NE20 is connected to the switch of C6XXX through optical fiber, and the LED for link at GE port of NE20 is bright, but that of C6XXX is down. Login NE20, and the port is up after checking. login C6XXX , and the port is down.
1. The problem persists after replacing the optical fibers.
2. Test the GE port of the vendor's equipment by using loopback through a pair of optical fibers, and the link LED is bright, indicating that GE port works well.
3. Check the port negotiation mode: the GE port of NE20 is forced 1000M full duplex, and that of the vendor's equipment is auto-negotiation.
4. The working mode of GE port of NE20 is not revisable, so we suggeste the carrier to change that of the vendor's equipment to forced 1000M full duplex. The LED for link is bright then, and the port is up at once.
1. The cable is problematic.
2. The GE port of equipment of other vendor is damaged.
3. Port negotiation differs.
In connection of GE ports, the negotiation mode of ports may differ, and the links are different. In troubleshooting the like problems, we summarize that when both GE ports of A and B connect, if A is forced 1000M full duplex, and B is auto-negotiation, the LED for A is bright and that for B is not.