H3C Technologies H3C S12500 Series Switches - Manual (Page 32)

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[SwitchB-Pos3/1/1] fr dlci 70
[SwitchB-Pos3/1/1] fr map ip 10.10.10.1 70
[SwitchB-Pos3/1/1] mtu 1500
3. Configure Switch C in the same way Switch B is configured.
Verifying the configuration
Check interface connectivity with the display interface pos command and test network connectivity
with the ping command.
Troubleshooting POS interfaces
Symptom 1
The physical state of a POS interface is down.
Solution
• Check that the transmitting and receiving optical fibers are correctly connected to the POS interface.
If you connect the two ends of an optical fiber to the transmitting end and the receiving end of the
same POS interface, you can see the message "loopback detected" on the screen when executing
the display interface command even if you have not enabled loopback.
• If the two switches are directly connected (back to back), check that the POS interfaces use different
clock modes.
Symptom 2
The physical layer is up but the link is down.
Solution
Check that:
• The settings of clock, scrambling and other physical parameters are consistent on the two
connected POS interfaces.
• The same link layer protocol is configured on two sides.
• Both ends are assigned IP addresses.
Symptom 3
A great amount of IP packets are dropped.
Solution
Check that:
• The correct clock mode is configured on the POS interface. If not, enormous amount of CRC errors
will be generated.
• The Maximum transmission unit (MTU) configuration is matched.
Configuring loopback and null interfaces
This chapter describes how to configure a loopback interface and a null interface.