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:
o rtt: round-trip time <https://en.wikipedia.org/wiki/Round-
trip_delay_time>
o send: one-way send delay <https://en.wikipedia.org/wiki/End-to-
end_delay> (requires external time synchronization)
o receive: one-way receive delay
<https://en.wikipedia.org/wiki/End-to-end_delay> (requires
external time synchronization)
o ipdv: IPDV
<https://en.wikipedia.org/wiki/Packet_delay_variation>
(instantaneous packet delay variation, or jitter)
o send_ipdv: IPDV for sent packets
o 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>
2.8.0 2021-08-11 Smokeping_probes_IRTT(3)
smokeping 2.8.0 - Generated Thu Aug 12 09:06:37 CDT 2021