220 Lab C Introduction to Cisco IP Telephony Pre-Lab Activities: None Purpose of the experiment: To explore the Cisco IP Telephony System configuration options, and its use. Smoking and any food or drinks are not permitted in the Applications Lab! Equipment: The heart of a Cisco telephony system is a device called Cisco Unified 500 Series. This device is located in the middle of the rack in your work area. (In the past Cisco used the Call Manager and Call Unity servers, these might be in the same rack but you will not be using them. You will use several Cisco phones, Arthur (7961 series), Zaphod (7941 series) and Marvin (7961 series), and an extra phone that you will configure during the lab. You will also call an extension number connected to the Norstar system (located next to the IDF panels in the lab). You ll use a client computer for two purposes: 1. Use a web browser to configure the system. 2. To monitor the network traffic generated by calls in and out of the extension called Zaphod. Acquiring Data At the end of these instructions, you will find a sheet with several labeled sections. Use this sheet to record data as you take measurements. The lab instructor may want to sign with his initials the data sheet before you leave the lab. You must include the data sheet with your lab report to receive full credit. Steps to be Performed: Using the Cisco Phone In this part you will make several phone calls. You should actually talk some on each call. Listen for delay, noise, echo, or any other audio problems. Note the steps needed to invoke various call handling steps. Make an internal call between two Cisco phones. To do this just lift up a handset and dial one of the other two phones. The extension numbers are: Marvin: 8001, Arthur 8002 and Zaphod 8003. To answer a phone that is ringing you might need to lift the handset and select answer by pressing one of the buttons adjacent to the lower part of the phone s screen. Call an outside phone from a Cisco phone dial 9, then 9000. A phone on the Norstar side will ring. Place calls from an outside Norstar phone to Marvin (8001) and then transfer that call to another station. To do this, from a Norstar phone dial 8 and then Marvin s extension. Answer Marvin s phone and press the transfer button, wait for dial tone and dial either Arthur s or Zaphod s extension Answer the phone that is ringing ITS 220 1 Printed 9/28/09
Press Transfer on Marvin s phone When done, hang up all phones Have Marvin answer an inbound call, then place the call on hold, call Arthur, then return to the original call. To do this, from a Norstar phone dial 8 and then Marvin s extension number Answer Marvin s phone and press the hold button Press New Call Dial Arthur s extension Answer Arthur s phone, now Marvin and Arthur are connected while the first call is on hold Hang up Arthur s phone and return to the original call by pressing resume on Marvin s phone Make a call between any two Cisco phones. Once you re actually talking, unplug one of the phones from the Cisco Unified 500. What happens? Now reconnect the phone, approximately how long does it take to get phone ready for calls again? On Marvin s phone, press the settings button. Look around this menu. Change her ring tone. Record the phone s IP and MAC addresses (under Network Configuration). Exit settings. On Marvin s phone, press the directories button. Look at the list of missed calls. Note the time and originator of the most recent unanswered call prior to the beginning of the lab period. Cisco Unified 500 On the PC screen bring up the window for Cisco Configuration Assistant application. (It is already running and logged in). Press the Topology button (located on the top toolbar, looks like a star with a yellow core) Right click Zaphod, select Properties and note its IP and MAC addresses. Repeat the process for the all other phones and the UC520. Copy the topology and this information to your data sheet. Adding a phone. Plug in the 7940 phone that is on top of the UC520 rack, connecting the black cable to the port labeled Power over Ethernet Act 3 Lnk. Wait for the phone to boot up and try using it to send and receive calls. It will be automatically assigned extension number 8004. Don t Panic! (Startup for a new phone may take a considerable amount of time to automatically configure itself). Go to the Cisco Configuration Assistant, close the Topology window if it is open and then reopen the Topology window, you should be able to see the new phone. Under Configure->Telephony->Voice select the User Extensions tab. You should be able to see the new phone, it has not been assigned a user s first, last names or User ID. Assign Trillian both to the