Provided by: flent_2.1.1-2_all bug

NAME

       flent - Flent: The FLExible Network Tester

INTRODUCTION

       Flent  is a wrapper around netperf and similar tools to run predefined tests and aggregate
       and plot the results. It defines several tests that can be run against one or more  hosts,
       primarily targeted at testing for the presence of bufferbloat under various conditions.

       The  aggregated  data is saved in (gzipped) JSON format for later processing and/or import
       into other tools. The JSON format is documented below.

       Apart from the JSON format, the data can be output as csv values, emacs org mode tables or
       plots.  Each  test can specify several different plots, including time-series plots of the
       values against each other, as well as CDF plots of (e.g.) ping times.

       Plots can be output to the formats  supported  by  matplotlib  by  specifying  the  output
       filename  with  -o  output.{png,ps,pdf,svg}.  If  no output file is specified, the plot is
       displayed using matplotlib’s interactive plot browser, which also  allows  saving  of  the
       output (in .png format).

   Requirements
       Flent  runs  on  Python, versions 2.7+ and 3.3+. Plotting requires a functional matplotlib
       installation (but everything else can run without matplotlib). For  the  interactive  plot
       viewer, a graphical display (and suitably configured matplotlib) is required.

       Most  tests  employ the netperf benchmarking tool to run the tests.  Version 2.6 or higher
       is required, and netperf  must  be  compiled  with  the  --enable-demo  option  passed  to
       ./configure.  Some  tests use iperf in addition to, or instead of netperf. Both tools must
       be available in the PATH.

       For ICMP ping measurements, the version of ping employed must support output  timestamping
       (the -D parameter to GNU ping). This is not supported by the BSD and OSX versions of ping.
       As an alternative to the regular ping command, the fping  utility  (see  http://fping.org)
       can  be employed. In that case fping must be version 3.5 or greater. Flent will attempt to
       detect the presence of fping in the PATH and check for support for the  -D  parameter.  If
       this  check is successful, fping will be employed for ping data, otherwise the system ping
       will be used.

       The    irtt    tool    is    highly    recommended    for    UDP     measurements.     See
       https://github.com/peteheist/irtt. Flent will automatically detect if irtt is available in
       the PATH and use it if it is detected. Note that the server component of irtt needs to  be
       running on the target host(s) as well.

RUNNING FLENT

       When  run,  flent  must  be  supplied either (a) a test name and one or more host names to
       connect to, or (b) one  or  more  input  files  containing  data  from  previous  runs  to
       post-process.

       Test  names, hostnames and input file names can all be specified as unqualified arguments,
       and flent will do its best to guess which is  which.  For  each  argument,  if  it  is  an
       existing  file,  it  is assumed to be an input file, if it is the name of an existing test
       configuration it’s assumed to be a test name, and if neither of  those  are  true,  it  is
       assumed  to  be  a host name. The -i and -H switches can be used to explicitly specify the
       interpretation of an argument.

   Invocation
       flent [options] <host|test|input file ...>

   General options
       -o OUTPUT, --output=OUTPUT
              File to write processed output to (default standard out).

       -D DATA_DIR, --data-dir=DATA_DIR
              Directory to store data files in. Defaults to the current directory.

       -i INPUT, --input=INPUT
              File to read input from (instead  of  running  tests).  Input  files  can  also  be
              specified as unqualified arguments without using the -i switch.

       -f FORMAT, --format=FORMAT
              Select  output format (plot, csv, org_table, stats). Default is no processed output
              (just writes the JSON data file).

       -p PLOT, --plot=PLOT
              Select which plot to  output  for  the  given  test  (implies  -f  plot).  Use  the
              --list-plots option to see available plots.

       -t TITLE, --title-extra=TITLE
              Text to add to plot title and data file name.

       -n NOTE, --note=NOTE
              Add arbitrary text as a note to be stored in the JSON data file (under the NOTE key
              in the metadata object).

       -r RCFILE, --rcfile=RCFILE
              Load configuration data from RCFILE (default ~/.flentrc).  See  section  below  for
              information on the rc file format.

       -x, --extended-metadata
              Collect  extended  metadata and store it with the data file. May include details of
              your machine you don’t want to distribute; see  the  section  on  the  data  format
              below.

       --remote-metadata=HOSTNAME
              Collect  extended  metadata from a remote host. HOSTNAME is passed verbatim to ssh,
              so can include hosts specified in ~/.ssh/config. Note that gathering the  data  can
              take  some  time,  since it involves executing several remote commands. This option
              can be specified multiple times and implies --extended-metadata.

       --gui  Run the flent GUI. All other options are used as defaults in the GUI,  but  can  be
              changed  once  it  is running. The GUI can also be started by running the flent-gui
              binary. For more information on the GUI, see the The Flent GUI section.

       --new-gui-instance
              Start a new GUI instance. Otherwise, flent  will  try  to  connect  to  an  already
              running  GUI instance and have that load any new data files specified as arguments.
              Implies --gui when passed on the command line, but not when set  in  the  rc  file.
              Note  that  when  multiple  GUI  instances are running, there is no guarantee as to
              which  instance  will  get  a  subsequent  open  request  (if  run  again   without
              --new-gui-instance).

