Verify That the Fast Ethernet or Gigabit Ethernet Interface Is Up

 

Purpose

Display the status of the Fast Ethernet or Gigabit Ethernet interface to provide the information you need to determine whether the physical link is up or down.

Action

To verify that the status of the Fast Ethernet or Gigabit Ethernet interface is up, use the following Junos OS command-line interface (CLI) operational mode command:

Sample Output

user@host# show interfaces ge-4/0/6 extensive

Meaning

The sample output shows that the link is up and there are no alarms in this loopback configuration. When an internal loopback is configured, the physical loopback should come up without an alarm.

Sample Output

When you see that the physical link is down, there may be a problem with the port. The following output is an example of the show interfaces fe-fpc/pic/port command when the physical link is down:

Meaning

The sample output shows that the physical link is down and there are active alarms and defects.

Table 1 presents problem situations and actions for a physical link that is down.

Table 1: Problems and Solutions for a Physical Link That Is Down

Problem

Action

Cable mismatch

Verify that the fiber connection is correct.

Damaged and/or dirty cable

Verify that the fiber can successfully loop a known good port of the same type.

Too much or too little optical attenuation

Verify that the attenuation is correct per the PIC optical specifications.

The transmit port is not transmitting within the dBm optical range per the specifications

Verify that the Tx power of the optics is within range of the PIC optical specification.

Mismatch between the cable type and the port

Verify that a single-mode fiber cable is connected to a single-mode interface and that a multimode fiber cable is connected to a multimode interface. (This problem does not always cause the physical link to go down; errors and dropped packets are sometimes the result.)