1. VSPERF LEVEL TEST PLAN (LTP)

1.1. Introduction

The objective of the OPNFV project titled Characterize vSwitch Performance for Telco NFV Use Cases, is to evaluate the performance of virtual switches to identify its suitability for a Telco Network Function Virtualization (NFV) environment. The intention of this Level Test Plan (LTP) document is to specify the scope, approach, resources, and schedule of the virtual switch performance benchmarking activities in OPNFV. The test cases will be identified in a separate document called the Level Test Design (LTD) document.

This document is currently in draft form.

1.1.1. Document identifier

The document id will be used to uniquely identify versions of the LTP. The format for the document id will be: OPNFV_vswitchperf_LTP_REL_STATUS, where by the status is one of: draft, reviewed, corrected or final. The document id for this version of the LTP is: OPNFV_vswitchperf_LTP_Colorado_REVIEWED.

1.1.2. Scope

The main purpose of this project is to specify a suite of performance tests in order to objectively measure the current packet transfer characteristics of a virtual switch in the NFVI. The intent of the project is to facilitate the performance testing of any virtual switch. Thus, a generic suite of tests shall be developed, with no hard dependencies to a single implementation. In addition, the test case suite shall be architecture independent.

The test cases developed in this project shall not form part of a separate test framework, all of these tests may be inserted into the Continuous Integration Test Framework and/or the Platform Functionality Test Framework - if a vSwitch becomes a standard component of an OPNFV release.

1.1.4. Level in the overall sequence

The level of testing conducted by vswitchperf in the overall testing sequence (among all the testing projects in OPNFV) is the performance benchmarking of a specific component (the vswitch) in the OPNFV platfrom. It’s expected that this testing will follow on from the functional and integration testing conducted by other testing projects in OPNFV, namely Functest and Yardstick.

1.1.5. Test classes and overall test conditions

A benchmark is defined by the IETF as: A standardized test that serves as a basis for performance evaluation and comparison. It’s important to note that benchmarks are not Functional tests. They do not provide PASS/FAIL criteria, and most importantly ARE NOT performed on live networks, or performed with live network traffic.

In order to determine the packet transfer characteristics of a virtual switch, the benchmarking tests will be broken down into the following categories:

  • Throughput Tests to measure the maximum forwarding rate (in frames per second or fps) and bit rate (in Mbps) for a constant load (as defined by RFC1242) without traffic loss.
  • Packet and Frame Delay Tests to measure average, min and max packet and frame delay for constant loads.
  • Stream Performance Tests (TCP, UDP) to measure bulk data transfer performance, i.e. how fast systems can send and receive data through the virtual switch.
  • Request/Response Performance Tests (TCP, UDP) the measure the transaction rate through the virtual switch.
  • Packet Delay Tests to understand latency distribution for different packet sizes and over an extended test run to uncover outliers.
  • Scalability Tests to understand how the virtual switch performs as the number of flows, active ports, complexity of the forwarding logic’s configuration... it has to deal with increases.
  • Control Path and Datapath Coupling Tests, to understand how closely coupled the datapath and the control path are as well as the effect of this coupling on the performance of the DUT.
  • CPU and Memory Consumption Tests to understand the virtual switch’s footprint on the system, this includes:
    • CPU core utilization.
    • CPU cache utilization.
    • Memory footprint.
    • System bus (QPI, PCI, ..) utilization.
    • Memory lanes utilization.
    • CPU cycles consumed per packet.
    • Time To Establish Flows Tests.
  • Noisy Neighbour Tests, to understand the effects of resource sharing on the performance of a virtual switch.

Note: some of the tests above can be conducted simultaneously where the combined results would be insightful, for example Packet/Frame Delay and Scalability.

1.2. Details of the Level Test Plan

This section describes the following items: * Test items and their identifiers (TestItems) * Test Traceability Matrix (TestMatrix) * Features to be tested (FeaturesToBeTested) * Features not to be tested (FeaturesNotToBeTested) * Approach (Approach) * Item pass/fail criteria (PassFailCriteria) * Suspension criteria and resumption requirements (SuspensionResumptionReqs)

1.2.1. Test items and their identifiers

The test item/application vsperf is trying to test are virtual switches and in particular their performance in an nfv environment. vsperf will first try to measure the maximum achievable performance by a virtual switch and then it will focus in on usecases that are as close to real life deployment scenarios as possible.

1.2.2. Test Traceability Matrix

vswitchperf leverages the “3x3” matrix (introduced in https://tools.ietf.org/html/draft-ietf-bmwg-virtual-net-02) to achieve test traceability. The matrix was expanded to 3x4 to accommodate scale metrics when displaying the coverage of many metrics/benchmarks). Test case covreage in the LTD is tracked using the following catagories:

  SPEED ACCURACY RELIABILITY SCALE
Activation X X X X
Operation X X X X
De-activation        

X = denotes a test catagory that has 1 or more test cases defined.

