[Show abstract][Hide abstract] ABSTRACT: This paper presents an integrated approach to IP fast reroute (IPFRR) of both unicast and multicast paths in wireless mobile networks. A distinct feature of the proposed approach is that, instead of modifying existing routing protocols, it employs a soft handoff technique, i.e., temporarily installs pre-computed Loop Free Alternative Paths (LFAPs) until the co-existing routing protocol converges to new routes. The proposed approach builds on our previously proposed IPFRR technology and uses the concept of pre-computed LFAPs not only for local but also for remote link failures within a certain neighborhood to achieve full alternative path coverage for a single link failure. This paper's contributions include: i) bandwidth efficient fast failure detection by integrating two novel mechanisms, namely probing and link quality prediction, ii) a novel method for calculating LFAPs, iii) a framework for switching seamlessly between LFAPs and OSPF paths, iv) a multicast fast reroute mechanism, and v) implementation in eXtensible Open Router Platform (XORP). We also present a generic framework for handling multiple simultaneous failures in the integrated IPFRR. The performance evaluation has been performed in both indoor and outdoor environments with real 802.11 radio links. The results confirm that our IPFRR technology consistently provides significant convergence time improvement during a single link failure event.
Communication Systems and Networks (COMSNETS), 2010 Second International Conference on; 02/2010
[Show abstract][Hide abstract] ABSTRACT: In this paper, we present a case study of emulation workflow in tactical wireless mobile network. The main contribution of this paper is an XML schema which has been recently developed by the Naval Research Laboratory (NRL) to support high level scenario definition for mobile network emulators in a tool independent manner. In the scenario definition phase, a high level mobility scenario defined using the NRL's XML schema is converted to WISER's run-time emulation files. Using the nodes' locations and terrain information, the RF module performs the relevant calculations and outputs a topology script that depicts node positions and link characteristics (i.e. bandwidth, BER) for all node pairs. To demonstrate emulation scenario definition workflow, Dynamic Routing Control Agent (DRCA) along with the snapshot generation tool is selected as a case study. DRCA, which is a run-time agent, monitors network topology, traffic and capacity and sets the OSPF link metrics dynamically to control routing paths. A snapshot generation tool is integrated with the WISER SDT to identify significant changes in the network. An objective is to identify a small but representative set of snapshots that capture all of the key changes in network topology over the course of a scenario. The above mentioned tools, which are integrated within the WISER SDT, are used to define and analyze DRCA scenarios for the WISER emulation system. EMANE emulation workflow is also described to demonstrate that the NRL's emulation script schema can be used to define scenarios in a tool independent manner.