03 evaluating wan performance lab manual

8/3/2019 03 Evaluating WAN Performance Lab Manual

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OPNET IT Guru Lab 3, Page 1

Lab 3: Evaluating Application Performance across a WAN

Objective

In this lab, we have a small LAN with 20 users for a startup company named

Deltasoft Technologies. We investigate the application performance for thiscompany over a T1 line. We will also plan the network by adding a redundantlink between the LAN and the ISP.

Overview

Deltasoft Technologies LAN consists of 20 user PCs sharing three printersand a local file and email server. The users run different online applicationsincluding E-mail, web browsing, video streaming, and FTP. Users also runlocally served applications like intranet E-mail, print, and database access.Our goal is to study the response time for two critical tasks: FTP downloads

and Web Page downloads. Well also analyze the link utilization between theLAN and the ISP.

After an initial assessment, well split the LAN into two smaller switchedsegments and add an extra T1 link between the LAN and the ISP to doublethe available capacity. Load balancing will ensure that both T1 links areequally utilized.

Then well study the effect of failing one of the devices and see the advantageof having the redundant link.

Lab Instructions

Step 1: Open Lab 1

1. Start IT Guru.

2. Select FileOpen

3. Scroll down to the project named Small_Company_LAN_over_WAN,select it and click OK.


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Deltasoft Technologies network is laid out as mentioned in the overview.

The company also has a shared local E-mail and File Server. As an exercise,add a server from the Object Palette and configure it for E-mail and FileSharing applications. This will give you an example of how objects aredeployed to modify a network model.


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Step 2: Add a local Server

1. Open the Object Palette.

2. There are a lot of different objects, which represent network components.From the pull-down menu at the top, you can select a group ofcomponents by vendor or protocol.

3. Select ethernet from the pull-down menu.

4. Select ethernet_server form the palette and click on the workspace todeploy the server. Right-click in the workspace to stop deploying moreservers.

5. To add a link connecting the server and the switch, select the 10BaseTlink from the Object Palette.

6. Click on the 10BT_Switch and then on the server you just added. Right-click in the workspace to stop deploying more links.

7. Close the Object Palette.


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Step 3: Configure the local server for Email and File Sharing

Configure the new server to support E-mail and File Sharing Applications.These applications are already defined in the Applications Object.

1. Right-click on the new server and select Edit Attributes.

2. Set the name attribute to Email & File Server.

3. Click in the Value column for Application: Supported Services where itsays None and select Edit

4. Configure the 2 Applications as follows:

Set the number of Rows to 2.

Click in the Name column for first row and select Email (Heavy).

Click in the second row and select Database.


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5. Click OK twice.

6. Save the project: Click FileSave.

Step 4: Configure and Run the Simulation

Now that the local E-mail and File Sharing server has been configured,

evaluate the network performance for a busy hour of the day.

1. Click on the configure/run simulation toolbar button.

2. Make sure the Simulation Duration is set to 1 hour.

3. Click Run. Monitor the progress bar as the simulation proceeds. It will takeabout 2 minutes for the simulation to finish.

4. When the simulation completes, Click Close.

Step 5: View Results

View the various statistics such as Web Application Response Time, FTPDownload Response Time and the WAN link utilization.

1. Right-click on the WAN link and select View Results to view the utilizationresults for this link.


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2. Expand point-to-point and select utilization since we are onlyinterested in the download link utilization.

3. Select Show. This is the graph for utilization, which will be discussed later,so do not close the graph window.

4. Click Close in the View Results window.

5. Right-click in an empty space in the workspace and select View Resultsto view the global Web Application and FTP Download Response Time.

6. Choose Global StatisticsHTTPPage Response Time (seconds).

7. Click Show.

8. With the same statistic (HTTP Response Time) selected, change the filteron the right-hand bottom corner to average and click on Add.

9. Click on the graph you just created to put the average curve on the samepanel.

10. Repeat the same procedure to view Ftp Download Response Time(sec). Unselect the previous statistic before selecting the new one.

Note: To toggle the graphs on and off, use the hide or show all graphsbutton.


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Your results should be similar to the graphs above.

Download link utilization averages 92%.

Web Application Response Time is close to 1.3 seconds.

FTP Download Response Time is close to 2.5 seconds.

With such high download link utilization; this does not give much availablebandwidth for potential user applications.

Now, we will perform two experiments. Well first add a redundant T1 link todouble the capacity. Load balancing is used to ensure traffic is evenlydistributed between the two links. Then, well fail one of the devices to see theadvantage of adding the new link.