1.2.3. Features to be tested

Characterizing virtual switches (i.e. Device Under Test (DUT) in this document) includes measuring the following performance metrics:

  • Throughput as defined by RFC1242: The maximum rate at which none of the offered frames are dropped by the DUT. The maximum frame rate and bit rate that can be transmitted by the DUT without any error should be recorded. Note there is an equivalent bit rate and a specific layer at which the payloads contribute to the bits. Errors and improperly formed frames or packets are dropped.
  • Packet delay introduced by the DUT and its cumulative effect on E2E networks. Frame delay can be measured equivalently.
  • Packet delay variation: measured from the perspective of the VNF/application. Packet delay variation is sometimes called “jitter”. However, we will avoid the term “jitter” as the term holds different meaning to different groups of people. In this document we will simply use the term packet delay variation. The preferred form for this metric is the PDV form of delay variation defined in RFC5481. The most relevant measurement of PDV considers the delay variation of a single user flow, as this will be relevant to the size of end-system buffers to compensate for delay variation. The measurement system’s ability to store the delays of individual packets in the flow of interest is a key factor that determines the specific measurement method. At the outset, it is ideal to view the complete PDV distribution. Systems that can capture and store packets and their delays have the freedom to calculate the reference minimum delay and to determine various quantiles of the PDV distribution accurately (in post-measurement processing routines). Systems without storage must apply algorithms to calculate delay and statistical measurements on the fly. For example, a system may store temporary estimates of the mimimum delay and the set of (100) packets with the longest delays during measurement (to calculate a high quantile, and update these sets with new values periodically. In some cases, a limited number of delay histogram bins will be available, and the bin limits will need to be set using results from repeated experiments. See section 8 of RFC5481.
  • Packet loss (within a configured waiting time at the receiver): All packets sent to the DUT should be accounted for.
  • Burst behaviour: measures the ability of the DUT to buffer packets.
  • Packet re-ordering: measures the ability of the device under test to maintain sending order throughout transfer to the destination.
  • Packet correctness: packets or Frames must be well-formed, in that they include all required fields, conform to length requirements, pass integrity checks, etc.
  • Availability and capacity of the DUT i.e. when the DUT is fully “up” and connected, following measurements should be captured for DUT without any network packet load:
    • Includes average power consumption of the CPUs (in various power states) and system over specified period of time. Time period should not be less than 60 seconds.
    • Includes average per core CPU utilization over specified period of time. Time period should not be less than 60 seconds.
    • Includes the number of NIC interfaces supported.
    • Includes headroom of VM workload processing cores (i.e. available for applications).

1.2.4. Features not to be tested

vsperf doesn’t intend to define or perform any functional tests. The aim is to focus on performance.

1.2.5. Approach

The testing approach adoped by the vswitchperf project is black box testing, meaning the test inputs can be generated and the outputs captured and completely evaluated from the outside of the System Under Test. Some metrics can be collected on the SUT, such as cpu or memory utilization if the collection has no/minimal impact on benchmark. This section will look at the deployment scenarios and the general methodology used by vswitchperf. In addition, this section will also specify the details of the Test Report that must be collected for each of the test cases.

1.2.5.1. Deployment Scenarios

The following represents possible deployment test scenarios which can help to determine the performance of both the virtual switch and the datapaths to physical ports (to NICs) and to logical ports (to VNFs):

