OPNET Modeller lab booklet Keith Sharp Glasgow Caledonian University - edited 2012 Lab Files for Opnet Modeler – Introductory Lab Manual To do the labs in the Opnet Modeler Introductory Lab Manual requires some additional files which can be downloaded from the following location, or can be issued to you by your lab instructor during a lab session. At present the lab files can be downloaded from the following location: Blackboard->Course Documents->Opnet Labs-> Week 1->Labs From here download the zip file – intro_modeler_labs.zip Extract the contents of this folder and you will find two folders: Hotel_Net project_environment To get started with the labs in the Introductory Lab Manual proceed with the following steps. Start Opnet Modeler via VMware player in the usual way (see the Handout entitled: “Working with Opnet and VMware Player at GCU ” for instructions on how to do this). Once you have initialized Opnet Modeler you will see that the following three folders will be added to the Desktop of the virtual machine: op_models op_admin op_reports Typically these folders are not found on the desktop for the application so we must associate these folders with Opnet Modeler so that the application knows to look in these folders.
Before we can associate the folders with the application we first follow these steps. i) Copy the folders Hotel_net and project_environment you extracted from the .zip file and put them into the newly created op_models folder on the virtual desktop. Note that files must be dragged and dropped to and from VMware player to action a copy and paste operation, cutting and pasting alone will not work. Keith Sharp Glasgow Caledonian University - edited 2012 ii) Go to the main console screen for Opnet Modeler Select File->Manage Model Files->Add Model Directory Once you click Add Model Diretory the following screen will appear, locate the op_models folder on your VMware desktop and select it.
Keith Sharp Glasgow Caledonian University - edited 2012 Click OK to add the directory, the following Confirm Model Directory screen will appear, select the check box named “Include all sub-directories” only and Click OK And, finally, from the main menu select: File -> Manage Model Files -> Refresh Model Directories, to update the application‟s environment variables. Keith Sharp Glasgow Caledonian University - edited 2012 3. BEFORE STARTING THE LABS PLEASE NOTE: When doing the introductory labs you may be required to open an existing project at some point, i. from the files you downloaded.
The default view you will see on doing a File->Open may look like this: (Please note that the below screenshot will be visible only when you will select the op_models from desktop by clicking on the Look in) Please note that this is the default view for opening files and projects in Opnet Modeler 16.1, however the traditional File->Open view for Opnet Modeler can be switched to by clicking on the Switch to file chooser organized by model directories button: which is located in the bottom left of the default File-Open view. To change to the traditional view – which is what we will be using and referring to in the lab material for this course – click this button and the view will change to the following screen view below. When you change to this view you can now see that the Model directories now associates the folder C:\Documents and Settings\Student\Desktop\op_models with the application. Keith Sharp Glasgow Caledonian University - edited 2012 When you expand this directory you will see that the Hotel_net and project_environment sub-directories, which are the project folders you extracted from the downloaded zip files, are also listed under the model directories.
To change back to the previous view click on the Switch to general file chooser button: Important: When you create a new Project in Opnet Modeler it will automatically create a folder with the name you give your project, make sure you select this folder when saving your project – try and keep all your projects organised in your op_models directory. This will make things easier if you wish to save your work between labs. Remember: It is up to you to save your work between lab sessions. Save your lab files to either a portable storage device, such as a USB memory stick – or you can save your lab files (i.
the folders op_admin, op_models, op_reports) each week to your student H: drive on the GCU network. You must drag and drop these folders to/from the VMware player to copy them across from/to your chosen storage location. If you do save your work each week in this way then any preferences you alter in Opnet Modeler can be maintained and the above procedure can be reduced to simply refreshing the model directories. Opnet Modeler projects can become quite large and so each student should have an increased quota for their H: drive disk space – this should be around 500MB.
If you have any problems storing projects to your student H: drive/personal storage device ask your lab instructor for assistance. Keith Sharp Glasgow Caledonian University - edited 2012 LAB 3 Keith Sharp Glasgow Caledonian University - edited 2012 Simulation of Computer Networks Lab 3: LAN Switching Lab Objectives: In this lab you will implement switched local area networks and examine the performance of different scenarios connecting LANs with switches and hubs. Here you will set up LANs using two different switching devices: hubs and switches. Remember that a hub forwards packets which arrive on any of its inputs to all of its outputs.
A switch on the other hand will forward incoming packets to one or more outputs depending on the destination of packets. In the lab below you are going to study how the throughput and collision of packets in a switched network are affected by the configuration of the network and the type of switching devices used. Overview: Computer networking involves understanding limitations of equipment and technology, be they physical (number of interfaces on a device) or logical (number of usable IP addresses within a subnet). There is a limit to how many hosts can be attached to a single network and to the size of the geographical area that a network can serve (e.
the physical limitations of transmission media -cabling, wireless signal etc). The most common form of network infrastructure in terms of Local Area Networks (LANs) is a switched Ethernet environment. A switch is a device with several inputs and outputs leading to and from the hosts that the switch interconnects. Switches allow for the intercommunication between one host and another.
