.. _dpdk:

Use DPDK to send packets between platforms
##########################################

This guide describes how to send packets between two platforms.

.. contents::
   :local:
   :depth: 1

Overview
********

Figure 1 shows how to send packets between two platforms in a simple
configuration. The example uses the :abbr:`Data Plane Development Kit (DPDK)`,
which is a set of libraries, drivers, sample applications, and tools for fast
packet processing.

.. figure:: ./figures/pktgen_lw3fd.png
   :align: center
   :alt: Platform A and B

   Figure 1: Environment for l3fwd DPDK application

This example uses the following DPDK components:

*  pktgen: Traffic generator. See `pktgen`_ documentation for details.
*  l3fwd: Layer 3 forwarding example application. See
   `l3fwd`_ documentation for details.

Prerequisites
*************

*  Two platforms using |CL-ATTR| release `13330`_ or higher.
*  Both images must include the :command:`kernel-native` bundle.
*  Install the :command:`network-basic-dev` bundle with the command:

   .. code-block:: bash

      sudo swupd bundle-add network-basic-dev

*  Each platform must have at least one :abbr:`NIC (Network Interface Card)`.
   Check the `DPDK project`_ for the list of supported `dpdk.org NICs`_.

* Two network cables.

Install dpdk and build l3fwd example (Platform B)
*************************************************

#. Change to the :file:`l3fwd` example directory.

   .. code-block:: bash

      sudo cd /usr/share/dpdk/examples/l3fwd

#. Assign :envvar:`RTE_SDK` variable to the makefiles path.

   .. code-block:: bash

      sudo export RTE_SDK=/usr/share/dpdk/

#. Assign :envvar:`RTE_TARGET` variable to the location of the gcc\* config
   file.

   .. code-block:: bash

      sudo export RTE_TARGET=x86_64-native-linuxapp-gcc

#. Build the `l3fwd` application and add the configuration header to
   the :makevar:`CFLAGS` variable.

   .. code-block:: bash

      sudo make CFLAGS+="-include /usr/include/rte_config.h"


Build pktgen (Platform A)
*************************

#. Download the `pktgen tar package`_ v3.1.2 or newer.

#. Decompress packages and move to uncompressed source directory.

#. Assign :envvar:`RTE_SDK` variable to the path where makefiles are located.

   .. code-block:: bash

      sudo export RTE_SDK=/usr/share/dpdk/

#. Assign :envvar:`RTE_TARGET` to the location of the gcc config file.

   .. code-block:: bash

      sudo export RTE_TARGET=x86_64-native-linuxapp-gcc

#. Build the `pktgen` project and set the :makevar:`CONFIG_RTE_BUILD_SHARED_LIB` variable
   to "n".

   .. code-block:: bash

      sudo make CONFIG_RTE_BUILD_SHARED_LIB=n

Bind NICs to DPDK kernel drivers (Platforms A and B)
****************************************************

The `l3fwd` application uses two NICs. The DPDK includes tools for binding
NICs to DPDK modules to run DPDK applications.

#. Load the DPDK I/O kernel module.

   .. code-block:: bash

      sudo modprobe vfio-pci

#. Check the NIC status to determine which network cards are not
   busy. When another application is using them, the status shows "Active",
   and those NICs cannot be bound.

   .. code-block:: bash

      sudo dpdk-devbind --status

#. Bind two available NICs. The general syntax for binding is:
   :command:`dpdk-devbind --bind=vfio-pci <device-entry>`.
   A working example is shown below:

   .. code-block:: bash

      sudo dpdk-devbind --bind=vfio-pci 01:00.0

#. Check the NIC status to verify that the NICs are bound correctly. If
   successful, `drv` displays the value `igb_uio`, which confirms
   that the NICs are using the DPDK modules.


Set hugepages (Platforms A and B)
*********************************

|CL| supports `hugepages` for the large memory pool allocation used for
packet buffers.

#. Set the number of hugepages.

   .. code-block:: bash

      sudo echo 1024 > /sys/kernel/mm/hugepages/hugepages-2048kB/nr_hugepages

#. Allocate pages on NUMA machines.

   .. code-block:: bash

      sudo echo 1024 > /sys/devices/system/node/node0/hugepages/hugepages-2048kB/nr_hugepages
      sudo echo 1024 > /sys/devices/system/node/node1/hugepages/hugepages-2048kB/nr_hugepages

#. Make memory available for DPDK.

   .. code-block:: bash

      sudo mkdir -p /mnt/huge $ mount -t hugetlbfs nodev /mnt/huge

   For more information, refer to the `DPDK guide`_ System Requirements
   section.


Set up the physical environment (Platforms A and B)
***************************************************

Connect the NICs on Platform A to the NICs on Platform B using the network
cables as shown in figure 2.

.. figure:: ./figures/pyshical_net.png

    Figure 2: Physical network environment


Run l3fwd application (Platform B)
**********************************

The `l3fwd` application is one of the DPDK examples available when you
install the :file:`dpdk-dev` bundle. `l3fwd` forwards packets from one
NIC to another. For details, refer to the `l3fwd`_ documentation.

#. Open the l3fwd example directory.

   .. code-block:: bash

      sudo cd  /usr/share/dpdk/examples/l3fwd

#. **This step is very important.**

   #. DPDK needs poll mode drivers to operate.
   #. Poll mode drivers are shared objects in :file:`/usr/lib64`.
   #. See the full list of supported NICs at `dpdk.org NICs`_.
   #. You must know which kernel module each NIC is using and choose a poll
      mode driver that corresponds to your NICs.

