LAN/WAN Optimization LAN/WAN Optimization TechniquesTechniques

Chp.1~Chp.4Chp.1~Chp.4

Harrell J. Van NormanHarrell J. Van Norman

Presented by Shaun ChangPresented by Shaun Chang

OutlineOutline

• NetworksNetworks– Local-Area Networks (LANs)Local-Area Networks (LANs)– Wide-Area Networks (WANs)Wide-Area Networks (WANs)

• Network DesignNetwork Design

• Network Engineering ProcessNetwork Engineering Process

• Network Design ToolsNetwork Design Tools

NetworksNetworks• LANsLANs

– Short-distance networks (less than 1 mile)Short-distance networks (less than 1 mile)– Data transfer between computers & devicesData transfer between computers & devices

• MANsMANs– Medium-distance networks (1 to 50 miles)Medium-distance networks (1 to 50 miles)– Voice, video, data transferVoice, video, data transfer

• WANsWANs– Long-distance networksLong-distance networks– Voice, data, video transfer between local, metrVoice, data, video transfer between local, metr

opolitan, campus, premise networksopolitan, campus, premise networks

LANsLANs

• StandardsStandards– EthernetEthernet– Token BusToken Bus– Token RingToken Ring– FDDIFDDI

Internetworking Internetworking

• Communications HardwareCommunications Hardware– BridgesBridges– BroutersBrouters– RoutersRouters– GatewaysGateways

WAN AccessWAN Access

• Communications HardwareCommunications Hardware– ModemsModems– Multiplexers (FDM, TDM, STDM)Multiplexers (FDM, TDM, STDM)– Channel BanksChannel Banks– CSUs, DSUsCSUs, DSUs

WAN TransportWAN Transport• PrivatePrivate

– Twisted PairTwisted Pair– T1T1– Fractional T-1Fractional T-1– T3T3– Fractional T-3Fractional T-3– DDSDDS– NHDNHD– SONETSONET– SatelliteSatellite– MicrowaveMicrowave

WAN TransportWAN Transport

• PublicPublic– Circuit SwitchingCircuit Switching

•dial-up linesdial-up lines

• ISDNISDN

– Packet Switching Packet Switching •X.25X.25

•Frame RelayFrame Relay

•ATMATM

•SMDSSMDS

OutlineOutline

• NetworksNetworks

• Network DesignNetwork Design– LAN DesignLAN Design– WAN DesignWAN Design

• Network Engineering ProcessNetwork Engineering Process

• Network Design ToolsNetwork Design Tools

Network DesignNetwork Design

• Cost-performance trade-offsCost-performance trade-offs– Prices of the hardwarePrices of the hardware– ReliabilityReliability– Response timeResponse time– AvailabilityAvailability– serviceabilityserviceability

LAN DesignLAN Design• Media choicesMedia choices

– Twisted-pairTwisted-pair– Coaxial cableCoaxial cable– Fiber opticsFiber optics– Wireless systemsWireless systems

• Media access protocolMedia access protocol– Token ring, token bus, Ethernet CSMA/CDToken ring, token bus, Ethernet CSMA/CD

• Cabling strategiesCabling strategies– Intelligent hub wiringIntelligent hub wiring– Distributed cabling systemDistributed cabling system– Centralized proprietary cablingCentralized proprietary cabling

LAN simulation toolsLAN simulation tools

• LAN simulation tools provide measures ofLAN simulation tools provide measures of– UtilizationUtilization– ConflictsConflicts– DelaysDelays– Response timesResponse times

• Identify cost-performance-reliability trade-Identify cost-performance-reliability trade-offsoffs

• Find the bottlenecks in network Find the bottlenecks in network performanceperformance

WAN DesignWAN Design

• Designs based on various routing, Designs based on various routing, multiplexing, and bridging multiplexing, and bridging approachesapproaches

• More complexMore complex– Tariff data changes frequentlyTariff data changes frequently– Many new service offeringsMany new service offerings– Numerous networking optionsNumerous networking options

OutlineOutline

• NetworksNetworks

• Network DesignNetwork Design

• Network Engineering ProcessNetwork Engineering Process– Network AwarenessNetwork Awareness– Network DesignNetwork Design– Network ManagementNetwork Management

