Very Lightweight Network & Service Platform for SDN Environments

We have designed and built a platform especially for Software Defined Network and Service environments called the Very Lightweight Network & Service Platform. It can be used for experiments in the domain of SDN. This includes run-time monitoiring, adaption, and adjustment of networks like Software Defined Networking, and also having a dynamic programming environment which allows the setup of complete network topologies on-the-fly — a fully Software Defined Network.

The Network & Service platform is based on a foundational framework called User Space Routing. This uses a set of Virtual Routers and Virtual Network Connections to create a network environment which can easily accommodate (i) fast setup and teardown of a Virtual Router, and (ii) fast setup and teardown of a Virtual Connection. As each Virtual Router can run programs and service elements, it becomes possible to construct an arbitrary network and compute topology.

Here we give our motivations plud an overview of the Virtual Network and Service platform, describe the platform itself and the components in more detail. The usage and startup of the platform together with the configuration options is presented in the attached release notes.


There were many motivations for designing and building the User Space Routing framework. These were accumulated from experience on the RESERVOIR project, which investigated running services in virtual machines, and the AutoI project, which investigated the virtualization of network elements, and the UniverSELF project, which invesitaged management techniques and systems for modern network architectures. It was found that the use of a hypervisor and the associated virtual machines did work as expected and as required, however, there were some issues that hindered various experimental situations.

We found that using a hypervisor and virtual machines added only 5% to 10% overhead to operations, compared to running the same operations in the physical machine, which is most cases was entirely acceptable. The small loss of efficiency was easily overcome by the flexibility of having virtual machines. In terms of experimental and research issues, some were general issues and others were specific to the domain. We found the following general issues:

and we found the following issues that were more domain specific:

It was felt that to make more progress in the area of dynamic and virtual networking experimentation and research, we needed to design and build a testbed that did not have these limits, but still retain virtual machine technology.

The main goals of the testbed over using a hypervisor running a standard virtual machine and standard OS are to have:

The choice was made to write our own simple router with simple service capabilities, in Java, that could run in a Java Virtual Machine (the JVM).


The benefits of a lightweight VM that includes a simple router and the basic capa- bilities of a service component are:

In general, it is a more effective platform for experimenting with many aspects of virtual networks.

The Platform

The platform is designed using 4 main layers:

  1. a management application layer which executes management applications that define the software components and network functions of a network service together with their configuration parameters.
  2. an orchestration layer which is a software element which does most of the management and orchestration and is in charge of managing the full lifecycle of the virtual routers in the network and the allocation of the applications running on the virtual nodes. It is called "Global Controller" and it does the orchestration of the all elements of a service,
  3. an abstraction layer which contains a software element which presents an abstraction for starting, stopping, and configurating virtual elements. It is called "Local Controller" and acts as a Network Hypervisor, and works in a similar way to a host level Hypervisor managing virtual machines.
  4. an infrastructure layer which contains both the virtual infrastructure and represents the virtual resources (i.e. the virtual routers) that make up the virtual networks, and the which are the physical resources that are the hosts running the virtual routers.

The main functions of the Very Lightweight Network & Service Platform are outlined in this subsection. The platform uses a set of Virtual Routers and Virtual Network Connections to create an environment which can easily accommodate:

so it becomes possible to construct an arbitrary network and compute topology.


So the main elements of the Platform are the the GlobalController, the LocalControllers, and the Virtual Routers. These are each explained in further detail below.

There is one GlobalController for the platform, and it has the following functions:

The GlobalController can run on the same host as a LocalController, or in a large setup it can run on a separate host.

There is one LocalController for each physical host that needs to execute virtual routers. A LocalController has the following functions:

A LocalController is similar to a hypervisor in a normal virtualization environment, as it has a role of stopping and stopping virtaul machines.

Within the platform, many Routers can be created. These virtaul routers behave like a real hardware router, with the caveat that they have much simpler functionality.

Figure 2.1: General Architecture

In figure 2.1, the relationship between these elements is shown. There is the GlobalController, shown in brown, which can take various configurations in order to setup and control a run. These configurations can be static configurations, where there is a fixed topology, or dynamic configurations, where the topology of the network and the number of links changes on-the-fly under the control of the GlobalController.

The GlobalController interacts with various LocalControllers. This interaction path is shown as a dotted line. A LocalController, shown in purple, executes on each physical host that participates in the platform. Each LocalController takes requests from the GlobalController and takes the required action. This can be to start or stop a virtual router, to create or remove a virtual link, to get or set attributes on routers or links.

To start a new Router, shown in blue, the LocalController on the relevant host will start a new Java Virtual Machine, shown in white, executing the specific Router code. The router has various elements, which will be discussed later, however for this discussion the most important one is the Router Management element, shown in yellow. Once a Router is up and running, the LocalController interacts with it via the Router Management interface. It is using this interface that commands and requests for the Router are sent by the LocalController. This path is also shown via a dotted line.

Although there is a considerable amoount of infrastructure in the platform dealing with control, the main aim of the platform is to create a topology of virtual routers. These routers execute on a set of hosts, with virtual links between the virtual routers. In figure 2.2, we see how the topology of virtual routers and virtual links manifests itself across multiple hosts, three in this case.

Figure 2.2: Hosts with Virtual Routers and Virtual Links Figure 2.3: Full Connectivity with Control Path

User Space Routing Code


You can download the source


You can download the compiled version

Dependent Libraries

You can download the dependent libraries

Release Notes

See the release notes and guide book , in PDF.

Online Javadoc

See the online documentation