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چكيده انگليسي :

69A New Algorithm for Load Balancing in Metro Ethernet Using Multiple Spanning Tree Protocol Mohammad Darvishan m darvishan@ec iut ac ir Date of Submission 2012 25 2 Department of Electrical and Computer Engineering Isfahan University of Technology Isfahan 84156 83111 Iran Degree M Sc Language FarsiSupervisor Mehdi Mahdavi m mahdavi@cc iut ac irAbstract The flexibility simplicity high speed and low cost of ethernet technology along with increasing use ofthis technology in local area networks makes ethernet an ideal technology for use in metro networks Butaccording to the fact that ethernet is primarily designed for small local area networks there are somechallenges in the way of expanding ethernet to large networks such as metro network Load balancing in thenetwork is one of the main challenges ahead in metro ethernet networks Due to the large size of the metroethernet networks and large number of users in these networks and also providing various services withhigh bandwidth it is a critical issue how to utilize all the capacity of the network Thus traffic engineeringis a major subject in such networks in order for the better management of network resources Spanning treeprotocol is used in the ethernet local area networks to prevent making loops in the network In spanning treeprotocol all the network subscribers use a common single spanning tree Thus due to large number of usersin metro ethernet network spanning tree protocol do not use network resources in an optimal manner andhas no capability to implement traffic engineering in metro ethernet network Using multiple spanning treeprotocol is a good solution to implement traffic engineering methods in metro ethernet networks Multiplespanning tree protocol allows building several trees in the network leading to better load distribution in thenetwork and prevents from overloading in the links The suggested algorithm in this thesis makes use ofmultiple spanning trees This algorithm makes use of dynamic link weights to create multiple instances ofspanning trees in the network In order to update the weights of network links the suggested algorithm usesan exponential relationship In this exponential relationship there is an inverse exponential relationshipbetween weights of the links and traffic of the links The suggested algorithm creates one instance of thespanning tree for each vlan and in order to obtain optimal spanning tree for vlan there is a mechanism thatuses feedback in creating spanning tree for vlan In this mechanism if constructing spanning tree andassigning traffic to it leads to overloading in the links the proposed algorithm first assigns proper weightsto the links and then reconstructs a new spanning tree for that vlan This procedure is repeated untilobtaining the appropriate tree Selecting root node of the tree is another important part of creating thespanning tree In the suggested algorithm a node with the highest sum of incoming and outgoing traffic isselected as the root node of each tree This is because of all ports of the root node can be in the activatemode Therefore the algorithm distributes traffic in a better way and prevents saturation in the links near theroot node Comparing the results of the algorithm simulation demonstrates that there is a proper use ofnetwork links These results show that suggested algorithm prevents overloading in the network andprovides more uniform traffic distribution Also the average load on the links is good Keywords Metro Ethernet Traffic Engineering Multiple Spanning Tree Load Balancing

درويشان، محمد

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