       --gui-no-defer
              Normally,  the  GUI defers redrawing plots until they are needed to avoid redrawing
              all  open  plots  every  time  an  option  changes.  This  switch  turns  off  that
              optimisation  in  favour  of  always  redrawing  everything straight away.  This is
              useful when loading a bunch of plots from the command line and then wanting to flip
              through them without drawing delay.

       -b BATCH_NAME, --batch-name=BATCH_NAME
              Run  test  batch  BATCH_NAME  (must  be  specified  in  a  batch file loaded by the
              --batch-file option). Can be supplied multiple times.

       -B BATCH_FILE, --batch-file=BATCH_FILE
              Load batch file BATCH_FILE. Can be specified multiple  times,  in  which  case  the
              files  will  be combined (with identically-named sections being overridden by later
              files). See appropriate section below for an explanation of the batch file format.

       --batch-override=key=value
              Override parameter ’key’ in the batch config and set it to ’value’.  The  key  name
              will be case folded to lower case. Can be specified multiple times.

       --batch-dry-run
              Dry batch run. Prints what would be done, but doesn’t actually run any tests.

       --batch-verbose
              Be verbose during batch run: Print all commands executed.

       --batch-no-shuffle
              Do not randomise the order of test runs within each batch.

       --batch-repetitions=REPETITIONS
              Shorthand for --batch-override 'repetitions=REPETITIONS’.

       --batch-title=TITLE
              Shorthand for --batch-override 'batch_title=TITLE’.

       --batch-resume=DIR
              Try  to  resume  a  previously interrupted batch run. The argument is the top-level
              output directory from the previous run.

              This will attempt to find a  data  file  in  the  resume  directory  and  load  the
              BATCH_TIME from the previous run from that and continue. The assumption is that the
              output directory and filenames are generated from the batch time, so that they will
              match  with the previous run when the same time is used. Then, tests for which data
              files already exist will be  skipped  on  this  run.  If  the  rest  of  the  batch
              invocation  is  different  from  the one being resumed, results may not be what you
              want.

              There's a check to ensure that the generated output path is a subdirectory  of  the
              resume directory, and the whole run will be aborted if it isn't.

   Test configuration options
       These  options  affect the behaviour of the test being run and have no effect when parsing
       input files.

       -H HOST, --host=HOST
              Host to connect to for tests. For tests that support  it,  multiple  hosts  can  be
              specified  by  supplying this option multiple times. Hosts can also be specified as
              unqualified arguments; this parameter guarantees that the argument  be  interpreted
              as  a  host  name (rather than being subject to auto-detection between input files,
              hostnames and test names).

       --local-bind=IP
              Local hostname or IP address to bind to (for test tools that support this).  Can be
              specified multiple times for tests that connect to more than one host; if it is, it
              must be specified as many times as there are hosts.

       --remote-host=idx=HOSTNAME
              A remote hostname to connect to when starting a test. The idx is the runner  index,
              which  is  assigned  sequentially  to each runner (and so it is not the same as the
              sequence of hostnames). Look for the 'IDX' key in SERIES_META for a  test  get  the
              idx  used  here, but note that the idx assignment depends on the exact arguments to
              the test.

              This works by simply prepending 'ssh HOSTNAME' to the runner command, so it  relies
              on  the same binaries being in the same places on both machines, and won't work for
              all runners.

              This option can be specified multiple times to have multiple runners run on  remote
              hosts.

       -l LENGTH, --length=LENGTH
              Base test length (some tests may add some time to this).

       -s STEP_SIZE, --step-size=STEP_SIZE
              Measurement data point step size.

       -d DELAY, --delay=DELAY
              Number of seconds to delay parts of test (such as bandwidth loaders).

       -4, --ipv4
              Use IPv4 for tests (some tests may ignore this).

       -6, --ipv6
              Use IPv6 for tests (some tests may ignore this).

       --socket-timeout=SOCKET_TIMEOUT
              Socket  timeout  (in  seconds) used for UDP delay measurement, to prevent stalls on
              packet loss. Only enabled if the installed netperf version is detected  to  support
              this (requires SVN version of netperf).

              For  the  default value, see the output of flent -h. The value of this parameter is
              an implicit upper bound on how long a round-trip time that can be measured. As such
              you  may need to adjust it if you are experiencing latency above the default value.
              Set to 0 to disable.

       --send-size=SEND_SIZE
              Send size (in bytes) used for TCP tests. Netperf uses the  socket  buffer  size  by
              default,  which  if too large can cause spikes in the throughput results.  Lowering
              this value will increase CPU usage but also improves the fidelity of the throughput
              results without having to decrease the socket buffer size.

              Can  be  specified  multiple  times, with each value corresponding to a stream of a
              test. If only specified once, the same value will be applied to all flows.

       --test-parameter=key=value
              Arbitrary test parameter in key=value format. Key will  be  case  folded  to  lower
              case.  The  values  are  stored  with  the results metadata, and so can be used for
              storing arbitrary information relevant for a particular test run.

              In addition to serving as simple metadata, the test parameters can also affect  the
              behaviour  of  some  test  configurations.  See  the  Supplied  Tests  section  for
              information on these.

              This option can be specified multiple times to set multiple test parameters.

