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Monitor T1 Interfaces

By monitoring T1 interfaces, you begin the process of isolating T1 interface problems when they occur.

To monitor your T1 interfaces, follow these steps:

  1. Display the Status of T1 Interfaces
  2. Display the Status of a Specific T1 Interface
  3. Display Extensive Status Information for a Specific T1 Interface
  4. Monitor Statistics for a T1 Interface

Display the Status of T1 Interfaces

Purpose

To display the status of T1 interfaces.

Action

Use the following JUNOS command-line interface (CLI) operational mode command to display the status of T1 interfaces:

user@host> show interfaces terse t1*

Sample Output


user@host> show interfaces terse t1*
Interface       Admin Link Proto Local                 Remote
t1-1/0/0        down  up --- administratively disabled
t1-1/0/0.0      up    down inet  1.1.1.1/30
t1-1/0/1        up    down --- physical layer down
t1-1/0/1.0      up    down inet  2.2.2.2/30  --- link layer down
t1-1/0/2        up    up
t1-1/0/2.0      up    up   inet  3.3.3.3/30  --- link layer up
t1-1/0/3        up    down

Meaning

This sample output shows the status of both the physical and logical interfaces. See Table 10 for a description of what the output means.

Table 10: Status of T1 Interfaces

Physical Interface

Logical Interface

Status Description

t1-1/0/0

AdminDown

Link Up

t1-1/0/0.0

Admin Up

Link Down

This interface is administratively disabled and the physical link is healthy (Link Up), but the logical interface is not established. The logical interface is administratively enabled (Admin Up), but is down because the physical link is disabled.

t1-1/0/1

Admin Up

Link Down

t1-1/0/1.0

Admin Up

Link Down

This interface is not functioning between the local router and the remote router because both the physical and logical links are down (Link Down). The interface is not administratively disabled because both the physical and logical links are up (Admin Up).

t1-1/0/2

Admin Up

Link Up

t1-1/0/2.0

Admin Up

Link Up

This interface has both the physical and logical links up and running.

t1-1/0/3

Admin Up

Link Down

  

The physical interfaces is added to the configuration, but the logical link is not configured.


Display the Status of a Specific T1 Interface

Purpose

To display the status of a specific T1 interface when you need to investigate its status further.

Action

To display the status of a specific T1 interface, use the following JUNOS CLI operational mode command:

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

Sample Output


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: PPP, 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
  Last flapped   : 2002-01-01 00:00:35 UTC (00:00:59 ago)
  Input rate     : 0 bps (0 pps)
  Output rate    : 0 bps (0 pps)
  DS1   alarms   : LOF, LOS
  DS1   defects  : LOF, LOS

Meaning

The first line of the sample output shows the status of the link. In this example, the first line shows that the physical link is down. If the first line shows that the physical link is up, the physical link is healthy and can pass packets. If this line shows that the physical link is down, the physical link is unhealthy and cannot pass packets. Also, the output shows loss of frame (LOF) and loss of signal (LOS) alarms active. Any active alarm or defect can cause the interface to be down.


Display Extensive Status Information for a Specific T1 Interface

Purpose

To display extensive status information about a specific T1 interface.

Action

To display extensive status information about a specific T1 interface, use the following JUNOS CLI operational mode command:

