Step 6: Verify the Status of the Logical Interface

Action

To verify the status of the logical interface, use the following two JUNOS CLI operational mode commands:

user@host# show interfaces t3-fpc/pic/port

user@host# show interfaces t3-fpc/pic/port terse

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  

What It Means

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

What It Means

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.