       --swap-up-down
              Switch upstream and downstream  directions  for  data  transfer.  This  means  that
              ’upload’  will  become  ’download’  and  vice  versa.  Works  by exchanging netperf
              TCP_MAERTS and TCP_STREAM parameters, so only works for tests that employ these  as
              their data transfer, and only for the TCP streams.

       --socket-stats
              Parse  socket  stats during test. This will capture and parse socket statistics for
              all TCP upload flows during a test, adding TCP cwnd and  RTT  values  to  the  test
              data.  Requires the 'ss' utility to be present on the system, and can fail if there
              are too many simultaneous upload flows; which is why this option is not enabled  by
              default.

       --marking-name
              Define a new symbolic name that can be used when specifying flow markings using the
              'markings' test parameter. This can be used to make it  easier  to  specify  custom
              diffserv  markings  on flows by using symbolic names for each marking value instead
              of the hex codes. Values specified here will be used  in  addition  to  the  common
              values  (listed  below),  and  cannot  override  the  built-in names. Names will be
              case-folded when matching.

              The list of symbolic markings natively supported, along with their hex  expansions,
              are:

                 AF11: 0x28    CS0: 0x00
                 AF12: 0x30    CS1: 0x20
                 AF13: 0x38    CS2: 0x40
                 AF21: 0x48    CS3: 0x60
                 AF22: 0x50    CS4: 0x80
                 AF23: 0x58    CS5: 0xa0
                 AF31: 0x68    CS6: 0xc0
                 AF32: 0x70    CS7: 0xe0
                 AF33: 0x78    EF:  0xb8
                 AF41: 0x88
                 AF42: 0x90
                 AF43: 0x98

              Note  that  the hexadecimal values denote the value of the full ToS byte (including
              the two ECN bits), so they need  to  be  right-shifted  by  two  bits  to  get  the
              corresponding diffserv code points.

   Plot configuration options
       These  options  are  used  to  configure the appearance of plot output and only make sense
       combined with -f plot.

       --label-x=LABEL

       --label-y=LABEL
              Override the figure axis labels. Can be specified twice, corresponding  to  figures
              with multiple axes.

       -I, --invert-latency-y
              Invert  latency data series axis (typically the Y-axis), making plots show ’better'
              values upwards.

       -z, --zero-y
              Always start Y axis of plot at zero, instead of autoscaling the axis.   Autoscaling
              is still enabled for the upper bound. This also disables log scale if enabled.

       --log-scale={log2,log10}
              Use the specified logarithmic scale on plots.

       --norm-factor=FACTOR
              Data  normalisation  factor. Divide all data points by this value. Can be specified
              multiple times, in which case each value corresponds to a data series.

       --bounds-x=BOUNDS

       --bounds-y=BOUNDS
              Specify bounds of the plot axes. If specifying one number,  that  will  become  the
              upper  bound.  Specify  two  numbers separated by a comma to specify both upper and
              lower bounds. To specify just the lower bound,  add  a  comma  afterwards.  Can  be
              specified twice, corresponding to figures with multiple axes.

       -S, --scale-mode
              Treat  file  names (except for the first one) passed as unqualified arguments as if
              passed as --scale-data (default as if passed as --input).

       --concatenate
              Concatenate multiple result sets into one data series. This means  that  each  data
              file  will have its time axis shifted by the preceding series duration and appended
              to the first data set specified. Only works for  data  sets  from  the  same  test,
              obviously.

       --absolute-time
              Plot  data points with absolute UNIX time on the x-axis. This requires the absolute
              starting time for the test run to be stored in the data file, and so it won’t  work
              with data files that predates this feature.

       --subplot-combine
              When  plotting multiple data series, plot each one on a separate subplot instead of
              combining them into one plot. This mode is not supported for all  plot  types,  and
              only works when --scale-mode is disabled.

       --skip-missing-series
              Skip  missing series entirely from bar plots, instead of leaving an empty space for
              it.

       --no-print-n
              Do not print the number of data points on combined plots.  When  using  plot  types
              that  combines  results  from  several test runs, the number of data series in each
              combined data point is normally added after the  series  name,  (n=X)  for  X  data
              series. This option turns that off.

       --no-annotation
              Exclude annotation with hostnames, time and test length from plots.

       --figure-note=NOTE, --fig-note=NOTE
              Add a note (arbitrary text) to the bottom-left of the figure.

       --no-title
              Exclude title from plots.

       --override-title=TITLE
              Override  plot  title  with  this  string. Completely discards the configured title
              (from the test configuration), as well as the title stored in  the  data  set,  and
              replaces it with the value supplied here. This is useful to override the plot title
              at the time of plotting, for instance to add a title  to  an  aggregate  plot  from
              several data series. When this parameter is specified, --no-title has no effect.

       --no-labels
              Hides tick labels from box and bar plots.

       --no-markers
              Don’t use line markers to differentiate data series on plots.

       --no-legend
              Exclude legend from plots.

       --horizontal-legend
              Place  a  horizontal  legend  below  the plot instead of a vertical one next to it.
              Doesn't always work well if there are too many items in the legend.

       --legend-title=LEGEND_TITLE
              Override legend title on plot.

