Data Communication and Networks

Figure 1: The Local Area Connection Status dialog box

4. In the Connection section, find the connection speed. Write down this information and, based on the speed listed, the Ethernet variety your computer is running:

Connection speed:

_______________________________________________________________________________

Ethernet variety:

_______________________________________________________________________________

5. At the command prompt, ping your partner by typing ping -l 60000 IPaddress and pressing Enter. The -l 60000 option in the command specifies that the ping message should be 60000 bytes instead of the typical length of 32 bytes. Note the time = values in the ping replies and write them down. For example, yours might say “time = 2ms,” meaning the reply took 2 milliseconds. Not all times might be the same. Sometimes the first time is slower than the rest. Try pinging a few times to get an idea of the average time.

Ping reply times:

_______________________________________________________________________________

6. Click the Properties button, and in the Local Area Connection Properties dialog box, click Configure.

7. Click the Advanced tab. In the Property list box, click Link Speed & Duplex (or a similar name). Figure 3-15 shows the connection options. Not all NICs have the same options, so you might see different options.

8. The default setting is usually Auto Negotiation. Click 10 Mpbs Half Duplex if this option is available, and then click OK. If you were able to set this option, what speed and variety of Ethernet is your computer running now?

Connection speed:

_______________________________________________________________________________

Ethernet variety:

_______________________________________________________________________________

Figure 2: Settings for the Link Speed & Duplex property

9. After you and your partner have changed the connection speed to a lower value, repeat the ping command you used in Step 6. Write down the reply times, and state whether they were different:

Ping reply times at 10 Mbps:

_____________________________________________________________________________

10. Figure 3 shows two sets of ping results. The first result was from two computers connected “Auto Negotiation mode”. The average reply took <1 ms. The second result was with the same computers connected at 10 Mbps half-duplex, and the average reply took =1 ms. Change your connection speed and duplex mode back to Auto Negotiation, and then close all open windows. Leave your computer running for the next project.

Figure 3: Ping results at different connection speeds

Hands-On Project 2: Viewing an Ethernet Frame

Objective: Capture packets and examine details of the Ethernet II frame format.

Required Tools/Equipment: Classroom computers connected to a classroom hub or switch with Wireshark installed

Description: In this project, you capture some packets and then examine the frame and protocol headers.

1. Use “Wireshark manual” to learn “how to use wireshark to capture data” then ---

2. Start Wireshark and click Capture Options. In the Capture Filter text box, type icmp, and then click Start.

3. Open a command prompt window, and then type ping IPaddress ( IP address of your peer) and press Enter (replacing IPaddress with the IP address of another student's computer or another device on your network).

4. In Wireshark, click the Stop the running live capture toolbar icon to stop the capture.

5. Click a packet summary in the top pane with ICMP listed in the protocol field.

6. In the middle pane, click to expand the Ethernet II row. It should look similar to Figure 4.

Figure 4: An Ethernet II frame in Wireshark

7. Notice the three fields in the Ethernet II frame: Destination, Source, and Type. The Destination and Source fields are the destination and source MAC addresses in the frame. In Figure 4, you see Cisco before the destination address and Vmware before the source address because Wireshark attempts to resolve the NIC manufacturer coded in the MAC address's first six digits. The full MAC address (without manufacturer name) is shown in parentheses. The Type field has the value 0x800, which indicates that the protocol in the frame is IP. Click to expand the Internet Protocol row.

8. Under Internet Protocol, you see details of the IP header, including the destination and source IP addresses. Click to expand the Internet Control Message Protocol row to view details of the ICMP protocol header. (You learn more about IP-related protocols later stage of this subject.)

9. Click to expand the Data portion of the frame, and then click the Data field to see the ICMP message data in hexadecimal in the bottom pane. The right side of this pane shows the translation from hexadecimal to ASCII (human-readable characters); as you can see, it's just portions of the alphabet repeated. Some Ping programs include more clever data, such as “Hello, are you there?” The actual data in a ping message doesn't matter; what matters is that the reply contains the same data as the ping request.

10. Exit Wireshark and click Quit without Saving when prompted. Close the command prompt window.

Hands-On Project 2: Designing a physical star topology using Packet Tracer

Objective: Learning to design a physical network topology

Required Tools/Equipment: Packet tracer only

Description: In this project, you will design physical network topologies.

1. Open Packet Tracer and design a physical star topology made of 6 computers and show it to your tutor.

Tutorial/Lab Activity 3 Page 1 of 4

Tutorial/Lab Activity 3 Page 1 of 4

Tutorial/Lab Activity 4 Page 1 of 5