7.3.3 Packet Tracer – Observe Data Flow in a LAN Answers

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Packet Tracer – Observe Data Flow in a LAN (Answers Version)

Answers Note: Red font color or gray highlights indicate text that appears in the Answers copy only.

Objectives

• Develop an understanding of the basic functions of Packet Tracer.
• Create/model a simple Ethernet network using 3 hosts and a switch.
• Observe traffic behavior on the network.
• Observer data flow of ARP broadcasts and pings.

Instructions

Part 1:  Create a logical network diagram with 3 PCs and a switch.

During an activity, to ensure that the instructions always remain visible, click the “top” check box in the instruction box window.

The bottom left hand corner of the Packet tracer screen displays the icons that represent device categories or groups, such as Routers, Switches, or End Devices.

Moving the cursor over the device categories will show the name of the category in the box. To select a device, first select the device category. When the device category is selected, the options within that category appear in the box next to the category listings. Select the device option that is required.

1. Select End Devices from the options in the bottom left-hand corner. Drag and drop 3 generic PCs onto your design area.
2. Select Switch from the options in the bottom left-hand corner. Add a 2960 switch to your prototype network by dragging it onto your design area.
3. Select Connections from the bottom left-hand corner. Choose a copper straight-through cable type. Click the first host (PC0) and assign the cable to the FastEthernet0 connector. Click the switch (Switch0) and select a connection FastEthernet0/1 for PC0.
4. Repeat step c for PC1 and PC2. Select FastEthernet0/2 on the Switch0 for PC1 and FastEthernet0/3 for PC2.

There should be green dots at both ends of each cable connection after the network has converged. If not, double check the cable type selected.

Part 2:  Configure host names and IP addresses on the PCs.

1. Click PC0. Select the Config tab. Change the PC Display Name to PC-A. Select FastEthernet tab on the left and add 192.168.1.1 as the IP address and 255.255.255.0 as the subnet mask. Close PC-A when done.
2. Click PC1. Select the Config tab. Change the PC Display Name to PC-B. Select FastEthernet tab on the left and add 192.168.1.2 as the IP address and 255.255.255.0 as the subnet mask. Close PC-B when done.
3. Click PC2. Select the Config tab. Change the PC Display Name to PC-C. Select FastEthernet tab on the left and add 192.168.1.3 as the IP address and 255.255.255.0 as the subnet mask. Close PC-C when done.

Part 3:  Observe the flow of data from PC-A to PC-C by creating network traffic.

1. Switch to Simulation Mode in the bottom right-hand corner.
2. Click Edit Filter in the Edit List Filter area. In the event list filter, click All/None to deselect every filter. Click Edit Filter. Select ARP and ICMP filters under IPv4 tab.
3. Select a Simple PDU by clicking the closed envelope in the upper toolbar. With the envelop icon, click PC-A to establish the source. Click PC-C to establish the destination.

Note: Notice that two envelopes are now positioned beside PC-A. One envelop is ICMP, while the other is ARP. The Event List in the Simulation Panel will identify exactly which envelop represents ICMP and which represents ARP.

4. Select Play from the Play Controls in the Simulation Panel. You can speed up the simulation using the Play Speed Slider. The Play Speed Slider is located below Play inside the Simulation Panel. Dragging the button to the right will speed up the simulation, while dragging is to the left will slow down the simulation.
5. Observe the path ICMP and ARP envelope. Click View Previous Event to continue when the buffer is full.
6. Click Reset Simulation in the Simulation Panel. Notice that the ARP envelop is no longer present. This has reset the simulation but has not cleared any configuration changes or dynamic table entries, such as ARP table entries. The ARP request is not necessary to complete the ping because PC-A already has the MAC address in the ARP table.
7. Click Capture then Forward inside the Simulation Panel. The ICMP envelop will moved from the source to the switch and stop. The Capture then Forward allows you to move the simulation one step at a time. Continue selecting the Capture then Forward until you complete the event.
8. Click the Power Cycle Device on the bottom left, above the device icons.
9. An error message will appear asking you to confirm reset. Click Yes. Now both the ICMP and ARP envelops are present again. The power cycle will clear any configuration changes not saved and will clear all dynamic table entries, such as the ARP and MAC table entries.
10. Exit the simulation mode by clicking Realtime a allow the network to converge.
11. After the network has converged, enter the simulation mode.

Part 4:  View ARP Tables on each PC.

1. Click Play to repopulate the ARP table on the PCs. Click View Previous Event when the buffer is full.
2. Click Inspect (magnifying glass) in the upper tool bar.
3. With the magnifying glass, click PC-A. Select ARP Table in the pop-up menu. Notice that PC-A has an ARP entry for PC-C. View the ARP tables for PC-B and PC-C as well. Close all ARP table windows.
4. Click Select in the upper tool bar.
5. Click PC-A and select the Desktop tab.
6. Select the Command Prompt and enter the command arp -a to view the ARP table from the desktop view. Close the PC-A configuration window.

C:\> arp -a

Internet Address        Physical Address      Type

192.168.1.3             0003.e406.e430        dynamic

7. Examine the ARP tables for PC-B and PC-C. Close the Command Prompt window when finished.

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