117 SYSTEM MAINTAINING ANDDEBUGGINGWhen maintaining and debugging the system, go to these sections forinformation you are interested in:■ “System Maintaining and Debugging Overview” on page 2119■ “System Maintaining and Debugging” on page 2121■ “System Maintaining Example” on page 2122System Maintainingand DebuggingOverviewIntroduction to SystemMaintaining andDebuggingYou can use the ping command and the tracert command to verify the currentnetwork connectivity.The ping commandYou can use the ping command to verify whether a device with a specifiedaddress is reachable, and to examine 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 sendingan ICMP echo reply to the source device after receiving the ICMP echo request.3 If there is network failure, the source device displays timeout or destinationunreachable.4 The source device displays related statistics.Output of the ping command falls into the following:■ The ping command can be applied to the destination’s name or IP address. Ifthe destination’s name is unknown, the prompt information is displayed.■ Information on the destination’s responses towards each ICMP echo request. Ifthe source device does not receive an ICMP echo reply within the timeout time,it displays the prompt information; if the source device receives an ICMP echoreply within the timeout time, it displays the number of bytes of the echo reply,the message sequence number, Time to Live (TTL), the response time, and thestatistics during the ping operation, which include number of packets sent,number of echo reply messages received, percentage of messages not received,the minimum, average, and maximum response time.
