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 fe-1/3/0Physical interface: fe-1/3/0, Enabled, Physical link is Up
Interface index: 44, SNMP ifIndex: 35
Link-level type: Ethernet, MTU: 1514, Source filtering: Disabled
Speed: 100mbps, Loopback: Disabled , Flow control: Enabled
Device flags : Present Running
Interface flags: SNMP-Traps
Link flags : None
Current address: 00:90:69:8d:2c:db, Hardware address: 00:90:69:8d:2c:db
Input rate : 0 bps (0 pps), Output rate: 0 bps (0 pps)
Active alarms : None
Active defects : None
MAC statistics:
Input octets: 0, Input packets: 0, Output octets: 0, Output packets: 0
Filter statistics:
Filtered packets: 0, Padded packets: 0, Output packet errors: 0
Autonegotiation information:
Negotiation status: Incomplete, Link partner status: OK
Link partner: Full-duplex, Flow control: None
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:
user@router> show interfaces fe-1/3/0
Physical interface: fe-1/3/0, Enabled, Physical link is Down
Interface index: 44, SNMP ifIndex: 35
Link-level type: Ethernet, MTU: 1514, Source filtering: Disabled
Speed: 100mbps, Loopback: Disabled, Flow control: Enabled
Device flags : Present Running Down
Interface flags: Hardware-Down SNMP-Traps
Link flags : None
Current address: 00:90:69:8d:2c:db, Hardware address: 00:90:69:8d:2c:db
Input rate : 0 bps (0 pps), Output rate: 0 bps (0 pps)
Active alarms : LINK
Active defects : LINK
MAC statistics:
Input octets: 0, Input packets: 0, Output octets: 0, Output packets: 0
Filter statistics:
Filtered packets: 0, Padded packets: 0, Output packet errors: 0
Autonegotiation information:
Negotiation status: Incomplete, Link partner status: Down
Reason: Link partner autonegotiation failure
Link partner: Half-duplex, Flow control: None
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.) |
