13.1.3 pt answers
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xpertcomputerrepairs13.1.
3 Packet Tracer - Identify MAC and IP Addresses
Objectives
Part 1: Gather PDU Information for a Local Network Communication
Part 2: Gather PDU Information for a Remote Network Communication
Background
If you are interested in a career in network administration or network security, it is important to
understand normal network communication processes. In this Packet Tracer activity, you will
inspect Ethernet frames and IP packets at different points in the network as they travel from
source to destination. You will focus on the way that the MAC and IP addresses change
depending on the destination (local or remote) and the place where the PDUs are captured.
Packet Tracer has a simulation mode which will enable you to investigate details about how
PDUs travel on networks. It enables you to check the Layer 2 MAC addressing and Layer 3 IPv4
addressing of the PDUs at different locations in the network as the PDUs flow from source to
destination.
This activity is optimized for viewing PDUs as they travel on local and remote networks. You will
gather PDU information in PT simulation mode and answer a series of questions about the data
you collect. No device configuration is required.
Instructions
Part 1: Gather PDU Information for a Local Network Communication
In this part, you will study how a device on a local network does not need a default gateway to
communicate with another device on the same local network.
Note: Review the Reflection Questions in Part 3 before proceeding with this part. It will give you
an idea of the type of information you will need to gather.
a. Click host 172.16.31.3 and open the Command Prompt.
b. Enter the ping 172.16.31.2 command. This command will issue a series of ICMP echo request
packets to the destination. If the packets reach the destination, it will send echo-reply messages
pack to the source of the ping requests.
c. Click the Simulation mode button to switch to simulation mode. Repeat the ping
172.16.31.2 command. An envelope icon that represents a PDU appears next to 172.16.31.3.
d. Click the PDU and locate the following information in both the OSI Model and Outbound PDU
Details tabs. The Outbound PDU Details tab shows simplified packet and frame headers for the
PDU. You should observe the following details regarding addressing for the PDU.
At Device: 172.16.31.3
Source MAC Address: 0060.7036.2849
Destination MAC Address: 000C:85CC:1DA7
Source IP Address: 172.16.31.3
Destination IP Address: 172.16.31.2
e. Click Capture / Forward (the right arrow followed by a vertical bar) and the PDU moves to
the next step in its journey. Use the OSI model tab to gather the same information from Step 1d.
Repeat this process until the PDU reaches its destination. For each step on the path to delivery,
record the information for each PDU into a spreadsheet that uses a format like the table shown
below. The information for the first step is shown in the table.
Example Spreadsheet Format
At Device Src MAC Dest. MAC Src IPv4 Dest IPv4
172.16.31.3 0060.7036.2849 000C:85CC:1DA7 172.16.31.3 172.16.31.2
Switch 2 0060.7036.2849 000C:85CC:1DA7 N/A N/A
172.16.31.2 (in) 000C:85CC:1DA7 000C:85CC:1DA7 172.16.31.3 172.16.31.2
172.16.31.2 (out) 0060.7036.2849 0060.7036.2849 172.16.31.2 172.16.31.3
f. You will notice that the information for the inbound PDU is unchanged.
In the PDU information window, click the tab for the outbound PDU. How does the addressing
differ, and why? Record the addressing in your table.
The source and destination address are reversed in both the frame and packet because this PDU
will be sent back to host 172.16.31.3. This message will be a ping echo-reply.
g. Return to Realtime mode.
Part 2: Gather PDU Information for a Remote Network Communication
To communicate with remote networks, a gateway device is necessary. The gateway device
connects two or more networks together. In this part, you will study the process that takes place
when one device communicates with another device that is on a remote network. Pay close
attention to the MAC addresses used.
