Spring 2017 Gabriel Kuri

Transcription

1 Lab 2 ECE 431L Spring 2017 Gabriel Kuri This lab is made up of two parts. Part 1 will consist of familiarizing yourself with the Raspberry Pi (RPi). It includes running Unix/Linux commands to become somewhat familiar with the environment. Part 2 of the lab will introduce the student to Layer 2 (Data Link) of the OSI model through the use of switches in the lab and some network based testing. Part 2 will also involve some networking with the workbench directly across from your own. The workbenches will be numbered by the instructor at the beginning of the lab. It s important you remember this number as it used in some of the exercises in this lab. Whenever you see wb# substitute the # for your workbench number. For this lab, document all of the command output by copying and pasting in to a separate document to be saved for later use within the lab report. The questions that are asked throughout the lab should be answered in the lab report and a copy of the command output should be included in the lab report. Part 1 Checkout an RPi and console cable from the Instructor or TA. The Linux operating system for the RPi (Raspbian) is preloaded on to the microsd card that s already installed in the RPi. There is also a power adapter with a micro USB plug to power the RPi. In order to connect to the console of the RPi, you need to connect the wires of the console cable to the RPi s GPIO header and connect the other end of the cable to one of the USB ports on your workstation. Connection of the console cable wires to the RPi are fairly simple. You will connect only 3 of the 4 wires to the RPi, black (pin 6), white (pin 8), and green (pin 10). DO NOT CON- NECT THE RED WIRE TO THE BOARD. See the diagram below for the pin numbers on the GPIO header and their location relative to the board: 1

2 Once the console cable is connected to both the board and workstation, run the program Putty. When the window opens, change the Connection Type to Serial and in the Serial Line box, you will need to change the port from COM1 to the port the USB console cable is attached to; it will probably be somewhere between COM4 - COM9. In order to figure out which port it s on, go to the Control Panel and open up Device Manager (you may need to search for it). In Device Manager you will expand Ports and look for Prolific USB-to-Serial. It should list the COM port number. In the Speed setting, change it to and then click Connect Press Enter in the Putty window and you should receive a login prompt. The username is pi and the password is engineering. If you do not receive a login prompt or you are unable to connect to the console, please ask the Instructor or TA for assistance. After logging in to the RPi, run the following commands to familiarize yourself with the RPi: 1. ifconfig eth0 If you recall from last week s lab, ifconfig is used on Unix/Linux operating systems to configure network interfaces. What is the MAC address (ie Layer 2 Hardware address) of your Raspberry Pi? The first 24 bits (ie 6 hexadecimal characters) are assigned by the IEEE to hardware manufacturers. Search the Internet for IEEE OUI assignments and search the first 6 hexadecimal characters (ie 24 bits) of your MAC address to see which manufacturer it s assigned to. 2. ls -l / ls command is used to list the contents of a directory. This particular command lists the files of the root file system. List the files in /lib. List the files in /home. 3. uname -a uname prints the name, version, and other details of the Unix operating system. What version of the operating system are you running? What date was it compiled? What Linux kernel architecture was it compiled for? 4. nano -w test-wb# nano is one of several text editors commonly used on Unix machines. Add your name and your lab partner s name each to a separate line of the file. Type Ctrl-X, then Y, then confirm the filename to save the file. You will exit to the command prompt. Type ls -l to confirm the file exists. You will use it later in the lab. 2

