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.. BSD LICENSE
Copyright(c) 2017 Intel Corporation. All rights reserved.
All rights reserved.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions
are met:
* Redistributions of source code must retain the above copyright
notice, this list of conditions and the following disclaimer.
* Redistributions in binary form must reproduce the above copyright
notice, this list of conditions and the following disclaimer in
the documentation and/or other materials provided with the
distribution.
* Neither the name of Intel Corporation nor the names of its
contributors may be used to endorse or promote products derived
from this software without specific prior written permission.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
DPDK pdump Library and pdump Tool
=================================
This document describes how the Data Plane Development Kit (DPDK) Packet
Capture Framework is used for capturing packets on DPDK ports. It is intended
for users of DPDK who want to know more about the Packet Capture feature and
for those who want to monitor traffic on DPDK-controlled devices.
The DPDK packet capture framework was introduced in DPDK v16.07. The DPDK
packet capture framework consists of the DPDK pdump library and DPDK pdump
tool.
Introduction
------------
The :ref:`librte_pdump <pdump_library>` library provides the APIs required to
allow users to initialize the packet capture framework and to enable or
disable packet capture. The library works on a client/server model and its
usage is recommended for debugging purposes.
The :ref:`dpdk-pdump <pdump_tool>` tool is developed based on the
``librte_pdump`` library. It runs as a DPDK secondary process and is capable
of enabling or disabling packet capture on DPDK ports. The ``dpdk-pdump`` tool
provides command-line options with which users can request enabling or
disabling of the packet capture on DPDK ports.
The application which initializes the packet capture framework will act as a
server and the application that enables or disables the packet capture will
act as a client. The server sends the Rx and Tx packets from the DPDK ports
to the client.
In DPDK the ``testpmd`` application can be used to initialize the packet
capture framework and act as a server, and the ``dpdk-pdump`` tool acts as a
client. To view Rx or Tx packets of ``testpmd``, the application should be
launched first, and then the ``dpdk-pdump`` tool. Packets from ``testpmd``
will be sent to the tool, which then sends them on to the Pcap PMD device and
that device writes them to the Pcap file or to an external interface depending
on the command-line option used.
Some things to note:
* The ``dpdk-pdump`` tool can only be used in conjunction with a primary
application which has the packet capture framework initialized already. In
dpdk, only ``testpmd`` is modified to initialize packet capture framework,
other applications remain untouched. So, if the ``dpdk-pdump`` tool has to
be used with any application other than the testpmd, the user needs to
explicitly modify that application to call the packet capture framework
initialization code. Refer to the ``app/test-pmd/testpmd.c`` code and look
for ``pdump`` keyword to see how this is done.
* The ``dpdk-pdump`` tool depends on the libpcap based PMD which is disabled
by default in the build configuration files, owing to an external dependency
on the libpcap development files. Once the libpcap development files are
installed, the libpcap based PMD can be enabled by setting
``CONFIG_RTE_LIBRTE_PMD_PCAP=y`` and recompiling the DPDK.
Test Environment
----------------
The overview of using the Packet Capture Framework and the ``dpdk-pdump`` tool
for packet capturing on the DPDK port in
:numref:`figure_packet_capture_framework`.
.. _figure_packet_capture_framework:
.. figure:: img/packet_capture_framework.*
Packet capturing on a DPDK port using the dpdk-pdump tool.
Configuration
-------------
Modify the DPDK primary application to initialize the packet capture framework
as mentioned in the above notes and enable the following config options and
build DPDK::
CONFIG_RTE_LIBRTE_PMD_PCAP=y
CONFIG_RTE_LIBRTE_PDUMP=y
Running the Application
-----------------------
The following steps demonstrate how to run the ``dpdk-pdump`` tool to capture
Rx side packets on dpdk_port0 in :numref:`figure_packet_capture_framework` and
inspect them using ``tcpdump``.
#. Launch testpmd as the primary application::
sudo ./app/testpmd -c 0xf0 -n 4 -- -i --port-topology=chained
#. Launch the pdump tool as follows::
sudo ./build/app/dpdk-pdump -- \
--pdump 'port=0,queue=*,rx-dev=/tmp/capture.pcap'
#. Send traffic to dpdk_port0 from traffic generator.
Inspect packets captured in the file capture.pcap using a tool
that can interpret Pcap files, for example tcpdump::
$tcpdump -nr /tmp/capture.pcap
reading from file /tmp/capture.pcap, link-type EN10MB (Ethernet)
11:11:36.891404 IP 4.4.4.4.whois++ > 3.3.3.3.whois++: UDP, length 18
11:11:36.891442 IP 4.4.4.4.whois++ > 3.3.3.3.whois++: UDP, length 18
11:11:36.891445 IP 4.4.4.4.whois++ > 3.3.3.3.whois++: UDP, length 18
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