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    show diagnostics tdr

    Syntax

    show diagnostics tdr
    <interface interface-name>

    Release Information

    Command introduced in Junos OS Release 12.3X53 for ACX Series routers.

    Description

    Display the results of a time domain reflectometry (TDR) diagnostic test run on an interface. A TDR test characterizes and locates faults on twisted-pair Ethernet cables. For example, it can detect a broken twisted pair and provide the approximate distance to the break. It can also detect polarity swaps, pair swaps, and excessive skew.

    The TDR test is supported on the following ACX routers and interfaces:

    • On ACX1000 routers, 4 RJ45 (Cu) ports or 8-port Gigabit Ethernet MICs with small form-factor pluggable (SFP) transceivers and RJ45 connectors.
    • On ACX1100 routers, 4-port or 8-port Gigabit Ethernet MICs with SFP transceivers and RJ45 connectors.
    • On ACX2000 routers, 8-port Gigabit Ethernet MICs with SFP transceivers and RJ45 connectors.
    • On ACX2100 and ACX2200 routers, 4-port Gigabit Ethernet MICs with SFP transceivers and RJ45 connectors.
    • On ACX4000 routers, 4-port, 6-port, or 8-port Gigabit Ethernet MICs with SFP transceivers and RJ45 connectors.

    Note: TDR diagnostics are applicable for copper ports only and not for optical fiber ports.

    Use the request diagnostics tdr command to request a TDR test on a specified interface. Use the show diagnostic tdr command to display the last TDR test results for a specified interface or the last TDR test results for all network interfaces on the router that support the TDR test.

    Options

    noneShow summarized last results for all interfaces on the router that support the TDR test.
    interface interface-name(Optional) Show detailed last results for the specified interface or a range of interfaces. Specify a range of interfaces by entering the beginning and ending interface in the range, separated by a dash—for example, ge-0/0/15-ge-0/0/20.

    Required Privilege Level

    view

    List of Sample Output

    show diagnostics tdr interface ge-0/0/19 (Normal Cable)
    show diagnostics tdr interface ge-2/0/2 (Faulty Cable)
    show diagnostics tdr (All Supported Interfaces)

    Output Fields

    Table 1 lists the output fields for the show diagnostics tdr command. Output fields are listed in the approximate order in which they appear.

    Table 1: show diagnostics tdr Output Fields

    Field Name

    Field Description

    Interface name or

    Interface

    Name of interface for which TDR test results are being reported.

    Test status

    Status of TDR test:

    • Aborted—Test was terminated by operator before it was complete.
    • Failed—Test was not completed successfully.
    • Interface interface-name not found—Specified interface does not exist.
    • Not Started—No TDR test results are available for the interface.
    • Passed—Test completed successfully. The cable, however, might still have a fault—see the Cable status field for information on the cable.
    • Started—Test is currently running and not yet complete.
    • VCT not supported on interface-name—TDR test is not supported on the interface.

    Link status

    Operating status of link: UP or Down.

    MDI pair

    Twisted pair for which test results are being reported, identified by pin numbers. (Displayed only when the interface option is used.)

    Cable status

    When detailed information is displayed, status for a twisted pair:

    • Failed—TDR test failed on the cable pair.
    • Impedance Mismatch—Impedance on the twisted pair is not correct. Possible reasons for an impedance mismatch include:
      • The twisted pair is not connected properly.
      • The twisted pair is damaged.
      • The connector is faulty.
    • Normal—No cable fault detected for the twisted pair.
    • Open—Lack of continuity between the pins at each end of the twisted-pair.
    • Short on Pair-n—A short-circuit was detected on the twisted pair.

    When summary information for all interfaces is displayed, status for the cable as a whole:

    • Fault—A fault was detected on one or more of the twisted-pairs.
    • OK—No fault was detected on any of the twisted pairs.

    Distance fault or

    Max distance fault

    Distance to the fault in whole meters. If there is no fault, this value is 0.

    When summary information for all interfaces is displayed, this value is the distance to the most distant fault if there is more than one twisted pair with a fault.

    Polarity swap

    Indicates the polarity status of the twisted pair:

    • Normal—Polarity is normal. Each conductor in the twisted pair has been connected the same pins at the both ends of the connection. For example, a conductor connected to pin 1 at the near end of the connection is connected to pin 1 at the far end.
    • Reversed—Polarity has been reversed. For the twisted pair, the conductors have switched which pins they are connected to at the near and far ends of the connection. For example, the conductor connected to pin 1 at the near end is connected to pin 2 at the far end.

    (Displayed only when the interface option is used)

    Skew time

    Difference in nanoseconds between the propagation delay on this twisted pair and the twisted pair with the shortest propagation delay. (Displayed only when the interface option is used.)