1.2.5.1.1. Physical port → vSwitch → physical port
                                                     _
+--------------------------------------------------+  |
|              +--------------------+              |  |
|              |                    |              |  |
|              |                    v              |  |  Host
|   +--------------+            +--------------+   |  |
|   |   phy port   |  vSwitch   |   phy port   |   |  |
+---+--------------+------------+--------------+---+ _|
           ^                           :
           |                           |
           :                           v
+--------------------------------------------------+
|                                                  |
|                traffic generator                 |
|                                                  |
+--------------------------------------------------+
1.2.5.1.2. Physical port → vSwitch → VNF → vSwitch → physical port
                                                      _
+---------------------------------------------------+  |
|                                                   |  |
|   +-------------------------------------------+   |  |
|   |                 Application               |   |  |
|   +-------------------------------------------+   |  |
|       ^                                  :        |  |
|       |                                  |        |  |  Guest
|       :                                  v        |  |
|   +---------------+           +---------------+   |  |
|   | logical port 0|           | logical port 1|   |  |
+---+---------------+-----------+---------------+---+ _|
        ^                                  :
        |                                  |
        :                                  v         _
+---+---------------+----------+---------------+---+  |
|   | logical port 0|          | logical port 1|   |  |
|   +---------------+          +---------------+   |  |
|       ^                                  :       |  |
|       |                                  |       |  |  Host
|       :                                  v       |  |
|   +--------------+            +--------------+   |  |
|   |   phy port   |  vSwitch   |   phy port   |   |  |
+---+--------------+------------+--------------+---+ _|
           ^                           :
           |                           |
           :                           v
+--------------------------------------------------+
|                                                  |
|                traffic generator                 |
|                                                  |
+--------------------------------------------------+
1.2.5.1.3. Physical port → vSwitch → VNF → vSwitch → VNF → vSwitch → physical port
                                                   _
+----------------------+  +----------------------+  |
|   Guest 1            |  |   Guest 2            |  |
|   +---------------+  |  |   +---------------+  |  |
|   |  Application  |  |  |   |  Application  |  |  |
|   +---------------+  |  |   +---------------+  |  |
|       ^       |      |  |       ^       |      |  |
|       |       v      |  |       |       v      |  |  Guests
|   +---------------+  |  |   +---------------+  |  |
|   | logical ports |  |  |   | logical ports |  |  |
|   |   0       1   |  |  |   |   0       1   |  |  |
+---+---------------+--+  +---+---------------+--+ _|
        ^       :                 ^       :
        |       |                 |       |
        :       v                 :       v        _
+---+---------------+---------+---------------+--+  |
|   |   0       1   |         |   3       4   |  |  |
|   | logical ports |         | logical ports |  |  |
|   +---------------+         +---------------+  |  |
|       ^       |                 ^       |      |  |  Host
|       |       L-----------------+       v      |  |
|   +--------------+          +--------------+   |  |
|   |   phy ports  | vSwitch  |   phy ports  |   |  |
+---+--------------+----------+--------------+---+ _|
        ^       ^                 :       :
        |       |                 |       |
        :       :                 v       v
+--------------------------------------------------+
|                                                  |
|                traffic generator                 |
|                                                  |
+--------------------------------------------------+
1.2.5.1.4. Physical port → VNF → vSwitch → VNF → physical port
                                                    _
+----------------------+  +----------------------+   |
|   Guest 1            |  |   Guest 2            |   |
|+-------------------+ |  | +-------------------+|   |
||     Application   | |  | |     Application   ||   |
|+-------------------+ |  | +-------------------+|   |
|       ^       |      |  |       ^       |      |   |  Guests
|       |       v      |  |       |       v      |   |
|+-------------------+ |  | +-------------------+|   |
||   logical ports   | |  | |   logical ports   ||   |
||  0              1 | |  | | 0              1  ||   |
++--------------------++  ++--------------------++  _|
    ^              :          ^              :
(PCI passthrough)  |          |     (PCI passthrough)
    |              v          :              |      _
+--------++------------+-+------------++---------+   |
|   |    ||        0   | |    1       ||     |   |   |
|   |    ||logical port| |logical port||     |   |   |
|   |    |+------------+ +------------+|     |   |   |
|   |    |     |                 ^     |     |   |   |
|   |    |     L-----------------+     |     |   |   |
|   |    |                             |     |   |   |  Host
|   |    |           vSwitch           |     |   |   |
|   |    +-----------------------------+     |   |   |
|   |                                        |   |   |
|   |                                        v   |   |
| +--------------+              +--------------+ |   |
| | phy port/VF  |              | phy port/VF  | |   |
+-+--------------+--------------+--------------+-+  _|
    ^                                        :
    |                                        |
    :                                        v
+--------------------------------------------------+
|                                                  |
|                traffic generator                 |
|                                                  |
+--------------------------------------------------+
1.2.5.1.5. Physical port → vSwitch → VNF
                                                      _
+---------------------------------------------------+  |
|                                                   |  |
|   +-------------------------------------------+   |  |
|   |                 Application               |   |  |
|   +-------------------------------------------+   |  |
|       ^                                           |  |
|       |                                           |  |  Guest
|       :                                           |  |
|   +---------------+                               |  |
|   | logical port 0|                               |  |
+---+---------------+-------------------------------+ _|
        ^
        |
        :                                            _
+---+---------------+------------------------------+  |
|   | logical port 0|                              |  |
|   +---------------+                              |  |
|       ^                                          |  |
|       |                                          |  |  Host
|       :                                          |  |
|   +--------------+                               |  |
|   |   phy port   |  vSwitch                      |  |
+---+--------------+------------ -------------- ---+ _|
           ^
           |
           :
+--------------------------------------------------+
|                                                  |
|                traffic generator                 |
|                                                  |
+--------------------------------------------------+
1.2.5.1.6. VNF → vSwitch → physical port
                                                      _
+---------------------------------------------------+  |
|                                                   |  |
|   +-------------------------------------------+   |  |
|   |                 Application               |   |  |
|   +-------------------------------------------+   |  |
|                                          :        |  |
|                                          |        |  |  Guest
|                                          v        |  |
|                               +---------------+   |  |
|                               | logical port  |   |  |
+-------------------------------+---------------+---+ _|
                                           :
                                           |
                                           v         _
+------------------------------+---------------+---+  |
|                              | logical port  |   |  |
|                              +---------------+   |  |
|                                          :       |  |
|                                          |       |  |  Host
|                                          v       |  |
|                               +--------------+   |  |
|                     vSwitch   |   phy port   |   |  |
+-------------------------------+--------------+---+ _|
                                       :
                                       |
                                       v
+--------------------------------------------------+
|                                                  |
|                traffic generator                 |
|                                                  |
+--------------------------------------------------+
1.2.5.1.7. VNF → vSwitch → VNF → vSwitch
                                                         _
+-------------------------+  +-------------------------+  |
|   Guest 1               |  |   Guest 2               |  |
|   +-----------------+   |  |   +-----------------+   |  |
|   |   Application   |   |  |   |   Application   |   |  |
|   +-----------------+   |  |   +-----------------+   |  |
|                :        |  |       ^                 |  |
|                |        |  |       |                 |  |  Guest
|                v        |  |       :                 |  |
|     +---------------+   |  |   +---------------+     |  |
|     | logical port 0|   |  |   | logical port 0|     |  |
+-----+---------------+---+  +---+---------------+-----+ _|
                :                    ^
                |                    |
                v                    :                    _
+----+---------------+------------+---------------+-----+  |
|    |     port 0    |            |     port 1    |     |  |
|    +---------------+            +---------------+     |  |
|              :                    ^                   |  |
|              |                    |                   |  |  Host
|              +--------------------+                   |  |
|                                                       |  |
|                     vswitch                           |  |
+-------------------------------------------------------+ _|

