DOKK / manpages / debian 12 / irtt / irtt-client.1.en
IRTT-CLIENT(1) IRTT Manual IRTT-CLIENT(1)

irtt-client - Isochronous Round-Trip Time Client

irtt client [args]

irtt client is the client for irtt(1) (irtt.html).

Total time to send (default 1m0s, see Duration units below)
Send interval (default 1s, see Duration units below)
Length of packet (default 0, increased as necessary for required headers), common values:
•
1472 (max unfragmented size of IPv4 datagram for 1500 byte MTU)
•
1452 (max unfragmented size of IPv6 datagram for 1500 byte MTU)
Write JSON output to file (use `-' for stdout). The extension used for file controls the gzip behavior as follows (output to stdout is not gzipped):

Extension Behavior
none extension .json.gz is added, output is gzipped
.json.gz output is gzipped
.gz output is gzipped, extension changed to .json.gz
.json output is not gzipped
Quiet, suppress per-packet output
Really quiet, suppress all output except errors to stderr
No test, connect to the server and validate test parameters but don't run the test
Server stats on received packets (default both). Possible values:

Value Meaning
none no server stats on received packets
count total count of received packets
window receipt status of last 64 packets with each reply
both both count and window
Server timestamp mode (default both). Possible values:

Value Meaning
none request no timestamps
send request timestamp at server send
receive request timestamp at server receive
both request both send and receive timestamps
midpoint request midpoint timestamp (send/receive avg)
Clock/s used for server timestamps (default both). Possible values:

Value Meaning
wall wall clock only
monotonic monotonic clock only
both both clocks
DSCP (ToS) value (default 0, 0x prefix for hex). Common values:

Value Meaning
0 Best effort
8 CS1- Bulk
40 CS5- Video
46 EF- Expedited forwarding

DSCP & ToS (https://www.tucny.com/Home/dscp-tos)

Setting for do not fragment (DF) bit in all packets. Possible values:

Value Meaning
default OS default
false DF bit not set
true DF bit set
Wait time at end of test for unreceived replies (default 3x4s). Possible values:

Format Meaning
#xduration # times max RTT, or duration if no response
#rduration # times RTT, or duration if no response
duration fixed duration (see Duration units below)

Examples:

Example Meaning
3x4s 3 times max RTT, or 4 seconds if no response
1500ms fixed 1500 milliseconds
Timer for waiting to send packets (default comp). Possible values:

Value Meaning
simple Go's standard time.Timer
comp Simple timer with error compensation (see -tcomp)
hybrid:# Hybrid comp/busy timer with sleep factor (default 0.95)
busy busy wait loop (high precision and CPU, blasphemy)
Comp timer averaging algorithm (default exp:0.10). Possible values:

Value Meaning
avg Cumulative average error
win:# Moving average error with window # (default 5)
exp:# Exponential average with alpha # (default 0.10)
Fill payload with given data (default none). Possible values:

Value Meaning
none Leave payload as all zeroes
rand Use random bytes from Go's math.rand
pattern:XX Use repeating pattern of hex (default 69727474)
Fill only once and repeat for all packets
Request server fill (default not specified). See values for –fill. Server must support and allow this fill with –allow-fills.
Local address (default from OS). Possible values:

Value Meaning
:port Unspecified address (all IPv4/IPv6 addresses) with port
host Host with dynamic port, see Host formats below
host:port Host with specified port, see Host formats below
Add HMAC with key (0x for hex) to all packets, provides:
•
Dropping of all packets without a correct HMAC
•
Protection for server against unauthorized discovery and use
-4
IPv4 only
-6
IPv6 only
Timeouts used when connecting to server (default 1s,2s,4s,8s). Comma separated list of durations (see Duration units below). Total wait time will be up to the sum of these Durations. Max packets sent is up to the number of Durations. Minimum timeout duration is 200ms.
Time to live (default 0, meaning use OS default)
Accept and use any server restricted test parameters instead of exiting with nonzero status.
Lock sending and receiving goroutines to OS threads
Show help
Show version

Hosts may be either hostnames (for IPv4 or IPv6) or IP addresses. IPv6 addresses must be surrounded by brackets and may include a zone after the % character. Examples:

Type Example
IPv4 IP 192.168.1.10
IPv6 IP [2001:db8:8f::2/32]
IPv4/6 hostname localhost

Note: IPv6 addresses must be quoted in most shells.

