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 t1-fpc/pic/port

user@host> show interfaces t1-fpc/pic/port terse

Sample Output

The following output is for a logical interface that is up:

user@host> show interfaces t1-1/1/0 

Physical interface: t1-1/1/0, Enabled, Physical link is Up

  Interface index: 29, SNMP ifIndex: 20

  Link-level type: Cisco-HDLC, MTU: 1504, Clocking: Internal, Speed: T1, 
Loopback: None, FCS: 16, Framing: ESF

  Device flags   : Present Running

  Interface flags: Point-To-Point SNMP-Traps

  Link flags     : No-Keepalives

  Last flapped   : 2002-01-06 01:09:00 UTC (00:00:44 ago)

  Input rate     : 0 bps (0 pps)

  Output rate    : 0 bps (0 pps)

  DS1   alarms   : None

  DS1   defects  : None

  Logical interface t1-1/1/0.0 (Index 9) (SNMP ifIndex 34) 

    Flags: Point-To-Point SNMP-Traps Encapsulation: Cisco-HDLC

    Bandwidth: 0

    Protocol inet, MTU: 1500, Flags: None

      Addresses, Flags: Is-Preferred Is-Primary

        Destination: 1.1.1.0/30, Local: 1.1.1.1

user@host> show interfaces terse t1-1/1/0  

Interface       Admin Link Proto Local                 Remote

t1-1/1/0        up    up  

t1-1/1/0.0      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 t1-1/0/0 is up.

Sample Output

The following output is for a logical interface that is down:

user@host> show interfaces t1-1/1/0

Physical interface: t1-1/1/0, Enabled, Physical link is Up

  Interface index: 29, SNMP ifIndex: 20

  Link-level type: Cisco-HDLC, MTU: 1504, Clocking: Internal, Speed: T1, 
Loopback: None, FCS: 16, Framing: ESF

  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: 14 (00:01:01 ago), Output: 9 (00:00:05 ago)

  Last flapped   : 2002-01-06 01:09:00 UTC (00:03:39 ago)

  Input rate     : 0 bps (0 pps)

  Output rate    : 0 bps (0 pps)

  DS1   alarms   : None

  DS1   defects  : None

  Logical interface t1-1/1/0.0 (Index 9) (SNMP ifIndex 34) 

    Flags: Device-Down Point-To-Point SNMP-Traps Encapsulation: Cisco-HDLC

    Bandwidth: 0

    Protocol inet, MTU: 1500, Flags: None

      Addresses, Flags: Dest-route-down Is-Preferred Is-Primary

        Destination: 1.1.1.0/30, Local: 1.1.1.1

user@host> show interfaces terse t1-1/1/0    

Interface       Admin Link Proto Local                 Remote

t1-1/1/0        up    down

t1-1/1/0.0      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 t1-1/1/0.0 is down.