HOST 1(Physical port → virtual switch → VNF → virtual switch → Physical port) → HOST 2(Physical port → virtual switch → VNF → virtual switch → Physical port)

1.2.5.1.8. HOST 1 (PVP) → HOST 2 (PVP)
                                                   _
+----------------------+  +----------------------+  |
|   Guest 1            |  |   Guest 2            |  |
|   +---------------+  |  |   +---------------+  |  |
|   |  Application  |  |  |   |  Application  |  |  |
|   +---------------+  |  |   +---------------+  |  |
|       ^       |      |  |       ^       |      |  |
|       |       v      |  |       |       v      |  |  Guests
|   +---------------+  |  |   +---------------+  |  |
|   | logical ports |  |  |   | logical ports |  |  |
|   |   0       1   |  |  |   |   0       1   |  |  |
+---+---------------+--+  +---+---------------+--+ _|
        ^       :                 ^       :
        |       |                 |       |
        :       v                 :       v        _
+---+---------------+--+  +---+---------------+--+  |
|   |   0       1   |  |  |   |   3       4   |  |  |
|   | logical ports |  |  |   | logical ports |  |  |
|   +---------------+  |  |   +---------------+  |  |
|       ^       |      |  |       ^       |      |  |  Hosts
|       |       v      |  |       |       v      |  |
|   +--------------+   |  |   +--------------+   |  |
|   |   phy ports  |   |  |   |   phy ports  |   |  |
+---+--------------+---+  +---+--------------+---+ _|
        ^       :                 :       :
        |       +-----------------+       |
        :                                 v
+--------------------------------------------------+
|                                                  |
|                traffic generator                 |
|                                                  |
+--------------------------------------------------+

Note: For tests where the traffic generator and/or measurement receiver are implemented on VM and connected to the virtual switch through vNIC, the issues of shared resources and interactions between the measurement devices and the device under test must be considered.

Note: Some RFC 2889 tests require a full-mesh sending and receiving pattern involving more than two ports. This possibility is illustrated in the Physical port → vSwitch → VNF → vSwitch → VNF → vSwitch → physical port diagram above (with 2 sending and 2 receiving ports, though all ports could be used bi-directionally).

Note: When Deployment Scenarios are used in RFC 2889 address learning or cache capacity testing, an additional port from the vSwitch must be connected to the test device. This port is used to listen for flooded frames.

1.2.5.2. General Methodology:

To establish the baseline performance of the virtual switch, tests would initially be run with a simple workload in the VNF (the recommended simple workload VNF would be DPDK‘s testpmd application forwarding packets in a VM or vloop_vnf a simple kernel module that forwards traffic between two network interfaces inside the virtualized environment while bypassing the networking stack). Subsequently, the tests would also be executed with a real Telco workload running in the VNF, which would exercise the virtual switch in the context of higher level Telco NFV use cases, and prove that its underlying characteristics and behaviour can be measured and validated. Suitable real Telco workload VNFs are yet to be identified.

1.2.5.2.1. Default Test Parameters

The following list identifies the default parameters for suite of tests:

  • Reference application: Simple forwarding or Open Source VNF.
  • Frame size (bytes): 64, 128, 256, 512, 1024, 1280, 1518, 2K, 4k OR Packet size based on use-case (e.g. RTP 64B, 256B) OR Mix of packet sizes as maintained by the Functest project <https://wiki.opnfv.org/traffic_profile_management>.
  • Reordering check: Tests should confirm that packets within a flow are not reordered.
  • Duplex: Unidirectional / Bidirectional. Default: Full duplex with traffic transmitting in both directions, as network traffic generally does not flow in a single direction. By default the data rate of transmitted traffic should be the same in both directions, please note that asymmetric traffic (e.g. downlink-heavy) tests will be mentioned explicitly for the relevant test cases.
  • Number of Flows: Default for non scalability tests is a single flow. For scalability tests the goal is to test with maximum supported flows but where possible will test up to 10 Million flows. Start with a single flow and scale up. By default flows should be added sequentially, tests that add flows simultaneously will explicitly call out their flow addition behaviour. Packets are generated across the flows uniformly with no burstiness. For multi-core tests should consider the number of packet flows based on vSwitch/VNF multi-thread implementation and behavior.
  • Traffic Types: UDP, SCTP, RTP, GTP and UDP traffic.
  • Deployment scenarios are:
  • Physical → virtual switch → physical.
  • Physical → virtual switch → VNF → virtual switch → physical.
  • Physical → virtual switch → VNF → virtual switch → VNF → virtual switch → physical.
  • Physical → VNF → virtual switch → VNF → physical.
  • Physical → virtual switch → VNF.
  • VNF → virtual switch → Physical.
  • VNF → virtual switch → VNF.

Tests MUST have these parameters unless otherwise stated. Test cases with non default parameters will be stated explicitly.