    Channel Pair

    Number of the 10/100BASE-T transmit/receive pair being reported on.

    Pair Swap

    Indicates whether or not the twisted pairs are swapped:

    • MDI—The pairs are not swapped (straight-through cable).
    • MDIX—The pairs are swapped (cross-over cable).

    (Displayed only when the interface option is used.)

    Downshift

    Indicates whether the connection speed is being downshifted:

    • No Downshift—No downshifting of connection speed.
    • Downshift occurs—Connection speed is downshifted to 10 or 100 Mbs. This occurs if the cable is a two-pair cable rather than the four-pair cable required by Gigabit Ethernet.

    (Displayed only when the interface option is used.)

    Sample Output

    show diagnostics tdr interface ge-0/0/19 (Normal Cable)

    user@host> show diagnostics tdr interface ge-0/0/19
    Interface TDR detail:
    Interface name                  : ge-0/0/19
    Test status                     : Passed
    Link status                     :  UP
    MDI pair                        : 1-2
      Cable status                  : Normal
      Distance fault                : 0 Meters
      Polartiy swap                 : Normal
      Skew time                     : 0 ns
    MDI pair                        : 3-6
      Cable status                  : Normal
      Distance fault                : 0 Meters
      Polartiy swap                 : Normal
      Skew time                     : 8 ns
    MDI pair                        : 4-5
      Cable status                  : Normal
      Distance fault                : 0 Meters
      Polartiy swap                 : Normal
      Skew time                     : 8 ns
    MDI pair                        : 7-8
      Cable status                  : Normal
      Distance fault                : 0 Meters
      Polartiy swap                 : Normal
      Skew time                     : 8 ns
    Channel pair                    : 1
      Pair swap                     : MDI
    Channel pair                    : 2
      Pair swap                     : MDI
    Downshift                       : No Downshift

    show diagnostics tdr interface ge-2/0/2 (Faulty Cable)

    user@host> show diagnostics tdr interface ge-2/0/2
    Interface TDR detail:
    Interface name                  : ge-2/0/2
    Test status                     : Passed
    Link status                     : Down
    MDI Pair                        : 1-2
       Cable status                 : 1-2
       Distance fault               : 2 Meters
       Polartiy swap                : N/A
       Skew time                    : N/A
    MDI Pair                        : 3-6
       Cable status                 : Impedance Mismatch
       Distance fault               : 3 Meters
       Polartiy swap                : N/A
       Skew time                    : N/A
    MDI Pair                        : 4-5
       Cable status                 : Impedance Mismatch
       Distance fault               : 3 Meters
       Polartiy swap                : N/A
       Skew time                    : N/A
    MDI Pair                        : 7-8
       Cable status                 : Short on Pair-2
       Distance fault               : 3 Meters
       Polartiy swap                : N/A
       Skew time                    : N/A
    Channel pair                    : 1
       Pair swap                    : N/A
    Channel pair                    : 2
       Pair swap                    : N/A
    Downshift                       : N/A

    show diagnostics tdr (All Supported Interfaces)

    user@host> show diagnostics tdr    
    Interface   Test status    Link status  Cable status  Max distance fault
     ge-0/0/0   Not Started    N/A          N/A           N/A
     ge-0/0/1   Not Started    N/A          N/A           N/A
     ge-0/0/2       Started    N/A          N/A           N/A
     ge-0/0/3       Started    N/A          N/A           N/A
     ge-0/0/4        Passed     UP           OK             0
     ge-0/0/5        Passed     UP          Fault         173
     ge-0/0/6        Passed     UP           OK             0
     ge-0/0/7        Passed     UP           OK             0
     ge-0/0/8        Passed     UP           OK             0
     ge-0/0/9        Passed     UP           OK             0
    ge-0/0/10        Passed     UP           OK             0
    ge-0/0/11        Passed     UP           OK             0
    ge-0/0/12        Passed     UP           OK             0
    ge-0/0/13        Passed     UP           OK             0
    ge-0/0/14        Passed     UP           OK             0
    ge-0/0/15        Passed     UP           OK             0
    ge-0/0/16        Passed     UP           OK             0
    ge-0/0/17        Passed     UP           OK             0
    ge-0/0/18        Passed     UP           OK             0
    ge-0/0/19        Passed     UP           OK             0
    ge-0/0/20        Passed    Down         Fault           0
    ge-0/0/21        Passed    Down         Fault           5
    ge-0/0/22        Passed     UP           OK             0
    ge-0/0/23        Passed     UP           OK             0

    Modified: 2013-12-16