• Network Design ToolsNetwork Design Tools

Network Engineering Network Engineering ProcessProcess

Network awareness

Network design

Network manageme

nt

Network awarenessNetwork awareness

• Technology assessmentTechnology assessment

• Current trafficCurrent traffic

• Equipment inventoryEquipment inventory

• Forecasted growthForecasted growth

• Operational evaluation criteriaOperational evaluation criteria

Network designNetwork design

• Network design toolNetwork design tool

• Cost/performance breakeven Cost/performance breakeven analysisanalysis

• Equipment acquisitionEquipment acquisition

Network managementNetwork management

• ConfigurationConfiguration

• Fault managementFault management

• Performance managementPerformance management

• Maintenance and administrationMaintenance and administration

Total network engineering decision Total network engineering decision approachapproach

OutlineOutline

• NetworksNetworks

• Network DesignNetwork Design

• Network Engineering ProcessNetwork Engineering Process

• Network Design ToolsNetwork Design Tools– SimulationSimulation– Analytic ModelsAnalytic Models– BenefitsBenefits– LimitationsLimitations

Experimental measurements Experimental measurements PrototypingPrototyping

• Quality measurement & monitoring Quality measurement & monitoring toolstools

• CumbersomeCumbersome

• ExpensiveExpensive

• Time-consumingTime-consuming

• Relatively inflexibleRelatively inflexible

SimulationSimulation

• Is driven by a stream of Is driven by a stream of pseudorandom numberspseudorandom numbers

• Time-consuming, but more accurateTime-consuming, but more accurate

• Overcome problems caused by Overcome problems caused by simplifying assumptionssimplifying assumptions

Analytic ModelsAnalytic Models

• Require a high degree of abstractionRequire a high degree of abstraction• Difficult to evaluate the performance of Difficult to evaluate the performance of

a complex communication systema complex communication system• Queuing theory plays a major roleQueuing theory plays a major role• Calculate answers in near real-timeCalculate answers in near real-time

BenefitsBenefits

• Minimize CostsMinimize Costs

• Reduce Design TimeReduce Design Time– 1000-devices network designed in about one 1000-devices network designed in about one

hourhour

• Ensure Proper PerformanceEnsure Proper Performance– Avoid costly overbuilding and rebuildingAvoid costly overbuilding and rebuilding

• Assist Design EvaluationAssist Design Evaluation– Evaluate vendor claims and networking Evaluate vendor claims and networking

strategiesstrategies– Verify performance predictionsVerify performance predictions

Benefits--Minimize CostsBenefits--Minimize Costs

• Low-speed access WAN lines are Low-speed access WAN lines are consolidatedconsolidated

• The best transmission services are The best transmission services are obtainedobtained

• Unnecessary facilities are eliminatedUnnecessary facilities are eliminated

• Communications equipment Communications equipment configurations are optimizedconfigurations are optimized

• Save 20 to 45 percentSave 20 to 45 percent

Overbuilding and RebuildingOverbuilding and Rebuilding

LimitationsLimitations

• Cost $5000-100,000 for WAN Cost $5000-100,000 for WAN optimization design tools and up to optimization design tools and up to $10,000 for LAN$10,000 for LAN

• Capable and knowledgeable network Capable and knowledgeable network designers are requireddesigners are required

• Input parameters of traffic volumes, Input parameters of traffic volumes, message sizes, etc are not good enoughmessage sizes, etc are not good enough

• Network design is a process of iterative Network design is a process of iterative design and refinementdesign and refinement

Feedback control Feedback control mechanismsmechanisms

Overall Gain of a SFGOverall Gain of a SFGThe 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 RuleMason's RuleMason'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 :

R

CT

Input

Output

iiPT

Where,

Pi : the total gains of the ith forward path

= 1 - ( of all individual loop gains) + ( of loop gains of all possible non-t

ouching loops taken two at a time) - ( of loop gains of all possible non-touchi

ng loops taken three at a time) + …

i = the value of evaluated with all gain loops touching Pi are eliminated.

Notice: In case, all loops are touching with forward paths (Pi ) , 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.

V5(s)

Example : Find C/R for the attached SFG.

Forward Path gain: (Only one path, So, i =1) P1 = 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 (Pi).

1 = - loop gains touching the forward path (Pi). 1 = 1 - G7.H4 …..……. ……… (3)

Now Substituting equations (1) , (2) & (3) into the Mason’s Rule as :

]1][[ 475432111 HGGGGGGPPT ii

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

iiPT

Using of Mason's Rule to solve Using of Mason's Rule to solve SFGSFG

The following procedure is used to solve any SFG using Mason's rule.

1) Identify the no. of forward paths and their gains (Pi).

2) Identify the number of the loops and determine their gains (Lj).

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.