Ad-hoc networks are completely wireless networks of mobile hosts, in which the topology rapidly changes due to the movement of mobile hosts. This frequent topology may lead to sudden packet losses and delays. Transport protocols like TCP have been built mainly for reliable, xed networks. Hence, when used in adhoc networks, TCP misinterprets this loss as congestion and invokes congestion control. This leads to unnecessary retransmissions and loss of throughput. To overcome this problem, a feedback scheme is proposed, so that the source can distinguish between route failure and network congestion. When a route is disrupted, the source is sent a Route Failure Noti cation(RFN) packet, allowing it to freeze its timers and stop sending packets. When the route is re-established, the source is informed through a Route Re-establishment Noti-cation (RRN) packet, upon which it resumes by unfreezing timers and continuing packet transmissions. The simulated performance of TCP on ad-hoc networks with and without feedback is compared and reported. It is observed that in the event of route failures, as the route re-establishment time increases, the use of feedback provides signi cant gains in throughput as well as savings in unnecessary packet transmissions. Several further enhancements and directions for future work are also sketched. 1

Ad hoc networks are completely wireless networks of mobile hosts, in which the topology rapidly changes due to the movement of mobile hosts. This frequent topology change may lead to sudden packet losses and delays. Transport protocols like TCP, which have been designed for reliable fixed networks, misinterpret this packet loss as congestion and invoke congestion control, leading to unnecessary retransmissions and loss of throughput. To overcome this problem, a feedback scheme is proposed so that the source can distinguish between a route failure and network congestion. When a route is disrupted, the source is sent a Route Failure Notification packet, allowing it to invalidate its timers and stop sending packets. When the route is reestablished, the source is informed through a Route Reestablishment Notification packet, upon which it resumes packet transmissions. Simulation experiments show that in the event of route failures, as the route reestablishment time increases, the use of feedback provides significant improvements in performance.