LAN/WAN Optimization LAN/WAN Optimization Techniques Techniques

AgendaAgenda

Current TrafficCurrent TrafficEquipment Inventory and Forecasted Equipment Inventory and Forecasted

GrowthGrowthOperational Evaluation CriteriaOperational Evaluation CriteriaNetwork Design Decision ApproachNetwork Design Decision Approach

Current TrafficCurrent Traffic

LoadsLoadsTraffic classesTraffic classesTraffic response timesTraffic response timesTransaction typesTransaction typesProtocol overheadProtocol overhead

LoadsLoads

Traffic Loads : the volume of data communTraffic Loads : the volume of data communication trafficication traffic

-data-data

-data transmission overhead-data transmission overhead

Loads (cont.)Loads (cont.)

Traffic Load is generally calculated by analTraffic Load is generally calculated by analytically-based NDTs on the following paraytically-based NDTs on the following parameters:meters:

-message definition-message definition

-message characteristics-message characteristics

- traffic load is required by NDTs for each l- traffic load is required by NDTs for each location on the networkocation on the network

Loads (cont.)Loads (cont.)

NDTs calculate traffic load based on standNDTs calculate traffic load based on standard deviations from average values accouard deviations from average values account for these peaks and valleys in traffic volnt for these peaks and valleys in traffic volumeume

-peak-peak

-normal-normal

-valley-valley

Traffic classesTraffic classes

Traffic loads should be broken down into Traffic loads should be broken down into these types of traffic classes for message these types of traffic classes for message prioritizingprioritizing

-real time-real time

-interactive-interactive

-file transfer-file transfer

Traffic response timesTraffic response times

Average transaction response timesAverage transaction response times

RT=I+CPU+ORT=I+CPU+O

Traffic response times (cont.)Traffic response times (cont.)

Polling environments :Polling environments :

I or O =T+W+SI or O =T+W+S

Traffic response times (cont.)Traffic response times (cont.)

Service timesService times

Transmission time is the time needed to send Transmission time is the time needed to send the entire message (overhead and text) down the entire message (overhead and text) down the linethe line

Traffic response times (cont.)Traffic response times (cont.)

Connection delay is the time needed by the front-Connection delay is the time needed by the front-end processor to establish a connection with end processor to establish a connection with terminal, including modem turnaroundsterminal, including modem turnarounds

Polling delay is attributed to multipoint lines in Polling delay is attributed to multipoint lines in which terminals must wait their turn before being which terminals must wait their turn before being polled by the front-end processorpolled by the front-end processor

Traffic response times (cont.)Traffic response times (cont.)

Arrival rates: number of messages that arrive Arrival rates: number of messages that arrive at all the terminals on the lineat all the terminals on the line

Line utilization (U)Line utilization (U)

Waiting time (W) Waiting time (W) P-K formula:P-K formula:

Transaction typesTransaction types

The most appropriate approach calculates The most appropriate approach calculates response time based on the varied mixture of response time based on the varied mixture of transaction types that each location supportstransaction types that each location supports

Protocol overheadProtocol overhead

Control messages are necessary in both Control messages are necessary in both poll and select scenarios to inquire if the poll and select scenarios to inquire if the terminal has data to send or is ready to terminal has data to send or is ready to receivereceive

-polling mode-polling mode -select mode-select mode -control message : requires data rates, line -control message : requires data rates, line

sizessizes -protocol overhead-protocol overhead

Protocol overhead (cont.)Protocol overhead (cont.)

agendaagenda

Current TrafficCurrent TrafficEquipment Inventory and Forecasted GroEquipment Inventory and Forecasted Gro

wthwthOperational Evaluation CriteriaOperational Evaluation CriteriaNetwork Design Decision ApproachNetwork Design Decision Approach

Equipment Inventory and ForecasteEquipment Inventory and Forecasted Growthd Growth

Equipment inventoryEquipment inventory InventoryInventory forecastingforecasting

Equipment inventoryEquipment inventory

Without an accurate awareness of the Without an accurate awareness of the communications network, design and communications network, design and analysis is impracticalanalysis is impractical

Equipment inventories and growth Equipment inventories and growth forecasts develop an understanding of the forecasts develop an understanding of the network that is fundamental to any network that is fundamental to any engineering processengineering process

InventoryInventory

An essential of network design is An essential of network design is identifying communications equipment identifying communications equipment

Physical resourcesPhysical resources

-compatibility-compatibility

-meet the needs of the network’s users-meet the needs of the network’s users

Inventory (cont.)Inventory (cont.) Location-in order to identifying communication equiLocation-in order to identifying communication equi

pment types, locations of all devices must be specipment types, locations of all devices must be specifiedfied

-equipment types and locations are known, fixed, un-equipment types and locations are known, fixed, unalterablealterable

-equipment types and location possibilities are know-equipment types and location possibilities are knownn

- equipment locations determination accommodates - equipment locations determination accommodates an unlimited selection of possibilitiesan unlimited selection of possibilities

Types-reference 6.4 communication hardwareTypes-reference 6.4 communication hardware

forecastingforecasting

Network engineers need to consider Network engineers need to consider forecasted growth when conducting design forecasted growth when conducting design exercisesexercises

Forecasting growth is critical during Forecasting growth is critical during network designnetwork design

Once current and future applications of Once current and future applications of data communications have been identified, data communications have been identified, engineer must forecast growth trends in engineer must forecast growth trends in usage over the planning periodusage over the planning period

Forecasting (cont.)Forecasting (cont.)

