Provided by: smokeping_2.7.3-4_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
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
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 acqusition 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:
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>