Monitor T3 Interfaces

By monitoring T3 interfaces, you begin the process of isolating T3 interface problems when they occur.

To monitor T3 interfaces, follow these steps:

Display the Status of T3 Interfaces

Purpose

To display the status of T3 interfaces, use the following Junos OS command-line interface (CLI) operational mode command:

Action

user@host> show interfaces terse t3*

Sample Output

user@host> show interfaces terse t3*

Interface       Admin Link Proto Local                 Remote
t3-1/0/0        down  up    - administratively disabled
t3-1/0/0.0      up    down inet  1.1.1.1/30
t3-1/0/1        up    down
t3-1/0/1.0      up    down inet  2.2.2.2/30  - link layer down
t3-1/0/2        up    up
t3-1/0/2.0      up    up   inet  3.3.3.3/30  - link layer up
t3-1/0/3        up    down

Meaning

The sample output shows the status of both the physical and logical interfaces. See Table 12 for a description of what the output means.

Table 12: Status of T3 Interfaces

Physical Interface	Logical Interface	Status Description
t3-1/0/0 Admin Down Link Up	t3-1/0/0.0 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 down because the physical link is disabled (Link Down).
t3-1/0/1 Admin Up Link Down	t3-1/0/1.0 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).
t3-1/0/2 Admin Up Link Up	t3-1/0/2.0 Admin Up Link Up	This interface has both the physical and logical links up and running.
t3-1/0/3 Admin Up Link Down		This interface does not have a logical link configured.

Display the Status of a Specific T3 Interface

Purpose

To display the status of a specific T3 interface when you need to investigate its status further, use the following Junos OS CLI operational mode command:

Action

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

Sample Output

user@host> show interfaces t3-1/0/0

Physical interface: t3-1/0/0, Enabled,  Physical link is Down
  Interface index: 9, SNMP ifIndex: 10
  Link-level type: Cisco-HDLC, MTU: 4474, Clocking: Internal
  Speed: T3, Loopback: None, CRC: 16, Mode: C/Bit parity
  Device flags   : Present Running Down
  Interface flags: Hardware-Down Link-Layer-Down Point-To-Point SNMP-Traps
  Link flags     : Keepalives
  Keepalive Input: 116 (00:02:32 ago), Output: 185 (00:00:02 ago)
  Input rate     : 0 bps (0 pps), Output rate: 0 bps (0 pps)
  Active alarms  : LOF, LOS
  Active defects : LOF, LOS
  Logical interface t3-1/0/0.0 (Index 12) (SNMP ifIndex 32)
    Flags: Device-down Point-To-Point SNMP-Traps, Encapsulation: Cisco-HDLC
    Protocol inet, MTU: 4470
      Addresses, Flags: Dest-route-down Is-Preferred Is-Primary
        Destination: 1.1.1.0/30, Local: 1.1.1.1

Meaning

The first line of the sample output shows the status of the link. If this 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.

Display Extensive Status Information for a Specific T3 Interface

Purpose

To display extensive status information about a specific T3 interface, use the following Junos OS CLI operational mode command:

