1-11 System Maintaining and DebuggingWhen maintaining and debugging the system, go to these sections for information you are interested in:z System Maintaining and Debugging Overviewz System Maintaining and Debuggingz System Maintaining ExampleSystem Maintaining and Debugging OverviewIntroduction to System MaintainingYou can use the ping command and the tracert command to verify the current network connectivity.The ping commandYou can use the ping command to verify whether a device with a specified address is reachable, and toexamine network connectivity.The ping command involves the following steps in its execution:1) The source device sends an ICMP echo request to the destination device.2) If the network is functioning properly, the destination device responds by sending an ICMP echoreply to the source device after receiving the ICMP echo request.3) If there is network failure, the source device displays timeout or destination unreachable.4) The source device displays related statistics.Output of the ping command falls into the following:z The ping command can be applied to the destination’s name or IP address. If the destination’sname is unknown, the prompt information is displayed.z Information on the destination’s responses towards each ICMP echo request. If the source devicedoes not receive an ICMP echo reply within the timeout time, it displays the prompt information. Ifthe source device receives an ICMP echo reply within the timeout time, it displays the number ofbytes of the echo reply, the message sequence number, Time to Live (TTL), the response time,and the statistics during the ping operation. The statistics include number of packets sent, numberof echo reply messages received, percentage of packets not responded to the total packets sent,and the minimum, average, and maximum response time.The tracert commandBy using the tracert command, you can trace the Layer 3 devices involved in delivering a packet fromsource to destination. This is useful for identification of failed node(s) in the event of network failure.The tracert command involves the following steps in its execution:1) The source device sends a packet with a TTL value of 1 to the destination device.
