A distributed algorithm for finding all best swap edges of a minimum diameter spanning tree blog.ocularsystems.in
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A distributed algorithm for finding all best swap edges of a minimum diameter spanning tree blog.ocularsystems.in

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Communication in networks suffers if a link fails. When the links are edges of a tree that has been chosen from an underlying graph of all possible links, a broken link even disconnects the network. ...

Communication in networks suffers if a link fails. When the links are edges of a tree that has been chosen from an underlying graph of all possible links, a broken link even disconnects the network. Most often, the link is restored rapidly. A good policy to deal with this sort of transient link failures is swap rerouting, where the temporarily broken link is replaced by a single swap link from the underlying graph. A rapid replacement of a broken link by a swap link is only possible if all swap links have been precomputed. The selection of high quality swap links is essential; it must follow the same objective as the originally chosen communication subnetwork.

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A distributed algorithm for finding all best swap edges of a minimum diameter spanning tree blog.ocularsystems.in Document Transcript

  • 1. Project Guidance: www.ocularsystems.inEmail: info@ocularsystems.in Call Us: 7385665306A Distributed March 17Algorithm for 2011Finding All BestSwap Edges of aMinimumDiameter SpanningTreeCommunication in networks suffers if a link fails. When the links Distributedare edges of a tree that has been chosen from an underlying Systems,graph of all possible links, a broken link even disconnects thenetwork. Most often, the link is restored rapidly..… Minimal Spanning tree Ocular Systems, Shop No: 01, Swagat Corner Building, Near NarayaniDham Temple, Katraj, Pune-46
  • 2. A Distributed Algorithmfor Finding All Best Swap Edgesof a Minimum DiameterSpanning TreeAbstract: Communication in networks suffers if a link fails.When the links are edges of a treethat has been chosen froman underlying graph of all possible links, a broken linkevendisconnects the network. Most often, the link is restored rapidly.A good policy todeal with this sort of transient link failures isswap rerouting, where the temporarilybroken link is replacedby a single swap link from the underlying graph. Arapidreplacement of a broken link by a swap link is only possible if allswap links havebeen precomputed. The selection of high qualityswap links is essential; it must follow thesame objective as theoriginally chosen communication subnetwork.We are interestedin a minimum diameter tree in a graph with edge weights (so astominimize the maximum travel time of messages). Hence, eachswap link must minimize(among all possible swaps) the diameterof the tree that results from swapping. Wepropose a distributedalgorithm that efficiently computes all of these swap links, andweexplain how to route messages across swap edges with acompact routing scheme. Finally,we consider the computationof swap edges in an arbitrary spanning tree, where swapedgesare chosen to minimize the time required to adapt routing incase of a failure, andgive efficient distributed algorithms fortwo variants of this problem.Existing System According to the previous technique, a message follows the normal routing tableinformation unless the next hop has failed; in this case, it is redirected towards aprecomputed link, called swap; once this link has been crossed, normal routing isresumed. The choice of the swap edge is done according to some optimization criteria onthe resulting new route. The amount of precomputed information required in addition tothe routing table is rather small: a single link per each destination. Several efficient serialalgorithms have been presented to compute this information for several optimizationcriteria distance, maximum,sum ,increment . Only the algorithm corresponding todistance has been efficiently implemented in a distributed environment, while for theother optimization criteria no distributed solution has been devised yetDisadvantage: once this link has been crossed, normal routing is resumed. The choice of theswap edge is done according to some optimization criteria on the resulting new route.
  • 3. Proposed System For communication in computer networks, often only asubset of the availableconnections is used to communicateat any given time. If all nodes are connected usingthesmallest number of links, the subset forms a spanning treeof the network. This haseconomical benefits compared tousing the entire set of available links, assuming thatmerelykeeping a link active for potentially sending messages inducessome cost.Furthermore, as only one path exists betweenany communication pair, a spanning treesimplifies routingand allows small routing tables.Depending on the purposeof the network, there is a variety of desirable properties ofaspanning tree. We are interested in a Minimum DiameterSpanning Tree (MDST), i.e., atree that minimizes the largestdistance between any pair of nodes, thus minimizing theworstcase length of any transmission path, even if edge lengths arenot uniform. Theimportance of minimizing the diameter of a spanning tree has been widely recognized ,the diameter of a network provides a lower bound(and often even an exact one) on thecomputation time of mostalgorithms in which all nodes participate.One downside ofusing a spanning tree is that a single linkfailure disconnects the network. Whenever linkfailures aretransient, i.e., a failed link soon becomes operational again, themomentarilybest possible way of reconnecting the networkis to replace the failed link by a singleother link, called aswap link. Among all possible swap links, one should choosea bestswap w.r.t. the original objective thatis in our case, a swap that minimizes the diameter oftheresulting swap tree.Advantages:The distributed computation of all best swaps has the further advantage of gainingefficiency (against computing swap edges individually), because dependencies betweenthe computations for different failing edges can be exploited.IMPLEMENTATION Implementation is the stage of the project when the theoretical design is turnedout into a working system. Thus it can be considered to be the most critical stage in
  • 4. achieving a successful new system and in giving the user, confidence that the new systemwill work and be effective. The implementation stage involves careful planning, investigation of the existingsystem and it’s constraints on implementation, designing of methods to achievechangeover and evaluation of changeover methods.Modules:Spanning Tree generation For communication in computer networks, often only a subset of the availableconnections is used to communicate at any given time. If all nodes are connected usingthe smallest number of links, the subset forms a spanning tree of the network.Minimum DiameterSpanning Tree(MDST) A tree that minimizes the largest distance between any pair of nodes, thusminimizing the worst case length of any transmission path, even if edge lengths are notuniform. Essentially, the diameter of a network provides a lower bound (and often evenan exact one) on the computation time of most algorithms in which all nodes participate.Swap link One downside of using a spanning tree is that a single link failure disconnects thenetwork. Whenever link failures are transient, i.e., a failed link soon becomes operationalagain, the momentarily best possible way of reconnecting the network is to replace thefailed link by a single other link, called a swap link. Among all possible swap links, oneshould choose a best swap w.r.t. the original objective.Swap rerouting A good policy to deal with this sort of transient link failures is swaprerouting, where the temporarily broken link is replaced by a single swap link from the
  • 5. underlying graph. A rapid replacement of a broken link by a swap link is only possible ifall swap links have been precomputed.Software Requirements:Hardware Requirement:  Minimum 1.1 GHz PROCESSOR should be on the computer.  128 MBRAM.  20 GB HDD.  1.44 MB FDD.  52x CD-ROM Drive.  MONITORS at 800x600 minimum resolution at 256 colors minimum.  I/O, One or two button mouse and standard 101-key keyboard.Software Requirement:  Operating System:Windows 95/98/2000/NT4.0.  Technology : JAVA, JFC(Swing)  Development IDE : Eclipse 3.x