241_Lab2_Instructions_2205_Netlab

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NSSA 241 Lab 2 – Introduction to Switching - Netlab Before starting each activity, review the questions to ensure that you have recorded all observations and data for your lab report. Only two students may work on one bench that has three PCs. Two benches comprise a pod of six PCs which are numbered 1-6. Overview In this lab you will setup and configure a switch. You will then use this switch in two different network topologies to examine network traffic and filtering. Lab objectives:  Set up a basic switched topology.  Learn the write erase procedure for the Cisco switches.  Examine switch filtering.  Examine SAT population.  Examine Ethernet frames and protocol encapsulation. Activity 0 – Setup  Before beginning any lab, reboot Windows 10 on all PCs to reset the network configurations. Part I – Examining Filtering on a Single Switch Network Activity 1 – Construct a Basic Single Switched Network 1. Power up your network rack and switch. 2. Manually configure the IP address and mask on each bench PC using: IP address: 192.168.100.PM Netmask 255.255.255.0 . 3. Do not configure anything else. Refer back to the directions from last week if you need a refresh on how to change the network settings. Verify and record the MAC and IP address for each PC on the bench in the table below. Use ipconfig or ipconfig /all as you did in last week’s lab. You will reference this information throughout the lab. Activity 1 Questions: IP Address MAC Address PC1/4 PC2/5 PC3/6 2205 – SPH/SPM Page 1

NSSA 241 Lab 2 – Introduction to Switching - Netlab 4. Construct the topology in the diagram below using the Cisco 3750 switch labeled E on the bench rack (F or G could also be used). You can connect to any ports on the switch. 5. Use ping to test that you have full connectivity between all your devices. Remember to physically examine the switch for connectivity indicators via the lights on the ports. PC 1/4 pings  PC 2/5 PC 2/5 pings  PC 1/4 PC 3/6 pings  PC 2/5 Activity 2 –Switch Setup and Configuration 1. On PC1/4 , setup a console connection to the switch so that you can see and make configuration settings and see switch data:  Locate the green PC console ports on the bench rack (one per PC) – this port is wired to the console port on the back of the PC. Look at the connection to trace the wiring.  Locate the green console port on the bench rack for the Cisco switch, labeled with the equipment letter. This port is wired to the console port on the back of the switch.  Use a straight-though Ethernet cable to connect the green PC1/4 console port in the bench rack to the green Cisco switch console port. 2205 – SPH/SPM Page 2

NSSA 241 Lab 2 – Introduction to Switching - Netlab 2. Open and configure a terminal emulator program to configure the switch:  Search for Putty on your Windows PC and start it Configure the Putty terminal session:  Session: Serial (change from SSH)  Connection: Serial  Serial Line: COM 1  9600 Baud  8 bits of data  1 stop bit  No parity  No flow control Open the connection. 3. Once Putty is running, you should see the switch booting up in the terminal window. If it has already booted, you may need to hit the enter key to see the switch activity. NOTE: as your switch boots up, there are two possibilities: (1) the switch may be completely unconfigured and set to factory defaults or (2) it may have previously been configured You will need to determine which state it is in to move ahead accordingly. Pay careful attention to this every week so that you are starting with a clean slate and not using a switch with unknown configurations. (1) If the switch is unconfigured (set at factory defaults), you will see the following prompt: === SYSTEM CONFIGURATION DIALOG === Would you like to enter the initial configuration dialog? [yes]: <no> Press RETURN (ENTER) to get started! If you are seeing this autoconfiguration prompt, move past this gray instruction box, but keep in mind that you may need to erase your switch in the upcoming weeks using the write erase procedure in the Appendix. (2) If the switch has been previously configured, you will see the following prompt: Switch> If you are seeing the prompt indicating that your switch has already been configured, you MUST erase the device and reset it to the factory defaults. See Appendix 2 for the directions on how to erase the switch. 4. Once your device is set to the factory defaults (write erased), answer NO to the question regarding the initial configuration dialogue. We do not want to ever use the autoconfiguration in this class because it is very limited. 2205 – SPH/SPM Page 3