Action

user@host> show interfaces t3-fpc/pic/port extensive

Sample Output

user@router> show interfaces t3-1/0/0 extensive

Physical interface: t3-1/0/0, Enabled, Physical link is Down
  Interface index: 9, SNMP ifIndex: 10
  Link-level type: Cisco-HDLC, MTU: 4474, Clocking: Internal
  Speed: T3, Loopback: None, CRC: 16, Mode: C/Bit parity
  Device flags   : Present Running Down
  Interface flags: Hardware-Down Link-Layer-Down Point-To-Point SNMP-Traps
  Link flags     : Keepalives
  Keepalive statistics:
    Input : 116 (last seen 00:02:59 ago)
    Output: 187 (last seen 00:00:09 ago)
  Statistics last cleared: Never
  Traffic statistics:
   Input  bytes  :                 2552                    0 bps
   Output bytes  :                 3703                    0 bps
   Input  packets:                  116                    0 pps
   Output packets:                  161                    0 pps
  Input errors: - Input errors
    Errors: 0, Drops: 0, Framing errors: 229, Policed discards: 1
    L3 incompletes: 0, L2 channel errors: 0, L2 mismatch timeouts: 0
    SRAM errors: 0, HS link CRC errors: 0
  Output errors: - Output errors
    Carrier transitions: 4, Errors: 0, Drops: 0, Aged packets: 0
  Active alarms  : LOF, LOS - DS3 active alarms and defects
  Active defects : LOF, LOS
  DS3 Media:            Seconds        Count  State  - T3 media-specific errors
    PLL Lock                  0            0  OK
    Reframing               273            2  Defect Active
    AIS                       0            0  OK
    LOF                     273            2  Defect Active
    LOS                     273            2  Defect Active
    IDLE                      0            0  OK
    YELLOW                    0            0  OK
    BPV                       0            0
    EXZ                       0            0
    LCV                     275     18022125
    PCV                       0            0
    CCV                       0            0
    LES                     275
    PES                     273
    PSES                    273
    CES                     273
    CSES                    273
    SEFS                    273
    UAS                     277
  HDLC configuration:
    Policing bucket: Disabled
    Shaping bucket : Disabled
    Giant threshold: 4484, Runt threshold: 3
  DSU configuration:
    Compatibility mode: None, Scrambling: Disabled, Subrate: Disabled
    FEAC loopback: Inactive, Response: Disabled, Count: 0
    BERT time period: 10 seconds, Elapsed: 0 seconds
    Algorithm: 2^3 - 1, Pseudorandom (1), Error rate: 10e-0
  PFE configuration:
    Destination slot: 1, Stream number: 0, PLP byte: 1 (0x00)
    COS transmit queue bandwidth:
      Queue0: 95, Queue1: 0, Queue2: 0, Queue3: 5
    COS weighted round robin:
      Queue0: 95, Queue1: 0, Queue2: 0, Queue3: 5
  Logical interface t3-1/0/0.0 (Index 12) (SNMP ifIndex 32)
    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, Broadcast: Unspecified

Meaning

The sample output shows where the errors might be occurring. Look at the active alarms and active defects for the T3 interface and investigate the T3 media accordingly. See Checklist of Common T3 Alarms and Errors for an explanation of T3 alarms.

Monitor Statistics for a T3 Interface

Purpose

To monitor statistics for a T3 interface, use the following Junos OS CLI operational mode command:

Action

user@host> monitor interface t3-fpc/pic/port

Sample Output

user@host> monitor interface t3-1/0/0

router                       Seconds: 78                  Time: 21:44:15
Interface: t3-1/0/0, Enabled, Link is Down
Encapsulation: Cisco-HDLC, Keepalives, Speed: T3
Traffic statistics:                              Current Delta
  Input bytes:              0 (0 bps)                      [0]
  Output bytes:           207 (184 bps)                  [184]
  Input packets:            0 (0 pps)                      [0]
  Output packets:           9 (1 pps)                      [8]
Encapsulation statistics:
  Input keepalives:         0                              [0]
  Output keepalives:        9                              [8]
Error statistics:
  Input errors:             0                              [0]
  Input drops:              0                              [0]
   Input framing errors :     9                              [8]
  CCV                       0                              [0]
Interface warnings:
  o Received keepalive count is zero
  o Framing errors, check FCS, scrambling and subrate configuration
Next='n', Quit='q' or ESC, Freeze='f', Thaw='t', Clear='c', Interface='i'

Meaning

This command checks for and displays common interface failures, indicates whether loopback is detected, and reports any increases in framing errors. Use the information from this command 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 13 presents problem situations and actions to help you further understand the problem.

Table 13: Problem Situations and Actions

Problem Situation	Action
Framing errors are increasing.	Check the frame check 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 troubleshooting purposes. Do not leave it on during normal router operations because real-time monitoring of traffic consumes additional CPU and memory resources.