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Showing posts with label ITGURU. Show all posts
Showing posts with label ITGURU. Show all posts

OSPF: Open Shortest Path First


A Routing Protocol Based on the Link-State Algorithm
Objective
The objective of this lab is to configure and analyze the performance of the Open Shortest Path First (OSPF) routing protocol.
Overview
In Lab 6 we discussed RIP, which is the canonical example of a routing protocol built on the distance-vector algorithm. Each node constructs a vector containing the distances (costs) to all other nodes and distributes that vector to its immediate neighbors. Link-state routing is the second major class of intra-domain routing protocol. The basic idea behind link-state protocols is very simple: Every node knows how to reach its directly connected neighbors, and if we make sure that the totality of this knowledge is disseminated to every node, then every node will have enough knowledge of the network to build a complete map of the network.
Once a given node has a complete map for the topology of the network, it is able to decide the best route to each destination. Calculating those routes is based on a well-known algorithm from graph theory—Dijkstra’s shortest-path algorithm.
OSPF introduces another layer of hierarchy into routing by allowing a domain to be partitioned into areas. This means that a router within a domain does not necessarily need to know how to reach every network within that domain—it may be sufficient for it to know how to get to the right area. Thus, there is a reduction in the amount of information that must be transmitted to and stored in each node. In addition, OSPF allows multiple routes to the same destination to be assigned the same cost and will cause traffic to be distributed evenly over those routers.
In this lab, you will set up a network that utilizes OSPF as its routing protocol. You will analyze the routing tables generated in the routers and will observe how the resulting routes are affected by assigning areas and enabling load balancing.
Procedure
Create a New Project
1. Start OPNET IT Guru Academic Edition ⇒ Choose New from the File menu.
2. Select Project and click OK ⇒ Name the project <your initials>_OSPF, and the scenario No_Areas ⇒ Click OK.
3. In the Startup Wizard: Initial Topology dialog box, make sure that Create Empty Scenario is selected Click Next Select Campus from the Network Scale list ⇒ Click Next three times ⇒ Click OK.
Create and Configure the Network
The slip8_gtwy node model represents an IP-based gateway supporting up to eight serial line interfaces at a selectable data rate. The RIP or OSPF protocols may be used to automatically and dynamically create the gateway's routing tables and select routes in an adaptive manner.
The PPP_DS3 link has a data rate of 44.736 Mbps.
Initialize the Network:
  1. The Object Palette dialog box should now be on top of your project workspace. If it is not there, open it by clicking clip_image004. Select the routers item from the pull-down menu on the object palette.
a. Add to the project workspace eight routers of type slip8_gtwy. To add an object from a palette, click its icon in the object palette ⇒ Move your mouse to the workspace and click to place the object ⇒ You can keep on left-clicking to create additional objects. Right-click when you are finished placing the last object.
  1. Switch the palette configuration so it contains the internet_toolbox. Use bidirectional PPP_DS3 links to connect the routers. Rename the routers as shown below.
  1. Close the Object Palette and then save your project.
clip_image006

Configure the Link Costs:
1. We need to assign link costs to match the following graph:









2. Like many popular commercial routers, OPNET router models support a parameter called a reference bandwidth to calculate the actual cost, as follows:
Cost = (Reference bandwidth) / (Link bandwidth)
where the default value of the reference bandwidth is 1,000,000 Kbps.
3. For example, to assign a cost of 5 to a link, assign a bandwidth of 200,000 Kbps to that link. Note that this is not the actual bandwidth of the link in the sense of transmission speed, but merely a parameter used to configure link costs.
  1. To assign the costs to the links of our network, do the following:
i. Select all links in your network that correspond to the links with a cost of 5 in the above graph by shift-clicking on them.
ii. Select the Protocols menu ⇒ IPRoutingConfigure Interface Metric Information.
iii. Assign 200000 to the Bandwidth (Kbps) field ⇒ Check the Interfaces across selected links radio button, as shown Click OK. 

