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This research paper focuses on the design of structured campus networks with the help of a proposed algorithm called the Fuzzy Simulated Algorithm. The objectives of good topology design, including monetary cost, average network delay, and hops between source-destination pairs, are discussed along with constraints like capacity limitations on links and network devices. The simulated evolution process is explained, outlining the steps of evaluation, selection, and allocation. The use of fuzzy logic for evaluation and the combination of fuzzy goodness functions are also detailed. The process of selecting and allocating links based on evaluation results to optimize the topology design is presented.
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Topology Design of Structured Campus Networks by Habib Youssef Sadiq M. Sait Salman A. Khan Department of Computer Engineering King Fahd University of Petroleum and Minerals
Outline • Introduction & Problem Statement • Proposed Algorithm • Simulated Evolution • Fuzzy Evaluation Scheme • Selection • Fuzzy Allocation Scheme • Experiments and Results • Conclusion
Introduction • Important objectives of good topology • Monetary Cost • Average network delay • Number of hops between any source-destination pair • Conflicting nature of the objectives
Constraints • Limitation of capacity on links • Limitation of ports on networking devices • Another possible constraint is that the designer might like to enforce certain hierarchies on network devices. • Topology is a tree
Purpose • Given the optimization parameters and constraints, we have to design a Spanning Tree Topology to satisfy all the constraints and optimize desired objectives.
Objectives of Good Topology Design • Monetary Cost • Reduction in monetary cost s = total cable length ccable = cost per unit of cable used cnd= cost of network devices
Objectives of Good Topology Design • Average Network Delay per packet • Reduction in the average network delay due to links. = total traffic in the network, ij = traffic between clusters i and j i j = delay per bit due to network device between cluster i and j
Objectives of Good Topology Design • Maximum hops between any source-destination pair. • This includes the networking devices due to which processing delays are encountered.
Simulated Evolution B = Bias value; ei = Individual link in Ci = Current cost of ith link in ; = complete solution Oi = Lower bound on cost of ith link gi = Goodness of ith link in S = Queue to store the selected links; INITIALIZATION Repeat EVALUATION : ForEach ei DO gi = Oi / Ci SELECTION : ForEach ei DO IF Random > Min (gi + B, 1) THEN begin S = S U ei ; Remove ei from end Sort element of S ALLOCATION : ForEach ei S DO ALLOCATE(ei ,) Until Stopping condition is satisfied. Return Best Solution
Evaluation • Goodness = Oi / Ci • A link is the individual to be evaluated, based on • Its cost. • Its depth in the current topology with respect to the root. • Goodness of link with respect to cost • Link with minimum cost (LCostMin). • Link with maximum cost (LCostMax).
Evaluation • Done using fuzzy logic. • Thus, we make a membership function which consists of the minimum, maximum, and the current cost and compare “goodness of link with respect to cost” using this function.
1.0 0.5 LCost LCostMax LCostMin LCostMax 1 Evaluation Membership of a kink in fuzzy subset “Link Cost”
Evaluation • Goodness of link with respect to depth • Minimum depth of link =1 (LDepthMin) • Maximum depth of link = (1.5) *Max. depth of any link in the first generation OR Maximum of 7 (LDepthMax)
Evaluation 1.0 0.5 LDepth LDepthMin LDepthMax Membership of a link in fuzzy subset “ Link Depth”
Evaluation • The two fuzzy goodness functions are combined using fuzzy rule. • The fuzzy rule used is: If the link has near optimum costAND near optimum depth THEN the link has high goodness. • Using OWA - andlike:
Selection • Based on the goodness found in the evaluation phase, link(s) is (are) selected to be removed from the topology. • Done using • Variable bias Bk = 1 - Gk-1 where Gk-1 is the average goodness of links in K-1st iteration
Allocation • Moves are made and the gain in cost of the overall topology is calculated based on • Monetary cost of the topology • Average network delay per packet • Maximum number of hops between any source-destination pair.
Allocation • For Monetary Cost, the minimum and maximum bounds are calculated as follows: • Minimum : from Esau-Williams algorithm with all the constraints fully relaxed. (TCostMin) • Maximum : we find it from the very first generation. (TCostMax)
Allocation 1.0 0.5 TCost TCostMax TCostMin TCostMax 1 Membership function of a tree in fuzzy subset of low cost trees
Allocation • For Average Network Delay, the minimum and maximum bounds are calculated as follows: • Minimum : delay when all the nodes are connected directly to the center (TDelayMin). • Maximum : initial solution (TDelayMax).
Allocation 1.0 0.5 TDelay TDelayMax TDelayMin TDelayMax 1 Membership function of a tree in fuzzy subset of low average delay tree
Allocation • For Maximum number of hops, the minimum and maximum bounds are calculated as follows: • minimum : 1 hop (THopsMin). • maximum : initial solution (THopsMax).
Allocation 1.0 0.5 THops ThopsMin THopsMax Membership function of a tree in fuzzy subset of low maximum number of hops between any s-d pair
Allocation • The three fuzzy tree measures are combined using the following fuzzy rule: If a solution has low monetarycostAND low average network delay AND low maximum hopsAND it is a good topology. • Using OWA - andlike:
Allocation • What is our move ? • For each selected link, maximum 10 moves are tried (valid or invalid) • Five greedy • Five random • Pick the move which gives the maximum gain among all the moves.
Tabu Search • Diversifies the search by imposing restrictions on the search process, preventing it from moving in certain directions.
Assumptions • The number of segments is known a priori and nodes have already been assigned to segments. • The location of a segment (or of a local site) is represented by its (x,y) coordinates with respect to some reference point. • A node is either 10/100baseT Ethernet or Token Ring Type. • A local site is made of 10/100BaseT Ethernet segments or all Token Ring segments.
Assumptions • The backbone is assumed to be running on Fast Ethernet using fiber optic cable. • Within a local site, only Category 5 cable is used, while between two local sites, only fiber optic cable is used . • Class C networks are assumed. Therefore, we limit the number of nodes per cluster to at most 254. • Hubs, switches, routers, and other networking devices cannot be placed in any location. There are designated location to do so.
