Virtualmesh: an Emulation Framework

Wireless Mesh Networks (WMN) have proven to be an important technology for interconnecting computer systems in a flexible way. There exist many application areas that profit from WMN technologies such as surveillance and monitoring systems, the wireless integration of mobile clients into a network infrastructure or simply the spontaneous setup of a network for data exchange between several mobile devices. The development process for new protocols and architectures in the area of WMN is typically split into a first implementation and evaluation phase performed with help of a network simulation, followed by a real-world prototype implementation, which is tested in a realistic test-bed. Especially for WMNs including wireless communication and mobile clients, the testing in a real test-bed is time-consuming and expensive. External interferences can occur and make debugging and performance evaluation difficult. Additionally, real-world test-beds usually only support a limited number of test topologies and wireless clients and rarely provide the possibility for repeatable experiments with mobile clients. For this reason, we developed VirtualMesh, a new WMN evaluation framework providing a virtual wireless network, which can be used for network protocol and application development before considering a real hardware test-bed. Its architecture offers the testing of real communication software including the operating system with the original network stack in a controlled environment. The wireless communication is handled by a real-time network emulation, which can imitate complex network scenarios in an inexpensive way. VirtualMesh captures the real network traffic through a virtual wireless interface at the mesh clients and redirects it to a wireless model based on the OMNeT++ network simulator. The simulator, which is responsible for the wireless emulation, computes the node connectivity and packet latency and forwards the traffic to the destination nodes accordingly. To be able to imitate a truly dynamic network environment, which even allow the reconfiguration of wireless parameters by routing protocols or applications, a sophisticated mechanism in VirtualMesh allows the corresponding adaptation of the wireless settings inside the simulation model during emulation run-time. In our experiments, VirtualMesh has proven to be very flexible and scalable in the network scenario. It is able to perfectly imitate the throughput behaviour in a WMN and only introduces a small packet delay mainly caused by the distributed emulation setup. VirtualMesh has therefore proven to be a valuable tool for protocol and application developers to test their real-world implementation in a controllable environment prior to the final development.