CCNA 4 Lab 1.4.3 Monitoring VLAN Traffic

Task 1: Demonstrate Broadcasts across a Single LAN

Step 1: Prepare the switch for configuration

NOTE: If the PCs used in this lab are also connected to your Academy LAN or to the Internet, ensure that you record the cable connections and TCP/IP settings so these can be restored at the conclusion of the lab.

1. Referring to the topology diagram, connect the console (or rollover) cable to the console port on the switch and the other cable end to the host computer with a DB-9 or DB-25 adapter to the COM 1 port. Ensure that power has been applied to both the host computer and switch.
2. Establish a HyperTerminal, or other terminal emulation program, connection from PC1 to the switch.
3. Ensure that the switch is ready for lab configuration by verifying that all existing VLAN and general configurations are removed.

1) Remove the switch startup configuration file from NVRAM.

Switch#erase startup-config

Erasing the nvram filesystem will remove all files! Continue? [confirm]

2) Press Enter to confirm.

The response should be:

Erase of nvram: complete

Step 2: Configure the PCs

a. Connect the two PCs to the switch as shown in the topology diagram.

b. Configure the two PCs to have the IP addresses and subnet mask shown in the topology table.

c. Clear the ARP cache on each PC by issuing the arp -d command at the PC command prompt.

d. Confirm that the ARP cache is clear by issuing the arp -a command.

Step 3: Generate and examine ARP broadcasts

1. Launch Wireshark on each PC and start the packet capture for the traffic seen by the NIC in each PC.
2. From the command line of each PC, ping all connected devices.
3. Monitor the operation of Wireshark. Note the ARP traffic registering on each PC.
4. Stop the Wireshark capture on each PC.
5. Examine the entries in the Wireshark Packet List (upper) Pane.
6. Exit Wireshark. (You have the option to save the capture file for later examination.)



Task 2: Demonstrate Broadcasts within Multiple VLANs

Step 1: Configure the VLANs on the switch

1. Using the established console session from PC1 to the switch, set the hostname by issuing the following command from the global configuration mode:

Switch(config)# hostname FC-ASW-1

1. Set interfaces Fa0/1 and Fa0/2 to VLAN 10 by issuing the following commands from the global configuration and interface configuration modes:

FC_ASW-1(config)#interface FastEthernet0/1

FC_ASW-1(config-if)#switchport access vlan 10

% Access VLAN does not exist. Creating vlan 10

FC_ASW-1(config-if)#interface FastEthernet0/2

FC_ASW-1(config-if)#switchport access vlan 10

1. Set interfaces Fa0/3 and Fa0/4 to VLAN 20 by issuing the following commands from the interface configuration mode:

FC_ASW-1(config-if)#interface FastEthernet0/3

FC_ASW-1(config-if)#switchport access vlan 20

% Access VLAN does not exist. Creating vlan 20

FC_ASW-1(config-if)#interface FastEthernet0/4

FC_ASW-1(config-if)#switchport access vlan 20

FC_ASW-1(config-if)#end

1. Confirm that the interfaces are assigned to the current VLANs by issuing the show vlan command from the Privileged EXEC mode. If the VLANs are not assigned correctly, troubleshoot the command entries shown in Steps 1b and 1c and reconfigure the switch.

Step 2: Prepare the PCs

1. Clear ARP cache on each PC by issuing the arp -d command at the PC command prompt.
2. Confirm the ARP cache is clear by issuing the arp -a command.

Step 3: Generate ARP broadcasts

1. Launch Wireshark on each PC and start the packet capture for the traffic seen by the NIC in each PC.
2. From the command line of each PC, ping each of the other three devices connected to the switch.
3. Monitor the operation of Wireshark. Note the ARP traffic registering on the two PCs.
4. Stop the Wireshark capture on each PC.
5. Examine the entries in the Wireshark Packet List (upper) Pane.
6. Exit Wireshark. (You have the option to save the capture file for later examination.)

Step 4: Clean up

Erase the configuration and reload the switch. Disconnect and store the cabling. For PC hosts that are normally connected to other networks (such as the school LAN or to the Internet), reconnect the appropriate cabling and restore the TCP/IP settings.

Task 3: Reflection

1. Discuss the use of VLANS in keeping data traffic separated. What are the advantages of doing this?
2. When designing a network list different criteria that could be used to divide a network into VLANs.