Simple Forward VNF

NVIDIA DOCA Simple Forward VNF Application Guide

This document provides a Simple Forward implementation on top of NVIDIA® BlueField® DPU.

Simple forward is a forwarding application that takes either VXLAN, GRE, or GTP traffic from a single RX port and transmits it on a single TX port.

For every packet received on an RX queue on a given port, DOCA Simple Forward checks the packet's key, which consists of a 5-tuple. If it finds that the packet matches an existing flow, then it does not create a new one. Otherwise, a new flow is created with a FORWARDING component. Finally, the packet is forwarded to the TX queue of the egress port. Refer to Arg Parser DOCA Flags if "rx-only" mode is not set.

The FORWARDING component type depends on the flags delivered when running the application. For example, if the hairpinq flag is provided, then the FORWARDING component would be hairpin. Otherwise, it would be RSS'd to software, and hence every VXLAN, GTP, or GRE packet would be received on RX queues.

Simple forward should be run with dual ports. By using a traffic generator, the RX port receives the VXLAN, GRE, or GTP packets and forwarding forwards them back to the traffic generator.

The following diagram illustrates simple forward's packet flows. It receives traffic coming from the wire and passes it to the other port.

system-design-diagram.png

Simple forward first initializes DPDK, after which the application handles the incoming packets.

The following diagram illustrates the initialization process.

initialization-process-illustration.png

  1. Init_DPDK – EAL init, parse argument from command line and register signal.
  2. Start port – mbuf_create, dev_configure, rx/tx/hairpin queue setup and start the port.
  3. Simple_fwd INIT – create flow tables, build default forward pipes.

The following diagram illustrates how to process the packet.

packet-processing-illustration.png

  1. Based on the packet's info, find the key values (e.g. src/dst IP, src/dst port, etc).
  2. Traverse the inner flow tables, check if the keys exist or not.
    • If yes, update inner counter
    • If no, a new flow table is added and new pipes are configured on the DPU
  3. Forward the packet to the other port.

This application leverages the DOCA Flow Library.

  1. Parse application argument.
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    doca_argp_init();

    1. Initialize arg parser resources.
    2. Register DOCA general flags.
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      register_simple_fwd_params();

    3. Register application flags.
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      doca_argp_start();

    4. Parse DPDK flags and invoke handler for calling the rte_eal_init() function.
    5. Parse app flags.
  2. DPDK initialization.
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    dpdk_init();

    Calls rte_eal_init() to initialize EAL resources with the provided EAL flags.

  3. DPDK port initialization and start.
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    dpdk_queues_and_ports_init();

    1. Initialize DPDK ports.
    2. Create mbuf pool using rte_pktmbuf_pool_create
    3. Driver initialization – use rte_eth_dev_configure to configure the number of queues
    4. Rx/Tx queue initialization – use rte_eth_rx_queue_setup and rte_eth_tx_queue_setup to initialize the queues
    5. Rx hairpin queue initialization – use rte_eth_rx_hairpin_queue_setup to initialize the queues
    6. Start the port using rte_eth_dev_start
  4. Simple forward initialization.
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    simple_fwd_init();

    1. simple_fwd_create_ins - create flow tables using simple_fwd_ft_create
    2. simple_fwd_init_ports_and_pipes – initialize DOCA port using simple_fwd_init_doca_port and build default pipes for each port.
  5. Main loop.
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    simple_fwd_process_pkts();

    1. Receive packets using rte_eth_rx_burst in a loop
    2. Process packets using simple_fwd_process_offload
    3. Transmit the packets on the other port by calling rte_eth_tx_burst. Or free the packet mbuf if rx_only is set to true.
  6. Process packets.
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    simple_fwd_process_offload();

    1. Parse the packet's rte_mbuf using simple_fwd_pkt_info.
    2. Handle the packet using simple_fwd_handle_packet. If the packet's key does not match the existed the flow entry, create a new flow entry and PIPE using simple_fwd_handle_new_flow. Otherwise, increase the total packet's counter.
  7. Simple forward destroy.
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    simple_fwd_destroy();

    Simple forward closes port and cleans the flow resources.

  8. DPDK ports and queues destruction.
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    dpdk_queues_and_ports_fini();

  9. DPDK finish.
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    dpdk_fini();

    Calls rte_eal_destroy() to destroy initialized EAL resources.

  10. Arg parser destroy.
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    doca_argp_destroy();

    • Free DPDK resources by call rte_eal_cleanup() function.

  1. Refer to the following documents:
  2. The simple forward binary is located under /opt/mellanox/doca/applications/simple_fwd_vnf/bin/doca_simple_fwd_vnf. To build all the applications together, run:
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    cd /opt/mellanox/doca/applications/ meson build ninja -C build


  3. To build the simple forward sample only:
    1. Edit the following flags in /opt/mellanox/doca/applications/meson_option.txt:
      • Set enable_all_applications to false
      • Set enable_simple_fwd_vnf to true
    2. Run the commands in step 2.
      Note:

      doca_simple_fwd_vnf is created under ./build/simple_fwd_vnf/src/.

