ECOC 2018 Demonstration: VNF Implementation of the Virtual DBA

We demonstrate a VNF implementation of a sliceable PON architecture which has been optimised using DPDK data plane acceleration techniques. This gives Virtual Network Operators optimal control over capacity scheduling in a large scale multi-tenant PON environment.

Experimental Setup

Our demonstrator (see figure 1), implements a shared PON scenario with a number of real and virtualised ONUs, each with 3 T-CONTs. The main components within the testbed are: a physical PON, a set of emulated ONUs, a traffic generator and a multi-access edge computing node. The physical PON is based on one OLT and two ONUs (with the ONUs multiplexed into the same physical board), implemented on FPGA development boards13 offering 10Gb/s symmetric capacity. The emulated ONUs, running in software, are used to increase the number of users, and generate typical self-similar traffic. The traffic generator produces both real-time sensitive and best effort traffic flows (such as file transfer and video streaming) through the physical PON. Traffic flows are VLAN-tagged which are then mapped to specific TCONTs at the ONUs. Openstack runs the Network Function Virtualisation (NFV) implementation of the PON, running the virtual DBA and the merging engine. The Merging Engine is the element that merges all virtual bandwidth maps from the different VNOs generating one physical bandwidth Map allocation and the SDN control plane. The virtualisation node is logically composed of the Virtual Network Functions(VNFs), an Openstack virtualization platform, a DPDK Data Plane Acceleration toolset and an Orchestration and Control layer.

We have implemented the Merging Engine (ME) and the vDBA functions for the Virtual Network Operators (VNOs) as Virtual Network Functions (VNFs), allowing these functions to be instantiated and scaled independently. The virtualized infrastructure, shown in figure 1, leverages Single Root Input/Output Virtualization (SRI-OV) technology? and Open vSwitch6 with Data Plane Development Kit (DPDK) enhancements7. The DPDK offers a set of lightweight software libraries and optimized drivers to accelerate packet processing. It utilizes polling threads, huge pages, numa locality, zero copy packet handling, lockless queue and multi core processing to achieve low latencies and a high packet processing rate. Thus, all VNFs leverage the DPDK drivers and libraries to minimize the I/O and packet processing cost. The PCI Special Interest Group8 on I/O Virtualization proposed the Single Root I/O Virtualization standard for scalable device assignment. PCI devices supporting the SRIOV standard present themselves to host software as multiple virtual PCI devices, thus introduce the idea of physical functions (PFs) and virtual functions (VFs). The PFs are the full-featured PCIe functions and represent the physical hardware ports; VFs are the lightweight functions that can be assigned to VMs. The userspace VF driver for the merging engine VNF helps VM to directly access the FPGA interface, thus, provides near line-rate packet I/O performance. The OVS-DPDK replaces the standard OVS kernel data-path with a DPDK-based data-path, creating a user-space vSwitch on the host for faster connectivity between VMs. The OVS-DPDK ports have vHost user interfaces which allow user to fetch/put packets from/to the VMs. Furthermore, all the VNFs in different VMs employs para-virtualized interface that utilizes the DPDK userspace virtio poll mode driver to accelerate packets I/O from OVS-DPDK. Each of the VNFs used for VNOs implements vDBA mechanism, thus, have identical functionality in terms of packet processing. The VM running merging engine VNF has two interfaces – VF interface for packets I/O with FPGA interface, and the second one is virtio interface to communicate packets with OVS-DPDK switch. There are two directions in which traffic flows in this virtualized system: North/South and East-/West. In the North/South flow pattern, traffic is received from the network through FPGA interface and sent back out to the network. In the East-/West flow pattern, traffic is processed by a VNF and sent to another VNF through OVS-DPDK for further processing.

 

F. Slyne, R. Giller, J. Singh and M. Ruffini, “Experimental Demonstration of DPDK Optimised VNF Implementation of Virtual DBA in a Multi-Tenant PON,” 2018 European Conference on Optical Communication (ECOC), Rome, Italy, 2018, pp. 1-3.
doi: 10.1109/ECOC.2018.8535109
keywords: {Acceleration;Bandwidth;Passive optical networks;Merging;Engines;Real-time systems;Cloud computing},
URL: http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=8535109&isnumber=8535099

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