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NSSA 241 Lab 2 – Introduction to Switching - Netlab Once you answer NO, the switch should immediately exit the autoconfiguration dialog and you will see the following prompt: Switch> If you accidentally start the automatic setup you can break out of the setup by enter <ctrl> c. If asked in the autoconfiguration dialog, you should never set a password (do not enable secret) on these devices. Activity 3 – Exploring the Switch Source Address Table Now we are ready to start gathering data about our network. We will look at what commands are available on the switch and examine the SAT. 1. Useful commands for the Cisco Command Line Interface (CLI) include: a. ? b. tab key c. exit Keep these in mind as you move through the lab exercises. 2. There are several layers of configuration on the switches. The first layer displays a prompt: Switch> This level is very limited - you can examine some of the switch settings but you are not able to make any changes at this level. Use the ? to see what commands are available. The space bar will continue your page scrolling. 3. From your MS DOS command window (not the terminal connection window to the switch), ping again across all your PCs to ensure connectivity . This will also populate the switch Source Address Table (SAT). 4. From the switch terminal window , run the command show mac address-table to see the SAT entries on the switch. Record the SAT entries using the table below. Ignore VLANS; you are looking for the dynamic entries in the table. These should directly correlate to your bench PC MAC addresses. Verify this with the data collected earlier or by using ipconfig again. 2205 – SPH/SPM Page 4

NSSA 241 Lab 2 – Introduction to Switching - Netlab Activity 3 Questions: Switch Port PC Mac Address PC Name (PC1, PC2, PC3 etc.) Explain step by step how this SAT table was built considering the messages (pings) that have been sent on your network. In other words, how did the entries above get added to the table? Activity 4 – Examining Switched Traffic Flow Wireshark will be used to examine the traffic that is visible on the three network segments. To ensure an accurate test, ping from PC1/4 to the other 2 bench PCs immediately before beginning this test. Note: Be sure to always ping from the MS-DOS command prompt and not from a console session that you have connected to the switch. 1. Start a Wireshark capture on all three PCs. (refer to last week’s lab for a refresher on instructions and remember to select the Ethernet 2 network adapter for capturing or you will see incorrect results) 2. PC1/4 pings  PC2/5 Stop the capture on all the PCs. Examine and record on which PCs the pings (echo request and echo reply) were captured and on which the pings were not visible. Use the table below to identify the ping results and explain why each ping is visible or not on each segment. Be sure to reference the switch SAT in your answer. PC1/4 pings  PC2/5 Activity 4 Questions: Wireshark observing from Is ping visible (yes/no) Explain why the ping is visible or not PC 1/4 PC 2 /5 2205 – SPH/SPM Page 5

NSSA 241 Lab 2 – Introduction to Switching - Netlab PC 3 /6 Part II – Examining Filtering on an Extended Switched Network (Using Multiple Switches) Activity 5 – Layer 2 Traffic Flow with Multiple Switches The objective of this activity is to observe how switches locate nodes (the PCs) on distant LAN segments. You will extend your topology by connecting the two pod switches to each other. 1. Build the topology below by connecting the two bench switches. Check that there are green lights on all switch ports to which there is a device connected (either a PC or another switch port). Activity 6 – Layer 2 Traffic Flow with Multiple Switches Expanded Ping and observe traffic as we did in our earlier experiments. 1. Examine the SAT on the switches. Note that you have changed the topology, so the question arises as to how the switch responds. It may do one of the following: a. Leave the SAT as it was. b. Flush the SAT so that they are all empty. c. Notice a topology change and try to determine how the SAT should be populated by doing a gratuitous ARP. 2. Start a capture on all six PCS. 3. PC1 pings  PC2 4. Stop the capture, examine and record where you are able to see the pings (echo request and echo reply) and where you are not able to see the pings. 5. Examine your SAT. Activity 6 Questions: What entries do the SATs on the two switches on the pod contain now? Record them in the tables below. Use more or fewer lines as necessary. Include all dynamic entries. Are there 2205 – SPH/SPM Page 6

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NSSA 241 Lab 2 – Introduction to Switching - Netlab entries for MAC addresses other than the PCs? If so, include them. What device(s) are they for? Switch 1 (PCs 1-3) Switch Port PC Mac Address PC Name (PC1, PC2, PC3 etc.) Switch 2 (PCs 4-6) Switch Port PC Mac Address PC Name (PC1, PC2, PC3 etc.) Explain what is different from the previous experiment with only your single bench switch and why . Consider what the switch may be doing as a result of the reconfiguration (see list above). Use the table below to identify each of the ping results and explain why each is visible or not on each segment. Be sure to reference the switch SAT in your answer. PC1 pings  PC2 Wireshark observing from Is ping visible (yes/no) Explain why the ping is visible or not PC 1 PC 2 PC 3 PC 4 PC 5 PC 6 Activity 7 – Pinging Across Switches We will do the experiment again, but we will ping between PCs across the switches. 1. Start (again) a capture on all six PCS. 2205 – SPH/SPM Page 7

