Distributed Cache Updating for the Dynamic Source Routing Protocol
The goal of our project is to proactively disseminating the broken link information to the nodes that have that link in their caches. We define a new cache structure called a cache table and present a distributed cache update algorithm. Each node maintains in its cache table the information necessary for cache updates. When a link failure is detected, the algorithm notifies all reachable nodes that have cached the link in a distributed manner
Distributed Cache Updating for the Dynamic Source Routing Protocol
On-demand routing protocols use route caches to make routing decisions. Due to mobility, cached routes easily become stale. To address the cache staleness issue, prior work in DSR used heuristics with ad hoc parameters to predict the lifetime of a link or a route.
The goal of our project is to proactively disseminating the broken link information to the nodes that have that link in their caches. We define a new cache structure called a cache table and present a distributed cache update algorithm. Each node maintains in its cache table the information necessary for cache updates.
When a link failure is detected, the algorithm notifies all reachable nodes that have cached the link in a distributed manner. We show that the algorithm outperforms DSR with path caches and with Link-MaxLife, an adaptive timeout mechanism for link caches. We conclude that proactive cache updating is key to the adaptation of on-demand routing protocols to mobility.
The Dynamic Source Routing Protocol have the following objectives
• The Node have the information about the neighboring Nodes in the Network
• The DSR reduce the Packet loss and latency time
• The Node maintains the Route Status and Path information for data transfer and path request
• The Node automatically handles the Cache Updation Process if any Link failure is happened in the Network
• Use On-Demand and Adaptive type of protocol for communication
• TCP performance degrades significantly in Mobile Ad hoc Networks due to the packet losses. Most of these packet losses result from the Route failures due to network mobility.
• TCP assumes such losses occur because of congestion, thus invokes congestion control mechanisms such as decreasing congestion windows, raising timeout, etc, thus greatly reduce TCP throughput.
• However, after a link failure is detected, several packets will be dropped from the network interface queue; TCP will time out because of these packet losses, as well as for Acknowledgement losses caused by route failures.
• There is no intimation information regarding about to the failure links to the Node from its neighboring Node’s. So that the Source Node cannot able to make the Route Decision’s at the time of data transfer.
Limitation of Existing System
• The Stale routes causes packet losses if packets cannot be salvaged by intermediate nodes
• The stale routes increases packet delivery latency, since the MAC layer goes through multiple retransmissions before concluding a link failure
• Use Adaptive time out mechanisms
• If the cache size is set large, more stale routes will stay in caches because FIFO replacement becomes less effective
• Prior work in DSR used heuristics with ad hoc parameters to predict the lifetime of a link or a route. However, heuristics cannot accurately estimate timeouts because topology changes are unpredictable.
• Prior researches have proposed to provide link failure feedback to TCP so that TCP can avoid responding to route failures as if congestion had occurred.
• We propose proactively disseminating the broken link information to the nodes that have that link in their caches. We define a new cache structure called a cache table and present a distributed cache update algorithm. Each node maintains in its cache table the Information necessary for cache updates.
• The Source Node has the information regarding about the Destination and the Intermediate Node links failure, So that it is useful from Packet loss and reduce the latency time while data transfer throughout the Network .
Advantage of Proposed System
• Proactive cache updating also prevents stale routes from being propagated to other nodes
• We defined a new cache structure called a cache table to maintain the information necessary for cache updates. We presented a distributed cache update algorithm that uses the local information kept by each node to notify all reachable nodes that have cached a broken link. The algorithm enables DSR to adapt quickly to topology changes.
• The algorithm quickly removes stale routes no matter how nodes move and which traffic model is used .
Module 1: Route Request
When a source node wants to send packets to a destination to which it does not have a route, it initiates a Route Discovery by broadcasting a ROUTE REQUEST. The node receiving a ROUTE REQUEST checks whether it has a route to the destination in its cache. If it has, it sends a ROUTE REPLY to the source including a source route, which is the concatenation of the source route in the ROUTE REQUEST and the cached route. If the node does not have a cached route to the destination, it adds its address to the source route and rebroadcasts the ROUTE REQUEST. When the destination receives the ROUTE REQUEST, it sends a ROUTE REPLY containing the source route to the source. Each node forwarding a ROUTE REPLY stores the route starting from itself to the destination. When the source receives the ROUTE REPLY, it caches the source route.
Module 2: Message Transfer
The Message transfer relates with that the sender node wants to send a message to the destination node after the path is selected and status of the destination node through is true. The receiver node receives the message completely and then it send the acknowledgement to the sender node through the router nodes where it is received the message.
Module 3: Route Maintenance
Route Maintenance, the node forwarding a packet is responsible for confirming that the packet has been successfully received by the next hop. If no acknowledgement is received after the maximum number of retransmissions, the forwarding node sends a ROUTE ERROR to the source, indicating the broken link. Each node forwarding the ROUTE ERROR removes from its cache the routes containing the broken link.
Module 4: Cache Updating
When a node detects a link failure, our goal is to notify all reachable nodes that have cached that link to update their caches. To achieve this goal, the node detecting a link failure needs to know which nodes have cached the broken link and needs to notify such nodes efficiently. Our solution is to keep track of topology propagation state in a distributed manner.
Processor : Pentium Iv 2.6 Ghz
Ram : 512 Mb
Monitor : 15”
Hard Disk : 20 Gb
Cddrive : 52x
Keyboard : Standard 102 Keys
Front End : Java, Swing
Tools Used : Jframe Builder
Operating System: Windows Xp
I need the coding for the DSR in any language.