       --legend-placement=LEGEND_PLACEMENT
              Control legend placement. Enabling this option will place  the  legend  inside  the
              plot  at the specified location. Can be one of 'best', 'upper right', 'upper left',
              'lower left',  'lower  right',  'right',  'center  left',  'center  right',  'lower
              center', 'upper center' or 'center'.

       --legend-columns=LEGEND_COLUMNS

       Set the number of columns in the legend.

       --reverse-legend
              Reverse  the  order  of  items in the legend. This can be useful to make the legend
              order match the data series in some cases.

       --filter-legend
              Filter legend labels by removing the longest common  substring  from  all  entries.
              This is not particularly smart, so use with care.

       --replace-legend=src=dest
              Replace 'src' with 'dst' in legends. Can be specified multiple times.

       --filter-regexp=REGEXP
              Filter  the  plot legend by the supplied regular expression (removing any text from
              the legend that matches the expression). Can be specified multiple times, in  which
              case  the  filters  will be applied in the order specified. Note that for combining
              several plot results, the regular expression is also applied  before  the  grouping
              logic, meaning that a too wide filter can mess up the grouping.

       --override-label=LABEL
              Override  dataset label. Can be specified multiple times when multiple datasets are
              being plotted, in which case the order  of  labels  corresponds  to  the  order  of
              datasets.

              Like --override-title, this is applied at the time of plotting.

       --filter-series=SERIES
              Filter out specified series from plot. Can be specified multiple times.

       --split-group=LABEL
              Split  data  sets into groups when creating box plots. Specify this option multiple
              times to define the new groups; the value of each option is the group name.

              Say you're plotting nine datasets which are really testing two variables with three
              values  each. In this case, it can be useful to have the box plot of the results be
              split into three parts (corresponding to the values  of  one  variable)  with  each
              three  boxes  in each of them (corresponding to the values of the second variable).
              This option makes this possible; simply specify it three times with the  labels  to
              be used for the three groups.

              A  constraint  on  this option is that the number of datasets being plotted must be
              divisible by the number of groups.

       --colours=COLOURS
              Comma-separated list of colours to be used  for  the  plot  colour  cycle.  Can  be
              specified  in  any  format  understood  by  matplotlib  (including  HTML hex values
              prefixed with a #).

              Yes, this option uses British spelling. No, American spelling is not supported.

       --override-colour-mode=MODE
              Override colour_mode attribute. This changes the way colours are  assigned  to  bar
              plots.  The  default  is  'groups' which assigns a separate colour to each group of
              data series. The alternative is 'series' which assigns a separate  colour  to  each
              series, repeating them for each data group.

       --override-group-by=GROUP
              Override  the  group_by  setting  for  combination  plots.  This  is useful to, for
              instance, switch to splitting up combined data sets by batch run instead of by file
              name.

       --combine-save-dir=DIRNAME
              When  doing a combination plot save the intermediate data to DIRNAME. This can then
              be used for subsequent plotting to avoid having to load all the source  data  files
              again on each plot.

       --figure-width=FIG_WIDTH
              Figure  width in inches. Used when saving plots to file and for default size of the
              interactive plot window.

       --figure-height=FIG_HEIGHT
              Figure height in inches. Used when saving plots to file and for default size of the
              interactive plot window.

       --figure-dpi=FIG_DPI
              Figure DPI. Used when saving plots to raster format files.

       --fallback-layout
              Use  the  fallback layout engine (tight_layout built in to matplotlib). Use this if
              text is cut off on saved figures. The downside to the fallback engine is  that  the
              size  of  the  figure  (as  specified  by --figure-width and --figure-height) is no
              longer kept constant.)

       --no-matplotlibrc
              Don’t load included matplotlibrc  values.  Use  this  if  autodetection  of  custom
              matplotlibrc fails and flent is inadvertently overriding rc values.

       --no-hover-highlight
              Don't  highlight  data  series  on  hover  in  interactive  plot views. Use this if
              redrawing is too slow, or the highlighting is undesired for other reasons.

       --scale-data=SCALE_DATA
              Additional data files to consider when scaling the plot axes (for plotting  several
              plots  with  identical axes). Note, this displays only the first data set, but with
              axis scaling taking into account the additional data sets. Can be supplied multiple
              times; see also --scale-mode.

   Test tool-related options
       --control-host=HOST
              Hostname  for  the  test  control  connection  (for  test tools that support this).
              Default: First hostname of test target.

              When running tests that uses D-ITG as a test tool (such as the voip-* tests),  this
              switch  controls  where  flent  will look for the D-ITG control server (see section
              below on running tests with D-ITG). For Netperf-based tests, this option is  passed
              to Netperf to control where to point the control connection. This is useful to, for
              instance, to run the control server communication over a separate  control  network
              so as to not interfere with test traffic.

              There is also a per-flow setting for this for tests that connect to multiple hosts;
              see the control_hosts test parameter in  Supplied  Tests.  If  both  are  set,  the
              per-flow setting takes precedence for those tests that use it.

       --control-local-bind=IP
              Local hostname or IP to bind control connection to (for test tools that support it;
              currently netperf). If not supplied, the value for --local-bind will be used.  Note
              that  if  this  value is passed but --local-bind is not, netperf will use the value
              specified here to bind the data connections to as well.

       --netperf-control-port=PORT
              Port for Netperf control server. Default: 12865.

