47. Loop-back Sample Application using Baseband Device (bbdev)

The baseband sample application is a simple example of packet processing using the Data Plane Development Kit (DPDK) for baseband workloads using Wireless Device abstraction library.

47.1. Overview

The Baseband device sample application performs a loop-back operation using a baseband device capable of transceiving data packets. A packet is received on an ethernet port -> enqueued for downlink baseband operation -> dequeued from the downlink baseband device -> enqueued for uplink baseband operation -> dequeued from the baseband device -> then the received packet is compared with the baseband operations output. Then it’s looped back to the ethernet port.

  • The MAC header is preserved in the packet

47.2. Limitations

  • Only one baseband device and one ethernet port can be used.

47.3. Compiling the Application

  1. DPDK needs to be built with baseband_turbo_sw PMD enabled along with FLEXRAN SDK Libraries. Refer to SW Turbo Poll Mode Driver documentation for more details on this.

  2. Go to the example directory:

    export RTE_SDK=/path/to/rte_sdk
cd ${RTE_SDK}/examples/bbdev_app

  3. Set the target (a default target is used if not specified). For example:

    export RTE_TARGET=x86_64-native-linux-gcc

    See the DPDK Getting Started Guide for possible RTE_TARGET values.

  4. Build the application:

    make

47.4. Running the Application

The application accepts a number of command line options:

$ ./build/bbdev [EAL options] -- [-e ENCODING_CORES] [-d DECODING_CORES] /
[-p ETH_PORT_ID] [-b BBDEV_ID]

where:

  • e ENCODING_CORES: hexmask for encoding lcores (default = 0x2)
  • d DECODING_CORES: hexmask for decoding lcores (default = 0x4)
  • p ETH_PORT_ID: ethernet port ID (default = 0)
  • b BBDEV_ID: BBDev ID (default = 0)

The application requires that baseband devices is capable of performing the specified baseband operation are available on application initialization. This means that HW baseband device/s must be bound to a DPDK driver or a SW baseband device/s (virtual BBdev) must be created (using –vdev).

To run the application in linux environment with the turbo_sw baseband device using the whitelisted port running on 1 encoding lcore and 1 decoding lcore issue the command:

$ ./build/bbdev --vdev='baseband_turbo_sw' -w <NIC0PCIADDR> -c 0x38 --socket-mem=2,2 \
--file-prefix=bbdev -- -e 0x10 -d 0x20

where, NIC0PCIADDR is the PCI address of the Rx port

This command creates one virtual bbdev devices baseband_turbo_sw where the device gets linked to a corresponding ethernet port as whitelisted by the parameter -w. 3 cores are allocated to the application, and assigned as:

  • core 3 is the master and used to print the stats live on screen,
  • core 4 is the encoding lcore performing Rx and Turbo Encode operations
  • core 5 is the downlink lcore performing Turbo Decode, validation and Tx operations

Refer to the DPDK Getting Started Guide for general information on running applications and the Environment Abstraction Layer (EAL) options.

47.5. Using Packet Generator with baseband device sample application

To allow the bbdev sample app to do the loopback, an influx of traffic is required. This can be done by using DPDK Pktgen to burst traffic on two ethernet ports, and it will print the transmitted along with the looped-back traffic on Rx ports. Executing the command below will generate traffic on the two whitelisted ethernet ports.

$ ./pktgen-3.4.0/app/x86_64-native-linux-gcc/pktgen -c 0x3 \
--socket-mem=1,1 --file-prefix=pg -w <NIC1PCIADDR> -- -m 1.0 -P

where:

  • -c COREMASK: A hexadecimal bitmask of cores to run on
  • --socket-mem: Memory to allocate on specific sockets (use comma separated values)
  • --file-prefix: Prefix for hugepage filenames
  • -w <NIC1PCIADDR>: Add a PCI device in white list. The argument format is <[domain:]bus:devid.func>.
  • -m <string>: Matrix for mapping ports to logical cores.
  • -P: PROMISCUOUS mode

Refer to The Pktgen Application documents for general information on running Pktgen with DPDK applications.