Benchmarking Virtual Switches in OPNFV

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. This memo describes the progress of the Open Platform for NFV (OPNFV) project on virtual switch performance characterization, "VSWITCHPERF". This project intends to build on the current and completed work of the Benchmarking Methodology Working Group in IETF, by referencing existing literature. For example, currently the most referenced RFC is (which depens on ) and foundation of the benchmarking work in OPNFV is common and strong. See https://wiki.opnfv.org/characterize_vswitch_performance_for_telco_nfv_use_cases for more background, and the OPNFV website for general information: https://www.opnfv.org/ 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 emhasis on performance dimensions when compared to cloud computing: support for and transfer of isochronous media streams is one example. Note also that the move to NFV Infrastructure has resulted in many new benchmarking initiatives across the industry, and the authors are currently doing their best to maintain alignment with many other projects, and this Internet Draft is evidence of the efforts.

The primary purpose and scope of the memo is to inform BMWG of work-in-progress that builds on the body of extensive literature and experience. Additionally, once the initial information conveyed here is received, this memo may be expanded to include more detail and commentary from both BMWG and OPNFV communities, under BMWG's chartered work to characterize the NFV Infrastructure (a virtual switch is an important aspect of that infrastructure).

This section highlights some specific considerations (from )related to Benchmarks for virtual switches.

To compare the performance of virtual designs and implementations with their physical counterparts, identical benchmarks are needed. BMWG has developed specifications for many network functions this memo re-uses existing benchmarks through references, and expands them during development of new methods. A key configuration aspect is the number of parallel cores required to achieve comparable performance with a given physical device, or whether some limit of scale was reached before the cores could achieve the comparable level. It's unlikely that the virtual switch will be the only application running on the SUT, so CPU utilization, Cache utilization, and Memory footprint should also be recorded for the virtual implementations of internetworking functions.

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.

The overall specification in preparation is referred to as a Level Test Design (LTD) document, which will contain a suite of performace tests. 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, we must begin to consider additional performance metrics. In this case, the project specifications have referenced metrics from the IETF IP Performance Metrics (IPPM) literature. This means that the test of Latency is replaced by measurement of a metric derived from IPPM's , where a set of statistical summaries will be provided (mean, max, min, etc.). Further metrics planned to be benchmarked include packet delay variation as defined by , 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 (or will be) designed to collect the metrics below: 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 Distribution Tests to measure average, min and max packet and frame delay for constant loads. 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. Stream Performance Tests (TCP, UDP) to measure bulk data transfer performance, i.e. how fast systems can send and receive data through the switch. Request/Response Performance Tests (TCP, UDP) the measure the transaction rate through the switch. 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 (example: delay of the initial packet of a flow). Noisy Neighbour Tests, to understand the effects of resource sharing on the performance of a virtual switch. CPU and Memory Consumption Tests to understand the virtual switch’s footprint on the system, usually conducted as auxilliary measurements with benchmarks above. They include: CPU utilization, Cache utilization and Memory footprint. The felixability of deployemnt of a virtual switch within a network means that the BMWG IETF existing literature needs to be used to characterize the performance of a switch in various deployment scenarios. The deployment scenarios under consideration include:

Physical port to virtual switch to physical port

Physical port to virtual switch to VNF to virtual switch to physical port

Physical port to virtual switch to VNF to virtual switch to VNF to virtual switch to physical port

Physical port to virtual switch to VNF

VNF to virtual switch to physical port

VNF to virtual switch to VNF

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 acknowledge