       --ditg-control-port=PORT
              Port for D-ITG control server. Default: 8000.

       --ditg-control-secret=SECRET
              Secret for D-ITG control server authentication. Default: ’’.

       --http-getter-urllist=FILENAME
              When running  HTTP  tests,  the  http-getter  tool  is  used  to  fetch  URLs  (see
              https://github.com/tohojo/http-getter).   This   option   specifies   the  filename
              containing the list of HTTP URLs to get. Can also be a  URL,  which  will  then  be
              downloaded  as  part  of  each  test  iteration.  If  not specified, this is set to
              http://<hostname>/filelist.txt where <hostname> is the first test hostname.

       --http-getter-dns-servers=DNS_SERVERS
              DNS servers to use for http-getter lookups. Format is  host[:port][,host[:port]]...
              This  option will only work if libcurl supports it (needs to be built with the ares
              resolver). Default is none (use the system resolver).

       --http-getter-timeout=MILLISECONDS
              Timeout for HTTP connections. Default is to use the test length.

       --http-getter-workers=NUMBER
              Number of workers to use for getting HTTP urls. Default is 4.

       --irtt-sampling-interval=MILLISECONDS
              Override the sampling interval passed to irtt, in milliseconds. Can be used to  run
              irtt  with a higher sampling frequency than the rest of the test. If set, this will
              override the sampling interval for all instances of irtt used in the test.

   Misc and debugging options:
       -L LOG_FILE, --log-file=LOG_FILE
              Write debug log (test program output) to log file.

       --list-tests
              List available tests and exit.

       --list-plots
              List available plots for selected test and exit.

       -V, --version
              Show Flent version information and exit.

       -v, --verbose
              Enable verbose logging to console.

       -q, --quiet
              Disable normal logging to console (and only log warnings and errors).

       --debug-error
              Print full exception backtraces to console.

       -h, --help
              Show usage help message and exit.

   Signals
       Flent will abort what it is currently doing on receiving a SIGINT -- this includes killing
       all  runners,  cleaning  up  temporary  files and shutting down as gracefully as possible.
       Runners are killed with SIGTERM in this mode, and their output is discarded.  If  a  batch
       run  is in progress, the current test will be interrupted in this way, and the rest of the
       batch run is aborted. Previously completed  tests  and  their  results  are  not  aborted.
       Post-commands   marked  as  ’essential’  will  be  run  after  the  test  is  interrupted.
       Additionally, flent converts SIGTERM into SIGINT internally and reacts accordingly.

       Upon receiving a SIGUSR1, flent will try to gracefully abort  the  test  it  is  currently
       running,  and  parse  the output of the runners to the extent that any such output exists.
       That is, each runner will be killed by a SIGINT, which will cause a graceful shutdown  for
       at  least  ping and netperf (although netperf running in TCP_MAERTS mode will bug out when
       interrupted like this, so end-of-tests statistics will be missing). Flent will only  react
       once to a SIGUSR1, sending exactly one SIGINT to the active runners, then wait for them to
       exit. This may take several seconds in the case of netperf. If the runners for some reason
       fail  to  exit,  flent will be stuck and will need to be killed with SIGINT. If running in
       batch mode, SIGUSR1 will only affect the currently running  test;  subsequent  tests  will
       still be run.

SUPPLIED TESTS

       Test are supplied as Python files and can specify commands to run etc.  For a full list of
       the tests supported by flent, see the --list-tests option.

   The Realtime Response Under Load (RRUL) test
       This test exists in a couple of variants and is  a  partial  implementation  of  the  RRUL
       specification         as         written         by         Dave         Taht         (see
       https://www.bufferbloat.net/projects/bloat/wiki/RRUL_Spec/).  It  works  by  running   RTT
       measurement  using ICMP ping and UDP roundtrip time measurement, while loading up the link
       with eight TCP streams (four downloads, four uploads).  This quite reliably saturates  the
       measured  link (wherever the bottleneck might be), and thus exposes bufferbloat when it is
       present.

   Simple TCP flow tests
       These tests combine a TCP flow (either in one  direction,  or  both)  with  an  ICMP  ping
       measurement.  It’s  a simpler test than RRUL, but in some cases the single TCP flow can be
       sufficient to saturate the link.

   UDP flood test
       This test runs iperf configured to emit 100Mbps of UDP packets targeted at the test  host,
       while  measuring  RTT using ICMP ping. It is useful for observing latency in the face of a
       completely unresponsive packet stream.

   Test parameters
       Some test parameters (set with --test-parameter) affect the way tests behave. These are:

       upload_streams

       download_streams

       bidir_streams
              These set the number of streams for the tests that are configurable.  The  tcp_nup,
              tcp_ndown  and rrul_be_nflows tests understand upload_streams and download_streams,
              while the rrul_var test understands bidir_streams. If any of these parameter is set
              to  the  special  value num_cpus the number of streams will be set to the number of
              CPUs on the system (if this information is available).

       tcp_cong_control
              Set the congestion control used for TCP flows, for platforms that supports  setting
              it. This can be specified as a simple string to set the same value for upstream and
              downstream, or two comma-separated values to set it separately for the upstream and
              downstream     directions.     On     Linux,    any    value    in    the    sysctl
              net.ipv4.tcp_allowed_congestion_control can be used.