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Step 6: Switch to Next Scenario

Select ScenariosSwitch To ScenarioSmall_Company_LAN_With_Two_Switches_Over_WAN.

The company network is divided into two smaller segments each connectedto a switch. The LAN is connected to the Internet with two T1 lines. EIGRP isused to perform load balancing on the two links.

Step 7: Configure and Run the Simulation

Rerun the simulation for a busy hour of the day to see if the load is balancedacross the two links as intended.

Refer to previous steps for setting the duration and running the simulation.

Step 8: Compare Results

Compare the link utilizations, Web Application and FTP Download Response

Times. We expect that the additional link to the ISP should reduce theapplication response times. The two links should also split the link utilizations.


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1. Right-click on the lower WAN link and select Compare Results.

2. Expand point-to-point under Company_LAN.WAN LINK 1[0] and selectutilization.

3. Click Show.

4. Click Close in the View Results window.

5. Right-click on the upper WAN link and select View Results.

6. Expand point-to-point and select utilization.

7. Click Show and select Close in the View Results window. Since this linkwas not present in the previous scenario, we only see a graph for thecurrent scenario.

8. Now compare the Response Times. Right-click in an empty space in the

workspace and select Compare Results.

9. Choose Global StatisticsFtpDownload Response Time (sec).

10. From the right-hand bottom corner pull-down menus, select average andclick Show.


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11. Repeat the same steps above to select Page Response Time (seconds)under Global Statistics /HTTP. Deselect the previous statistics beforeselecting the new one.

As expected, the link utilization for the lower link reduced from 92% to55% and the new link utilization is close to408%. Thus, load balancing hasbeen done.

Web Application Response Time went down from about 1.1 seconds to0.45 seconds.

FTP Download Response Time went down from 1.25 seconds to 0.6seconds.

This is a significant improvement in both, link utilizations and responsetimes.


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The advantage of using an additional T1 line can be seen by failing one of therouters or links. Well fail one router and compare the utilizations andapplication response times.

Step 9: Switch to Next Scenario

Select ScenariosSwitch To ScenarioSmall_Company_LAN_Failed_One_Router_Over_WAN.

Step 10: Fail one Device

We will fail one of the routers connecting the LAN to the ISP.

Right-click on any one of the routers and select Fail This Node. A red Xappears on the router.

Step 11:Configure and run the simulation

Rerun the simulation for a busy hour to evaluate the network performance.

Refer to previous steps for setting the duration and running the simulation.

Step 12: Compare Results

Compare the results of utilizations and Response Times for all 3 scenarios.This will give a clear picture of the effect of having an additional T1 link.


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1. Select ResultsCompare Results

2. To compare the lower link utilization statistics, choose Object Statistics

Company_LANWAN LINK 1 [0]utilization.

3. Click Show.

4. To compare the link utilization for the upper T1 link, unselect the previousstatistics, then choose Object StatisticsCompany_LANWAN

LINK 2 [0]utilization and click Show.


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5. To compare the response times, choose GlobalStatisticsFtpDownload Response Time (sec).

6. Select average from the pull-down menus on the bottom right corner.

7. Click Show.


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8. Repeat the same procedure for comparing HTTP Page Response Time.


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Conclusion

These results show that the additional T1 link has a significantimprovement in link utilizations as well as the applicationresponse times.

Also, if one of the link or router fails, all the users can still access theInternet at the cost of higher utilization and response times.


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Advanced Scenario

Advanced Scenario 1. Create duplicate scenario ofSmall_Company_LAN_With_One_Switch_Over_WAN and change thedata rate of the WAN link to get an average web response time of 0.5

seconds. Then duplicate the scenarioSmall_Company_LAN_With_Two_Switches_Over_WAN and set the datarate for both the WAN links to the value you used in the previous scenario.Observe the web response time with this data rate.

Advanced Scenario 2. There is continuous streaming between the musicserver and several users defined by a traffic demand object. You can view

this object by selecting ViewDemand ObjectsShow All. Trychanging the traffic volume for these demands.Hint: Edit the Traffic (packets/sec) and Traffic (bits/sec) attributes of thedemand object. Observe its effect on the Web Application and FTP

Download Response Times.

Advanced Scenario 3. Duplicate the last scenario. Recover the failedrouter and then fail one of the WAN links. Check to see if the resultschange.

03 evaluating wan performance lab manual

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