Note: For throughput tests unless stated otherwise, test configurations should ensure that traffic traverses the installed flows through the virtual switch, i.e. flows are installed and have an appropriate time out that doesn’t expire before packet transmission starts.

1.2.5.2.2. Flow Classification

Virtual switches classify packets into flows by processing and matching particular header fields in the packet/frame and/or the input port where the packets/frames arrived. The vSwitch then carries out an action on the group of packets that match the classification parameters. Thus a flow is considered to be a sequence of packets that have a shared set of header field values or have arrived on the same port and have the same action applied to them. Performance results can vary based on the parameters the vSwitch uses to match for a flow. The recommended flow classification parameters for L3 vSwitch performance tests are: the input port, the source IP address, the destination IP address and the Ethernet protocol type field. It is essential to increase the flow time-out time on a vSwitch before conducting any performance tests that do not measure the flow set-up time. Normally the first packet of a particular flow will install the flow in the vSwitch which adds an additional latency, subsequent packets of the same flow are not subject to this latency if the flow is already installed on the vSwitch.

1.2.5.2.3. Test Priority

Tests will be assigned a priority in order to determine which tests should be implemented immediately and which tests implementations can be deferred.

Priority can be of following types: - Urgent: Must be implemented immediately. - High: Must be implemented in the next release. - Medium: May be implemented after the release. - Low: May or may not be implemented at all.

1.2.5.2.4. SUT Setup

The SUT should be configured to its “default” state. The SUT’s configuration or set-up must not change between tests in any way other than what is required to do the test. All supported protocols must be configured and enabled for each test set up.

1.2.5.2.5. Port Configuration

The DUT should be configured with n ports where n is a multiple of 2. Half of the ports on the DUT should be used as ingress ports and the other half of the ports on the DUT should be used as egress ports. Where a DUT has more than 2 ports, the ingress data streams should be set-up so that they transmit packets to the egress ports in sequence so that there is an even distribution of traffic across ports. For example, if a DUT has 4 ports 0(ingress), 1(ingress), 2(egress) and 3(egress), the traffic stream directed at port 0 should output a packet to port 2 followed by a packet to port 3. The traffic stream directed at port 1 should also output a packet to port 2 followed by a packet to port 3.

1.2.5.2.6. Frame Formats

Frame formats Layer 2 (data link layer) protocols

  • Ethernet II
+---------------------------+-----------+
| Ethernet Header | Payload | Check Sum |
+-----------------+---------+-----------+
|_________________|_________|___________|
      14 Bytes     46 - 1500   4 Bytes
                     Bytes

Layer 3 (network layer) protocols

  • IPv4
+-----------------+-----------+---------+-----------+
| Ethernet Header | IP Header | Payload | Checksum  |
+-----------------+-----------+---------+-----------+
|_________________|___________|_________|___________|
      14 Bytes       20 bytes  26 - 1480   4 Bytes
                                 Bytes
  • IPv6
+-----------------+-----------+---------+-----------+
| Ethernet Header | IP Header | Payload | Checksum  |
+-----------------+-----------+---------+-----------+
|_________________|___________|_________|___________|
      14 Bytes       40 bytes  26 - 1460   4 Bytes
                                 Bytes

Layer 4 (transport layer) protocols

  • TCP
  • UDP
  • SCTP
+-----------------+-----------+-----------------+---------+-----------+
| Ethernet Header | IP Header | Layer 4 Header  | Payload | Checksum  |
+-----------------+-----------+-----------------+---------+-----------+
|_________________|___________|_________________|_________|___________|
      14 Bytes      40 bytes      20 Bytes       6 - 1460   4 Bytes
                                                  Bytes

Layer 5 (application layer) protocols

  • RTP
  • GTP
+-----------------+-----------+-----------------+---------+-----------+
| Ethernet Header | IP Header | Layer 4 Header  | Payload | Checksum  |
+-----------------+-----------+-----------------+---------+-----------+
|_________________|___________|_________________|_________|___________|
      14 Bytes      20 bytes     20 Bytes        >= 6 Bytes   4 Bytes
1.2.5.2.7. Packet Throughput

There is a difference between an Ethernet frame, an IP packet, and a UDP datagram. In the seven-layer OSI model of computer networking, packet refers to a data unit at layer 3 (network layer). The correct term for a data unit at layer 2 (data link layer) is a frame, and at layer 4 (transport layer) is a segment or datagram.

Important concepts related to 10GbE performance are frame rate and throughput. The MAC bit rate of 10GbE, defined in the IEEE standard 802 .3ae, is 10 billion bits per second. Frame rate is based on the bit rate and frame format definitions. Throughput, defined in IETF RFC 1242, is the highest rate at which the system under test can forward the offered load, without loss.

The frame rate for 10GbE is determined by a formula that divides the 10 billion bits per second by the preamble + frame length + inter-frame gap.