Durations are a sequence of decimal numbers, each with optional fraction, and unit suffix, such as: “300ms”, “1m30s” or “2.5m”. Sanity not enforced.

Suffix Unit
h hours
m minutes
s seconds
ms milliseconds
ns nanoseconds

IRTT's JSON output format consists of five top-level objects:

1.
version
2.
system_info
3.
config
4.
stats
5.
round_trips

These are documented through the examples below. All attributes are present unless otherwise noted.

version information

"version": {
    "irtt": "0.9.0",
    "protocol": 1,
    "json_format": 1
},
•
irtt the IRTT version number
•
protocol the protocol version number (increments mean incompatible changes)
•
json_format the JSON format number (increments mean incompatible changes)

a few basic pieces of system information

"system_info": {
    "os": "darwin",
    "cpus": 8,
    "go_version": "go1.9.2",
    "hostname": "tron.local"
},
•
os the Operating System from Go's runtime.GOOS
•
cpus the number of CPUs reported by Go's runtime.NumCPU(), which reflects the number of logical rather than physical CPUs. In the example below, the number 8 is reported for a Core i7 (quad core) with hyperthreading (2 threads per core).
•
go_version the version of Go the executable was built with
•
hostname the local hostname

the configuration used for the test

"config": {
    "local_address": "127.0.0.1:51203",
    "remote_address": "127.0.0.1:2112",
    "open_timeouts": "1s,2s,4s,8s",
    "params": {
        "proto_version": 1,
        "duration": 600000000,
        "interval": 200000000,
        "length": 48,
        "received_stats": "both",
        "stamp_at": "both",
        "clock": "both",
        "dscp": 0,
        "server_fill": ""
    },
    "loose": false,
    "ip_version": "IPv4",
    "df": 0,
    "ttl": 0,
    "timer": "comp",
    "waiter": "3x4s",
    "filler": "none",
    "fill_one": false,
    "thread_lock": false,
    "supplied": {
        "local_address": ":0",
        "remote_address": "localhost",
        "open_timeouts": "1s,2s,4s,8s",
        "params": {
            "proto_version": 1,
            "duration": 600000000,
            "interval": 200000000,
            "length": 0,
            "received_stats": "both",
            "stamp_at": "both",
            "clock": "both",
            "dscp": 0,
            "server_fill": ""
        },
        "loose": false,
        "ip_version": "IPv4+6",
        "df": 0,
        "ttl": 0,
        "timer": "comp",
        "waiter": "3x4s",
        "filler": "none",
        "fill_one": false,
        "thread_lock": false
    }
},
•
local_address the local address (IP:port) for the client
•
remote_address the remote address (IP:port) for the server
•
open_timeouts a list of timeout durations used after an open packet is sent
•
params are the parameters that were negotiated with the server, including:
•
proto_version protocol version number
•
duration duration of the test, in nanoseconds
•
interval send interval, in nanoseconds
•
length packet length
•
received_stats statistics for packets received by server (none, count, window or both, --stats flag for irtt client)
•
stamp_at timestamp selection parameter (none, send, receive, both or midpoint, --tstamp flag for irtt client)
•
clock clock selection parameter (wall or monotonic, --clock flag for irtt client)
•
dscp the DSCP (https://en.wikipedia.org/wiki/Differentiated_services) value
•
server_fill the requested server fill (--sfill flag for irtt client)
•
loose if true, client accepts and uses restricted server parameters, with a warning
•
ip_version the IP version used (IPv4 or IPv6)
•
df the do-not-fragment setting (0 == OS default, 1 == false, 2 == true)
•
ttl the IP time-to-live (https://en.wikipedia.org/wiki/Time_to_live) value
•
timer the timer used: simple, comp, hybrid or busy (irtt client --timer flag)
•
waiter the waiter used: fixed duration, multiple of RTT or multiple of max RTT (irtt client --wait flag)
•
filler the packet filler used: none, rand or pattern (irtt client --fill flag)
•
fill_one whether to fill only once and repeat for all packets (irtt client --fill-one flag)
•
thread_lock whether to lock packet handling goroutines to OS threads
•
supplied a nested config object with the configuration as originally supplied to the API or irtt command. The supplied configuration can differ from the final configuration in the following ways:
•
local_address and remote_address may have hostnames or named ports before being resolved to an IP and numbered port
•
ip_version may be IPv4+6 before it is determined after address resolution
•
params may be different before the server applies restrictions based on its configuration

