Application Framework for Programmable Network Control - Advances in Network-Embedded Management and Applications - page 44

domain experts can simply apply graph algorithms to find and remove
(through network manipulation) articulation vertices; vertices that may
disconnect a graph. Besides control, the application layer can also include
visualization or other means of interaction with the network. The integration
with toolboxes, such as those available in Mathematica, makes the application
layer a powerful environment to develop network control applications.
5 Implementation and Test Bed
In the preceding sections, we introduced the framework for control
applications as well as a four-layered functional model to implement such
applications. We developed a test bed according to the presented functional
model ( Figure 3 ) to gain practical insight in the implementation of the
application framework to support network control programs. The test bed
implements the first three functional layers and enables further exploration of
the network control applications that are part of the fourth layer.
5.1 Hardware
The test bed consists of eight machines (four dual processor AMD Opteron
with 16GB RAM and dual port 10Gb NICs and four Sun Fire X4100 with
4GB RAM and 1Gb NICs) interconnected by two 1Gb switches and a Dell
hybrid 1/10Gb switch. All machines run VMWare [38] ESXi hypervisor
software and the virtual hardware is centrally managed and monitored with
VMware vSphere management software. The test bed was bootstrapped with
one Linux instance containing the software we developed, and iteratively
grown to 20 instances to create a non-trivial configuration of networks and
computers ( Figure 4 ) .
The setup involves two datacenter locations: a virtual infrastructure running
in our datacenter in Groningen and an interactive programming environment
including an interface to a multi-touch table running in our lab in Amsterdam.
The multi-touch table enables users to interact with NCs (Section 6). The two
locations are connected by two OSI-Layer 2 Virtual Private Networks (VPN)
on basis of OpenVPN [39]: one for control traffic and one for data traffic. At
the receiving host in Amsterdam, the control and data networks are separated
by VLANs.
5.2 Software
The primary purpose of developing a prototype is to gain insight in the
challenges and details to control a network from applications that require