Forecasting based on trends is the safest Forecasting based on trends is the safest method of determining the future of data method of determining the future of data communications traffic demandscommunications traffic demands

-trend lines are independent of business -trend lines are independent of business activityactivity

-outside affects are suspected-outside affects are suspected

-trend lines generally follow business -trend lines generally follow business activity activity

Forecasting (cont.)Forecasting (cont.)

trend lines are not directly dependent on trend lines are not directly dependent on business activity, survey must be business activity, survey must be conducted in an attempt to explain the conducted in an attempt to explain the independenceindependence

Purpose of surveys is to establish the Purpose of surveys is to establish the aspects of business activity on which the aspects of business activity on which the data communications usage will dependdata communications usage will depend

agendaagenda

Current TrafficCurrent TrafficEquipment Inventory and Forecasted GroEquipment Inventory and Forecasted Gro

wthwthOperational Evaluation CriteriaOperational Evaluation CriteriaNetwork Design Decision ApproachNetwork Design Decision Approach

Operational Evaluation CriteriaOperational Evaluation Criteria

PerformancePerformanceAvailabilityAvailabilityReliabilityReliabilityCostCostsecuritysecurity

PerformancePerformance

Evaluate what performance criteria are Evaluate what performance criteria are necessary for acceptable operational necessary for acceptable operational characteristics of the networkcharacteristics of the network

-response time-response time

-throughput-throughput

-utilization-utilization

-blocking rate-blocking rate

AvailabilityAvailability

AvailabilityAvailability

　　 -reliability (MTBF)-reliability (MTBF)

-serviceability (MTTR)-serviceability (MTTR)

Serial-overall system availabilitySerial-overall system availability

Availability (cont.)Availability (cont.)

Parallel-overall system availabilityParallel-overall system availability

ReliabilityReliability

Mean time between failuresMean time between failures

CostCost

Line cost –recurring monthly service Line cost –recurring monthly service charges & nonrecurring one-time charges & nonrecurring one-time installation costsinstallation costs

Equipment costEquipment costSoftware costSoftware cost

securitysecurity

The most effective security measures The most effective security measures involve a variety of barriers of different involve a variety of barriers of different types and different placestypes and different places

agendaagenda

Current TrafficCurrent TrafficEquipment Inventory and Forecasted GroEquipment Inventory and Forecasted Gro

wthwthOperational Evaluation CriteriaOperational Evaluation CriteriaNetwork Design Decision ApproachNetwork Design Decision Approach

Network Design Decision ApproachNetwork Design Decision Approach

Network design tool utilizationNetwork design tool utilizationCost-performance break-even analysisCost-performance break-even analysisEquipment acquisitionEquipment acquisition

Network design tool utilizationNetwork design tool utilization

This step involved selection of the most This step involved selection of the most appropriate design technique, acquisition appropriate design technique, acquisition of an NDT, development of a network of an NDT, development of a network model, and analysis of the modelmodel, and analysis of the model

--most critical step of the entire network --most critical step of the entire network engineering processengineering process

Network design phaseNetwork design phase

Cost-performance break-even analCost-performance break-even analysisysis

This step involved generating and This step involved generating and evaluating alternative network designsevaluating alternative network designs

What-if questions are used to evaluate What-if questions are used to evaluate various alternative configurationsvarious alternative configurations

-proposals for adding / deleting resources-proposals for adding / deleting resources

-redesign application to improve the -redesign application to improve the performanceperformance

-modeling different routing strategies-modeling different routing strategies

Cost-performance break-even analCost-performance break-even analysis (cont.)ysis (cont.)

Each of the various alternative Each of the various alternative configurations will have associated costs configurations will have associated costs and performance levelsand performance levels

Trade-off between cost/performanceTrade-off between cost/performance

Equipment acquisitionEquipment acquisition

This step involves obtaining the necessary This step involves obtaining the necessary equipment as specified in the optimal equipment as specified in the optimal optimized network designoptimized network design

Once this step is complete, an optimizedOnce this step is complete, an optimized

implementable design is available as input implementable design is available as input into the next phase: network managementinto the next phase: network management