Verify the Status of the Logical Interface
Purpose
To verify the status of the logical interface, use the following two Junos OS CLI operational mode commands:
Action
Sample Output
The following sample output is for a T3 logical interface that is up:
user@router> show interfaces t3-1/0/0
Physical interface: t3-1/0/0, Enabled, Physical link is Up
Interface index: 13, SNMP ifIndex: 12
Link-level type: Cisco-HDLC, MTU: 4474, Clocking: Internal, Speed: T3, Loopback: None, FCS: 16,
Mode: C/Bit parity
Device flags : Present Running
Interface flags: Point-To-Point SNMP-Traps
Link flags : No-Keepalives
Input rate : 0 bps (0 pps)
Output rate : 0 bps (0 pps)
Active alarms : None
Active defects : None
Logical interface t3-1/0/0.0 (Index 126) (SNMP ifIndex 13)
Flags: Point-To-Point SNMP-Traps Encapsulation: Cisco-HDLC
Protocol inet, MTU: 4470, Flags: None
Addresses, Flags: Is-Preferred Is-Primary
Destination: 1.1.1.0/30, Local: 1.1.1.1
user@router> show interfaces terse t3-1/0/0
Interface Admin Link Proto Local Remote
t3-1/0/0 up up
t3-1/0/0.0 up up inet 1.1.1.1/30
Meaning
The sample output for the first command shows that the logical link is up because there are no flags indicating that the link layer is down. The output for the show interfaces terse command shows that logical interface t3-1/0/0 is up.
Sample Output
The following sample output is for a T3 logical interface that is down:
user@router> show interfaces t3-0/2/0
Physical interface: t3-0/2/0, Enabled, Physical link is Up
Interface index: 13, SNMP ifIndex: 12
Link-level type: Cisco-HDLC, MTU: 4474, Clocking: Internal, Speed: T3, Loopback: None, FCS: 16,
Mode: C/Bit parity
Device flags : Present Running
Interface flags: Link-Layer-Down Point-To-Point SNMP-Traps
Link flags : Keepalives
Keepalive settings: Interval 10 seconds, Up-count 1, Down-count 3
Keepalive: Input: 0 (never), Output: 9 (00:00:04 ago)
Input rate : 0 bps (0 pps)
Output rate : 0 bps (0 pps)
Active alarms : None
Active defects : None
Logical interface t3-0/2/0.0 (Index 126) (SNMP ifIndex 13)
Flags: Device-Down Point-To-Point SNMP-Traps Encapsulation: Cisco-HDLC
Protocol inet, MTU: 4470, Flags: None
Addresses, Flags: Dest-route-down Is-Preferred Is-Primary
Destination: 1.1.1.0/30, Local: 1.1.1.1
user@router> show interfaces terse t3-0/2/0
Interface Admin Link Proto Local Remote
t3-0/2/0 up down
t3-0/2/0.0 up down inet 1.1.1.1/30
Meaning
The sample output for both commands shows that the logical interface is down. The first command shows that the link layer, device, and destination route are all down. The second command shows that logical interface t3-0/2/0 is down.