clip_image010

  1. Repeat step 4 for all links with a cost of 10 but assign 100,000 Kbps to the
Bandwidth (Kbps) field.
  1. Repeat step 4 for all links with a cost of 20 but assign 50,000 Kbps to the
Bandwidth (Kbps) field.
  1. Save your project.
Configure the Traffic Demands:
  1. Select both RouterA and RouterC by shift-clicking on them.
i. Select the Protocols menu ⇒ IPDemandsCreate Traffic Demands
⇒ Check the From RouterA radio button as shown ⇒ Keep the color as blue ⇒ Click Create. Now you should see a blue-dotted line representing the traffic demand between RouterA and RouterC.


clip_image012

2. Select both RouterB and RouterH by shift-clicking on them.
i. Select the Protocols menu ⇒ IPDemandsCreate Traffic Demands
⇒ Check the From RouterB radio button ⇒ Change the color to red ⇒ Click
OK Click Create.
Now you can see the lines representing the traffic demands as shown.

clip_image014

3. To hide these lines: Select the View menu ⇒ Select Demand Objects ⇒ Select
Hide All.
  1. Save your project.
Configure the Routing Protocol and Addresses:
Auto-Assign IP Addresses assigns a unique IP address to connected IP interfaces whose IP address is currently set to auto-assigned. It does not change the value of manually set IP addresses.
1. Select the Protocols menu ⇒ IPRoutingConfigure Routing Protocols.
2. Check the OSPF check box ⇒ Uncheck the RIP check box ⇒ Uncheck the
Visualize Routing Domains check box, as shown:


clip_image016

3. Click OK.
4. Select RouterA and RouterB only ⇒ Select the Protocols menu ⇒ IPRouting Select Export Routing Table for Selected Routers Click OK on
the Status Confirm dialog box.
5. Select the Protocols menu ⇒ IPAddressing ⇒ Select Auto-Assign IP Addresses.
6. Save your project.
Configure the Simulation
Here we need to configure some of the simulation parameters:
1. Click on clip_image018 and the Configure Simulation window should appear.
2. Set the duration to be 10.0 minutes.
3. Click OK and then save your project.
Duplicate the Scenario
In the network we just created, all routers belong to one level of hierarchy (i.e., one area). Also, we didn’t enforce load balancing for any routes. Two new scenarios will be created. The first new scenario will define two new areas in addition to the backbone area. The second one will be configured to balance the load for the traffic demands between RouterB and RouterH.

The Areas Scenario:

Loopback interface allows a client and a server on the same host to communicate with each other using TCP/IP.
1. Select Duplicate Scenario from the Scenarios menu and give it the name
Areas Click OK.
2. Area 0.0.0.1:
i. Select the three links that connect RouterA, RouterB, and RouterC by shift-clicking on them ⇒ Select the Protocols menu ⇒ OSPFConfigure Areas ⇒ Assign the value 0.0.0.1 to the Area Identifier, as shown ⇒ Click OK.

clip_image020

ii. Right-click on RouterCEdit Attributes ⇒ Expand the OSPF Parameters hierarchy ⇒ Expand the Loopback Interfaces hierarchy ⇒ Expand the row0 hierarchy ⇒ Assign 0.0.0.1 to the value of the Area ID attribute ⇒ Click OK.
3. Area 0.0.0.2:
i. Click somewhere in the project workspace to disable the selected links and then repeat step 2-i for the three links that connect RouterF, RouterG, and RouterH but assign the value 0.0.0.2 to their Area Identifier.

OPNET provides two types of IP load balancing:

With Destination Based, load balancing is done on a per-destination basis. The route chosen from the source router to the destination network is the same for all packets. With Packet Based, load balancing is done on a per-packet basis. The route chosen from the source router to the destination network is redetermined for every individual packet.
4. To visualize the areas we just created, select the Protocols menu ⇒ OSPFVisualize Areas Click OK. The network should look like the following one with different colors assigned to each area (you may get different colors though).
Note:
- The area you did not configure is the backbone area and its Area Identifier = 0.0.0.0.
- The figure shows the links with a thickness of 3.


clip_image022
The Balanced Scenario:
  1. Under the Scenarios menu, Switch to Scenario ⇒ Select No_Areas.
  1. Select Duplicate Scenario from the Scenarios menu, and give it the name
Balanced Click OK.
3. In the new scenario, select both RouterB and RouterH by shift-clicking on them.
  1. Select the Protocols menu ⇒ IPRoutingConfigure Load Balancing Options Make sure that the option is Packet-Based and the radio button Selected Routers is selected as shown Click OK.
clip_image024