              If a congestion control is specified that is not available on  the  system  running
              the  test,  setting  it  will  simply  fail.  In  addition, some tests override the
              congestion control for one or more flows. The actual  congestion  control  used  is
              stored in the CONG_CONTROL per-test metadata field.

       udp_bandwidth

       udp_bandwidths

       udp_pktsize

       udp_pktsizes
              This  sets the bandwidth and packet size of each UDP stream in the udp_* tests. The
              option is passed to iperf so can be in any syntax the iperf understands  (e.g.  20M
              for 20 Mbps).

              When  running  multiple  UDP  streams  use  the  plural  versions  of  the  options
              (udp_bandwidths  and  udp_pktsizes)  to  specify   individual   per-stream   values
              (comma-separated  per  stream),  or the singular versions to specify the same value
              for all streams.

       burst_length

       burst_ports

       burst_psize

       burst_tos
              These set the length, number of ports to use, packet size and  TOS  value  for  the
              packet bursts generated in the burst* tests.

       cpu_stats_hosts

       netstat_hosts

       qdisc_stats_hosts

       wifi_stats_hosts
              These  set  hostnames to gather statistics from from during the test. The hostnames
              are passed  to  SSH,  so  can  be  anything  understood  by  SSH  (including  using
              username@host  syntax, or using hosts defined in ~/.ssh/config).  This will attempt
              to run remote commands on  these  hosts  to  gather  the  required  statistics,  so
              passwordless  login  has  to  be  enabled for. Multiple hostnames can be specified,
              separated by commas.

              CPU stats and netstat output is global to the machine being connected to. The qdisc
              and  WiFi  stats  need  extra parameters to work. These are qdisc_stats_interfaces,
              wifi_stats_interfaces  and  wifi_stats_stations.  The  two  former  specify   which
              interfaces  to  gather statistics from. These are paired with the hostnames, and so
              must contain the same number of  elements  (also  comma-separated)  as  the  _hosts
              variables.   To  specify  multiple  interfaces  on  the  same  host,  duplicate the
              hostname. The wifi_stats_stations parameter specifies MAC addresses of stations  to
              gather  statistics  for.  This  list  is  the same for all hosts, but only stations
              present in debugfs on each host are actually captured.

              The qdisc stats gather statistics output from tc -s, while the  WiFi  stats  gather
              statistics  from debugfs. These are gathered by looping in a shell script; however,
              for better performance, the tc_iterate and wifistats_iterate  programmes  available
              in  the misc/ directory of the source code tarball can be installed. On low-powered
              systems this can be critical to get correct statistics. The helper  programmes  are
              packaged for LEDE/OpenWrt in the flent-tools package.

       ping_hosts

       ping_local_binds

       ping_labels
              These are used to define one or more extra host names that will receive a ping flow
              while a test is run. The ping_hosts variable simply  specifies  hostnames  to  ping
              (several  can  be  specified by separating them with commas).  The ping_local_binds
              variable sets local IP address(es)  to  bind  to  for  the  extra  ping  flows.  If
              specified, it must contain the same number of local addresses as the number of ping
              hosts. The same local  address  can  be  specified  multiple  times,  however.  The
              ping_labels  variable  is  used  to label each of the ping flows; if not specified,
              Flent will create a default label based on the target hostname for each flow.

       voip_host

       voip_local_bind

       voip_control_host

       voip_marking
              Similar to the ping variants above, these parameters specify a hostname  that  will
              receive  a VoIP test. However, unlike the ping parameters, only one hostname can be
              specified for VoIP tests, and that end-host needs to have  either  D-ITG  (and  the
              control  server)  or  the  IRTT  server running. The marking setting controls which
              DiffServ marking is applied to the VoIP flow and defaults to no marking being set.

       control_hosts
              Hostnames  to  use  for  the  control  connections   for   the   rtt_fair*   tests.
              Comma-separated.  If  specified, it must contain as many hostnames as the number of
              target hostnames specified for the test.

       markings

       labels Flow markings to use for each of the flows in the rtt_fair* tests.  Comma-separated
              values  of  markings  understood by Netperf (such as "CS0").  Only supports setting
              the same marking on both the upstream and downstream packets of each  flow  (so  no
              "CS0,CS0"  setting  as  can be used for Netperf). If not set, defaults to CS0 (best
              effort). If set, each value corresponds to a flow, and any extra flows will be  set
              to CS0. By default each flow will be labelled according to its marking; to override
              these labels, use the labels parameter.

       stream_delays
              Specify a per-stream delay (in seconds) for the different streams started up  by  a
              test.  Use commas to separate values for the different streams. This can be used to
              create tests with staggered start times, for  example  to  test  TCP  flow  startup
              convergence  times.  What  exactly  constitutes  a  stream depends on the test. For
              example, the rtt_fair* tests considers each hostname a stream, whether or not there
              is one or two flows going to that host.

THE FLENT GUI

       Flent  comes equipped with a GUI to browse and plot previously captured datasets.  The GUI
       requires PyQt4; if this is installed, it can be launched with the --gui parameter,  or  by
       launching the flent-gui binary.  Additionally, if Flent is launched without parameters and
       without a controlling terminal, the GUI will be launched automatically.

