Wiki

• Proposed name for the project: Data Plane Acceleration
• Proposed name for the repository: dpacc
• Project Categories: (Requirements)

As a result of traffic convergence feature and the pervasive real-time high performance requirement for traditional data plane devices, combined with the inability to carry out computational-intensive tasks cost-efficiently by general CPU, various hardware acceleration solutions optimized for specific tasks are widely applied in traditional data plane devices, and is expected to continue to be a common practice in virtualized data plane devices (i.e. as VNFs).

• Usecase1: Packet forwarding
• Usecase2: Encryption
• Usecase3: Transcoding

The ultimate goal of this project is to specify a common suite of data plane acceleration (or DPA for short) related APIs at various OPNFV interfaces, to enable VNF portability across various underlying hardware accelerators or platforms.

By using these common APIs, it is expected that data plane VNFs can be easily migrated across available platforms and/or hardware accelerators per ISP’s demand, while the ISPs could also change the platform or apply new hardware accelerators with the VNFs intact.

As shown by the following figure, there are basically two alternatives to enable the use of a common APIs by a data plane VNF. The functional abstraction layer framework and architecture should support both, and provide a unified interface to the upper VNF. It will be the person configuring the VNF, hypervisor/host OS and hardware (policies) that decides which mode to use.

Note: for simplicity, the figures are drawn for hardware offloading accelerators (or HWAs) on the local hardware platform, but the scope of this project is by no means limited to local hardware acceleration.

The “pass-through” model where the VNF is making use of a common suite of acceleration APIs in discovering the hardware accelerators available and using the correct and specific “direct drivers” to directly access the allocated hardware resources. The features of this model include:

1. It enables the most efficient use of hardware resources by bypassing the hypervisor/host OS, yielding higher performance than the other model.
2. It cannot provide “absolute transparency” to the VNFs using hardware accelerators, as they have to upgrade to make changes to their VM image each time they are making use to a new type of hardware accelerator, to load the specific driver and make it known to the application.

The “fully intermediated” model where the VNF talks to a group of abstracted functional “synthetic drivers”. These “synthetic drivers” relays the call to a backend driver in the hypervisor that actually interacts with specific HWA driver. The features of this model include:

1. Through this intermediate layer in the hypervisor, a registration mechanism is possible for a new HWA to make them mapped to the backend driver and then be used automatically without any change to its upper VNFs.
2. Access control and/or resource scheduling mechanisms for HWA allocation to different VNFs can also be included in the hypervisor to enable flexible policies for operation considerations.

• Problem Statement

As stated earlier, despite of the fact that hardware assisted data plane acceleration is expected to be a common practice in production data plane VNFs, no common APIs exists for VNFs to use for accessing these specialized hardware accelerators.

As a result, the VNF developers have to rewrite their code to do hardware migration, which leaves them reluctant to support new acceleration technologies available, while ISPs have to suffer from the undesirable binding between VNF software with the underlying platform and/or hardware accelerator in use.

By specifying a common suite of hardware-independent APIs for data plane VNFs, the SW implementation can be fully decoupled from the HW architecture, fulfilling the OPNFV’s vision towards an open layered architecture. To this end, the proposed project is intended to (tentatively scheduled)

1. document typical VNF use-cases and high-level functional abstraction for hardware acceleration;
2. identify the potential extensions across various NFV interfaces to enable hardware-independent data plane acceleration;
3. identify the high-level requirements for an efficient and extensible framework for implementing the specified APIs;
4. specify detailed API design and test cases;
5. provide open source implementation for both the framework and test tools; and
6. coordinate integrated testing and release testing results.

• Interface/API specification

Using the small cell GW VNF as an example, where the VNF is composed of a signaling GW (SmGW) VM and a security GW (SeGW) VM. In this example, SmGW VM is using hardware acceleration technology for high performance packet forwarding, while SeGW VW is using IPSec offloading in addition. The following figure highlights the potential extensions to OPNFV interfaces that might be needed to enable hardware-independent data plane VNFs.

• What is in or out of scope

1. Data plane acceleration use-cases other than packet-forwarding, encryption or transcoding are currently out of scope, which could be included in later phases.
2. Management plane APIs are currently out of scope, for the sake of quick application, and could be included in later phases.

• The project can be extended in the following aspects in future

1. To include more use-cases and to extend detailed API design and test cases;
2. To include management plane APIs in to the scope;
3. To coordinate integrated testing and release testing results.

• Identify similar projects is underway or being proposed in OPNFV or upstream project
• Identify any open source upstream projects and release timeline.
• Identify any specific development be staged with respect to the upstream project and releases.
• Are there any external fora or standard development organization dependencies. If possible, list and informative and normative reference specifications.
• If project is an integration and test, identify hardware dependency.

Names and affiliations of the committers:

• Lingli Deng (China Mobile, denglingli@chinamobile.com)
• Bob Monkman (ARM, Bob.Monkman@arm.com)
• Peter Willis (British Telecom, peter.j.willis@bt.com)
• Kin-Yip Liu (Cavium, Kin-Yip.Liu@caviumnetworks.com)
• Fahd Abidi (EZCHIP, fabidi@ezchip.com)
• Arashmid Akhavain (Huawei, arashmid.akhavain@huawei.com)
• Xinyu Hu (Huawei, huxinyu@huawei.com)
• Vincent Jardin (6WIND, vincent.jardin@6wind.com)
• François-Frédéric Ozog (6WIND, ff.ozog@6wind.com)

• Use-cases, requirements and gap anlaysis
• Functional block description for the general architecture/framework
• API design and test guidelines

• When is the first release planned?

Q2 2015 (tentatively)

• Will this align with the current release cadence?

Not included in the first release.