#. NIC binding and `pktgen` configuration depends upon network use cases and
   available system resources. Use the :command:`-d` flag to set the poll mode
   driver.

   The following example assumes that the NICs use the `e1000` network driver
   and the `e1000` poll mode driver. The :file:`librte_pmd_e1000.so` is
   located in :file:`/usr/lib64` in |CL|.

   .. code-block:: bash

      sudo ./build/l3fwd -c 0x3 -n 2 -d librte_pmd_e1000.so -- -p 0x3 --config="(0,0,0),(1,0,1)"

#. The `l3fwd` application shows port initialization details at startup.
   After port 0 initialization completes, `l3fwd` shows a MAC address and
   information for port 1.

   Save the MAC address for configuring the `pktgen` project.

Run pktgen application (Platform A)
***********************************

`pktgen` is a network traffic generator included in the DPDK.

#. `pktgen` configuration depends upon the network setup and the
   available system resources. The following example shows a basic
   configuration.

   .. code-block:: bash

      sudo ./app/app/x86_64-native-linuxapp-gcc/pktgen -c 0xf -n 4 -- -p 0xf -P -m "1.0, 2.1"

#. Enable active colorful output (optional).

   .. code-block:: bash

      Pktgen> theme enable

#. Use the MAC addresses shown by the `l3fwd` application during initialization.
   The command to set the MAC addresses in `pktgen` has the format:

   .. code-block:: bash

      set mac <port number> <mac address>

   Here is a working example:

   .. code-block:: bash

      Pktgen> set mac 0 00:1E:67:CB:E8:C9
      Pktgen> set mac 1 00:1E:67:CB:E8:C9

#. Send packets.

   .. code-block:: bash

      Pktgen> start 0-1

For more details, see the `pktgen`_ documentation.

Appendix A: Use pass-through for virtual machines
*************************************************

This section explains how to set up a virtual environment where virtual
machines control the NICs on the host.

#. Create a new directory and move to it.

#. Download or create a :file:`start_qemu.sh` script for running a kvm virtual
   machine:

   .. code-block:: bash

      sudo curl -O https://cdn.download.clearlinux.org/image/start_qemu.sh

#. Download a bare-metal image of |CL| and rename it as :file:`clear.img`.

#. Look for an Ethernet\* device entry that contains vendor and device ID:

   .. code-block:: bash

      sudo lspci -nn | grep Ethernet

   An example output:

   .. code-block:: console

       03:00.0 Ethernet controller [0200]: Intel Corporation I350 Gigabit Network Connection [8086:1521]

   where `03:00.0` is the device entry and `8086:1521` is the `vendor:device
   ID`. Record this information, because you need it to unbind the NICs from a
   host.


#. Unbind the NICs from the host to do pass-through with virtual machines. |CL|
   supports this action. The commands take the format:

   .. code-block:: bash

      echo "vendor device_ID" > /sys/bus/pci/drivers/pci-stub/new_id
      echo "entry for device" > /sys/bus/pci/drivers/igb/unbind
      echo "entry for device" > /sys/bus/pci/drivers/pci-stub/bind
      echo "vendor device_ID" > /sys/bus/pci/drivers/pci-stub/remove_id

   Here is a working example:

   .. code-block:: bash

      sudo echo "8086 1521" > /sys/bus/pci/drivers/pci-stub/new_id
      sudo echo "0000:03:00.0" > /sys/bus/pci/drivers/igb/unbind
      sudo echo "0000:03:00.0" > /sys/bus/pci/drivers/pci-stub/bind
      sudo echo "8086 1521" > /sys/bus/pci/drivers/pci-stub/remove_id

#. Assign the unbound NICs to the KVM virtual machine (guest).
   Modify the :file:`start_qemu.sh` script in `qemu-system-x86_64` arguments, and
   add the lines with the host's NICs information in the format:

   .. code-block:: bash

      -device pci-assign,host="<entry for device>",id=passnic0,addr=03.0
      -device pci-assign,host="<entry for device>",id=passnic1,addr=04.0

   Here is a working example:

   .. code-block:: bash

      -device pci-assign,host=03:00.0,id=passnic0,addr=03.0 \
      -device pci-assign,host=03:00.3,id=passnic1,addr=04.0 \

#. Add more NUMA machines to the virtual machine by adding lines to the
   Makefile boot target in the format:

   .. code-block:: bash

      -numa node,mem=<memory>,cpus=<number of cpus>

   Here is a working example for a virtual machine with 4096 memory and four
   CPUs:

   .. code-block:: bash

    -numa node,mem=2048,cpus=0-1 \
    -numa node,mem=2048,cpus=2-3 \

   .. note:: Each NUMA machine must use the same quantity of memory.

#. Run the :file:`start_qemu.sh` script.


.. _13330: https://cdn.download.clearlinux.org/releases/13330/
.. _DPDK project: http://dpdk.org
.. _dpdk.org NICs: http://dpdk.org/doc/nics
.. _pktgen tar package: http://dpdk.org/browse/apps/pktgen-dpdk/refs
.. _DPDK guide: http://dpdk.org/doc/guides/linux_gsg/sys_reqs.html
.. _l3fwd: http://dpdk.org/doc/guides/sample_app_ug/l3_forward.html
.. _pktgen: http://pktgen-dpdk.readthedocs.io/en/latest/index.html