5. Save your project.
Run the Simulation
To run the simulation for the three scenarios simultaneously:
1. Go to the Scenarios menu ⇒ Select Manage Scenarios.
2. Click on the row of each scenario and click the Collect Results button. This should change the values under the Results column to <collect> as shown.

clip_image026

3. Click OK to run the three simulations. Depending on the speed of your processor, this may take several seconds to complete.
4. After the three simulation runs complete, one for each scenario, click Close and then save your project.
View the Results
The No_Areas Scenario:
1. Go back to the No_Areas scenario.
2. To display the route for the traffic demand between RouterA and RouterC: Select the Protocols menu ⇒ IPDemandsDisplay Routes for Configured Demands Expand the hierarchies as shown and select RouterA Æ RouterC ⇒ Go to the Display column and pick Yes ⇒ Click Close.

clip_image028

3. The resulting route will appear on the network as shown:

clip_image030

4. Repeat step 2 to show the route for the traffic demand between RouterB and RouterH. The route is as shown below. (Note: Depending on the order in which you created the network topology, the other “equal-cost” path can be used, that is, the RouterB-RouterA-RouterD-RouterF-RouterH path).
clip_image032

The Areas Scenario:
  1. Go to scenario Areas.
  1. Display the route for the traffic demand between RouterA and RouterC. The route is as shown:
clip_image034

3. Save your project.
The Balanced Scenario:
  1. Go to scenario Balanced.
  1. Display the route for the traffic demand between RouterB and RouterH. The route is as shown:
clip_image036

3. Save your project.

RIP: Routing Information Protocol


A Routing Protocol Based on the Distance-Vector Algorithm
Objective
The objective of this lab is to configure and analyze the performance of the Routing Information Protocol (RIP) model.
Overview
A router in the network needs to be able to look at a packet’s destination address and then determine which of the output ports is the best choice to get the packet to that address. The router makes this decision by consulting a forwarding table. The fundamental problem of routing is: How do routers acquire the information in their forwarding tables?
Routing algorithms are required to build the routing tables and hence forwarding tables. The basic problem of routing is to find the lowest-cost path between any two nodes, where the cost of a path equals the sum of the costs of all the edges that make up the path. Routing is achieved in most practical networks by running routing protocols among the nodes. The protocols provide a distributed, dynamic way to solve the problem of finding the lowest-cost path in the presence of link and node failures and changing edge costs.
One of the main classes of routing algorithms is the distance-vector algorithm. Each node constructs a vector containing the distances (costs) to all other nodes and distributes that vector to its immediate neighbors. RIP is the canonical example of a routing protocol built on the distance-vector algorithm. Routers running RIP send their advertisements regularly (e.g., every 30 seconds). A router also sends an update message whenever a triggered update from another router causes it to change its routing table.
In this lab you will set up a network that utilizes RIP as its routing protocol. You will analyze the routing tables generated in the routers, and you will observe how RIP is affected by link failures.
Procedure
Create a New Project
1. Start OPNET IT Guru Academic Edition ⇒ Choose New from the File menu.
2. Select Project and click OK ⇒ Name the project <your initials>_RIP, and the scenario NO_Failure ⇒ Click OK.
3. In the Startup Wizard: Initial Topology dialog box, make sure that Create Empty Scenario is selected Click Next Select Campus from the Network Scale list ⇒ Click Next three times ⇒ Click OK.
Create and Configure the Network
The ethernet4_slip8_ gtwy node model represents an IP-based gateway supporting four Ethernet hub interfaces and eight serial line interfaces. IP packets arriving on any interface are routed to the appropriate output interface based on their destination IP address. The Routing Information Protocol (RIP) or the Open Shortest Path First (OSPF) protocol may be used to dynamically and automatically create the gateway's routing tables and select routes in an adaptive manner.
Initialize the Network:
  1. The Object Palette dialog box should now be on top of your project workspace. If it is not there, open it by clicking clip_image004. Make sure that the internet_toolbox is selected from the pull-down menu on the object palette.
  1. Add to the project workspace the following objects from the palette: one ethernet4_slip8_gtwy router and two 100BaseT_LAN objects.
a. To add an object from a palette, click its icon in the object palette ⇒ Move your mouse to the workspace ⇒ Click to place the object ⇒ Right-click to stop creating objects of that type.
  1. Use bidirectional 100BaseT links to connect the objects you just added as in the following figure. Also, rename the objects as shown (right-click on the node ⇒ Set Name).
  1. Close the Object Palette dialog box.
  1. Save your project.
clip_image006
Configure the Router:
  1. Right-click on Router1Edit Attributes ⇒ Expand the IP Routing Parameters hierarchy and set the following:
i. Routing Table Export = Once at End of Simulation. This asks the router to export its routing table at the end of the simulation to the simulation log.
  1. Click OK and then save your project.
Add the Remaining LANs:
The PPP_DS3 link has a data rate of 44.736 Mbps.
1. Highlight or select simultaneously (using shift and left-click) all five objects that you currently have in the project workspace (one router, two LANs, and two links). You can click-and-drag a box around the objects to do this.
2. Press Ctrl+C to copy the selected objects and then press Ctrl+V to paste them.
3. Repeat step 2 three times to generate three new copies of the objects and arrange them in a way similar to the following figure. Rename all objects as shown.
4. Connect routers, as shown, using PPP_DS3 links.
clip_image008