       The GUI can be used for interactively plotting previously captured datasets, and makes  it
       easy  to  compare results from several test runs. It presents a tabbed interface to graphs
       of data files, allows dynamic configuration of plots, and includes a metadata browser. For
       each  loaded data file, additional data files can be loaded and added to the plot, similar
       to what happens when specifying multiple input files for plotting on the command  line.  A
       checkbox  controls whether the added data files are added as separate entries to the plot,
       or whether they are used for scaling the output (mirroring the --scale-mode) command  line
       switch.

       The  GUI also incorporates matplotlib’s interactive browsing toolbar, enabling panning and
       zooming of the plot area, dynamic configuration of plot and axis parameters and labels and
       saving  the  plots  to file. The exact dynamic features supported depends on the installed
       version of matplotlib.

CONFIGURATION FILES

   The RC file
       Some of the command line options can be specified in an rc file. By default,  flent  looks
       for  this  in  ~/.flentrc,  but an alternative location can be specified with the --rcfile
       command line option.

       The rc file allows options to be specified globally, an optionally overridden for specific
       tests.  For  an  explanation  of  the  options, refer to the annotated example rc file, by
       default installed to /usr/share/doc/flent/flentrc.example.

   Batch Files
       Flent supports reading batch files to automate running several tests and do setup/teardown
       of test environment etc. This greatly aids reproducibility of tests.

       The  batch  file  is parsed as an ini file, and can have three types of sections: batches,
       commands and args. Each section also has a name; type and  name  are  separated  with  two
       colons.  'Batches'  are named tests that can be selected from the command line, 'commands'
       are system commands to be run before or after each test run, and 'args' are  used  in  the
       looping mechanism (which allows repeating tests multiple times with different parameters).

       Variables  in sections control the operation of Flent and can be modified in several ways:
       Sections of the same type can inherit from each  other  and  the  variables  in  an  'arg'
       section  will  be  interpolated  into the batch definition on each iteration of a loop. In
       addition, variable  contents  can  be  substituted  into  other  variables  by  using  the
       ${varname}  syntax.  These  three  operations are resolved in this order (inheritance, arg
       interpolation and variable substitution).

       An annotated example batchfile is distributed with the source  code,  and  is  by  default
       installed to /usr/share/doc/flent/batchfile.example.

THE DATA FILE FORMAT

       The  aggregated  test  data  is saved in a file called <test_name>-<date>.<title>.flent.gz
       (the title part is omitted if no title is  specified  by  the  -t  parameter).  This  file
       contains the data points generated during the test, as well as some metadata.

   The top-level object keys
       version
              The file format version as an integer.

       x_values
              An  array  of  the  x  values  for  the  test  data  (typically the time values for
              timeseries data).

       results
              A JSON object containing the result data series.  The  keys  are  the  data  series
              names;  the  value  for  each key is an array of y values for that data series. The
              data array has the same length as the x_values array, but there may be missing data
              points (signified by null values).

       metadata
              An  object  containing  various data points about the test run. The metadata values
              are read in as configuration parameters when the data set is loaded in for  further
              processing. Not all tests use all the parameters, but they are saved anyway.

       raw_values
              An  array  of  objects for each data series. Each element of the array contains the
              raw values as parsed from the test tool corresponding to that data series.

   Metadata keys
       NAME   The test name.

       TITLE  Any extra title specified by the --title-extra parameter when the test was run.

       HOSTS  List of the server hostnames connected to during the test.

       LOCAL_HOST
              The hostname of the machine that ran the test.

       LENGTH Test length in seconds, as specified by the --length parameter.

       TOTAL_LENGTH
              Actual data series length, after the test has added time to the LENGTH.

       STEP_SIZE
              Time step size granularity.

       TIME   ISO timestamp of the time the test was initiated.

       NOTE   Arbitrary text as entered with the --note switch when the test was run.

       FLENT_VERSION
              Version of Flent that generated the data file.

       IP_VERSION
              IP version  used  to  run  test  (as  specified  by  command  line  parameters,  or
              auto-detected from getaddrinfo() if unspecified).

       KERNEL_NAME
              The kernel name as reported by uname -s.

       KERNEL_RELEASE
              The kernel release as reported by uname -r.

       MODULE_VERSIONS
              The  sha1sum of certain interesting Linux kernel modules, if available. Can be used
              to match test data to specific code versions, if the kernel build  is  instrumented
              to, e.g., set the build ID to a git revision.

       SYSCTLS
              The  values  of several networking-related sysctls on the host (if available; Linux
              only).

       EGRESS_INFO
              Interface name, qdisc, offload, driver and BQL configuration of the interface  used
              to reach the test target. This requires that the ip binary is present on Linux, but
              can be extracted from route on BSD. Qdisc information requires the tc binary to  be
              present, and offload information requires ethtool.

              If  the  --remote-metadata is used, the extended metadata info is gathered for each
              of the hostnames specified. This is gathered under the REMOTE_METADATA key  in  the
              metadata  object,  keyed  by  the  hostname  values  passed  to  --remote-metadata.
              Additionally, the REMOTE_METADATA object will contain an object called INGRESS_INFO
              which  is a duplicate of EGRESS_INFO, but with the destination IP exchanged for the
              source  address  of  the  host  running  flent.  The  assumption   here   is   that
              --remote-metadata  is  used to capture metadata of a router known to be in the test
              path, in which case INGRESS_INFO will contain information about  the  reverse  path
              from  the  router  (which  is  ingress  from  the point of view of the host running
              flent). If the host being queried for remote metadata is off the path, the contents
              of INGRESS_INFO will probably be the same as that of EGRESS_INFO .

