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Chapter 66 Monitor and Debug
When the users configures the switch, they will need to verify whether the configurations are correct and the
switch is operating as expected, and in net work failure, the users will also need to diagnostic the problem.
Switch provides various debug commands including ping, telnet, show and debug, etc. to help the users to
check system configuration, operating status and locate problem caus es.
66.1 Ping
Ping command is mainly used for sending ICMP query packet from the switches to remote devices, also for
check the accessibility between the switch and the remote device. Refer to the Ping command chapter in the
Command Manual for explanations of various parameters and options of the Ping command.
66.2 Ping6
Ping6 command is mainly used by the switch to send ICMP v6 query packet to the remote equipment,
verifying the accessibility between the switch and the remote equipment. Options and explanations of the
parameters of the Ping6 command please refer to Ping6 command chapter in the command manual.
66.3 Traceroute
Traceroute command is for testing the gateways through which the data packets travel from the source device
to the destination device, so to check the network accessibility and locate the net work failure.
Execution procedure of the Traceroute command consists of: first a data packet with TTL at 1 is sent to the
destination address, if the first hop returns an ICMP error message to inform this packet can not be sent (due
to TTL timeout), a data packet with TTL at 2 will be sent. Also the send hop may be a TTL timeout return, but
the proc edure will carries on till the data packet is sent to its destination. These procedures is for recording
every source address which returned ICMP TTL timeout message, so to describe a path the IP data packets
traveled to reach the destination.
Traceroute Options and explanations of the parameters of the Traceroute command please refer to traceroute
command chapter in the command manual.
66.4 Traceroute6
The Traceroute6 function is used on testing the gateways passed through by the data packets from the source
equipment to the destination equipment, to verify the accessibility and locate the network failure. The principle
of the Tracerout e6 under IP v6 is the same as that under IP v4, which adopts the hop limit field of the ICMP v6
and IP v6 header. First, Traceroute6 sends an IP v6 datagram (including source address, destination address
and packet sent time) whose HOP LIMIT is set to 1. When first rout e on the path receives this datagram, it
minus the HOPLIMIT by 1 and the HOPLIMIT is now 0. So the router will discard this datagram and returns
with a 「ICMP v6 time exceeded」 message (including the source address of the IP v6 packet, all content in the
IP v6 packet and the IP v6 address of the router). Upon receiving this message, the Traceroute6 sends another
datagram of which the HOPLIMIT is increased to 2 so to discover t he second router. Plus 1 to the HOPLIMIT
66-1
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Table of Contents
Troubleshooting