Choose the Statistics
RIP traffic is the total amount of RIP update traffic (in bits) sent/received per second by all the nodes using RIP as the routing protocol in the IP interfaces in the node.
Total Number of Updates is the number of times the routing table at this node gets updated (e.g., due to a new route addition, an existing route deletion, and/or a next hop update).
To test the performance of the RIP protocol, we will collect the following statistics:
  1. Right-click anywhere in the project workspace and select Choose Individual Statistics from the pop-up menu.
  1. In the Choose Results dialog box, check the following statistics:
    1. Global Statistics RIP Traffic Sent (bits/sec).
    1. Global Statistics RIP Traffic Received (bits/sec).
    1. Nodes Statistics Route Table Total Number of Updates.
  1. Click OK and then save your project.
Configure the Simulation
Auto Addressed means that all IP interfaces are assigned IP addresses automatically during simulation. The class of address (e.g., A, B, or C) is determined based on the number of hosts in the designed network. Subnet masks assigned to these interfaces are the default subnet masks for that class.
Export causes the auto-assigned IP interface to be exported to a file (name of the file is <net_name>-ip_addresses.gdf and gets saved in the primary model directory).
Here we need to configure some of the simulation parameters:
1. Click on clip_image010 and the Configure Simulation window should appear.
2. Set the duration to be 10.0 minutes.
3. Click on the Global Attributes tab and change the following attributes:
a. IP Dynamic Routing Protocol = RIP. This sets the RIP protocol to be the routing protocol of all routers in the network.
b. IP Interface Addressing Mode = Auto Addressed/Export.
c. RIP Sim Efficiency = Disabled. If this attribute is enabled, RIP will stop after the "RIP Stop Time." But we need the RIP to keep updating the routing table in case there is any change in the network (as we will see in the second scenario).
4. Click OK and then save the project.
clip_image012

Duplicate the Scenario
In the network we just created, the routers will build their routing tables, and then they will not need to update them further because we didn’t simulate any node or link failures. In this scenario we will simulate failures so that we can compare the behavior of the routers in both cases.
1. Select Duplicate Scenario from the Scenarios menu and name it Failure
Click OK.
2. Open Object Palette by clicking clip_image004[1]. Select the Utilities palette from the drop-down menu.
4
3. Add a Failure Recovery object to your workspace and name it Failure as shown ⇒ Close the Object Palette dialog box.
clip_image014

4. Right-click on the Failure object ⇒ Edit Attributes ⇒ Expand the Link Failure/Recovery Specification hierarchy Set rows to 1 Set the attributes of the added row, row 0, as follows:
clip_image016

This will “fail” the link between Router1 and Router2 200 seconds into the simulation.
5. Click OK and then save the project.
Run the Simulation
To run the simulation for both scenarios simultaneously:
1. Go to the Scenarios menu ⇒ Select Manage Scenarios.
2. Change the values under the Results column to <collect> (or <recollect>) for both scenarios. Compare to the following figure.
clip_image018

