Rollback recovery with low overhead for fault tolerance in mobile ad hoc networks

AbstractMobile ad hoc networks (MANETs) have significantly enhanced the wireless networks by eliminating the need for any fixed infrastructure. Hence, these are increasingly being used for expanding the computing capacity of existing networks or for implementation of autonomous mobile computing Grids. However, the fragile nature of MANETs makes the constituent nodes susceptible to failures and the computing potential of these networks can be utilized only if they are fault tolerant. The technique of checkpointing based rollback recovery has been used effectively for fault tolerance in static and cellular mobile systems; yet, the implementation of existing protocols for MANETs is not straightforward. The paper presents a novel rollback recovery protocol for handling the failures of mobile nodes in a MANET using checkpointing and sender based message logging. The proposed protocol utilizes the routing protocol existing in the network for implementing a low overhead recovery mechanism. The presented recovery procedure at a node is completely domino-free and asynchronous. The protocol is resilient to the dynamic characteristics of the MANET; allowing a distributed application to be executed independently without access to any wired Grid or cellular network access points. We also present an algorithm to record a consistent global snapshot of the MANET

Message efficient global snapshot recording using a self stabilizing spanning tree in a MANET

 Distributed snapshots are a significant paradigm for distributed systems. These are applied for constructing checkpoint protocols, apart from investigating, testing, or proving properties in distributed executions such as deadlocks and termination. Though a number of snapshot algorithms exist for traditional distributed systems, they cannot be directly applied to mobile ad hoc networks due to the constraints of topology and hostile conditions in which the MANETs operate. The paper presents an algorithm for recording the global state of a clustered and multi-hop mobile ad hoc network. The proposed algorithm imposes a self stabilizing spanning tree upon the network topology to reduce the message overhead in the system due to the algorithm and to deal with the dynamic nature of MANETs. Moreover, the protocol handles concurrent snapshot initiation and does not require FIFO channels. The message complexity of snapshot recording is O(n-1) where n is the number of clusters in the syste