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

Sample Output


user@host> show interfaces t1-1/1/0 extensive 
Physical interface: t1-1/1/0, Enabled, Physical link is Down
  Interface index: 24, SNMP ifIndex: 20, Generation: 27
  Link-level type: PPP, 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
  Hold-times     : Up 0 ms, Down 0 ms
  Last flapped   : 2002-01-01 00:00:35 UTC (00:01:00 ago)
  Statistics last cleared: 2002-01-01 00:01:03 UTC (00:00:32 ago)
  Traffic statistics:
   Input  bytes  :                    0                    0 bps
   Output bytes  :                    0                    0 bps
   Input  packets:                    0                    0 pps
   Output packets:                    0                    0 pps
   Input errors :
    Errors: 0, Drops: 0, Framing errors: 0, Policed discards: 0, L3 incompletes: 0, L2 channel errors: 0, L2 mismatch timeouts: 0,
    HS link CRC errors: 0, SRAM errors: 0
   Output errors :
    Carrier transitions: 0, Errors: 0, Drops: 0, Aged packets: 0
   DS1   alarms   : LOF, LOS
  DS1   defects  : LOF, LOS
   T1  media :            Seconds        Count  State
    SEF                      32            0  Defect Active
    BEE                       0            0  OK
    AIS                       0            0  OK
    LOF                      32            0  Defect Active
    LOS                      32            0  Defect Active
    YELLOW                    0            0  OK
    BPV                       0            0
    EXZ                       0            0
    LCV                       0            0
    PCV                      32        10667
    CS                        0            0
    LES                       0
    ES                       32
    SES                      32
    SEFS                     32
    BES                       0
    UAS                      32
  HDLC configuration:
    Policing bucket: Disabled
    Shaping bucket : Disabled
    Giant threshold: 1514, Runt threshold: 3
    Timeslots      : All active
    Line encoding: B8ZS, Byte encoding: Nx64K, Data inversion: Disabled
    Buildout       : 0 to 132 feet
  DS1 BERT configuration:
    BERT time period: 10 seconds, Elapsed: 0 seconds
    Induced Error rate: 10e-0, Algorithm: Unknown (0)
  Packet Forwarding Engine configuration:
    Destination slot: 1, PLP byte: 1 (0x00)
    CoS transmit queue          Bandwidth          Buffer     Priority   Limit
                              %          bps   %        bytes
    0 best-effort             0            0   0            0      low    none
    1 expedited-forwarding    0            0   0            0      low    none
    2 assured-forwarding      0            0   0            0      low    none
    3 network-control         0            0   0            0      low    none

Meaning

The sample output shows where the errors might be occurring. Look at the active alarms and active defects for the T1 interface and investigate the T1 media accordingly. See Locate T1 Alarms and Errors for an explanation of T1 alarms.


Monitor Statistics for a T1 Interface

Purpose

To monitor statistics for a T1 interface.

Action

To monitor statistics for a T1 interface, use the following JUNOS CLI operational mode command:

user@host> monitor interface t1-fpc/pic/port

Sample Output


user@host> monitor interface t1-1/0/0
Seconds: 2                   Time: 00:04:49    Delay: 0/0/1
Interface: t1-1/1/0, Enabled, Link is Down
Encapsulation: PPP, Keepalives, Speed: T1
Traffic statistics:                                           Current delta
  Input bytes:                           0 (0 bps)                       [0]
  Output bytes:                          0 (0 bps)                       [0]
  Input packets:                        0 (0 pps)                       [0]
  Output packets:                       0 (0 pps)                       [0]
Error statistics:
  Input errors:                         0                               [0]
  Input drops:                          0                               [0]
  Input framing errors:                 0                               [0]
  Policed discards:                     0                               [0]
  L3 incompletes:                       0                               [0]
  L2 channel errors:                    0                               [0]
  L2 mismatch timeouts:                 0                               [0]
  Carrier transitions:                  0                               [0]
  Output errors:                        0                               [0]
  Output drops:                         0                               [0]
  Aged packets:                         0                               [0]
Active alarms : LOF LOS
Active defects: LOF LOS
T1 statistics:
  BPV                                   0                               [0]
  EXZ                                   0                               [0]
  LCV                                   0                               [0]
  PCV                               40335                             [332]
  CS                                    0                               [0]
Interface warnings:
  o Outstanding DS1 alarm(s)
Next='n', Quit='q' or ESC, Freeze='f', Thaw='t', Clear='c', Interface='i'

Meaning

The sample output shows that the T1 interface is enabled but the link is down. The bps value is in bytes per second and not bits per second. To calculate bits per second, multiply the bps value by 8.

The monitor command checks for and displays common interface failures, indicates whether loopback is detected, and shows any increases in framing errors. Use information from this command to help to narrow down possible causes of an interface problem.

Note: If you are accessing the router from the console connection, make sure you set the CLI terminal type using the set cli terminal command.

Table 11 lists additional problem situations and actions to help you further diagnose a problem.

Table 11: Problem Situations and Actions

Problem Situation

Action

Framing errors are increasing.

Check the frame checksum sequence (FCS), scrambling, and subrate configuration.

Framing errors are increasing, and the configuration is correct.

Check the cabling to the router and have the carrier verify the integrity of the line.

Input errors are increasing.

Check the cabling to the router and have the carrier verify the integrity of the line.

Note: We recommend that you use this command only for diagnostic purposes. Do not leave it on during normal router operations because real-time monitoring of traffic consumes additional CPU and memory resources.

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