Network Working Group | M. Tahhan |
Internet-Draft | B. O'Mahony |
Intended status: Informational | Intel |
Expires: December 10, 2017 | A. Morton |
AT&T Labs | |
June 8, 2017 |
Benchmarking Virtual Switches in OPNFV
draft-ietf-bmwg-vswitch-opnfv-04
This memo describes the contributions of the Open Platform for NFV (OPNFV) project on virtual switch performance "VSPERF", particularly in the areas of test set-ups and configuration parameters for the system under test. This project has extended the current and completed work of the Benchmarking Methodology Working Group in IETF, and references existing literature. The Benchmarking Methodology Working Group has traditionally conducted laboratory characterization of dedicated physical implementations of internetworking functions. Therefore, this memo describes the additional considerations when virtual switches are implemented in general-purpose hardware. The expanded tests and benchmarks are also influenced by the OPNFV mission to support virtualization of the "telco" infrastructure.
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC 2119.
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Benchmarking Methodology Working Group (BMWG) has traditionally conducted laboratory characterization of dedicated physical implementations of internetworking functions. The Black-box Benchmarks of Throughput, Latency, Forwarding Rates and others have served our industry for many years. Now, Network Function Virtualization (NFV) has the goal to transform how internetwork functions are implemented, and therefore has garnered much attention.
A virtual switch (vswitch) is an important aspect of the NFV infrastructure; it provides connectivity between and among physical network functions and virtual network functions. As a result, there are many vswitch benchmarking efforts, but few specifications to guide the many new test design choices. This is a complex problem and an industry-wide work-in-progress. In future, several of BMWG's fundamental specifications will likely be updated as more testing experience helps to form consensus around new methodologies, and BMWG should continue to collaborate with all organizations who share the same goal.
This memo describes the contributions of the Open Platform for NFV (OPNFV) project on virtual switch performance characterization, "VSPERF", through the Danube 3.0 (fourth) release [DanubeRel] to the chartered work of the BMWG (with stable references to their test descriptions). This project has extended the current and completed work of the BMWG in IETF, and references existing literature. For example, the most often referenced RFC is [RFC2544] (which depends on [RFC1242]), so the foundation of the benchmarking work in OPNFV is common and strong. The recommended extensions are specifically in the areas of test set-ups and configuration parameters for the system under test.
See [VSPERFhome] for more background, and the OPNFV website for general information [OPNFV].
The authors note that OPNFV distinguishes itself from other open source compute and networking projects through its emphasis on existing "telco" services as opposed to cloud-computing. There are many ways in which telco requirements have different emphasis on performance dimensions when compared to cloud computing: support for and transfer of isochronous media streams is one example.
ACK Acknowledge ACPI Advanced Configuration and Power Interface BIOS Basic Input Output System BMWG Benchmarking Methodology Working Group CPDP Control Plane Data Plane CPU Central Processing Unit DIMM Dual In-line Memory Module DPDK Data Plane Development Kit DUT Device Under Test GRUB Grand Unified Bootloader ID Identification IMIX Internet Mix IP Internet Protocol IPPM IP Performance Metrics LAN Local Area Network LTD Level Test Design NFV Network Functions Virtualisation NIC Network Interface Card NUMA Non Uniform Memory Access OPNFV Open Platform for NFV OS Operating System PCI Peripheral Component Interconnect PDV Packet Delay Variation SR/IOV Single Root/Input Output Virtualization SUT System Under Test SW Software TCP Transmission control Protocol TSO TCP Segment Offload UDP User Datagram Protocol VM Virtual Machine VNF Virtualised Network Function VSPERF OPNFV vSwitch Performance Project
For the purposes of this document, the following abbreviations apply:
The primary purpose and scope of the memo is to describe key aspects of vswitch benchmarking, particularly in the areas of test set-ups and configuration parameters for the system under test, and extend the body of extensive BMWG literature and experience. Initial feedback indicates that many of these extensions may be applicable beyond this memo's current scope (to hardware switches in the NFV Infrastructure and to virtual routers, for example). Additionally, this memo serves as a vehicle to include more detail and relevant commentary from BMWG and other Open Source communities, under BMWG's chartered work to characterize the NFV Infrastructure.
The benchmarking covered in this memo should be applicable to many types of vswitches, and remain vswitch-agnostic to great degree. There has been no attempt to track and test all features of any specific vswitch implementation.
This section highlights some specific considerations (from [I-D.ietf-bmwg-virtual-net])related to Benchmarks for virtual switches. The OPNFV project is sharing its present view on these areas, as they develop their specifications in the Level Test Design (LTD) document.
To compare the performance of virtual designs and implementations with their physical counterparts, identical benchmarks are needed. BMWG has developed specifications for many physical network functions. The BMWG has recommended to re-use existing benchmarks and methods in [I-D.ietf-bmwg-virtual-net], and the OPNFV LTD expands on them as described here. A key configuration aspect for vswitches is the number of parallel CPU cores required to achieve comparable performance with a given physical device, or whether some limit of scale will be reached before the vswitch can achieve the comparable performance level.
