DOCA Documentation v1.1.1

Simple Forward VNF

NVIDIA DOCA Simple Forward VNF Reference Application

This document provides a Simple Forward implementation on top NVIDIA® BlueField®-2 DPU.

Simple forward is a forwarding application which takes VXLAN traffic from a single RX port and transmits it on a single TX port.

For a packet received on an RX port, simple forward will create a flow based on the packet’s tunnel and 5-tuples. For the following packets with the same key, simple forward checks the packet’s keys. If it finds that the packet matches the existing flow, then it does not create a new flow. Otherwise, a new flow is created. And then the packets are forwarded on the other port.

Simple forward should be run with dual ports. By using a traffic generator, the RX port receives the VXLAN 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 initializes DPDK first, during which time simple forward handles the incoming packets.

The following diagram illustrates the initialization process.

initialization-process-illustration.png

  1. DPDK_init – 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.

  1. DPDK initialization.
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    dpdk_init(&argc, &argv, &nb_queues, &nb_ports)

  2. Port initialization and start.
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    simple_fwd_start_dpdk_port(&port_cfg);

    • Mbuf pool created using rte_pktmbuf_pool_create
    • Driver initialization – use rte_eth_dev_configure to configure the number of queues
    • Rx/Tx queue initialization – use rte_eth_rx_queue_setup and rte_eth_tx_queue_setup to initialize the queues
    • Rx hairpin queue initialization – use rte_eth_rx_hairpin_queue_setup to initialize the queues
    • Start the port using rte_eth_dev_start
  3. Simple forward initialization.
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    simple_fwd_init((void *)&port_cfg);

    • simple_fwd_create - create flow tables using doca_ft_create
    • simple_fwd_init_ports_and_pipes – initialize DOCA port using simple_fwd_init_doca_port and build default pipes for ports using build_fwd_pipe
  4. Main loop.
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    simple_fwd_process_packets(void *p);

    • Receive packets using rte_eth_rx_burst in a loop
    • Process packets using simple_fwd_process_offload
    • Tx_burst the packets on the other port. Or mbuf free if rx_only is set to true.
  5. Process packets.
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    simple_fwd_process_offload(mbufs[j]);

    • Parse the packet's rte_mbuf using simple_fwd_parse_packet.
    • 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 counter.
  6. Simple forward destroy.
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    simple_fwd_destroy();

  7. Simple forward close port.
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    simple_fwd_close_port(port_id)

  1. Please refer to the DOCA Installation Guide for details on how to install BlueField related software.
  2. To build the application
    1. The binary of simple forward example is located under /opt/mellanox/doca/examples/simple_fwd_vnf/bin/doca_simple_fwd_vnf. To re-build the simple forward sample, run the following:
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      cd /opt/mellanox/doca/examples/simple_fwd_vnf/src meson /tmp/build ninja -C /tmp/build


      doca_simple_fwd_vnf will be created under tmp/build.

    2. The build process depends on the PKG_CONFIG_PATH environment variable to locate the DPDK libraries. If the variable was accidently corrupted, and the build fails, run the following command:
      • For Ubuntu:
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        export PKG_CONFIG_PATH=$PKG_CONFIG_PATH:/opt/mellanox/dpdk/lib/aarch64-linux-gnu/pkgconfig

      • For CentOS:
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        export PKG_CONFIG_PATH=$PKG_CONFIG_PATH:/opt/mellanox/dpdk/lib64/pkgconfig

    3. The simple forward example is based on DPDK libraries. Therefore, the user is required to provide DPDK flags, and allocate huge pages. Run:
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      echo 1024 > /sys/kernel/mm/hugepages/hugepages-2048kB/nr_hugepages sudo mkdir /mnt/huge sudo mount -t hugetlbfs nodev /mnt/huge


  3. To run the application:
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    doca_simple_fwd_vnf [dpdk_flags] -- [additional application flags]

    Note:

    SFs must be enabled according to Scalable Function Setup Guide.

    For example:
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    /opt/mellanox/doca/examples/simple_fwd_vnf/bin/doca_simple_fwd_vnf -a auxiliary:mlx5_core.sf.4 -a auxiliary:mlx5_core.sf.5 -- --nr_queues=4 --stats_timer=2

    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 will result unexpected behavior as only 2 ports are supported. The SF number is arbitrary and configurable. For additional information on available flags for DPDK, use -h before the -- separator.


    The command quit terminates the application.

    Supported EAL options:

    • --log_level – set log level

    • --stats_timer – set interval to dump stats information

    • --nr_queues – set queues number

    • --rx_only – set rx_only (0 or 1)

    • --hw_offload – set HW offload (0 or 1)

    • --hairpinq – set fowarding to hairpin queue

  • /opt/mellanox/doca/examples/simple_fwd_vnf/src/simple_fwd.c

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