LAN/WAN Optimization Techniques Chp.1~Chp.4 Harrell J. Van Norman Presented by Shaun Chang

Outline Networks Networks –Local-Area Networks (LANs) –Wide-Area Networks (WANs) Network Design Network Design Network Engineering Process Network Engineering Process Network Design Tools Network Design Tools

Networks LANs LANs –Short-distance networks (less than 1 mile) –Data transfer between computers & devices MANs MANs –Medium-distance networks (1 to 50 miles) –Voice, video, data transfer WANs WANs –Long-distance networks –Voice, data, video transfer between local, metropolitan, campus, premise networks

LANs Standards Standards –Ethernet –Token Bus –Token Ring –FDDI

Internetworking Communications Hardware Communications Hardware –Bridges –Brouters –Routers –Gateways

WAN Access Communications Hardware Communications Hardware –Modems –Multiplexers (FDM, TDM, STDM) –Channel Banks –CSUs, DSUs

WAN Transport Private Private –Twisted Pair –T1 –Fractional T-1 –T3 –Fractional T-3 –DDS –NHD –SONET –Satellite –Microwave

WAN Transport Public Public –Circuit Switching dial-up lines dial-up lines ISDN ISDN –Packet Switching X.25 X.25 Frame Relay Frame Relay ATM ATM SMDS SMDS

Outline Networks Networks Network Design Network Design –LAN Design –WAN Design Network Engineering Process Network Engineering Process Network Design Tools Network Design Tools

Network Design Cost-performance trade-offs Cost-performance trade-offs –Prices of the hardware –Reliability –Response time –Availability –serviceability

LAN Design Media choices Media choices –Twisted-pair –Coaxial cable –Fiber optics –Wireless systems Media access protocol Media access protocol –Token ring, token bus, Ethernet CSMA/CD Cabling strategies Cabling strategies –Intelligent hub wiring –Distributed cabling system –Centralized proprietary cabling

LAN simulation tools LAN simulation tools provide measures of LAN simulation tools provide measures of –Utilization –Conflicts –Delays –Response times Identify cost-performance-reliability trade-offs Identify cost-performance-reliability trade-offs Find the bottlenecks in network performance Find the bottlenecks in network performance

WAN Design Designs based on various routing, multiplexing, and bridging approaches Designs based on various routing, multiplexing, and bridging approaches More complex More complex –Tariff data changes frequently –Many new service offerings –Numerous networking options

Outline Networks Networks Network Design Network Design Network Engineering Process Network Engineering Process –Network Awareness –Network Design –Network Management Network Design Tools Network Design Tools

Network Engineering Process Network awareness Network design Network management

Network awareness Technology assessment Technology assessment Current traffic Current traffic Equipment inventory Equipment inventory Forecasted growth Forecasted growth Operational evaluation criteria Operational evaluation criteria

Network design Network design tool Network design tool Cost/performance breakeven analysis Cost/performance breakeven analysis Equipment acquisition Equipment acquisition

Network management Configuration Configuration Fault management Fault management Performance management Performance management Maintenance and administration Maintenance and administration

Total network engineering decision approach

Outline Networks Networks Network Design Network Design Network Engineering Process Network Engineering Process Network Design Tools Network Design Tools –Simulation –Analytic Models –Benefits –Limitations

Experimental measurements Prototyping Quality measurement & monitoring tools Quality measurement & monitoring tools Cumbersome Cumbersome Expensive Expensive Time-consuming Time-consuming Relatively inflexible Relatively inflexible

Simulation Is driven by a stream of pseudorandom numbers Is driven by a stream of pseudorandom numbers Time-consuming, but more accurate Time-consuming, but more accurate Overcome problems caused by simplifying assumptions Overcome problems caused by simplifying assumptions

Analytic Models Require a high degree of abstraction Require a high degree of abstraction Difficult to evaluate the performance of a complex communication system Difficult to evaluate the performance of a complex communication system Queuing theory plays a major role Queuing theory plays a major role Calculate answers in near real-time Calculate answers in near real-time