   Extended metadata
       If  the  --extended-metadata  switch  is  turned  on,  the following additional values are
       collected and stored (to the extent they are available from the platform):

       IP_ADDRS
              IP addresses assigned to the machine running flent.

       GATEWAYS
              IP addresses of all detected default gateways on the  system,  and  the  interfaces
              they  are reachable through. Only available if the netstat binary is present on the
              system.

       EGRESS_INFO
              In the EGRESS_INFO key, the IP address of the next-hop router and the interface MAC
              address are added if extended metadata is enabled.

OUTPUT FORMATS

       The following output formats are currently supported by Flent:

   Plot output (-f plot)
       Output test data as one of a series of graphical plots of timeseries data or summarised as
       a CDF plot. Each test supplies a number of different plots; the list of plots for a  given
       test is output by the --list-plots switch (which must be supplied along with a test name).

       The  plots  are  drawn  by  matplotlib,  and  can be displayed on the screen interactively
       (requires a graphical display), or output to a file in svg, pdf, ps and png formats. Using
       the  -o  switch  turns  out  file output (the file format is inferred from the file name),
       while not supplying the switch turns on the interactive plot viewer.

   Tabulated output (-f csv and -f org_table)
       These formats output the numeric data in a  tabulated  format  to  be  consumed  by  other
       applications.  The csv output format is a comma-separated output that can be imported into
       e.g. spreadsheets, while  org_table  outputs  a  tabulated  output  in  the  table  format
       supported  by  Emacs  org  mode.  The data is output in text format to standard output, or
       written to a file if invoked with the -o parameter.

   Statistics output (-f stats)
       This output format outputs various statistics about the test data, such as total bandwidth
       consumed, and various statistical measures (min/max/mean/median/std dev/variance) for each
       data source specified in the relevant  test  (this  can  include  some  data  sources  not
       includes  on plots). The data is output in text format to standard output, or written to a
       file if invoked with the -o parameter.

   Metadata output (-f metadata)
       This output format outputs the test metadata as pretty-printed  JSON  (also  suitable  for
       human  consumption).  It  is output as a list of objects, where each object corresponds to
       the metadata of one test. Mostly useful for inspecting metadata of stored data files.

MISC INFO

   Running Tests With The D-ITG Tool
       This version of flent has experimental support for running and parsing the output  of  the
       D-ITG test tool (see http://traffic.comics.unina.it/software/ITG/). Flent supports parsing
       the one-way delay as measured by D-ITG. However, in order to do so, the data needs  to  be
       collected  at  the receiver end, statistics extracted, and the result passed back to flent
       on the sending side.

       To perform this function, flent supports a control server which  will  listen  to  XML-RPC
       requests,  spawn  an  appropriate  ITGRecv instance and, after the test is done, parse its
       output and make it available for flent to retrieve. This control server is available as  a
       Python  file  that  by  default  is  installed  in /usr/share/doc/flent/misc. It currently
       requires a patched version of D-ITG v2.8.1.  The  patch  is  also  included  in  the  same
       directory.

       Note  that  the  D-ITG server is finicky and not designed with security in mind.  For this
       reason, the control server  includes  HMAC  authentication  to  only  allow  authenticated
       clients  to  run  a  test  against  the  server; however there is currently no support for
       enforcement of this in e.g. firewall rules. Please  bear  this  in  mind  when  running  a
       publicly reachable ITGRecv instance (with or without the control server). Another security
       issue with the control server is that the Python XML-RPC library by default is  vulnerable
       to XML entity expansion attacks.  For this reason, it is highly recommended to install the
       defusedxml library (available at  https://pypi.python.org/pypi/defusedxml/)  on  the  host
       running  the control server. The server will try to find the library on startup and refuse
       to run if it is not available, unless explicitly told otherwise.

       Due to the hassle of using D-ITG, it is recommended to install irtt instead and  use  that
       for VoIP tests.

   Bugs
       Under  some  conditions  (such  as  severe  bufferbloat), the UDP RTT measurements done by
       netperf can experience packet loss to the extent that the test  aborts  completely,  which
       can  cause  missing data points for some measurement series.  The --socket-timeout feature
       can alleviate this, but requires a recent SVN version of netperf to work. Flent  tries  to
       detect if netperf supports this option and enables it for the UDP measurements if it does.
       Using irtt for UDP measurements is a way  to  alleviate  this;  Flent  will  automatically
       detect the availability of irtt and use it if available.

       Probably      many      other      bugs.      Please      report      any     found     to
       https://github.com/tohojo/flent/issues and include the output of flent  --version  in  the
       report. A debug log (as obtained with flent --log-file) is also often useful.

AUTHOR

       Toke Høiland-Jørgensen

COPYRIGHT

       2012-2022, Toke Høiland-Jørgensen and contributors. Source code is GPLv3. Documentation is
       CC-BY-SA. Neither license affects any output produced by Flent