The maximum frame rate is calculated using the minimum values of the following parameters, as described in the IEEE 802 .3ae standard:

  • Preamble: 8 bytes * 8 = 64 bits
  • Frame Length: 64 bytes (minimum) * 8 = 512 bits
  • Inter-frame Gap: 12 bytes (minimum) * 8 = 96 bits

Therefore, Maximum Frame Rate (64B Frames) = MAC Transmit Bit Rate / (Preamble + Frame Length + Inter-frame Gap) = 10,000,000,000 / (64 + 512 + 96) = 10,000,000,000 / 672 = 14,880,952.38 frame per second (fps)

1.2.5.3. RFCs for testing virtual switch performance

The starting point for defining the suite of tests for benchmarking the performance of a virtual switch is to take existing RFCs and standards that were designed to test their physical counterparts and adapting them for testing virtual switches. The rationale behind this is to establish a fair comparison between the performance of virtual and physical switches. This section outlines the RFCs that are used by this specification.

1.2.5.3.1. RFC 1242 Benchmarking Terminology for Network Interconnection

Devices RFC 1242 defines the terminology that is used in describing performance benchmarking tests and their results. Definitions and discussions covered include: Back-to-back, bridge, bridge/router, constant load, data link frame size, frame loss rate, inter frame gap, latency, and many more.

1.2.5.3.2. RFC 2544 Benchmarking Methodology for Network Interconnect Devices

RFC 2544 outlines a benchmarking methodology for network Interconnect Devices. The methodology results in performance metrics such as latency, frame loss percentage, and maximum data throughput.

In this document network “throughput” (measured in millions of frames per second) is based on RFC 2544, unless otherwise noted. Frame size refers to Ethernet frames ranging from smallest frames of 64 bytes to largest frames of 9K bytes.

Types of tests are:

  1. Throughput test defines the maximum number of frames per second that can be transmitted without any error, or 0% loss ratio. In some Throughput tests (and those tests with long duration), evaluation of an additional frame loss ratio is suggested. The current ratio (10^-7 %) is based on understanding the typical user-to-user packet loss ratio needed for good application performance and recognizing that a single transfer through a vswitch must contribute a tiny fraction of user-to-user loss. Further, the ratio 10^-7 % also recognizes practical limitations when measuring loss ratio.
  2. Latency test measures the time required for a frame to travel from the originating device through the network to the destination device. Please note that RFC2544 Latency measurement will be superseded with a measurement of average latency over all successfully transferred packets or frames.
  3. Frame loss test measures the network’s response in overload conditions - a critical indicator of the network’s ability to support real-time applications in which a large amount of frame loss will rapidly degrade service quality.
  4. Burst test assesses the buffering capability of a virtual switch. It measures the maximum number of frames received at full line rate before a frame is lost. In carrier Ethernet networks, this measurement validates the excess information rate (EIR) as defined in many SLAs.
  5. System recovery to characterize speed of recovery from an overload condition.
  6. Reset to characterize speed of recovery from device or software reset. This type of test has been updated by RFC6201 as such, the methodology defined by this specification will be that of RFC 6201.

Although not included in the defined RFC 2544 standard, another crucial measurement in Ethernet networking is packet delay variation. The definition set out by this specification comes from RFC5481.

1.2.5.3.3. RFC 2285 Benchmarking Terminology for LAN Switching Devices

RFC 2285 defines the terminology that is used to describe the terminology for benchmarking a LAN switching device. It extends RFC 1242 and defines: DUTs, SUTs, Traffic orientation and distribution, bursts, loads, forwarding rates, etc.

1.2.5.3.4. RFC 2889 Benchmarking Methodology for LAN Switching

RFC 2889 outlines a benchmarking methodology for LAN switching, it extends RFC 2544. The outlined methodology gathers performance metrics for forwarding, congestion control, latency, address handling and finally filtering.

1.2.5.3.5. RFC 3918 Methodology for IP Multicast Benchmarking

RFC 3918 outlines a methodology for IP Multicast benchmarking.

1.2.5.3.6. RFC 4737 Packet Reordering Metrics

RFC 4737 describes metrics for identifying and counting re-ordered packets within a stream, and metrics to measure the extent each packet has been re-ordered.

1.2.5.3.7. RFC 5481 Packet Delay Variation Applicability Statement

RFC 5481 defined two common, but different forms of delay variation metrics, and compares the metrics over a range of networking circumstances and tasks. The most suitable form for vSwitch benchmarking is the “PDV” form.

1.2.5.3.8. RFC 6201 Device Reset Characterization

RFC 6201 extends the methodology for characterizing the speed of recovery of the DUT from device or software reset described in RFC 2544.

1.2.6. Item pass/fail criteria

vswitchperf does not specify Pass/Fail criteria for the tests in terms of a threshold, as benchmarks do not (and should not do this). The results/metrics for a test are simply reported. If it had to be defined, a test is considered to have passed if it succesfully completed and a relavent metric was recorded/reported for the SUT.

1.2.7. Suspension criteria and resumption requirements

In the case of a throughput test, a test should be suspended if a virtual switch is failing to forward any traffic. A test should be restarted from a clean state if the intention is to carry out the test again.