    Application usage:

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    Usage: doca_simple_forward_vnf [DPDK Flags] -- [DOCA Flags] [Program Flags] DOCA Flags: -h, --help Print a help synopsis -v, --version Print program version information -l, --log-level Set the log level for the app <CRITICAL=0, DEBUG=4> Program Flags: -t, --stats-timer <time> Set interval to dump stats information -q, --nr-queues <num> Set queues number -r, --rx-only Set rx only -o, --hw-offload Set hw offload -hq, --hairpinq Set forwarding to hairpin queue -a, --age-thread Start thread do aging

    Note:

    For additional information on available flags for EAL, use -h before the -- separator:

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    /opt/mellanox/doca/applications/simple_fwd_vnf/bin/doca_simple_fwd_vnf -h

    Note:

    For additional information on the application, use -h after the -- separator:

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    /opt/mellanox/doca/applications/simple_fwd_vnf/bin/doca_simple_fwd_vnf -- -h


  4. Running the application on BlueField:
    • Pre-run setup: The simple forward example is based on DPDK libraries. Therefore, the user is required to provide DPDK flags, and allocate huge pages.
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      sudo echo 2048 > /sys/kernel/mm/hugepages/hugepages-2048kB/nr_hugepages


    • CLI example for running the app:
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      /opt/mellanox/doca/applications/simple_fwd_vnf/bin/doca_simple_fwd_vnf -a auxiliary:mlx5_core.sf.4 -a auxiliary:mlx5_core.sf.5 -- -l 4

      Note:

      The flag -a auxiliary:mlx5_core.sf.4 -a auxiliary:mlx5_core.sf.5 is mandatory for proper usage of the application. Modifying this flag results unexpected behavior as only 2 ports are supported. The SF number is arbitrary and configurable.

      Note:

      SFs must be enabled according to Scalable Function Setup Guide. Before creating SFs on a specific physical port, it is important to verify the encap mode on the respective PF FDB. The default mode is basic. To check the encap mode, run:

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      cat /sys/class/net/p0/compat/devlink/encap


      In this case, disable encap on the PF FDB before creating the SFs by running:

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      /opt/mellanox/iproute2/sbin/devlink dev eswitch set pci/0000:03:00.0 mode legacy /opt/mellanox/iproute2/sbin/devlink dev eswitch set pci/0000:03:00.1 mode legacy echo none > /sys/class/net/p0/compat/devlink/encap echo none > /sys/class/net/p1/compat/devlink/encap /opt/mellanox/iproute2/sbin/devlink dev eswitch set pci/0000:03:00.0 mode switchdev /opt/mellanox/iproute2/sbin/devlink dev eswitch set pci/0000:03:00.1 mode switchdev


      Note that if the encap mode is set to basic then the application fails upon initialization.

  5. Running the application on the host, CLI example:
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    /opt/mellanox/doca/applications/simple_fwd_vnf/bin/doca_simple_fwd_vnf -a 04:00.3 -a 04:00.4 -- -l 4

    Note:

    Refer to section "Running DOCA Application on Host" in NVIDIA DOCA Virtual Functions User Guide.

  6. To run doca_simple_fwd_vnf using a JSON file:
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    doca_simple_fwd_vnf --json [json_file]

    For example:
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    cd /opt/mellanox/doca/applications/simple_fwd_vnf/bin ./doca_simple_fwd_vnf --json simple_fwd_params.json


Refer to NVIDIA DOCA Arg Parser User Guide for more information.

Flag Type Short Flag Long Flag/JSON Key Description JSON Content
DPDK Flags a devices Add a PCIe device into the list of devices to probe.
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"devices": [ {"device": "sf", "id": “4”,"sft": true}, {"device": "sf", "id": “5”,"sft": true}, ]

General Flags l log-level Set the log level for the application:
  • CRITICAL=0
  • ERROR=1
  • WARNING=2
  • INFO=3
  • DEBUG=4
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"log-level": 4

v version Print program version information. N/A
h help Print a help synopsis. N/A
Program Flags t stats-timer Set interval to dump stats information.
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"stats-timer": 2

q nr-queues Set queues number.
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"nr-queues": 4

r rx-only Set RX only. When set, the packets will not be sent to the TX queues.
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"rx-only": false

o hw-offload Set HW offload of the RXP engine to use.
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"hw-offload": false

hq hairpinq Set forwarding to hairpin queue.
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"hairpinq": false

a age-thread Start a dedicated thread that handles the aged flows.
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"age-thread": false

  • /opt/mellanox/doca/applications/simple_fwd_vnf/src/simple_fwd_vnf.c

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