As a general rule of thumb, it is a good idea to start troubleshooting at Layer 1 and work your way up the stack. There are occasions when you just can't get to site, and testing L1 - including cabling - can be a challenge.
TDR
This is where the TDR (time domain reflectometer) comes into play. The TDR is built-in to the latest Aruba CX 6xxx switches (RJ45 ports only). That includes:
Console Commands
Some examples of the command "diag cable-diagnostic n/n/n" on a CX6300F 24 port POE switch. Ensure you enable diagnostics mode first, otherwise the diag command will not be available.
CX6300# diagnostics
CX6300# diag cable-diagnostic 1/1/5
This command will cause a loss of link on the port under test
and will take several seconds to complete.
Continue (y/n)? y
MDI Cable Distance MDI
Interface Pair Status to Fault Mode
(Meters)
-------------------------------------------------
1/1/5 1-2 good 8 mdix
3-6 good 5 mdix
4-5 open 2 mdix
7-8 open 2 mdix
CX6300# diag cable-diagnostic 1/1/12
This command will cause a loss of link on the port under test
and will take several seconds to complete.
Continue (y/n)? y
MDI Cable Distance MDI
Interface Pair Status to Fault Mode
(Meters)
-------------------------------------------------
1/1/12 1-2 good 11 mdi
3-6 good 11 mdi
4-5 good 11 mdi
7-8 good 11 mdi
CX6300# diag cable-diagnostic 1/1/13
This command will cause a loss of link on the port under test
and will take several seconds to complete.
Continue (y/n)? y
MDI Cable Distance MDI
Interface Pair Status to Fault Mode
(Meters)
-------------------------------------------------
1/1/13 1-2 good 11 mdi
3-6 good 11 mdi
4-5 short 2 mdi
7-8 short 2 mdi
- 1/1/5 = old MSM410 AP running as a remote client
- 1/1/12 = HP Lync Phone
- 1/1/13 = dodgy IP camera
I also tried one of the SFP56 ports (connected with a 1m DAC), and as expected, it was not supported.
CX6300# diag cable-diagnostic 1/1/27
Cable diagnostic not available on this port
Previous Posts
I have posted several times previously about the TDR in the ArubaOS-Switch devices, you can find those posts here: