Terminology

  • Frame size: size of an Ethernet Layer-2 frame on the wire, including any VLAN tags (dot1q, dot1ad) and Ethernet FCS, but excluding Ethernet preamble and inter-frame gap. Measured in Bytes.

  • Packet size: same as frame size, both terms used interchangeably.

  • Inner L2 size: for tunneled L2 frames only, size of an encapsulated Ethernet Layer-2 frame, preceded with tunnel header, and followed by tunnel trailer. Measured in Bytes.

  • Inner IP size: for tunneled IP packets only, size of an encapsulated IPv4 or IPv6 packet, preceded with tunnel header, and followed by tunnel trailer. Measured in Bytes.

  • Device Under Test (DUT): In software networking, “device” denotes a specific piece of software tasked with packet processing. Such device is surrounded with other software components (such as operating system kernel). It is not possible to run devices without also running the other components, and hardware resources are shared between both. For purposes of testing, the whole set of hardware and software components is called “System Under Test” (SUT). As SUT is the part of the whole test setup performance of which can be measured with RFC 2544, using SUT instead of RFC 2544 DUT. Device under test (DUT) can be re-introduced when analyzing test results using whitebox techniques, but this document sticks to blackbox testing.

  • System Under Test (SUT): System under test (SUT) is a part of the whole test setup whose performance is to be benchmarked. The complete methodology contains other parts, whose performance is either already established, or not affecting the benchmarking result.

  • Bi-directional throughput tests: involve packets/frames flowing in both transmit and receive directions over every tested interface of SUT/DUT. Packet flow metrics are measured per direction, and can be reported as aggregate for both directions (i.e. throughput) and/or separately for each measured direction (i.e. latency). In most cases bi-directional tests use the same (symmetric) load in both directions.

  • Uni-directional throughput tests: involve packets/frames flowing in only one direction, i.e. either transmit or receive direction, over every tested interface of SUT/DUT. Packet flow metrics are measured and are reported for measured direction.

  • Packet Loss Ratio (PLR): ratio of packets received relative to packets transmitted over the test trial duration, calculated using formula: PLR = ( pkts_transmitted - pkts_received ) / pkts_transmitted. For bi-directional throughput tests aggregate PLR is calculated based on the aggregate number of packets transmitted and received.

  • Packet Throughput Rate: maximum packet offered load DUT/SUT forwards within the specified Packet Loss Ratio (PLR). In many cases the rate depends on the frame size processed by DUT/SUT. Hence packet throughput rate MUST be quoted with specific frame size as received by DUT/SUT during the measurement. For bi-directional tests, packet throughput rate should be reported as aggregate for both directions. Measured in packets-per-second (pps) or frames-per-second (fps), equivalent metrics.

  • Bandwidth Throughput Rate: a secondary metric calculated from packet throughput rate using formula: bw_rate = pkt_rate - (frame_size + L1_overhead) - 8, where L1_overhead for Ethernet includes preamble (8 Bytes) and inter-frame gap (12 Bytes). For bi-directional tests, bandwidth throughput rate should be reported as aggregate for both directions. Expressed in bits-per-second (bps).

  • Non Drop Rate (NDR): maximum packet/bandwith throughput rate sustained by DUT/SUT at PLR equal zero (zero packet loss) specific to tested frame size(s). MUST be quoted with specific packet size as received by DUT/SUT during the measurement. Packet NDR measured in packets-per-second (or fps), bandwidth NDR expressed in bits-per-second (bps).

  • Partial Drop Rate (PDR): maximum packet/bandwith throughput rate sustained by DUT/SUT at PLR greater than zero (non-zero packet loss) specific to tested frame size(s). MUST be quoted with specific packet size as received by DUT/SUT during the measurement. Packet PDR measured in packets-per-second (or fps), bandwidth PDR expressed in bits-per-second (bps).

  • Maximum Receive Rate (MRR): packet/bandwidth rate regardless of PLR sustained by DUT/SUT under specified Maximum Transmit Rate (MTR) packet load offered by traffic generator. MUST be quoted with both specific packet size and MTR as received by DUT/SUT during the measurement. Packet MRR measured in packets-per-second (or fps), bandwidth MRR expressed in bits-per-second (bps).

  • Trial: a single measurement step.

  • Trial duration: amount of time over which packets are transmitted and received in a single throughput measurement step.