44. L3 Forwarding Exact Match Tests

The Layer-3 Forwarding results are produced using l3fwd application.

44.1. Prerequisites

  1. Hardware requirements:

    • For each CPU socket, each memory channel should be populated with at least 1x DIMM

    • Board is populated with 4x 1GbE or 10GbE ports. Special PCIe restrictions may be required for performance. For example, the following requirements should be met for Intel 82599 (Niantic) NICs:

      • NICs are plugged into PCIe Gen2 or Gen3 slots
      • For PCIe Gen2 slots, the number of lanes should be 8x or higher
      • A single port from each NIC should be used, so for 4x ports, 4x NICs should be used

    • NIC ports connected to traffic generator. It is assumed that the NIC ports P0, P1, P2, P3 (as identified by the DPDK application) are connected to the traffic generator ports TG0, TG1, TG2, TG3. The application-side port mask of NIC ports P0, P1, P2, P3 is noted as PORTMASK in this section.

  2. BIOS requirements:

    • Intel Hyper-Threading Technology is ENABLED
    • Hardware Prefetcher is DISABLED
    • Adjacent Cache Line Prefetch is DISABLED
    • Direct Cache Access is DISABLED

  3. Linux kernel requirements:

    • Linux kernel has the following features enabled: huge page support, UIO, HPET
    • Appropriate number of huge pages are reserved at kernel boot time
    • The IDs of the hardware threads (logical cores) per each CPU socket can be determined by parsing the file /proc/cpuinfo. The naming convention for the logical cores is: C{x.y.z} = hyper-thread z of physical core y of CPU socket x, with typical values of x = 0 .. 3, y = 0 .. 7, z = 0 .. 1. Logical cores C{0.0.1} and C{0.0.1} should be avoided while executing the test, as they are used by the Linux kernel for running regular processes.

  4. Software application requirements

  5. If using vfio the kernel must be >= 3.6+ and VT-d must be enabled in bios.When using vfio, use the following commands to load the vfio driver and bind it to the device under test:

    modprobe vfio
modprobe vfio-pci
usertools/dpdk-devbind.py --bind=vfio-pci device_bus_id
  • In hash mode, the hash table used for packet routing is:

# IPv4 destination address IPv4 source address Port destination Port source L4 protocol Output port
0 201.0.0.0 200.20.0.1 102 12 TCP P1
1 101.0.0.0 100.10.0.1 101 11 TCP P0
2 211.0.0.0 200.40.0.1 102 12 TCP P3
3 111.0.0.0 100.30.0.1 101 11 TCP P2
  1. Traffic generator requirements

The flows need to be configured and started by the traffic generator:


Flow Traffic Gen. Port IPv4 Dst. Address IPv4 Src. Address Port Dst. Port Src. L4 Proto. IPv4 Dst Addr Mask(Continuous Increment Host)
1 TG0 201.0.0.0 200.20.0.1 102 12 TCP 255.240.0.0
2 TG1 101.0.0.0| 100.10.0.1 101 11 TCP 255.240.0.0

The queue column represents the expected NIC port RX queue where the packet should be written by the NIC hardware when RSS is enabled for that port.

44.2. Test Case: Layer-3 Forwarding (in Hash Mode)

The following items are configured through the command line interface of the application:

  • The set of one or several RX queues to be enabled for each NIC port
  • The set of logical cores to execute the packet forwarding task
  • Mapping of the NIC RX queues to logical cores handling them.
  • The set of hash-entry-num for the exact match

The test report should provide the throughput rate measurements (in mpps and % of the line rate for 4x NIC ports) as listed in the table below:


# Number of RX Queues per NIC Port Total Number of NIC RX Queues Number of Sockets/ Cores/Threads Total Number of Threads Number of NIX RX Queues per Thread Throughput Rate Exact Match Mode
mpps | %
1 1 2 1S/1C/1T 1 1    
2 1 2 1S/2C/1T 2 1    
3 2 4 1S/4C/1T 4 2    

The application command line associated with each of the above tests is presented in the table below. The test report should present this table with the actual command line used, replacing the PORTMASK and C{x.y.z} with their actual values used during test execution.


# Command Line
1 ./l3fwd -c coremask -n 3 – -E -p 0x3 –config ‘(P0,0,C{0.1.0}),(P1,0,C{0.1.0})’
2 ./l3fwd -c coremask -n 3 – -E -p 0x3 –config ‘(P0,0,C{0.1.0}),(P1,0,C{0.2.0})’
3 ./l3fwd -c coremask -n 3 – -E -p 0x3 –config ‘(P0,0,C{0.1.0}),(P0,1,C{0.2.0}),(P1,0,C{0.3.0}),(P1,1,C{0.4.0})’