#+EXPORT_FILE_NAME: xdp-trafficgen
#+TITLE: xdp-trafficgen
#+OPTIONS: ^:nil
#+MAN_CLASS_OPTIONS: :section-id "8\" \"DATE\" \"VERSION\" \"An XDP-based traffic generator"
# This file serves both as a README on github, and as the source for the man
# page; the latter through the org-mode man page export support.
# .
# To export the man page, simply use the org-mode exporter; (require 'ox-man) if
# it's not available. There's also a Makefile rule to export it.

* XDP-trafficgen - an XDP-based traffic generator

XDP-trafficgen is a packet generator utilising the XDP kernel subsystem to
generate packets transmit them through a network interface. Packets are
dynamically generated and transmitted in the kernel, allowing for high
performance (millions of packets per second per core).

XDP-trafficgen supports generating UDP traffic with fixed or dynamic destination
ports, and also has basic support for generating dummy TCP traffic on a single
flow.

** Running xdp-traffigen
The syntax for running xdp-trafficgen is:

#+begin_src sh
Usage: xdp-trafficgen COMMAND [options]

COMMAND can be one of:
       udp         - run in UDP mode
       tcp         - run in TCP mode
       probe       - probe kernel support
#+end_src

Each command, and its options are explained below. Or use =xdp-trafficgen COMMAND
--help= to see the options for each command.

* The UDP command
The UDP command generates UDP traffic to a given destination IP and either a
fixed destination port, or a range of port numbers. Only IPv6 traffic is
supported, and the generated packets will have their IP hop limit set to 1, so
they can't be routed.

The syntax for the =udp= command is:

=xdp-trafficgen udp [options] <ifname>=

Where =<ifname>= is the name of the destination interface that packets will be
transmitted on. Note that the network driver of this network interface must
support being the target of XDP redirects (it must implement the =ndo_xdp_xmit=
driver operation).

The supported options are:

** -m, --dst-mac <mac addr>
Set the destination MAC address of generated packets. The default is to generate
packets with an all-zero destination MAC.

** -M, --src-mac <mac addr>
Set the source MAC address of the generated packets. The default is to use the
MAC address of the interface packets are transmitted on.

** -a, --dst-addr <addr>
Destination IP address of generated packets. The default is the link-local
=fe80::2= address.

** -A, --src-addr <addr>
Source IP address of generated packets. The default is the link-local =fe80::1=
address.

** -p, --dst-port <port>
Destination UDP port of generated packets, or the first port in the range if
running with =--dyn-ports= set. Defaults to 1.

** -P, --src-port <port>
Source UDP port of generated packets. Defaults to 1.

** -d, --dyn-ports <num ports>
Enable dynamic port mode where the destination port is varied over a range of
=<num ports>= starting from the =--dst-port=.

** -n, --num-packets <num packets>
Number of packets to send before exiting. If not supplied, =xdp-trafficgen= will
keep sending packets until interrupted.

** -s, --pkt-size <bytes>
Size of each UDP packet being sent, including the Ethernet header. The minimum
size, which is also the default, is 64 bytes.

** -t, --threads <threads>
Number of simultaneous threads to transmit from. Each thread will be pinned to a
separate CPU core if possible. Defaults to 1.

** -I, --interval <s>
Output transmission statistics with this interval (in seconds).

** -v, --verbose
Enable verbose logging (-vv: more verbose).

** --version
Display version information and exit.

** -h, --help
Display a summary of the available options


* The TCP command
The TCP command generates dummy TCP traffic in a single TCP flow. This relies on
first installing an ingress XDP program on the interface used to transmit on.
Then, a regular TCP socket connection is established from userspace, and once
the handshake is completed, the XDP program will take over and start generating
traffic on that flow tuple. The ingress XDP program will intercept ACK packets
from the receiver, and keep track of the receive window.

The traffic generator has no congestion control, and only very basic retransmit
tracking: in essence, any duplicate ACKs from the receiver will cause the sender
to reset its send sequence number to the last ACKed value and restart from
there. The same thing happens if no progress on the window is made within two
seconds. This means that the traffic generator can generate a large amount of
dummy traffic, but if there's packet loss a lot of this can be retransmissions.

The syntax for the =tcp= command is:

=xdp-trafficgen tcp [options] -i <ifname> <hostname>=

Where =<ifname>= is the name of the destination interface that packets will be
transmitted on and =<hostname>= is the peer hostname or IP address to connect to
(only IPv6 is supported). Note that the network driver of this network interface
must support being the target of XDP redirects (it must implement the
=ndo_xdp_xmit= driver operation).

The supported options are:

** -p, --dst-port <port>
Connect to destination <port>. Default 10000.

** -m, --mode <mode>
Load ingress XDP program in <mode>; default native (valid values: native,skb,hw)

** -n, --num-packets <port>
Number of packets to send before exiting. If not supplied, =xdp-trafficgen= will
keep sending packets until interrupted.

** -I, --interval <s>
Output transmission statistics with this interval (in seconds).

** -v, --verbose
Enable verbose logging (-vv: more verbose).

** --version
Display version information and exit.

** -h, --help
Display a summary of the available options

* The PROBE command
The PROBE command probes the kernel to discover whether it supports the features
needed to run xdp-trafficgen. This can be used to discover whether the running
kernel is compatible with xdp-trafficgen, as well as to discover whether a
particular interface supports sending packets generated by xdp-trafficgen.

The syntax for the =probe= command is:

=xdp-trafficgen probe [options]=

After probing, xdp-trafficgen will print the results of the probing of the
kernel, and (if an interface name is supplied), whether the interface supports
sending packets generated by xdp-trafficgen. The exit code will be 0 if all
probes succeed, and 1 otherwise.

Note that the probing relies on the kernel XDP feature reporting, which was
added after the XDP support itself. This means that with some older kernel
versions, the probing may fail even though xdp-trafficgen would in fact be able
to transmit packets.

The supported options are:

** -i, --ifname <ifname>
Probe the supplied interface name, in addition to doing the general kernel probing.

** -v, --verbose
Enable verbose logging (-vv: more verbose).

** --version
Display version information and exit.

** -h, --help
Display a summary of the available options

* BUGS

Please report any bugs on Github: https://github.com/xdp-project/xdp-tools/issues

* AUTHOR

xdp-trafficgen and this man page were written by Toke Høiland-Jørgensen.