3 Part 2 1. ifconfig eth #/24 up Substitute # for your workbench number. What is the IP address you configured for your RPi? Validate the IP address on your RPi using ifconfig? 2. ping -n -c # Substitute # for the workbench across from yours. Is their RPi responding to pings? If not, see if they ve made it this far in the lab, if not, wait for them to get to this portion of their lab to configure the network interface on their RPi. Once you start receiving successful ping responses from the other workbench, we will examine the traffic between the two RPis by using tshark. Run the following command, which will run tshark in realtime to capture traffic on the network and filter for the ping traffic (in the TCP/IP world it s a type of ICMP traffic), and write that output to a file in /tmp/icmp.out. sudo tshark -V -i eth0 -f icmp -l > /tmp/icmp.out 2>&1 Then go ahead and run the ping command again. After the ping command is finished, type: sudo pkill tshark The last command terminated the tshark process. Now we will review the output of what tshark captured. In order to view the output of the capture, type: cat /tmp/icmp.out Review the capture output. What is the source MAC address? Is it the MAC address of your RPi? What is the destination MAC address? Ask the workbench students at the workbench next to you for their RPi s MAC address. Does it match the destination MAC address? Do you see the IP address of your RPi and the IP address of the RPi at the workbench next to you in the capture? How many bytes is the frame? 3. iperf3 -i 1 -s iperf3 is a command that tests network performance. You are going to work with the workbench across from you. One RPi will act as the server the other will act as the client, decide ahead of time who will be the server or client. The RPi acting as the server needs to run their command first: 3

4 iperf3 -i 1 -s The RPi acting as the client then runs their command: iperf3 -i 1 -u -t 30 -c # Substitute the # for the workbench across from yours. Review the output, what was the highest and lowest speed? Now repeat this procedure but with your workbench acting as the client or server, what ever you were not last time. Type man iperf3 and review the manual. What would you change so that iperf3 would run for 2 minutes? 4. scp test-wb# pi@ # The scp command (secure copy) will copy the file you created earlier in the lab over to the workbench across from you. The command will ask for a password, which is the same password you use to login to the RPi. Make sure the workbench across from you has copied their file to your RPi. To confirm, type ls -l and see if the file that matches their workbench number is there. If so, type cat test-wb# substituting # for their workbench number. cat is a command that reads files sequentially and prints their contents. Do you see the names of the people in the workbench across from you? If so, they have successfully copied their file to your RPi. What is the date and time listed on the file they copied over? Part 3 Part 3 focuses on examining the test switch in the lab. We will look at a variety of information and statistics on the switch, including the MAC address table. The switch is in the back of the lab and serves the port your RPi is plugged in to. First you ll need to login to the switch from the RPi: ssh student@ When prompted for the password, type ece431l and press Enter. Run the following commands and review the output. 1. show mac address-table dynamic This command tells the switch to show you the MAC addresses it has learned on it s own interfaces. This particular test switch has a total of 48 built-in copper interfaces. The interfaces are labeled F1/0/x, where x is a number between Look for the MAC address of your RPi, which interface is it on? Make note of the interface, because you will use it for the remainder of the lab. 4

5 2. show interfaces F1/0/x controller Replace x with your interface number. Review the output. What speed is your interface on the switch (ie what speed connection do your RPi have to the test switch)? Is flow-control enabled? Has your interface seen any FCS errors? How many Unicast Frames has your interface seen? What size frames has your interface received the most? 3. show version This command display the information about the switch, including the make, model, version of software it s running, and other related information. What model is the switch? What version of software is it running? Lab Report In addition to answering the questions in Parts 1-3 and including the contents of the output in Parts 1-3 in your lab report, answer the following questions: 1. Why do you suppose the first 24 bits of a MAC address are assigned by the IEEE to the hardware manufacturer rather than simply letting the manufacturer choose whatever they want for the first 24 bits? 2. Why was the ping response time to the RPi on the workbench across from you so low? What might have made it higher? 3. Why do you think the destination MAC address in the tshark output was that of the RPi of the workbench across from you? 4. When examining the tshark output, you saw two addresses (MAC address and IP address). Why do we need two different addresses (MAC address and IP address) to get to the same destination, shouldn t the RPi only need 1 address to send the ping? 5. Did the network performance test reach a speed close to the speed of the network interface the RPi is plugged in to on the test switch? If not, what do you think prevented it from reaching the speed of the network interface of the switch? 6. When you reviewed the ooutput from the switch, why didn t the switch also have record of the RPi s IP address? 7. Explain in your own words what you learned from this lab about the RPi? 8. Explain in your own words what you learned from this lab about how the test switch operates and passes frames around the local network? 5