3. Click OK to run the two simulations. Depending on the speed of your processor, this may take several seconds to complete.
4. After the two simulation runs complete, one for each scenario, click Close ⇒ Save your project.
View the Results
Compare the Number of Updates:
1. Select Compare Results from the Results menu.
2. Change the drop-down menu in the right-lower part of the Compare Results dialog box to Stacked Statistics as shown.
clip_image020
3. Select the Total Number of Updates statistic for Router1 and click Show.
4. You should get two graphs, one for each scenario. Right-click on each graph and select Draw StyleBar.
5. The resulting graphs should resemble the following (you can zoom in on the graphs by clicking-and-dragging a box over the region of interest):
clip_image022
Obtain the IP Addresses of the Interface:
Before checking the contents of the routing tables, we need to determine the IP address information for all interfaces in the current network. Recall that these IP addresses are assigned automatically during simulation, and we set the global attribute IP Interface Addressing Mode to export this information to a file.
1. From the File menu choose Model FilesRefresh Model Directories. This causes OPNET IT Guru to search the model directories and update its list of files.
  1. From the File menu choose Open ⇒ From the drop-down menu choose Generic Data File Select the <your initials>_RIP-NO_Failure-ip_addresses file (the other file created from the Failure scenario should contain the same information) ⇒ Click OK.
clip_image024


  1. The following is a part of the gdf file content. It shows the IP addresses assigned to the interfaces of Router1 in our network. For example the interface of Router1 that is connected to Net11 has the IP address 192.0.0.1 (Note: Your result may vary due to different nodes placement.) The Subnet Mask associated with that interface indicates that the address of the subnetwork, to which the interface is connected, is 192.0.0.0 (i.e., the logical AND of the interface IP address and the subnet mask).
clip_image026
  1. Print out the layout of the network you implemented in this lab. On this layout, from the information included in the gdf file, write down the IP addresses associated with Router1 as well as the addresses assigned to each subnetwork as shown in the following two figures (Note: Your IP addresses may vary due to different nodes placement.)
clip_image028


Compare the Routing Tables Content:
  1. To check the content of the routing tables in Router1 for both scenarios:
i. Go to the Results menu ⇒ Open Simulation Log ⇒ Expand the hierarchy on the left as shown below ⇒ Click on the field COMMON ROUTE TABLE.
clip_image030
2. Carry out the previous step for both scenarios. The following are partial contents of Router1’s routing table for both scenarios (Note: Your results may vary due to different nodes placement):
Routing table of Router1 (NO_Failure scenario):
clip_image032

Loopback interface allows a client and a server on the same host to communicate with each other using
TCP/IP.
Routing table of Router1 (Failure scenario):
clip_image034

Simulation of a Small Office Network in IT Guru

Introduction

In this lesson, you will learn how IT Guru can model organizational scaling by using the tool to model a real-world “what if” problem. You will learn how to use

IT Guru features to build and analyze network models.

In this lesson, you will

• Build a network quickly

• Collect statistics about network performance

• Analyze these statistics

clip_image001[14]

In this lesson, you use the Project Editor to build a topology of a small internetwork, choose statistics to collect, run a simulation, and analyze the results.

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In this lesson, you plan for the expansion of a small company’s intranet. Currently, the company has a star topology network on the first floor of its office building and plans to add an additional star topology network on another floor. You will build and test this “what-if” scenario to ensure that the load added by the second network will not cause the network to fail.

 

image

Getting Started

When creating a new network model, you must first create a new project and scenario. A project is a group of related scenarios that each explore a different aspect of the network. Projects can contain multiple scenarios.

After you create a new project, you use the Startup Wizard to set up a new scenario. The options in the

Wizard let you

• Define the initial topology of the network

• Define the scale and size of the network

• Select a background map for the network.

• Associate an object palette with the scenario

clip_image001[8]

Startup Wizard automatically appears each time you create a new project. The Startup Wizard allows you to define certain aspects of the network environment.

To use the Startup Wizard to set up a new scenario, do the following:

1 If IT Guru is not already running, start it.

2 Select File > New....

3 Select Project from the pull-down menu and click

OK.