first and last names. Assign Trillian to the UserId and 12345 as the password Click the Apply button, the configuration will be sent to the phone Adding the intercom option. You are going to configure Arthur to have intercom access to Trillian. Go to the Cisco Configuration Assistant Screen If you are not already under Configure->Telephony->Voice (User Extensions tab), go there and click on Arthur. On the bottom part of the screen you can modify the behavior of Arthur s 6 buttons (the ones to the right of Arthur s screen) Change one of Arthur s buttons to Type Intercom to call Trillian s Extension. You can label it Trillian Intercom. The system will also ask you to select which button on Trillian s phone the Intercom will appear. After a few seconds both Arthur s and Trillian s phones will have the Intercom option enabled ITS 220 2 Printed 9/28/09
through one of their buttons. Use Arthur to have access to Trillian s speaker by pressing the Intercom button. Removing the intercom option. Select Arthur s phone under the Configure->Telephony->Voice screen (User Extensions tab) Select the button used for intercom on the bottom part of the screen and change its type to None Apply the configuration. You will notice that both Arthur s and Trillian s screens have been updated and no longer show the Intercom option. Removing a phone Unplug Trillian s phone from the UC520, remember this is the new phone you just added and is on the UC520 rack. Select Trillian s phone under the Configure->Telephony->Voice screen (User Extensions tab) and click Delete Phone Creating a Hunt Group In the Cisco Configuration Assistant close the Voice window if it is still open Go to Configure->Telephony->Phone Groups->Hunt Groups We are going to put Arthur and Zaphod in a hunt group. Whenever someone calls a particular number we are about to define, first Arthur s phone should ring then if there is no answer Zaphod s phone should ring. In the Hunt Groups windows enable the first line (which has the Pilot #1 set to 5001). On the bottom part of the screen select Arthur from the Available list and move it to the Selected list using the Add button. Do the same for Zaphod. Click apply From Marvin call the pilot number 5001. Arthur s phone should ring, let it ring for a few seconds. After that Zaphod s phone will ring. Go back to the Cisco Configuration Assistant software and disable hunt group 1 and click Apply. Traffic Analysis of an ongoing call You will be analyzing the traffic generated by the Cisco phones. To do so you will be using the Wireshark software installed on the computer you have been working on. You will capture traffic sent and received between extensions 8003 and 8001. Launch Wireshark by clicking on its icon on the desktop (The Wireshark window might appear on the television on your left, if necessary turn on the TV, hit the tv/video button until you see the computer screen, grab the window and drag it to your monitor). Go to the Capture pull down menu and click on Interfaces, the Capture Intefaces window will appear Click on the Start button for the 3 Com Etherlink PCI line in the Capture Options window If Wireshark had a capture already in memory it is going to ask you if you want to save it, answer Continue Without Saving The Capture window will appear From extension 8001 call 8003 After you answer the ringing phone you will start seeing new captured packets on the screen going to and from Zaphod s and Marvin s phone While the capture list is being updated, enter a new filter in the Filter textbox (located under the main toolbar). Enter ip.src == ZaphodsIPAddress and hit Enter. (Instead of ZaphodsIPAddress you need to type the actual IP address you recorded in your topology, it should look something ITS 220 3 Printed 9/28/09
like 10.11.1.some number). You just created a Wireshark filter (you can check the syntax of your filter by inspecting the text box under the main toolbar). Copy the filter text you just created by highlighting it and pressing CTRL-C. You are now capturing just the traffic coming from one of the phones. To graphically visualize the traffic generated by one of the phones (the one selected in the filter), select Statistics from the pull down menu. Then select IO Graphs, you should now see a real time graphic of the traffic flowing through your filter Click on the Filter for Graph 1, the Display Filter IO-Stat Window appears. Paste the contents of the clipboard (the filter syntax) in the Filter String textbox by pressing CTRL-V and then hit Enter. Adjust the units of the picture by setting the Y Axis Unit to Bits/Tick. (Keep the scale to Auto). Make sure the X Axis unit is set to a Tick interval of 1 second. Let the