It's unlikely that the virtual switch will be the only application running on the System Under Test (SUT), so CPU utilization, Cache utilization, and Memory footprint should also be recorded for the virtual implementations of internetworking functions. However, internally-measured metrics such as these are not benchmarks; they may be useful for the audience (operations) to know, and may also be useful if there is a problem encountered during testing.
Benchmark Comparability between virtual and physical/hardware implementations of equivalent functions will likely place more detailed and exact requirements on the *testing systems* (in terms of stream generation, algorithms to search for max values, and their configurations of course). This is another area for standards development to appreciate. However, the is a topic for a future draft.
External observations remain essential as the basis for Benchmarks. Internal observations with fixed specification and interpretation will be provided in parallel to assist the development of operations procedures when the technology is deployed.
A key consideration when conducting any sort of benchmark is trying to ensure the consistency and repeatability of test results. When benchmarking the performance of a vswitch there are many factors that can affect the consistency of results, one key factor is matching the various hardware and software details of the SUT. This section lists some of the many new parameters which this project believes are critical to report in order to achieve repeatability.
It has been the goal of the project to produce repeatable results, and a large set of the parameters believed to be critical is provided so that the benchmarking community can better appreciate the increase in configuration complexity inherent in this work. The parameter set below is assumed sufficient for the infrastructure in use by the VSPERF project to obtain repeatable results from test-to-test.
Hardware details (platform, processor, memory, and network) including:
Software details including:
Test Traffic Information:
Virtual switches group packets into flows by processing and matching particular packet or frame header information, or by matching packets based on the input ports. Thus a flow can be thought of a sequence of packets that have the same set of header field values, or have arrived on the same physical or logical port. Performance results can vary based on the parameters the vswitch uses to match for a flow. The recommended flow classification parameters for any vswitch performance tests are: the input port (physical or logical), the source MAC address, the destination MAC address, the source IP address, the destination IP address and the Ethernet protocol type field (although classification may take place on other fields, such as source and destination transport port numbers). It is essential to increase the flow timeout time on a vswitch before conducting any performance tests that do not intend to measure the flow setup time, see Section 3 of [RFC2889]. Normally the first packet of a particular stream will install the flow in the virtual switch 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.
This outline describes measurement of baseline with isolated resources at a high level, which is the intended approach at this time.
Figure 1 Benchmark platform forwarding capability
__ +--------------------------------------------------+ | | +------------------------------------------+ | | | | | | | | | Simple Forwarding App | | Host | | | | | | +------------------------------------------+ | | | | NIC | | | +---+------------------------------------------+---+ __| ^ : | | : v +--------------------------------------------------+ | | | traffic generator | | | +--------------------------------------------------+
Figure 2 Benchmark VNF forwarding capability
__ +--------------------------------------------------+ | | +------------------------------------------+ | | | | | | | | | VNF | | | | | | | | | +------------------------------------------+ | | | | Passthrough/SR-IOV | | Host | +------------------------------------------+ | | | | NIC | | | +---+------------------------------------------+---+ __| ^ : | | : v +--------------------------------------------------+ | | | traffic generator | | | +--------------------------------------------------+
The overall specification in preparation is referred to as a Level Test Design (LTD) document, which will contain a suite of performance tests. The base performance tests in the LTD are based on the pre-existing specifications developed by BMWG to test the performance of physical switches. These specifications include:
Some of the above/newer RFCs are being applied in benchmarking for the first time, and represent a development challenge for test equipment developers. Fortunately, many members of the testing system community have engaged on the VSPERF project, including an open source test system.
In addition to this, the LTD also re-uses the terminology defined by:
It is recommended that these references are included in future benchmarking specifications:
As one might expect, the most fundamental internetworking characteristics of Throughput and Latency remain important when the switch is virtualized, and these benchmarks figure prominently in the specification.
When considering characteristics important to "telco" network functions, additional performance metrics are needed. In this case, the project specifications have referenced metrics from the IETF IP Performance Metrics (IPPM) literature. This means that the [RFC2544] test of Latency is replaced by measurement of a metric derived from IPPM's [RFC2679], where a set of statistical summaries will be provided (mean, max, min, and percentiles). Further metrics planned to be benchmarked include packet delay variation as defined by [RFC5481] , reordering, burst behaviour, DUT availability, DUT capacity and packet loss in long term testing at Throughput level, where some low-level of background loss may be present and characterized.
