992698 - Cache Management of Dynamic Source Routing for...

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Cache Management of Dynamic Source Routing for Fault Tolerance in Mobile Ad Hoc Networks Ching-Hua Chuan and Sy-Yen Kuo Department of Electrical Engineering National Taiwan University Taipei, Taiwan Email: sykuo@cc.ee.ntu.edu.tw Abstract Mobile ad hoc networks have gained more and more research attentions by provisions of wireless communications without location limitations and pre-built fixed infrastructure. Because of the absence of any static support structure, ad hoc networks are prone to link failure. This has become the most serious cause of throughput degradations when using TCP over ad hoc networks. Some researches chose Qvnamic Source Routing (DSR) as the routing protocol and showed that disabling the assigning of a route directly from cache gives better performance. In this papec we introduce an eficient cache management mechanism to increase the TCP throughput by repbins with a route direct@ from the cache of DSR and perform the cache recovery when a host failure has occurred We use simulations to compare the performance of our algorithm with the original DSR under the link failure prone environment due to mobility We also provide ihe simulation results when host failures are considered in the ad hoc networks. 1. Introduction An ad hoc network is a dynamic network consisted of a group of mobile devices which communicate with each other by wireless media. Communications only can be done when a node is in the wireless transmission region of another node. Through a group of intermediate nodes willing to forward packets, a source can send data to a destination which is not in its communication region. In an ad hoc network, every node may work as a host or a router at some time. There have been a lot of routing protocols proposed for ad hoc networks [6-111. The Dynamic Source Routing (DSR) protocol [7] is an on-demand routing protocol based on the concept of source routing. The protocol consists of two major phases: route discovery and route maintenance. Whenever a source has a packet to send, it first checks its routing table to see if there is a route to the destination. If not found, then the source broadcasts a route request. When an intermediate node receives a route request, it again broadcasts this request by appending its address to the request packet until this packet reaches the destination. The destination replies to the first arrived request. It sends a route reply to the source containing the whole route from source to destination. When this packet reaches the source, the connection is established and all the subsequent packets will go through the route with the route in their packet headers. To reduce the number of route discoveries, each node maintains a route cache for the routes it has learned.
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This note was uploaded on 03/19/2012 for the course CS 1313 taught by Professor Aman during the Spring '12 term at Punjab Engineering College.

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992698 - Cache Management of Dynamic Source Routing for...

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