Display the status of the Fast and Gigabit Ethernet Interface to provide the information you need to determine whether the physical link is up or down.
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Action
To verify that the status of the Fast and Gigabit Ethernet Interface is up, use the following
Junos OS command-line interface (CLI) operational mode command:
user@host> show interfaces (fe-fpc/port|ge-fpc/pic/port)
Sample Output
user@host# show interfaces ge-4/0/6 extensive
Physical interface: ge-4/0/6, Enabled, Physical link is Up Interface index: 144, SNMP ifIndex: 516, Generation: 147
Link-level type: Ethernet, MTU: , Speed: mbps, BPDU Error: None,
MAC-REWRITE Error: None, Loopback: Enabled, Source filtering: Disabled,
Flow control: Enabled, Auto-negotiation: Enabled, Remote fault: Online
Device flags : Present Running Loop-Detected
Interface flags: SNMP-Traps Internal: 0x
Link flags : None
CoS queues : 8 supported, 4 maximum usable queues
Schedulers : 0
Hold-times : Up 0 ms, Down 0 ms
Current address: 00:1f:12:fe:c5:2e, Hardware address: 00:1f:12:fe:c5:2e
Last flapped : -01-20 23:40:04 PST (00:02:12 ago)
Statistics last cleared: Never
Traffic statistics:
Input bytes : 0 0 bps
Output bytes : 0 0 bps
Input packets: 0 0 pps
Output packets: 0 0 pps
IPv6 transit statistics:
Input bytes : 0
Output bytes : 0
Input packets: 0
Output packets: 0
Dropped traffic statistics due to STP State:
Input bytes : 0
Output bytes : 0
Input packets: 0
Output packets: 0
Input errors:
Errors: 0, Drops: 0, Framing errors: 0, Runts: 0, Policed discards: 0,
L3 incompletes: 0, L2 channel errors: 0, L2 mismatch timeouts: 0, FIFO errors: 0,
Resource errors: 0
Output errors:
Carrier transitions: 1, Errors: 0, Drops: 0, Collisions: 0, Aged packets: 0,
FIFO errors: 0, HS link CRC errors: 0, MTU errors: 0, Resource errors: 0
Egress queues: 8 supported, 4 in use
Queue counters: Queued packets Transmitted packets Dropped packets
0 best-effort 0 0 0
1 expedited-fo 0 0 0
2 assured-forw 0 0 0
3 network-cont 0 0 0
Queue number: Mapped forwarding classes
0 best-effort
1 expedited-forwarding
2 assured-forwarding
3 network-control
Active alarms : None
Active defects : None
MAC statistics: Receive Transmit
Total octets 0 0
Total packets 0 0
Unicast packets 0 0
Broadcast packets 0 0
Multicast packets 0 0
CRC/Align errors 0 0
FIFO errors 0 0
MAC control frames 0 0
MAC pause frames 0 0
Oversized frames 0
Jabber frames 0
Fragment frames 0
VLAN tagged frames 0
Code violations 0
Filter statistics:
Input packet count 0
Input packet rejects 0
Input DA rejects 0
Input SA rejects 0
Output packet count 0
Output packet pad count 0
Output packet error count 0
CAM destination filters: 0, CAM source filters: 0
Autonegotiation information:
Negotiation status: Complete
Link partner:
Link mode: Full-duplex, Flow control: Symmetric/Asymmetric, Remote fault: OK
Local resolution:
Flow control: Symmetric, Remote fault: Link OK
Packet Forwarding Engine configuration:
Destination slot: 4
CoS information:
Direction : Output
CoS transmit queue Bandwidth Buffer Priority Limit
% bps % usec
0 best-effort 95 95 0 low none
3 network-control 5 5 0 low none
Interface transmit statistics: Disabled
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: , 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
Performing a loopback test on an Ethernet interface
If an Ethernet interface does not work correctly, you can perform a loopback test on it to identify the problem. An Ethernet interface in a loopback test does not forward data traffic.
Loopback tests include the following types:
Internal loopback test&#;Tests all on-chip functions related to Ethernet interfaces.
External loopback test&#;Tests the hardware of Ethernet interfaces. To perform an external loopback test on an Ethernet interface, connect a loopback plug to the Ethernet interface. The device sends test packets out of the interface, which are expected to loop over the plug and back to the interface. If the interface fails to receive any test packets, the hardware of the interface is faulty.
Configuration restrictions and guidelines
When you perform a loopback test on an Ethernet interface, follow these restrictions and guidelines:
On an administratively shut down interface (displayed as in ADM or Administratively DOWN state), you cannot perform an internal or external loopback test.
The speed, duplex, mdix-mode, and shutdown commands are not available during a loopback test.
Link to Wirenet
Recommended article:
Multi Service Terminal Box vs. Traditional Wiring Solutions: Which Wins?During a loopback test, the Ethernet interface operates in full duplex mode. When a loopback test is complete, the port returns to its duplex setting.
Configuration procedure
To perform a loopback test on an Ethernet interface:
Step
Command
Remarks
1. Enter system view.
system-view
N/A
2. Enter Ethernet interface view.
interface interface-type interface-number
N/A
3. Perform a loopback test.
loopback { external | internal }
By default, no loopback test is performed.
The external keyword is not supported in the current version, and it is reserved for future support.
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