Tests have been designed to collect the metrics below:
Additional test specification development should include:
The flexibility of deployment of a virtual switch within a network means that it is necessary to characterize the performance of a vswitch in various deployment scenarios. The deployment scenarios under consideration include:
Figure 3 Physical port to virtual switch to physical port
__ +--------------------------------------------------+ | | +--------------------+ | | | | | | | | | v | | Host | +--------------+ +--------------+ | | | | phy port | vswitch | phy port | | | +---+--------------+------------+--------------+---+ __| ^ : | | : v +--------------------------------------------------+ | | | traffic generator | | | +--------------------------------------------------+
Figure 4 Physical port to virtual switch to VNF to virtual switch to 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 | | | +--------------------------------------------------+
Figure 5 Physical port to virtual switch to VNF to virtual switch to VNF to virtual switch to 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 | | |-----------------| v | | | +--------------+ +--------------+ | | | | phy ports | vswitch | phy ports | | | +---+--------------+----------+--------------+---+_| ^ : | | : v +--------------------------------------------------+ | | | traffic generator | | | +--------------------------------------------------+
Figure 6 Physical port to virtual switch to VNF
__ +---------------------------------------------------+ | | | | | +-------------------------------------------+ | | | | Application | | | | +-------------------------------------------+ | | | ^ | | | | | | Guest | : | | | +---------------+ | | | | logical port 0| | | +---+---------------+-------------------------------+ __| ^ | : __ +---+---------------+------------------------------+ | | | logical port 0| | | | +---------------+ | | | ^ | | | | | | Host | : | | | +--------------+ | | | | phy port | vswitch | | +---+--------------+------------ -------------- ---+ __| ^ | : +--------------------------------------------------+ | | | traffic generator | | | +--------------------------------------------------+
Figure 7 VNF to virtual switch to physical port
__ +---------------------------------------------------+ | | | | | +-------------------------------------------+ | | | | Application | | | | +-------------------------------------------+ | | | : | | | | | | Guest | v | | | +---------------+ | | | | logical port | | | +-------------------------------+---------------+---+ __| : | v __ +------------------------------+---------------+---+ | | | logical port | | | | +---------------+ | | | : | | | | | | Host | v | | | +--------------+ | | | vswitch | phy port | | | +-------------------------------+--------------+---+ __| : | v +--------------------------------------------------+ | | | traffic generator | | | +--------------------------------------------------+
Figure 8 VNF to virtual switch to VNF
__ +----------------------+ +----------------------+ | | Guest 1 | | Guest 2 | | | +---------------+ | | +---------------+ | | | | Application | | | | Application | | | | +---------------+ | | +---------------+ | | | | | | ^ | | | v | | | | | Guests | +---------------+ | | +---------------+ | | | | logical ports | | | | logical ports | | | | | 0 | | | | 0 | | | +---+---------------+--+ +---+---------------+--+__| : ^ | | v : _ +---+---------------+---------+---------------+--+ | | | 1 | | 1 | | | | | logical ports | | logical ports | | | | +---------------+ +---------------+ | | | | ^ | | Host | L-----------------+ | | | | | | vswitch | | +------------------------------------------------+_|
A set of Deployment Scenario figures is available on the VSPERF Test Methodology Wiki page [TestTopo].
This section organizes the many existing test specifications into the "3x3" matrix (introduced in [I-D.ietf-bmwg-virtual-net]). Because the LTD specification ID names are quite long, this section is organized into lists for each occupied cell of the matrix (not all are occupied, also the matrix has grown to 3x4 to accommodate scale metrics when displaying the coverage of many metrics/benchmarks). The current version of the LTD specification is available [LTD].
The tests listed below assess the activation of paths in the data plane, rather than the control plane.
A complete list of tests with short summaries is available on the VSPERF "LTD Test Spec Overview" Wiki page [LTDoverV].
|------------------------------------------------------------------------| | | | | | | | | SPEED | ACCURACY | RELIABILITY | SCALE | | | | | | | |------------------------------------------------------------------------| | | | | | | | Activation | X | X | X | X | | | | | | | |------------------------------------------------------------------------| | | | | | | | Operation | X | X | X | X | | | | | | | |------------------------------------------------------------------------| | | | | | | | De-activation | | | | | | | | | | | |------------------------------------------------------------------------|
Benchmarking activities as described in this memo are limited to technology characterization of a Device Under Test/System Under Test (DUT/SUT) using controlled stimuli in a laboratory environment, with dedicated address space and the constraints specified in the sections above.
The benchmarking network topology will be an independent test setup and MUST NOT be connected to devices that may forward the test traffic into a production network, or misroute traffic to the test management network.
Further, benchmarking is performed on a "black-box" basis, relying solely on measurements observable external to the DUT/SUT.
Special capabilities SHOULD NOT exist in the DUT/SUT specifically for benchmarking purposes. Any implications for network security arising from the DUT/SUT SHOULD be identical in the lab and in production networks.
No IANA Action is requested at this time.
The authors appreciate and acknowledge comments from Scott Bradner, Marius Georgescu, Ramki Krishnan, Doug Montgomery, Martin Klozik, Christian Trautman, and others for their reviews.
We also acknowledge the early work in [I-D.huang-bmwg-virtual-network-performance], and useful discussion with the authors.