Provided by: smokeping_2.8.2+ds-1_all 
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>
2.8.2 2024-02-04 Smokeping_probes_IRTT(3)