H3C S3610 Series Operation Manual

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H3C S3610 Series Operation Manual Manual pdf 18 page image

Operation Manual – System Maintaining and DebuggingH3C S3610&S5510 Series Ethernet Switches Chapter 2 System Maintaining and Debugging2-2II. The tracert commandBy using the tracert command, you can trace the routers involved in delivering a packetfrom source to destination. This is useful for identification of failed node(s) in the eventof 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.2) The first hop (the router that first receives the packet) responds by sending aTTL-expired ICMP message to the source, with its IP address encapsulated. Inthis way, the source device can get the address of the first router.3) The source device sends a packet with a TTL value of 2 to the destination device.4) The second hop responds with a TTL-expired ICMP message, which gives thesource device the address of the second router.5) The above process continues until the ultimate destination device is reached. Inthis way, the source device can trace the addresses of all the routers that havebeen used to get to the destination device.2.1.2 Introduction to System DebuggingThe device provides various debugging functions. For the majority of protocols andfeatures supported, the system provides corresponding debugging information to helpusers diagnose errors.The following two switches control the display of debugging information:z Protocol debugging switch, which controls protocol-specific debugging informationz Screen output switch, which controls whether to display the debugging informationon a certain screen.Figure 2-1 illustrates the relationship between the protocol debugging switch and thescreen output switch. Assume that the device can output debugging information tomodule 1, 2 and 3. Only when both are turned on can debugging information be outputon a terminal.