statistics for the results

"stats": {
    "start_time": "2017-10-16T21:05:23.502719056+02:00",
    "send_call": {
        "total": 79547,
        "n": 3,
        "min": 17790,
        "max": 33926,
        "mean": 26515,
        "stddev": 8148,
        "variance": 66390200
    },
    "timer_error": {
        "total": 227261,
        "n": 2,
        "min": 59003,
        "max": 168258,
        "mean": 113630,
        "stddev": 77254,
        "variance": 5968327512
    },
    "rtt": {
        "total": 233915,
        "n": 2,
        "min": 99455,
        "max": 134460,
        "mean": 116957,
        "median": 116957,
        "stddev": 24752,
        "variance": 612675012
    },
    "send_delay": {
        "total": 143470,
        "n": 2,
        "min": 54187,
        "max": 89283,
        "mean": 71735,
        "median": 71735,
        "stddev": 24816,
        "variance": 615864608
    },
    "receive_delay": {
        "total": 90445,
        "n": 2,
        "min": 45177,
        "max": 45268,
        "mean": 45222,
        "median": 45222,
        "stddev": 64,
        "variance": 4140
    },
    "server_packets_received": 2,
    "bytes_sent": 144,
    "bytes_received": 96,
    "duplicates": 0,
    "late_packets": 0,
    "wait": 403380,
    "duration": 400964028,
    "packets_sent": 3,
    "packets_received": 2,
    "packet_loss_percent": 33.333333333333336,
    "upstream_loss_percent": 33.333333333333336,
    "downstream_loss_percent": 0,
    "duplicate_percent": 0,
    "late_packets_percent": 0,
    "ipdv_send": {
        "total": 35096,
        "n": 1,
        "min": 35096,
        "max": 35096,
        "mean": 35096,
        "median": 35096,
        "stddev": 0,
        "variance": 0
    },
    "ipdv_receive": {
        "total": 91,
        "n": 1,
        "min": 91,
        "max": 91,
        "mean": 91,
        "median": 91,
        "stddev": 0,
        "variance": 0
    },
    "ipdv_round_trip": {
        "total": 35005,
        "n": 1,
        "min": 35005,
        "max": 35005,
        "mean": 35005,
        "median": 35005,
        "stddev": 0,
        "variance": 0
    },
    "server_processing_time": {
        "total": 20931,
        "n": 2,
        "min": 9979,
        "max": 10952,
        "mean": 10465,
        "stddev": 688,
        "variance": 473364
    },
    "timer_err_percent": 0.056815,
    "timer_misses": 0,
    "timer_miss_percent": 0,
    "send_rate": {
        "bps": 2878,
        "string": "2.9 Kbps"
    },
    "receive_rate": {
        "bps": 3839,
        "string": "3.8 Kbps"
    }
},

Note: In the stats object, a duration stats class of object repeats and will not be repeated in the individual descriptions. It contains statistics about nanosecond duration values and has the following attributes:

•
total the total of the duration values
•
n the number of duration values
•
min the minimum duration value
•
max the maximum duration value
•
mean the mean duration value
•
stddev the standard deviation
•
variance the variance

The regular attributes in stats are as follows:

