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ArubaOS-Switch test cable-diagnostic versus duplex/speed on diagnosed port.

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  • 1.  ArubaOS-Switch test cable-diagnostic versus duplex/speed on diagnosed port.

    Posted Apr 04, 2019 04:32 AM

    Hello,

     

    How cable-diagnostic behaves when the test cable-diagnostic is performed on a ethernet interface connected to a 100Mbit Full-Duplex (eventually with PoE) [*] host or a 100Mbit Half-Duplex [**] host? 

     

    I admit I've to diagnose if those host types are correctly set by using the Auto-Sensing...but, apart from that, I want to know if test cable-diagnostic results can differ if the cable's end is connected to hosts behaving differently (100FDx vs 100HDx vs 1000FDx). 

     

    [*] such as a DECT-IP Base Station (as per Auto-Sensing)

     

    I observe this:

    Aruba(config)# test cable-diagnostics ethernet 1
    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
    Aruba(config)# test cable-diagnostics ethernet 2
    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
    Aruba(config)# test cable-diagnostics ethernet 3
    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
    
    Aruba(config)# show cable-diagnostics ethernet 1
    
     Cable Diagnostic Status - Copper Ports
    
           MDI    Cable       Cable Length or
      Port Pair   Status      Distance to Fault
      ---- ------ ----------- ---------------------
      1    1-2    OK          33m
           3-6    OK          38m
           4-5    Short       31m
           7-8    Short       32m
    
    Aruba(config)# show cable-diagnostics ethernet 2
    
     Cable Diagnostic Status - Copper Ports
    
           MDI    Cable       Cable Length or
      Port Pair   Status      Distance to Fault
      ---- ------ ----------- ---------------------
      2    1-2    OK          51m
           3-6    OK          51m
           4-5    Open        1m
           7-8    Short       53m
    
    Aruba(config)# show cable-diagnostics ethernet 3
    
     Cable Diagnostic Status - Copper Ports
    
           MDI    Cable       Cable Length or
      Port Pair   Status      Distance to Fault
      ---- ------ ----------- ---------------------
      3    1-2    OK          31m
           3-6    OK          36m
           4-5    Short       34m
           7-8    Short       34m
    
    Aruba(config)# show interfaces status
      Port     Name       Status  Config-mode   Speed    Type       Tagged Untagged
      -------- ---------- ------- ------------- -------- ---------- ------ --------
      1        DECT-IP... Up      Auto          100FDx   100/1000T  No     1000
      2        DECT-IP... Up      Auto          100FDx   100/1000T  No     1000
      3        DECT-IP... Up      Auto          100FDx   100/1000T  No     1000
    
    Aruba(config)# show interfaces
    
     Status and Counters - Port Counters
     
                                                                     Flow Bcast
      Port         Total Bytes    Total Frames   Errors Rx Drops Tx  Ctrl Limit
      ------------ -------------- -------------- --------- --------- ---- -----
      1            26,397,080     401,898        0         0         off  0
      2            26,444,482     402,386        0         0         off  0
      3            26,359,582     401,525        0         0         off  0

    As you note on all three ports (Spectralink DECT IP Base Station working at 100Mbps Full-Duplex) pair 7-8 results as "Short"...but on Port 2 pair 4-5 is "Open" while the very same pair on Port 1 and 3 results "Short"...so, in the end, is "Short" on 4-5 and 7-8 normal for 100Mbps Full-Duplex and "Open" means that our port 2 connected Spectralink DECT IP Base Station has a real problem? 

     

     

    [**] such as a Label Printer (as per Auto-Sensing)



  • 2.  RE: ArubaOS-Switch test cable-diagnostic versus duplex/speed on diagnosed port.

    Posted Apr 04, 2019 06:53 AM

    This is the output from three devices that we re plugged into one of the test switches. Ports 8 and 21 report in the switch as 100 full duplex.

     

    2930F-31(config)# sh cable-diagnostics
    
     Cable Diagnostic Status - Copper Ports
    
           MDI    Cable       Cable Length or
      Port Pair   Status      Distance to Fault
      ---- ------ ----------- ---------------------
      8    1-2    OK          0m
           3-6    OK          0m
           4-5    Short       1m
           7-8    Short       1m
      16   1-2    OK          0m
           3-6    OK          0m
           4-5    OK          0m
           7-8    OK          0m
      21   1-2    OK          4m
           3-6    OK          4m
           4-5    Short       0m
           7-8    Short       0m

    It is interesting that they both report pairs 4-5 and 7-8 as "short".



  • 3.  RE: ArubaOS-Switch test cable-diagnostic versus duplex/speed on diagnosed port.

    Posted Apr 04, 2019 08:11 AM

    Yes, it's pretty much interesting (and strange too)...but this pattern can't be taken as a general rule...I've found an host (not a DECT IP BS, I haven't any LLDP nor CDP references about it) which is recognized by the switch as 100Mbps Full-Duplex (Auto-Sensing) and it shows four "OK" on the four pairs:

     

    Aruba(config)# test cable-diagnostics ethernet 26
    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
    
    DL1-113# show cable-diagnostics ethernet 26
    
     Cable Diagnostic Status - Copper Ports
    
           MDI    Cable       Cable Length or
      Port Pair   Status      Distance to Fault
      ---- ------ ----------- ---------------------
      26   1-2    OK          43m
           3-6    OK          41m
           4-5    OK          43m
           7-8    OK          43m
    
    	   
    Aruba(config)# show interfaces
    
     Status and Counters - Port Counters
    
                                                                     Flow Bcast
      Port         Total Bytes    Total Frames   Errors Rx Drops Tx  Ctrl Limit
      ------------ -------------- -------------- --------- --------- ---- -----
      26           30,936         437            0         0         off  0
    
      
    Aruba(config)# show interfaces status
    
      Port     Name       Status  Config-mode   Speed    Type       Tagged Untagged
      -------- ---------- ------- ------------- -------- ---------- ------ --------
      26       Sub_192... Up      Auto          100FDx   100/1000T  1000   4
      
    Aruba(config)# show interfaces brief
    
     Status and Counters - Port Status
    
                              | Intrusion                           MDI  Flow Bcast
      Port         Type       | Alert     Enabled Status Mode       Mode Ctrl Limit
      ------------ ---------- + --------- ------- ------ ---------- ---- ---- -----
      26           100/1000T  | No        Yes     Up     100FDx     MDIX off  0

    So it could be difficult to understand what is the correct output one should expect.