Networking System on

Overview

Mon, 17 Feb 2025 00:00:00 +0000

When a new Virtual Machine is launched, OpenNebula will connect its virtual network interfaces (defined by NIC attributes) to hypervisor network link devices as defined in the corresponding Virtual Network. This will allow the VM to have access to public and private networks.

OpenNebula supports the following networking modes:

Bridged: The VM NIC is added to a Linux bridge on the Host. This mode can be configured to use Security Groups and network isolation.
802.1Q VLAN: The VM NIC is added to a Linux bridge on the Host and the Virtual Network is configured to handle 802.1Q VLAN isolation.
VXLAN: The VM NIC is added to a Linux bridge on the Host and the Virtual Network implements isolation using the VXLAN encapsulation.
Open vSwitch: The VM NIC is added to a Open vSwitch bridge on the Host and the Virtual Network optionally handles 802.1Q VLAN isolation.
Open vSwitch DPDK: The VM NIC uses vhost-user to connect to an Open vSwitch userspace datapath accelerated with DPDK.
Open vSwitch on VXLAN: The VM NIC is added to a Open vSwitch bridge on the Host and the Virtual Network is configured to provide both isolation with VXLAN encapsulation and optionally 802.1Q VLAN.

The attribute VN_MAD of a Virtual Network determines which of the above networking modes is used.

Defining and Managing Virtual Networks

Mon, 17 Feb 2025 00:00:00 +0000

Commonly a Host is connected to one or more networks that are available to the VMs through bridges. OpenNebula allows the creation of Virtual Networks by mapping them on top of the physical ones.

Virtual Network Definition

A Virtual Network definition consists of three different parts:

The underlying physical network infrastructure that will support it, including the network driver.
The logical address space available. Addresses associated to a Virtual Network can be IPv4, IPv6, dual stack IPv4-IPv6, or Ethernet.
The guest configuration attributes to set up the Virtual Machine network, that may include for example network masks, DNS servers, or gateways.

Physical Network Attributes

To define a Virtual Network include:

Bridged Networking

Mon, 17 Feb 2025 00:00:00 +0000

This guide describes how to deploy Bridged networks. In this mode, the Virtual Machine traffic is directly bridged through the Linux bridge on the hypervisor nodes. Bridged networks can operate in four different modes depending on the additional traffic filtering made by OpenNebula:

Dummy Bridged, no filtering, no bridge setup (legacy no-op driver).
Bridged, no filtering is made, managed bridge.
Bridged with Security Groups, iptables rules are installed to implement security groups rules.

802.1Q VLAN Networks

Mon, 17 Feb 2025 00:00:00 +0000

This guide describes how to enable network isolation provided through Host-managed VLANs. This driver will create a bridge for each OpenNebula Virtual Network and attach a VLAN-tagged network interface to the bridge. This mechanism is compliant with IEEE 802.1Q.

The VLAN ID will be the same for every interface in a given network, automatically computed by OpenNebula. It may also be forced by specifying a VLAN_ID parameter in the Virtual Network template.

VXLAN Networks

Mon, 17 Feb 2025 00:00:00 +0000

This guide describes how to enable Network isolation provided through the VXLAN encapsulation protocol. This driver will create a bridge for each OpenNebula Virtual Network and attach a VXLAN-tagged network interface to the bridge.

The VXLAN ID will be the same for every interface in a given network, calculated automatically by OpenNebula. It may also be forced by setting the VLAN_ID attribute in the Virtual Network template.

Open vSwitch Networks

Mon, 17 Feb 2025 00:00:00 +0000

This guide describes how to use the Open vSwitch network drivers. They provide network isolation using VLANs by tagging ports and basic network filtering using OpenFlow. Other traffic attributes that may be configured through Open vSwitch are not modified.

The VLAN ID will be the same for every interface in a given network, calculated automatically by OpenNebula. It may also be forced by specifying an VLAN_ID parameter in the Virtual Network template.

Open vSwitch DPDK

Mon, 10 Aug 2026 00:00:00 +0000

Open vSwitch (OVS) can use the Data Plane Development Kit (DPDK) to move packet processing from the kernel to dedicated userspace polling threads. This provides an accelerated, shareable network path when assigning a physical NIC directly to each Virtual Machine is not appropriate.

Warning

Open vSwitch DPDK is supported only for KVM Hosts.

The physical NIC is owned by ovs-vswitchd, normally through vfio-pci; it is not passed through to the VM. OpenNebula connects each VM to the userspace bridge with a dpdkvhostuserclient port. QEMU creates the corresponding vhost-user socket under /var/run/one/vhost-socks/.

InfiniBand

Fri, 10 Jul 2026 00:00:00 +0000

InfiniBand is a high-performance networking technology designed for environments where extremely low latency, high throughput, and efficient CPU utilization are critical. It is widely used in High Performance Computing (HPC), AI training and inference Clusters, and other data-intensive workloads that require significantly higher performance than conventional Ethernet networks. InfiniBand achieves this through technologies such as Remote Direct Memory Access (RDMA), allowing applications to exchange data directly between systems with minimal CPU involvement.

NVIDIA Spectrum-X Integration (AI)

Wed, 17 Dec 2025 00:00:00 +0000

This guide provides a high-level overview of the OpenNebula integration with the NVIDIA Spectrum-X™ Ethernet networking platform. This integration allows OpenNebula to act as a single pane of glass for managing an entire AI factory, from compute and storage to the high-performance network fabric.

The integration works by mapping OpenNebula’s logical resource constructs (like Users and Virtual Networks) directly to the Spectrum-X fabric’s tenant segments, which are based on a routed L3EVPN architecture to deliver isolated, high-bandwidth East-West (E/W) traffic for demanding AI and HPC workloads.

NVIDIA BlueField DPU (AI)

Tue, 30 Jun 2026 00:00:00 +0000

Work in progress.