NSSA 241 Lab 2 – Introduction to Switching - Netlab 2. PC2 pings  PC5 (this ping should be successful, be sure to look for the green light on the ports after connecting the two switches together) 3. Stop the capture, examine and record where you are able to see the pings (echo request and echo reply) and where you are not able to see the pings. 4. Examine your SAT. Activity 7 Questions: Record the SAT entries on both switches in the tables below. Use more or fewer lines as needed. Include all dynamic entries. Are there entries for MAC addresses other than the PCs? If so, include them. What device(s) are they for? Switch 1 (PCs 1-3) Switch Port PC Mac Address PC Name (PC1, PC2, PC3 etc.) Switch 2 (PCs 4-6) Switch Port PC Mac Address PC Name (PC1, PC2, PC3 etc.) Explain what is different from the previous experiment with only your single bench switch and why . Use the table below to identify the ping results and explain why they are visible or not on each segment. Be sure to reference the switch SAT in your answer. PC2 pings  PC5 Wireshark observing from Is ping visible (yes/no) Explain why the ping is visible or not PC 1 PC 2 PC 3 PC 4 PC 5 PC 6 2205 – SPH/SPM Page 8

NSSA 241 Lab 2 – Introduction to Switching - Netlab Part III – Examining Filtering and SATs After Moving a Host In this part of the lab, you will physically move a host from one network switch to the other network switch to examine the effects. We will look at both the SATs and the messages visible through Wireshark on the LAN segments to see what changes. Activity 8 – Move a Host from One Switch to the Other Physically connect PC5 to the switch on the other bench network so that your topology looks like the diagram below. 1. Start (again) a capture on all six PCS. 2. PC2 pings  PC5 (this should be successful, be sure to look for the green lights as the switch is learning) 3. Stop the capture, examine and record where you are able to see the pings (echo request and echo reply) and where you are not able to see the pings. 4. Examine your SATs. Activity 8 Questions: Record the SAT entries on both switches in the tables below. Use more or fewer lines as needed. Include all dynamic entries. Are there entries for MAC addresses other than the PCs? If so, include them. What device(s) are they for? Switch 1 (Bench PCs 1-3) 2205 – SPH/SPM Page 9

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NSSA 241 Lab 2 – Introduction to Switching - Netlab Switch Port PC Mac Address PC Name (PC1, PC2, PC3 etc.) Switch 2 (Bench PCs 4 and 6) Switch Port PC Mac Address PC Name (PC1, PC2, PC3 etc.) Explain what is different from the previous experiment before PC5 moved and why . Use the table below to identify the ping results and explain why they are visible or not on each segment. Be sure to reference the switch SAT in your answer. PC2 pings  PC5 Wireshark observing from Is ping visible (yes/no) Explain why the ping is visible or not PC 1 PC 2 PC 3 PC 4 PC 5 PC 6 2205 – SPH/SPM Page 10

NSSA 241 Lab 2 – Introduction to Switching - Netlab Appendix 1 – List of Cisco IOS commands Cisco 3750 Switch enable configure terminal shutdown / no shutdown show interfaces <interface number> spanning-tree mac-address-table or mac address-table run switchport access ctrl z ctrl c exit ? tab interface f 0/1 2205 – SPH/SPM Page 11

NSSA 241 Lab 2 – Introduction to Switching - Netlab Appendix 2 – Switch Write Erase Procedure 1. Use the following procedure to erase the switch:  Wait for the device to present a Switch> prompt  Issue the enable command. The device will present a Switch# prompt  Issue the write erase command at the prompt (this erases the non-volatile memory, NVRAM)  Enter delete flash:vlan.dat (this deletes any VLAN configurations)  If you are prompted to confirm these choices, type “y” and enter.  Issue the reload command at the prompt  If prompted to save the configuration, select “ no ”.  When asked to confirm the reload, select “ yes ”.  After the reload, the system prompts with “enter the initial configuration dialog”, select “ no ”.  When asked to “terminate the autoinstall,” select “yes”.  When the message, “Press RETURN to get started!” displays hit return. At this point the switch should be set to its default configuration settings. 2205 – SPH/SPM Page 12

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