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| 4.2 |  | End-System Commands for Gathering Data Link Information |
| 4.2.1 |  | Common end-system commands |

The following commands are basic tools for Layer 2 troubleshooting and are implemented on Windows, UNIX and Max OS X operating systems:

- ping
- arp -a

Although ping operates as part of the IP suite of protocols, it is useful for troubleshooting Layer 2 as it is a means of establishing the boundaries of the fault. The continuous ping is also a useful method for generating test frames and observing error counters.

The arp –a command is useful for verifying that the ARP process is functioning correctly and is not being overridden by static entries configured on a workstation or router.

| Lab Activity Lab Exercise: Troubleshooting Problems at the Physical and Data Link Layers After completing this lab, the student will be able to follow a logical troubleshooting process to define, isolate, and correct problems outlined in a trouble ticket.