Note: Move your mouse over the Router. You will see information about the addressing of the
router interfaces. Refer to these addresses as you observe the PDU flow through the router.
a. Return to the Command Prompt for 172.16.31.3.
b. Enter the ping 10.10.10.2 command. The first couple of pings may time out.
c. Switch to Simulation mode and repeat the ping 10.10.10.2 command. A PDU appears next
to 172.16.31.3.
d. Click the PDU and note the following information tab:
At Device: 172.16.31.3
Source MAC Address: 0060.7036.2849
Destination MAC Address: 00D0:BA8E:741A
Source IP Address: 172.16.31.3
Destination IP Address: 10.10.10.2
What device and interface has the destination MAC address that is shown?
The router interface FasteEthernet1/0
e. Click Capture / Forward (the right arrow followed by a vertical bar) to move the PDU to the
next device. Gather the same information from Step 1d. Repeat this process until the PDU
reaches its destination. Record the PDU information you gathered from pinging 172.16.31.5 to
10.10.10.2 into a spreadsheet using a format like the sample table shown below. Enter details
for both the inbound and outbound PDUs at the Router.
At Device Src MAC Dest. MAC Src IPv4 Dest IPv4
172.16.31.3 00D0:D311:C788 00D0:BA8E:741A 172.16.31.3 10.10.10.2
Switch 2 0060.7036.2849 00D0:BA8E:741A N/A N/A
Router (in) 0060.7036.2849 00D0:BA8E:741A 172.16.31.3 10.10.10.2
At Device Src MAC Dest. MAC Src IPv4 Dest IPv4
Router (out) 00D0:588C:2401 0060:2F84:4AB6 172.16.31.3 10.10.10.2
Switch 1 00D0:588C:2401 0060:2F84:4AB6 N/A N/A
Access Point N/A N/A N/A N/A
10.10.10.2 0060:2F84:4AB6 00D0:588C:2401 10.10.10.2 172.16.31.5
f. Repeat the process for the echo-reply message that originates from host 10.10.10.2. Complete
the table for each step.
At Device Src MAC Dest. MAC Src IPv4 Dest IPv4
10.10.10.2 0060:2F84:4AB6 00D0:588C:2401 10.10.10.2 172.16.31.3
Access Point N/A N/A N/A N/A
Switch 1 0060:2F84:4AB6 00D0:588C:2401 N/A N/A
Router (in) 0060:2F84:4AB6 00D0:588C:2401 10.10.10.2 172.16.31.3
Router (out) 00D0.BA8E.741A 0060.7036.2849 10.10.10.2 172.16.31.3
Switch 1 00D0.BA8E.741A 0060.7036.2849 N/A N/A
Access Point N/A N/A N/A N/A
10.10.10.2 00D0.BA8E.741A 0060.7036.2849 10.10.10.2 172.16.31.5
Reflection Questions
Answer the following questions regarding the captured data:
1. What different types of cables/media were used to connect devices?
copper, fiber, and wireless
2. Did the cables change the handling of the PDU in any way?
No
3. Did the wireless Access Point do anything to the PDUs that it received?
Yes. It repackaged them as wireless 802.11 frames.
4. Was PDU addressing changed by the access point?
No
5. What was the highest OSI layer that the Access Point used?
Layer 1
6. At what Layer of the OSI model do cables and access points operate?
Layer 1
7. When examining the PDU Details tab, which MAC address appeared first, the source or the
destination?
Destination
8. Sometimes PDUs were marked with red Xs while others had green check marks. What is the
significance of these markings?
The PDUs that are marked with Xs were not accepted by a device because the destination
address did not match the device’s MAC address.
9. Every time that the PDU was sent between the 10 network and the 172 network, there was a
point where the MAC addresses suddenly changed. Where did that occur?
It occurred at the router
10. Which device uses MAC addresses that start with 00D0:BA?
The router
11. What devices did the other MAC addresses belong to?
To the sending device and receiving device
12. Did the sending and receiving IPv4 addresses change in any of the PDUs?
No
13. When you follow the reply to a ping, sometimes called a pong, what happens to the source
and destination addresses?
They switch because the receiving device is now the source.
14. Why do you think the interfaces of the router are part of two different IP networks?
The function of a router is to interconnect different IP networks. It must be a member of both
networks to do this.