> | Lab 4.4.3 ICMP ping Estimated time: 30 min. Objectives: Use the ping command to send ICMP Datagrams to target host. Verify that the network layer between source and destination is working properly. Retrieve information to evaluate the path-to-host reliability. Determine delays over the path and whether the host can be reached or is functioning. Background: In this lab you will use ICMP or Internet Control Message Protocol. ICMP will give you the ability to diagnose basic network connectivity. Using ping xxx.xxx.xxx.xxx will send an ICMP packet to the specified host and then wait for a reply packet from that host. You can ping the host name of a router but you must have a static host lookup table in the router or DNS server for name resolution to IP addresses. Ping is an excellent tool for troubleshooting layers 1 though 3 of the OSI model. If you cannot connect to a host computer (such as a server) but you can ping the server's IP address, then your problem is probably not with the physical cabling connections, the NICs or the routers between you and the server. With this lab, you will also have a chance to see the differences between using the ping command from a router and from a workstation. Tools / Preparation: Prior to starting the lab you will need to connect a PC w/ HyperTerminal to a router using the router's console Interface with a roll-over cable. You should have access to the standard 5-router lab if possible. Work individually or in teams. Before beginning this lab you may want to read the Networking Academy First Year Companion Guide, Chapter 13 and you should also review On-line Chapter 4. Resources Required: PC with Windows operating system and HyperTerminal installed Router connected to the PC with a console roll-over cable At least 3 routers interconnected via Ethernet or WAN simulation cables Websites Sites Resources: Routing basics General information on routers 2500 series routers 1600 series routers Terms and acronyms IP routing protocol IOS command summary Beginning IP for new users Notes: Step 1 - Log on to router. Explanation: Connect to the router and login. Enter the password cisco if prompted. 1. a. What prompt did the router display? b. What does it mean? Step 2 - Display a cached list of host names and addresses. Task: Enter show host at the router prompt. Explanation: The router will display information about host to Layer 3 (IP) address mappings, how this information was acquired and the age of the entry. 2. List four (4) host names and the first IP address listed for each one.
> Host name | IP Address
> Step 3 - Test layer 3 addressing - Ping from router to router. Task: Enter ping xxx.xxx.xxx.xxx where xxx.xxx.xxx.xxx is an IP address from one of the other hosts listed above. Repeat with all IP addresses you listed. Explanation: The router sends an Internet Control Message Protocol (ICMP) packet to verify the hardware connection and network layer address. Since your PC is acting as the console to the router, you are pinging from your router to another router. 3. Were you able to ping all the IP address? 4. List four (4) important pieces of information that you receive back from issuing the ping command. Step 4 - Examine the output generated by the ping command. 5. Look at the example of the ping command generated by a router.
> lab-b#ping 210.93.105.1 Type escape sequence to abort. Sending 5, 100-byte ICMP Echoes to 210.93.105.1, timeout is 2 seconds: !!!.! Success rate is 80 percent (4/5), round-trip min/avg/max = 68/68/168 ms
a. What does the exclamation point (!) indicate? b. What does the period (.) indicate? c. What does the ping command test for? Step 5 - Access the workstation command prompt. Task: From a Windows 95/98 or NT workstation click on Start/Programs/MS DOS Command prompt. This will open a Command Prompt window. Explanation: Using the command prompt to ping the routers allows you to test that the TCP/IP stack and default gateway on the workstation are configured and working properly. Step 6 - Test the workstation default gateway. Task: Using the command prompt enter ping and the IP address of the workstation default gateway. Default gateway is the nearside router interface IP address. Explanation: By pinging your default gateway you are able to test if you can successfully send packets to and from the router that is directly connected to your LAN. 6. Are you able to ping your default gateway? ( Hint: You may need to check the TCP/IP settings using the Windows Control panel, network icon) Step 7 - Test layer 3 addressing from a workstation to remote router. Task: Using the command prompt enter ping and the IP address of a remote router. Explanation: This will test layer 3 connectivity between your workstation and the remote router. 7. Is the output from the workstations ping command, the same as the output from the ping command from a router? Step 8 - Test the connections to other remote routers. Task: Using the command prompt enter ping and the IP address of another remote router. Explanation: This will test layer 3 connectivity between your workstation and the other remote routers. 8. List the differences between the router's ping command and the workstation ping command.