4 Name the project and scenario, as follows:

4.1 Name the project <initials>_Sm_Int

Include your initials in the project name to distinguish it from other versions of this project.

4.2 Name the scenario first_floor.

4.3 Click OK.

➥ The Startup Wizard opens.

Enter the values shown in the following table in the dialog boxes of the Startup Wizard:

image

image

You can use any of three methods to create a network topology, or a combination of all three. One method is to import the topology (discussed in a later lesson).

Another is to place individual nodes from the object palette into the workspace. The third method is to use

Rapid Configuration.

Rapid Configuration creates a network in one action after you select a network configuration, the types of nodes within the network, and the types of links that connect the nodes.

To create the first-floor network using Rapid Configuration:

1 Select Topology > Rapid Configuration.

Select Star from the drop-down menu of available configurations, then click OK....

image

Specify the node models and link models in the network. Models follow this naming scheme:

<protocol1>_..._<protocoln>_<function>_<mod>

where:

<protocol> specifies the specific protocol(s) supported by the model

<function> is an abbreviation of the general function of the model

<mod> indicates the level of derivation of the model

For example:

ethernet2_bridge_int

specifies the intermediate (int) derivation of a 2-port

Ethernet (ethernet2) bridge (bridge).

Vendor models have an additional prefix that specifies the vendor and the vendor product number for that particular network object.

For example, the 3Com switch used in this lesson is named:

3C_SSII_1100_3300_4s_ae52_e48_ge3

This node is a stack of two 3Com SuperStack II 1100 and two Superstack II 3300 chassis

(3C_SSII_1100_3300) with four slots (4s), 52 auto-sensing Ethernet ports (ae52), 48 Ethernet ports

(e48), and 3 Gigabit Ethernet ports (ge3).

To specify the nodes and links to use to build the network:

1 Set the Center Node Model to 3C_SSII_1100_3300_4s_ae52_e48_ge3. This is a 3Com switch.

2 Set the Periphery Node Model to Sm_Int_wkstn, and change the Number of periphery nodes to 30. This provides 30 Ethernet workstations as the peripheral nodes.

Set the Link Model to 10BaseT.

Specify where the new network will be placed:

1 Set the X center and Y center to 25.

2 Set the Radius to 20.

image

3 Click OK.

➥ The network is drawn in the Project Editor:

image

Now that the general network topology has been built, you need to add a server. You will use the second method of creating network objects: dragging them from the object palette into the workspace.

1 If it is not already open, open the object palette by clicking on the

Object Palette action button.

image 

2 Find the Sm_Int_server object in the palette and drag it into the workspace.

You will not find this exact server model on other object palettes because we created it with the correct configuration for this tutorial.

By default, you can create additional instances of the same object by left-clicking after the initial “drag-and-drop” from the palette.

3 Because you do not need additional copies of this model, right-click to turn off node creation.

You also need to connect the server to the star network.

1 Find the 10BaseT link object in the palette and click on it.

2 Click on the server object, then click on the switch object in the center of the star.

➥ A link is drawn, connecting the two objects.

3 Right-click to turn off link creation.

Finally, you need to add configuration objects to specify the application traffic that will exist on the network. Configuring the application definition and profile definition objects can be complicated, so you do not have to do these tasks right now. For this tutorial, we included, on the object palette:

• an application definition object with the default configurations of the standard applications, and

• a profile definition object with a profile that models light database access

You need only drag the objects into your network. Doing so means that the traffic caused by workstations accessing a database at a low rate will be modeled.

1 Find the Sm_Application_Config object in the palette and drag it into the workspace

2 Right-click to turn off object creation.

3 Find the Sm_Profile_Config object in the palette, drag it into the workspace, and right-click.

4 Close the object palette.

The network is now built and should look similar to the following figure.

image

You are now ready to begin collecting statistics.

Collecting Statistics

clip_image001[10]

You can collect statistics from individual nodes in your network (object statistics) or from the entire network (global statistics).

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Now that you have created the network, you should decide which statistics you need to collect to answer the questions presented earlier in this lesson:

• Will the server be able to handle the additional load of the second network?

• Will the total delay across the network be acceptable once the second network is installed?