•
start_time the start time of the test, in TZ format
•
send_call a duration stats object for the call time when sending packets
•
timer_error a duration stats object for the observed sleep time error
•
rtt a duration stats object for the round-trip time
•
send_delay a duration stats object for the one-way send delay (only available if server timestamps are enabled)
•
receive_delay a duration stats object for the one-way receive delay (only available if server timestamps are enabled)
•
server_packets_received the number of packets received by the server, including duplicates (always present, but only valid if the ReceivedStats parameter includes ReceivedStatsCount, or the --stats flag to the irtt client is count or both)
•
bytes_sent the number of UDP payload bytes sent during the test
•
bytes_received the number of UDP payload bytes received during the test
•
duplicates the number of packets received with the same sequence number
•
late_packets the number of packets received with a sequence number lower than the previously received sequence number (one simple metric for out-of-order packets)
•
wait the actual time spent waiting for final packets, in nanoseconds
•
duration the actual duration of the test, in nanoseconds, from the time just before the first packet was sent to the time after the last packet was received and results are starting to be calculated
•
packets_sent the number of packets sent to the server
•
packets_received the number of packets received from the server
•
packet_loss_percent 100 * (packets_sent - packets_received) / packets_sent
•
upstream_loss_percent 100 * (packets_sent - server_packets_received / packets_sent) (always present, but only valid if server_packets_received is valid)
•
downstream_loss_percent 100 * (server_packets_received - packets_received / server_packets_received) (always present, but only valid if server_packets_received is valid)
•
duplicate_percent 100 * duplicates / packets_received
•
late_packets_percent 100 * late_packets / packets_received
•
ipdv_send a duration stats object for the send IPDV (https://en.wikipedia.org/wiki/Packet_delay_variation) (only available if server timestamps are enabled)
•
ipdv_receive a duration stats object for the receive IPDV (https://en.wikipedia.org/wiki/Packet_delay_variation) (only available if server timestamps are enabled)
•
ipdv_round_trip a duration stats object for the round-trip IPDV (https://en.wikipedia.org/wiki/Packet_delay_variation) (available regardless of whether server timestamps are enabled or not)
•
server_processing_time a duration stats object for the time the server took after it received the packet to when it sent the response (only available when both send and receive timestamps are enabled)
•
timer_err_percent the mean of the absolute values of the timer error, as a percentage of the interval
•
timer_misses the number of times the timer missed the interval (was at least 50% over the scheduled time)
•
timer_miss_percent 100 * timer_misses / expected packets sent
•
send_rate the send bitrate (bits-per-second and corresponding string), calculated using the number of UDP payload bytes sent between the time right before the first send call and the time right after the last send call
•
receive_rate the receive bitrate (bits-per-second and corresponding string), calculated using the number of UDP payload bytes received between the time right after the first receive call and the time right after the last receive call

each round-trip is a single request to / reply from the server

"round_trips": [
    {
        "seqno": 0,
        "lost": false,
        "timestamps": {
            "client": {
                "receive": {
                    "wall": 1508180723502871779,
                    "monotonic": 2921143
                },
                "send": {
                    "wall": 1508180723502727340,
                    "monotonic": 2776704
                }
            },
            "server": {
                "receive": {
                    "wall": 1508180723502816623,
                    "monotonic": 32644353327
                },
                "send": {
                    "wall": 1508180723502826602,
                    "monotonic": 32644363306
                }
            }
        },
        "delay": {
            "receive": 45177,
            "rtt": 134460,
            "send": 89283
        },
        "ipdv": {}
    },
    {
        "seqno": 1,
        "lost": false,
        "timestamps": {
            "client": {
                "receive": {
                    "wall": 1508180723702917735,
                    "monotonic": 202967099
                },
                "send": {
                    "wall": 1508180723702807328,
                    "monotonic": 202856692
                }
            },
            "server": {
                "receive": {
                    "wall": 1508180723702861515,
                    "monotonic": 32844398219
                },
                "send": {
                    "wall": 1508180723702872467,
                    "monotonic": 32844409171
                }
            }
        },
        "delay": {
            "receive": 45268,
            "rtt": 99455,
            "send": 54187
        },
        "ipdv": {
            "receive": 91,
            "rtt": -35005,
            "send": -35096
        }
    },
    {
        "seqno": 2,
        "lost": true,
        "timestamps": {
            "client": {
                "receive": {},
                "send": {
                    "wall": 1508180723902925971,
                    "monotonic": 402975335
                }
            },
            "server": {
                "receive": {},
                "send": {}
            }
        },
        "delay": {},
        "ipdv": {}
    }
]