Benefits Minimize Costs Minimize Costs Reduce Design Time Reduce Design Time –1000-devices network designed in about one hour Ensure Proper Performance Ensure Proper Performance –Avoid costly overbuilding and rebuilding Assist Design Evaluation Assist Design Evaluation –Evaluate vendor claims and networking strategies –Verify performance predictions

Benefits--Minimize Costs Low-speed access WAN lines are consolidated Low-speed access WAN lines are consolidated The best transmission services are obtained The best transmission services are obtained Unnecessary facilities are eliminated Unnecessary facilities are eliminated Communications equipment configurations are optimized Communications equipment configurations are optimized Save 20 to 45 percent Save 20 to 45 percent

Overbuilding and Rebuilding

Limitations Cost $ ,000 for WAN optimization design tools and up to $10,000 for LAN Cost $ ,000 for WAN optimization design tools and up to $10,000 for LAN Capable and knowledgeable network designers are required Capable and knowledgeable network designers are required Input parameters of traffic volumes, message sizes, etc are not good enough Input parameters of traffic volumes, message sizes, etc are not good enough Network design is a process of iterative design and refinement Network design is a process of iterative design and refinement

Feedback control mechanisms

Network Awareness Decision Approach Needs Analysis Needs Analysis Technology assessment Technology assessment Traffic and equipment inventory Traffic and equipment inventory Growth forecast Growth forecast Operational evaluation criteria Operational evaluation criteria

Overall Gain of a SFG The general problem in network analysis of finding the relation between response (output) to stimulus (input) signals is equivalent to finding the overall gain of that network. In SFG analysis, this can be done by two general methods:  Node Absorption (Elimination) method. In this method, the overall gain of SFG from a source node to a sink node may be obtained by eliminating the intermediate nodes.  Mason's rule method.

Mason's Rule Mason's rule is a general gain formula can be used to determine the transfer functions directly. (i.e., relates the output to the input for a SFG. ) Thus the general formula for any SFG is given by : Where, P i : the total gains of the ith forward path  = 1 - (  of all individual loop gains) + (  of loop gains of all possible non- touching loops taken two at a time) - (  of loop gains of all possible non- touching loops taken three at a time) + …  i = the value of  evaluated with all gain loops touching P i are eliminated. Notice: In case, all loops are touching with forward paths (P i ),   i = 1

Touching loops: Loops with one or more nodes in common are called touching. A loop and a path are touching when they have a common node. Non-touching loops : Loops that do not have any nodes in common Non-touching loop gain : The product of loop gains from non-touching loops. V 5 (s) Example : Find C/R for the attached SFG. Forward Path gain: (Only one path, So, i =1)  P 1 = G1.G2.G3.G4.G5 ……………. (1) Loop gains: L1: G2.H1 L2: G4.H2 L3: G7.H4 L4:G2.G3.G4.G5.G6.G6.G7.G8 Non-touching loops taken two at a time: L1&L2 : G2.H1.G4.H2 L1&L3 : G2.H1.G7.H4 L2&L3 : G4.H2.G7.H4 Non-touching loops taken three at a time: L1,L2&L3: G2.H1.G4.H2.G7.H4

According to Mason’s rule:  = 1 - (G2.H1 + G4.H2 + G7.H4 + G2.G3.G4.G5.G6.G7) + [G2.H1.G4.H2 + G2.H1.G7.H4 + G4.H2.G7.H4] – [G2.H1.G4.H2.G7.H4] ……. ……. ……… (2) Then, we form  i by eliminating from  the loop gains that touch the forward path (P i ).   1 =  -  loop gains touching the forward path (P i ).   1 = 1 - G7.H4 …..……. ……… (3) Now Substituting equations (1), (2) & (3) into the Mason’s Rule as : sum of all individual loop gains sum of gain products of all possible non-touching loops taken two at a time sum of gain products of all possible non-touching loops taken three at a time

Using of Mason's Rule to solve SFG The following procedure is used to solve any SFG using Mason's rule. 1) Identify the no. of forward paths and their gains (P i ). 2) Identify the number of the loops and determine their gains (L j ). 3) Identify the non-touching loops taken two at a time, a three at a time, … etc. 4)Determine  5)Determine  i  6) Substitute all of the above information in the Mason's formula.