| description |
During the development of network protocols and distributed
applications, their performance has to be analyzed in appropriate
environments. Network emulation testbeds provide a synthetic,
configurable network environment for comparative performance
measurements of real implementations. Realistic scenarios have to
consider hundreds of communicating nodes. Common network emulation
approaches limit the number of nodes in a scenario to the number of
computers in an emulation testbed. To overcome this limitation, we
introduce a virtual node concept for network emulation. The key
problem for node virtualization is a transparent, yet efficient
separation of node resources. In this paper, we provide a brief
survey of candidate node virtualization approaches to facilitate
scalable network emulation. Based on the gathered insights, we
propose a lightweight virtualization solution to achieve maximum
scalability and discuss the main points regarding its
implementation. We present extensive evaluations that show the
scalability and transparency of our approach in both a traditional
wired infrastructure-based, and in two wireless ad hoc network
emulation scenarios. The measurements indicate that our solution can
push the upper limit of emulation scenario sizes by a factor of
10--28. Given our emulation testbed consisting of 64 computers, this
translates to possible scenario sizes of up to 1792 nodes. In
addition to the evaluation of our virtualization approach, we
discuss key concepts for controlling comprehensive emulation
scenarios to support scalability of our system as a whole.
|