Note: wall values are from Go's time.Time.UnixNano(), the number of nanoseconds elapsed since January 1, 1970 UTC

Note: monotonic values are the number of nanoseconds since the start of the test for the client, and since start of the process for the server

•
seqno the sequence number
•
lost the lost status of the packet, which can be one of false, true, true_down or true_up. The true_down and true_up values are only possible if the ReceivedStats parameter includes ReceivedStatsWindow (irtt client --stats flag). Even then, if it could not be determined whether the packet was lost upstream or downstream, the value true is used.
•
timestamps the client and server timestamps
•
client the client send and receive wall and monotonic timestamps (receive values only present if lost is false)
•
server the server send and receive wall and monotonic timestamps (both send and receive values not present if lost is true), and additionally:
•
send values are not present if the StampAt (irtt client --tstamp flag) does not include send timestamps
•
receive values are not present if the StampAt (irtt client --tstamp flag) does not include receive timestamps
•
wall values are not present if the Clock (irtt client --clock flag) does not include wall values or server timestamps are not enabled
•
monotonic values are not present if the Clock (irtt client --clock flag) does not include monotonic values or server timestamps are not enabled
•
delay an object containing the delay values
•
receive the one-way receive delay, in nanoseconds (present only if server timestamps are enabled and at least one wall clock value is available)
•
rtt the round-trip time, in nanoseconds, always present
•
send the one-way send delay, in nanoseconds (present only if server timestamps are enabled and at least one wall clock value is available)
•
ipdv an object containing the IPDV (https://en.wikipedia.org/wiki/Packet_delay_variation) values (attributes present only for seqno > 0, and if lost is false for both the current and previous round_trip)
•
receive the difference in receive delay relative to the previous packet (present only if at least one server timestamp is available)
•
rtt the difference in round-trip time relative to the previous packet (always present for seqno > 0)
•
send the difference in send delay relative to the previous packet (present only if at least one server timestamp is available)

irtt client exits with one of the following status codes:

Code Meaning
0 Success
1 Runtime error
2 Command line error
3 Two interrupt signals received

It is possible with the irtt client to dramatically harm network performance by using intervals that are too low, particularly in combination with large packet lengths. Careful consideration should be given before using sub-millisecond intervals, not only because of the impact on the network, but also because:

•
Timer accuracy at sub-millisecond intervals may begin to suffer without the use of a custom kernel or the busy timer (which pins the CPU)
•
Memory consumption for results storage and system CPU time both rise rapidly
•
The granularity of the results reported may very well not be required

$ irtt client localhost
Sends requests once per second for one minute to localhost.
$ irtt client -i 200ms -d 10s -o - localhost
Sends requests every 0.2 sec for 10 seconds to localhost. Writes JSON output to stdout.
$ irtt client -i 20ms -d 1m -l 172 --fill=rand --sfill=rand 192.168.100.10
Sends requests every 20ms for one minute to 192.168.100.10. Fills both the client and server payload with random data. This simulates a G.711 VoIP conversation, one of the most commonly used codecs for VoIP as of this writing.
$ irtt client -i 0.1s -d 5s -6 --dscp=46 irtt.example.org
Sends requests with IPv6 every 100ms for 5 seconds to irtt.example.org. Sets the DSCP value (ToS field) of requests and responses to 46 (Expedited Forwarding).
$ irtt client --hmac=secret -d 10s “[2001:db8:8f::2/32]:64381”
Sends requests to the specified IPv6 IP on port 64381 every second for 10 seconds. Adds an HMAC to each packet with the key secret.

irtt(1) (irtt.html), irtt-server(1) (irtt-server.html)

IRTT GitHub repository (https://github.com/peteheist/irtt/)

February 11, 2018 v0.9.0