1.2.8. Test deliverables

Each test should produce a test report that details SUT information as well as the test results. There are a number of parameters related to the system, DUT and tests that can affect the repeatability of a test results and should be recorded. In order to minimise the variation in the results of a test, it is recommended that the test report includes the following information:

  • Hardware details including:
    • Platform details.
    • Processor details.
    • Memory information (see below)
    • Number of enabled cores.
    • Number of cores used for the test.
    • Number of physical NICs, as well as their details (manufacturer, versions, type and the PCI slot they are plugged into).
    • NIC interrupt configuration.
    • BIOS version, release date and any configurations that were modified.
  • Software details including:
    • OS version (for host and VNF)
    • Kernel version (for host and VNF)
    • GRUB boot parameters (for host and VNF).
    • Hypervisor details (Type and version).
    • Selected vSwitch, version number or commit id used.
    • vSwitch launch command line if it has been parameterised.
    • Memory allocation to the vSwitch – which NUMA node it is using, and how many memory channels.
    • Where the vswitch is built from source: compiler details including versions and the flags that were used to compile the vSwitch.
    • DPDK or any other SW dependency version number or commit id used.
    • Memory allocation to a VM - if it’s from Hugpages/elsewhere.
    • VM storage type: snapshot/independent persistent/independent non-persistent.
    • Number of VMs.
    • Number of Virtual NICs (vNICs), versions, type and driver.
    • Number of virtual CPUs and their core affinity on the host.
    • Number vNIC interrupt configuration.
    • Thread affinitization for the applications (including the vSwitch itself) on the host.
    • Details of Resource isolation, such as CPUs designated for Host/Kernel (isolcpu) and CPUs designated for specific processes (taskset).
  • Memory Details
    • Total memory
    • Type of memory
    • Used memory
    • Active memory
    • Inactive memory
    • Free memory
    • Buffer memory
    • Swap cache
    • Total swap
    • Used swap
    • Free swap
  • Test duration.
  • Number of flows.
  • Traffic Information:
    • Traffic type - UDP, TCP, IMIX / Other.
    • Packet Sizes.
  • Deployment Scenario.

Note: Tests that require additional parameters to be recorded will explicitly specify this.

1.2.9. Test management

This section will detail the test activities that will be conducted by vsperf as well as the infrastructure that will be used to complete the tests in OPNFV.

1.2.10. Planned activities and tasks; test progression

A key consideration when conducting any sort of benchmark is trying to ensure the consistency and repeatability of test results between runs. When benchmarking the performance of a virtual switch there are many factors that can affect the consistency of results. This section describes these factors and the measures that can be taken to limit their effects. In addition, this section will outline some system tests to validate the platform and the VNF before conducting any vSwitch benchmarking tests.

System Isolation:

When conducting a benchmarking test on any SUT, it is essential to limit (and if reasonable, eliminate) any noise that may interfere with the accuracy of the metrics collected by the test. This noise may be introduced by other hardware or software (OS, other applications), and can result in significantly varying performance metrics being collected between consecutive runs of the same test. In the case of characterizing the performance of a virtual switch, there are a number of configuration parameters that can help increase the repeatability and stability of test results, including:

  • OS/GRUB configuration:
    • maxcpus = n where n >= 0; limits the kernel to using ‘n’ processors. Only use exactly what you need.
    • isolcpus: Isolate CPUs from the general scheduler. Isolate all CPUs bar one which will be used by the OS.
    • use taskset to affinitize the forwarding application and the VNFs onto isolated cores. VNFs and the vSwitch should be allocated their own cores, i.e. must not share the same cores. vCPUs for the VNF should be affinitized to individual cores also.
    • Limit the amount of background applications that are running and set OS to boot to runlevel 3. Make sure to kill any unnecessary system processes/daemons.
    • Only enable hardware that you need to use for your test – to ensure there are no other interrupts on the system.
    • Configure NIC interrupts to only use the cores that are not allocated to any other process (VNF/vSwitch).
  • NUMA configuration: Any unused sockets in a multi-socket system should be disabled.
  • CPU pinning: The vSwitch and the VNF should each be affinitized to separate logical cores using a combination of maxcpus, isolcpus and taskset.
  • BIOS configuration: BIOS should be configured for performance where an explicit option exists, sleep states should be disabled, any virtualization optimization technologies should be enabled, and hyperthreading should also be enabled, turbo boost and overclocking should be disabled.

System Validation:

System validation is broken down into two sub-categories: Platform validation and VNF validation. The validation test itself involves verifying the forwarding capability and stability for the sub-system under test. The rationale behind system validation is two fold. Firstly to give a tester confidence in the stability of the platform or VNF that is being tested; and secondly to provide base performance comparison points to understand the overhead introduced by the virtual switch.

  • Benchmark platform forwarding capability: This is an OPTIONAL test used to verify the platform and measure the base performance (maximum forwarding rate in fps and latency) that can be achieved by the platform without a vSwitch or a VNF. The following diagram outlines the set-up for benchmarking Platform forwarding capability:

                                                         __
    +--------------------------------------------------+   |
    |   +------------------------------------------+   |   |
    |   |                                          |   |   |
    |   |          l2fw or DPDK L2FWD app          |   |  Host
    |   |                                          |   |   |
    |   +------------------------------------------+   |   |
    |   |                 NIC                      |   |   |
    +---+------------------------------------------+---+ __|
               ^                           :
               |                           |
               :                           v
    +--------------------------------------------------+
    |                                                  |
    |                traffic generator                 |
    |                                                  |
    +--------------------------------------------------+
    