The central role of the switch in the LAN is to take packets that arrive on an input and forward (or switch) them to the correct output so that they will reach their required destination. One key issue with a switch is that it must cope with the finite bandwidth of its outputs. If packets for a certain output arrive at the switch and their arrival rate is greater than the capacity of the switch output then we have a problem of contention. The switch will be forced to queue, or buffer, packets until the contention lessens.
If the contention lasts for too long, then the switch will run out of buffer space and will have to discard packets. If packets are discarded too frequently, we end up with a congested switch and this makes for an inefficient network. PART 1 - Creating the Project 1. Start Opnet Modeler – Choose File, New, Project, then click OK.
Name the project <you_initials>_SwitchedLAN, and the scenario HubOnly and then click OK. In the Startup Wizard: Initial Topology dialogue box, ensure that Create Empty Scenario is selected. Click Next, then choose Office from the Network Scale list, -> Click Next, three times – and then finally click Finish. Close the Object Palette when your empty project opens.
Keith Sharp Glasgow Caledonian University - edited 2012 PART 2 - Building the Network Model To create the switched LAN: 1. From the Project Editor choose Topology -> Rapid Configuration…. Then from the drop down menu select Star and click Next. Click the Select Models… button in the Rapid Configuration dialogue box.
From the Model List drop down menu choose ethernet and click OK. In the Rapid Configuration dialogue box set the following values: a. Center Node Model = ethernet16_hub b. Periphery Node Model = ethernet_station c.
Link Model = 10BaseT d. Radius = 42 Click OK once you have entered the values (note: the 10BaseT link represents an Ethernet connection operating at 10Mbps). Right-click on node_16, which is the hub -> Edit Attributes and change the name attribute to “Hub1” and click OK. Save your project.
From the Project Editor, File -> Save then you should already have a folder listed <your_initials>_SwitchedLAN.project in the left hand pane (in file chooser mode) of the Save As dialogue box, click on this folder and then keeping the File name as <your_initials_SwitchedLAN> click Save. Now that you have created the network it should look similar to the one pictured here: Keith Sharp Glasgow Caledonian University - edited 2012 PART 3 - Configuring the Workstations Here you will configure the workstations to generate traffic. Right click on any of the 16 workstations (node_0 to node_15) – and from the menu Select Similar Nodes. All the workstations in the workspace will be selected when you do this.
Right click on any of the 16 stations, Edit Attributes: Check the Apply Changes to Selected Objects check box - this an important feature to use to prevent you configuring each node individually. Expand the Traffic Generation Parameters attribute, and the Packet Generation Arguments in the hierarchy. Set the following 4 values by clicking in the Value field and selecting Edit: ON State Time: (exponential) 100 OFF State Time: (constant) 0.02 Packet Size (bytes): (constant) 1500 Note: Packet Size in a switched Ethernet LAN will differ depending on what the networks Maximum Transmission Unit MTU needs to be. This is the maximum size of the Ethernet Frame traversing the network at Layer 2.
Click OK to close the attribute editing window(s) then Save your project changes. Note that the parameters that have just been set are only available to a limited number of models in Opnet‟s standard model library – referred to as the packet generating nodes. These models usually have names that end in “station” or “uni_source” and contain the Keith Sharp Glasgow Caledonian University - edited 2012 compound attribute called “Traffic Generation Parameters” which lets the modeller generate streams of “generic packets” (i. not linked to any specific network Keith Sharp Glasgow Caledonian University - edited 2012 application layer or layer 3 protocol).
Consequently this method of traffic generation is often used to study Layer 2 technologies such as Ethernet, Frame Relay, and ATM, but there are traffic generating workstation nodes for IP also (however here we are investigating Ethernet traffic). PART 4 – Choosing Statistics for Collection Now that we have configured the nodes to generate traffic within the LAN we now need to choose the traffic-related statistics we wish to collect during the simulation. To choose statistics to be collected during the simulation: 1) Right click anywhere in the project workspace and select from the menu Choose Individual DES Statistics. 2) In the Choose Results dialogue box, choose the following 4 statistics: Ethernet Delay: Global Statistics->Ethernet->Delay (sec) The Ethernet Delay represents the end to end delay of all packets received by all the stations.
Traffic Received: Global Statistics->Traffic Sink->Traffic Received (packets/sec) Represents the amount of traffic received by all the sinks across all the nodes in the network, a sink is where a packet terminates, on termination any associated statistics are updated for example the Traffic Received global statistic would be incremented (Double-click on a workstation node, how many sinks does a workstation have?).