graph run for about 60 seconds and notice the long term average bits per tick (Each tick represents one second). Write this value on your data sheet; obtain this value by reading it not from the latest sample but from samples taken 30 seconds ago. Hang up the phones, you should see the line on the graphic drop to zero Close the Wireshark IO Graphs window From the list packets on the screen write down the time between two packets in milliseconds and write it on your Data Sheet. You ll do this by analyzing the time column between two consecutive packets. (Notice that each packet includes some Time information too, make sure you read the time stamps from the time column and compute the difference between any consecutive two packets from your phone call) Under the Capture pull down menu select Stop Double click on a packet shown on the screen, the details about this packet will open in a new window. Maximize this window Write down the total length in bytes of the packet, this should appear in the summary line of the packet (Example: Frame 359 (xxx bytes on wire)). You are now going to determine all the pieces that make up this packet and their lengths. These are already partially identified in your data sheet. Complete the rest of the information from the table in your data sheet. You can determine how many bytes each section occupies by clicking it on Wireshark and then counting the number of bytes represented on the bottom of the screen in hexadecimal or ASCII format. (Note that each pair of numbers in hexadecimal format represents 1 byte). To better understand how to count bytes, the Ethernet and 802.1Q fields have already been completed for you. Use these to understand how to determine the remaining values using Wireshark. Leave the system as is. ITS 220 4 Printed 9/28/09
Requirements for your lab report General Rules Your report must be typed, except that drawings may be made by hand. While your raw data sheet must be attached, all relevant data must be copied into your typed report. Do not put things like see data sheet into your typed report. Things to put into your lab report A header section with your name, your teammates names, group number, and date/time of the lab. The initialed raw data sheet (always attach this at the end of the report) Each of the subsections below requires a brief description of what you measured, your results, and when requested a reference to and a quote from a reference source that you can compare your measurement to (for example, one of our readings or an internet source). 1. Topology view of the system with all the information you wrote down in your data sheet 2. What is the load in bits per second you recorded using the IO Graph? 3. What is the time between packets you recorded using the packet trace from Wireshark? 4. What is the packet size in bytes of each packet a phone transmits? 5. What is the packet size in bits of each packet a phone transmits? 6. Divide the packet size in bits by the time between packets in seconds, how does this compare to the value from the IO Graph? 7. The RTP section of the packet actually includes voice samples; Wireshark does not report this. Using an external reference indicate how big is a typical RTP header in bytes? 8. Using the answer above, compute the number of bytes used by the voice samples. 9. Using the answer above, compute the voice rate by converting the answer above to bits and dividing it by the time between packets. Show your result. 10. The phones in your setup used the G.711 PCMU codec (usually called simply G.711). Using an external reference look for the data rate of a G.711 codec that generates packets every 20 ms. ITS 220 5 Printed 9/28/09
ITS 220 Lab C Data Sheet Name: Group: Group Number: Date/Time: Comment on the overall voice quality of the system What happens to a call if a phone is disconnected while on a call? How much time (approx.) does it take to boot up a phone? Draw a picture showing the topology (similar to the one shown in the Topology window) including IP addresses, MAC addresses, extensions and device names ITS 220 6 Printed 9/28/09
Traffic analysis: (the phones are preconfigured to use a G.711 voice codec) Bits per second (read from the Wireshark figure) Time between packets generated by extension 8003 or 8001 in seconds: Total number of bytes in a packet: Packet composition Ethernet II length in bytes: 14 802.1Q Virtual LAN length in bytes: 4 Internet Protocol length in bytes : User Datagram Protocol length in bytes: Real-Time Transport Protocol length in bytes: Total number of bytes (add all of the above you should get the same value as the total number of bytes in a packet you wrote above): ITS 220 7 Printed 9/28/09