Step 3: Verify That the T1 Interface Is Up

Purpose

Display the status of the T1 interface to determine whether the physical link is up or down.

Action

To verify that the status of the T1 interface is up, use the following JUNOS command-line interface (CLI) operational mode command:

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

Sample Output

The following output is for a T1 interface with the physical link up:

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

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

  Interface index: 24, SNMP ifIndex: 20

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

  Device flags   : Present Running Loop-Detected

  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: 3 (00:00:06 ago), Output: 9 (00:00:06 ago)

  Last flapped   : 2002-01-06 00:59:00 UTC (00:00:40 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

    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

What It Means

The sample output shows that the physical link is up, the loop is detected, and there are no T1 alarms or defects.

Sample Output

If the physical link is down, there may be a problem with the port. The following output is an example of the show interfaces t1-fpc/pic/port command when the physical link is down:

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

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

  Interface index: 24, SNMP ifIndex: 20

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

  Device flags   : Present Running Down

  Interface flags: Hardware-Down Point-To-Point SNMP-Traps

  Link flags     : Keepalives

  Keepalive settings: Interval 10 seconds, Up-count 1, Down-count 3

  Keepalive: Input: 32 (00:00:23 ago), Output: 35 (00:00:04 ago)

  Input rate     : 0 bps (0 pps)

  Output rate    : 0 bps (0 pps)

  DS1   alarms   : LOF, LOS

  DS1   defects  : LOF, LOS

  Logical interface t1-0/0/0.0 (Index 9) (SNMP ifIndex 34) 

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

    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

What It Means

The sample output shows that the physical link is down, the device flags and interface flags are down, and that there are T1 alarms and defects. Verify that the fiber can successfully loop a known good port of the same type by checking for damage to the cable.