --sfill"). The	length variable	must be	large enough
	   to accommodate a payload.  Use "rand" for random fill, or see
	   irtt-client(1) for more options.

	   Example value: rand

       sleep
	   The amount of time to sleep before starting requests	or processing
	   results (a float in seconds). This may be used to avoid CPU spikes
	   caused by invoking multiple instances of IRTT at the	same time.

	   Example value: 0.5

       writeto
	   The name of a file to write results to after	running	IRTT. Use in
	   combination with readfrom to	use the	results	from this IRTT run to
	   record multiple metrics. The	value will become the name of a	file
	   in tmpdir, and any targets with readfrom set	to the same value will
	   use this target's results. There must be only one target with
	   writeto set for a given file, and writeto and readfrom may not be
	   both	set for	a given	target.

	   When	using this feature, be sure to have at least as	many forks for
	   the IRTT probe as you have total IRTT targets defined. See the
	   "DESCRIPTION" section for more information.

	   Example value: irtt1

AUTHORS
       Pete Heist <pete@heistp.net>

2.9.0				  2025-11-03	      Smokeping_probes_IRTT(3)

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