Testbed

• What is a Mesh Network?
• Testbed Realization
  • Motivation
  • Architecture
  • Location
  • Hardware
  • Software
  • References
• Real-Time Status
• Other Testbeds

Testbed Software

As described in the Section Architecture, one goal of the UMIC-Mesh.net implementation is to achieve a central configuration. For this reason a single OS image, a standard Ubuntu Linux distribution, is provided to all nodes via network by using the Network File System (NFS) protocol. To enable the network booting we deploy a combination of EtherBoot [EtherBoot] and PXELinux [PXELinux]. The vital parts of this process are to get an IP configuration and a kernel to boot. The central audit trail processing is realized with a combination of logging and monitoring. The logging is performed by syslog-ng [Lon01], the de facto standard for forwarding log messages in IP networks. It provides a centralized, securely stored log of all network devices. The monitoring is performed by the NET-SNMP [CasMunPar+02]. Its extensible design is achieved by management information bases (MIB). Thus, it is not only possible to retrieve information from the mesh routers but also to apply changes to the managed testbed, e.g., to change the wireless channel or the transmitting power.

To implement the WMN architecture in the real testbed we employ the WLAN driver madwifi-ng madwifi-ng [Madwifi] The nodes in the virtualized environment are driven by the virtual machine monitor Xen [Cambridge]. To emulate the multi-hop behavior in the virtualized environment a combination of the packet filtering and advanced routing features [LARTC] of the Linux kernel is used. At the core, we deploy a virtual private network on top of our wired a virtual backbone. For this, the Generic Routing Encapsulation (GRE) [FarLiHan+00] tunneling protocol is utilized. It emulates a broadcast medium on top of an existing network by using a multicast address for its broadcast traffic. To control the communication between all participants of the network, standard packet filtering as provided by iptables [Netfilter] is employed. As mentioned before, there is no need to emulate a wireless medium in the virtualized environment, since it is used only for software development and functionality testing and not for performance evaluation. However, if the functionality testing requires a wireless medium behavior, e.g., wireless packet loss or additional delay, it can be realized with NetEm [NetEm].

Currently, the Dynamic Manet On-Demand (DYMO) routing protocol [ChaPer06] implementation from the University of Murcia [Murcia] and the Optimized Link-state Routing Protocol (OLSR) protocol [ClaJac03] implementation from the OLSR.org Project [OLSR] are employed. We made this choice since these protocols are typical representatives of the two routing philosophies in mobile ad-hoc networks: reactive and proactive routing.