SWITCH VCT – Virtual Cable Test

glitchlist Uncategorized 3 Comments

if you don’t have a CableIQ qualification Tester you can use VCT to determine cable quality or detect problems on your LAN. Like an OTDR for fiber, VCT uses TDR technology to detect cable problems by analyzing the returning pulse signal on every pin of RG45. Latest version on most switches have this utility embedded on the firmware. If everything ends well this utility is also useful to know the length of the cable.

Here some examples:

Warning: The command will stop service for a while. Continue? [Y/N]:y
Info: This operation may take a few seconds. Please wait for a moment..................done.
Pair A length: 12meter(s)
Pair B length: 12meter(s)
Pair C length: 12meter(s)
Pair D length: 12meter(s)
Pair A state: Ok
Pair B state: Ok
Pair C state: Ok
Pair D state: Ok
Info: The test result is only for reference.

Cable status: normal, 33 metres
Pair Impedance mismatch: -
Pair skew: - ns
Pair swap: -
Pair polarity: -
Insertion loss: - db
Return loss: - db
Near-end crosstalk: - db

SWITCH# test cable-diagnostics 1/34 
This command will cause a loss of link on all tested ports and will take
several seconds per port to complete.  Use the 'show cable-diagnostics'
command to view the results.

Continue (y/n)?  y

SWITCH# show cable-diagnostics 1/34

 Cable Diagnostic Status - Copper Ports

       MDI    Cable       Cable Length or       
  Port Pair   Status      Distance to Fault     
  ---- ------ ----------- --------------------- 
  1/34 1-2    OK          14m                    
       3-6    OK          14m                    
       4-5    OK          14m                    
       7-8    OK          14m                    


test cable-diagnos tdr int gig0/0
show cable-diagnostics tdr int gig0/0
show cable-diagnostics tdr

# D-Link

cable_diag ports 1

# Mikrotik RouterOS:

/interface ethernet cable-test ether1

in our environment, for deeper analysis, we use DSX-600 CableAnalyzer™

.glitchlist crew

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