R3303-HP 6600/HSR6600 Routers Interface Configuration Guide

3. Configure Router C in the same way Router 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 POS interface is down.

Solution

• Check that the transmitting and receiving fibers-optic are correctly connected to the POS interface.

If you connect the two ends of a fiber-optic to the transmitting end and the receiving end of the same

POS interface, when you execute the display interface command, a "loopback detected" message

is displayed on the screen even if loopback is not enabled.

• If the two routers are directly connected back to back, check that the internal clock is enabled on

either of the two POS interfaces.

Symptom 2

The physical layer is up but the link is down.

Solution

Check the following items:

• The configurations of clock mode, scrambling, and other physical parameters are consistent on the

connected two POS interfaces.

• The same link layer protocol is configured on two sides.

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 can be generated.