show diagnostics tdr
Syntax
show diagnostics tdr <interface interface-name>
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.
Use Time domain reflectometry (TDR) to confirm platform and release support for TDR.
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.
-
The last TDR test results for all network interfaces on the switch that support the TDR test.
Options
none |
Show summarized last results for all interfaces on the switch 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
Output Fields
The following table lists all possible options for the show diagnostics
tdr
command. The options that appear may vary depending on the platform and
software release. Output fields are listed in the approximate order in which they
appear.
Field Name |
Field Description |
---|---|
Interface name or Interface |
Name of interface for which you report TDR test results. |
Test status |
Status of TDR test:
|
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:
When summary information for all interfaces is displayed, status for the cable as a whole:
|
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:
(Not available on EX8200 switches.) (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. (Not available on EX8200 switches.) (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:
(Displayed only when the interface option is used.) |
Downshift |
Indicates whether the connection speed is being downshifted:
(Displayed only when the interface option is used.) |
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)
show diagnostics tdr interface ge-0/0/19 (Normal Cable)
user@switch> 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@switch> 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@switch> 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
Release Information
Command introduced in Junos OS Release 9.0.