To answer these questions, you need a snapshot of current performance for comparison. To get this baseline, you will collect one object statistic, Server Load, and one global statistic, Ethernet Delay.

Server load is a key statistic that reflects the performance of the entire network. To collect statistics related to the server’s load, do the following steps:

1 Right-click on the server node (node_31) and select Choose Individual Statistics from the server’s Object pop-up menu.

➥ The Choose Results dialog box for node_31 appears.

The Choose Results dialog box hierarchically organizes the statistics you may collect. To collect the Ethernet load on the server:

2 Click the plus sign next to Ethernet in the Choose Results dialog box to expand the Ethernet statistic hierarchy.

image

3 Click the checkbox next to Load (bits/sec) to enable collection for that statistic.

4 Click OK to close the dialog box.

Global statistics can be used to gather information about the network as a whole. For example, you can find out the delay for the entire network by collecting the global Delay statistic:

1 Right-click in the workspace (but not on an object) and select Choose Individual Statistics from the

Workspace pop-up menu.

image

2 Expand the Global Statistics hierarchy.

3 Expand the Ethernet hierarchy.

4 Click the checkbox next to Delay (sec) to enable data collection.

5 Click OK to close the Choose Results dialog box.

It is good to get into the habit of saving your project every so often. To save the project:

1 Choose File > Save, then click OK (the project already has a name, so you don’t need to rename it).

Now that you have specified which statistics to collect and saved the project, you are almost ready to run your simulation.

First, though, verify that your repositories preference is set. Repositories contain user-defined components such as process models and pipeline stages that are saved so that simulations will take less time to begin execution.

1 Choose Edit > Preferences.

2 Type repositories in the Find field and click on the Find button.

3 If the value for repositories is not stdmod, click on the field and enter stdmod in the dialog box.

4 Click OK to close the repositories and

Preferences dialog boxes

To run a simulation:

1 Select Simulation > Configure Discrete Event Simulation….

You can also open the Configure Discrete Event Simulation dialog box by clicking on the configure/run simulation action button.

2 Type 0.5 in the Duration: field to simulate one-half hour of network activity.

image

Click the Run button to begin the simulation.

While the simulation runs, a dialog box appears showing the simulation’s progress.

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The dialog box above shows that, in 5 seconds of elapsed (actual) time, IT Guru has simulated 15 minutes and 19 seconds of network time. The entire simulation should take less than one minute to complete—the elapsed time varies according to the speed of your computer.

4 When the simulation finishes, the contents of the

Messages tab appears. Click the Close button in the Simulation Sequence dialog box.

5 If your simulation does not complete, if no results were collected, or if the results vary significantly from those shown, you will have to troubleshoot your simulation. See "Troubleshooting Tutorial Simulations".

Viewing Results

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You can view results graphically in the Project Editor by selecting View Results from the Workspace pop-up menu.

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After your simulation has executed, you will want to see the information collected for each statistic. There are several ways to view results; in this lesson you will use the View Results option in the Workspace pop-up menu.

You will learn different ways to view results in later lessons.

To view the server Ethernet load for the simulation:

1 Right-click on the server node (node_31) choose

View Results from the server’s Object pop-up menu.

➥ The node’s View Results dialog box opens.

2 Expand the Office network.node_31 > Ethernet hierarchy.

Click on the checkbox next to Load (bits/sec) to indicate that you want to view that result.

4 Click the Show button in the View Results dialog box.

➥ The graph of the server load appears in the Project Editor, as shown in the following figure.

The graph of the server load should resemble the following graph. Your results may differ slightly due to differences in node placement and link length, but the general trends should be consistent.

Server Load Graph

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Note that at its peak, the load on the server is well below 6,000 bits/second. You will need this baseline for comparison after you add the second network.

When you finish viewing the server load graph, close this dialog box and the View Results dialog box. (If the system prompts you, choose to delete the graph panel.)

You also should look at the Global Ethernet Delay on the network. To view this statistic:

1 Right-click in the workspace, then select View Results from the pop-up menu.

2 Check the box next to Global Statistics > Ethernet > Delay, then click the Show button to view the Ethernet delay for the whole network.

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➥ The Ethernet delay graph appears in the Project Editor.The graph should resemble the following figure.

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