  • Benchmark VNF forwarding capability: This test is used to verify the VNF and measure the base performance (maximum forwarding rate in fps and latency) that can be achieved by the VNF without a vSwitch. The performance metrics collected by this test will serve as a key comparison point for NIC passthrough technologies and vSwitches. VNF in this context refers to the hypervisor and the VM. The following diagram outlines the set-up for benchmarking VNF forwarding capability:

                                                         __
    +--------------------------------------------------+   |
    |   +------------------------------------------+   |   |
    |   |                                          |   |   |
    |   |                 VNF                      |   |   |
    |   |                                          |   |   |
    |   +------------------------------------------+   |   |
    |   |          Passthrough/SR-IOV              |   |  Host
    |   +------------------------------------------+   |   |
    |   |                 NIC                      |   |   |
    +---+------------------------------------------+---+ __|
               ^                           :
               |                           |
               :                           v
    +--------------------------------------------------+
    |                                                  |
    |                traffic generator                 |
    |                                                  |
    +--------------------------------------------------+
    

Methodology to benchmark Platform/VNF forwarding capability

The recommended methodology for the platform/VNF validation and benchmark is: - Run RFC2889 Maximum Forwarding Rate test, this test will produce maximum forwarding rate and latency results that will serve as the expected values. These expected values can be used in subsequent steps or compared with in subsequent validation tests. - Transmit bidirectional traffic at line rate/max forwarding rate (whichever is higher) for at least 72 hours, measure throughput (fps) and latency. - Note: Traffic should be bidirectional. - Establish a baseline forwarding rate for what the platform can achieve. - Additional validation: After the test has completed for 72 hours run bidirectional traffic at the maximum forwarding rate once more to see if the system is still functional and measure throughput (fps) and latency. Compare the measure the new obtained values with the expected values.

NOTE 1: How the Platform is configured for its forwarding capability test (BIOS settings, GRUB configuration, runlevel...) is how the platform should be configured for every test after this

NOTE 2: How the VNF is configured for its forwarding capability test (# of vCPUs, vNICs, Memory, affinitization…) is how it should be configured for every test that uses a VNF after this.

Methodology to benchmark the VNF to vSwitch to VNF deployment scenario

vsperf has identified the following concerns when benchmarking the VNF to vSwitch to VNF deployment scenario:

  • The accuracy of the timing synchronization between VNFs/VMs.
  • The clock accuracy of a VNF/VM if they were to be used as traffic generators.
  • VNF traffic generator/receiver may be using resources of the system under test, causing at least three forms of workload to increase as the traffic load increases (generation, switching, receiving).

The recommendation from vsperf is that tests for this sceanario must include an external HW traffic generator to act as the tester/traffic transmitter and receiver. The perscribed methodology to benchmark this deployment scanrio with an external tester involves the following three steps:

#. Determine the forwarding capability and latency through the virtual interface connected to the VNF/VM.

_images/vm2vm_virtual_interface_benchmark.png

Fig. 1.1 Virtual interfaces performance benchmark

  1. Determine the forwarding capability and latency through the VNF/hypervisor.
_images/vm2vm_hypervisor_benchmark.png

Fig. 1.2 Hypervisor performance benchmark

  1. Determine the forwarding capability and latency for the VNF to vSwitch to VNF taking the information from the previous two steps into account.
_images/vm2vm_benchmark.png

Fig. 1.3 VNF to vSwitch to VNF performance benchmark

vsperf also identified an alternative configuration for the final step:

_images/vm2vm_alternative_benchmark.png

Fig. 1.4 VNF to vSwitch to VNF alternative performance benchmark

1.2.11. Environment/infrastructure

Intel is providing a hosted test-bed with nine bare-metal environments allocated to different OPNFV projects. Currently a number of servers in Intel POD 3 are allocated to vsperf:

  • pod3-wcp-node3 and pod3-wcp-node4 which are used for CI jobs.
  • pod3-node6 which is used as a vsperf sandbox environment.

1.2.11.1. vsperf CI

vsperf CI jobs are broken down into:

  • Daily job:
    • Runs everyday takes about 10 hours to complete.
    • TESTCASES_DAILY=’phy2phy_tput back2back phy2phy_tput_mod_vlan phy2phy_scalability pvp_tput pvp_back2back pvvp_tput pvvp_back2back’.
    • TESTPARAM_DAILY=’–test-params pkt_sizes=64,128,512,1024,1518’.
  • Merge job:
    • Runs whenever patches are merged to master.
    • Runs a basic Sanity test.
  • Verify job:
    • Runs every time a patch is pushed to gerrit.
    • Builds documentation.

1.2.11.2. Scripts:

There are 2 scripts that are part of VSPERFs CI:

  • build-vsperf.sh: Lives in the VSPERF repository in the ci/ directory and is used to run vsperf with the appropriate cli parameters.
  • vswitchperf.yml: YAML description of our jenkins job. lives in the RELENG repository.

More info on vsperf CI can be found here: https://wiki.opnfv.org/display/vsperf/VSPERF+CI

1.2.12. Responsibilities and authority

The group responsible for managing, designing, preparing and executing the tests listed in the LTD are the vsperf committers and contributors. The vsperf committers and contributors should work with the relavent OPNFV projects to ensure that the infrastructure is in place for testing vswitches, and that the results are published to common end point (a results database).