I have written previously about the benefits of having a built-in TDR (time domain reflectometer) in most of the new Aruba-branded access switches Cable Testing with TDR to the Rescue!
This week I had two other use cases where the built-in testing was very useful.
Cable Length Confirmation
I have a switch in a store-room that is essentially just an intermediate hop. Could we leave the switch out and just patch the cables together? The maximum distance for Ethernet is 100m, and having joins is less than ideal, potentially reducing the maximum working distance due to avoid excessive errors.
The results for the first hop are shown below - doesn't that make it easy!
Cable Diagnostic Status - Copper Ports
MDI Cable Cable Length or
Port Pair Status Distance to Fault
---- ------ ----------- ---------------------
1 1-2 Open 74m
3-6 Open 71m
4-5 Open 75m
7-8 Open 71m
2 1-2 Open 63m
3-6 Open 61m
4-5 Open 64m
7-8 Open 61m
3 1-2 Open 63m
3-6 Open 61m
4-5 Open 64m
7-8 Open 61m
4 1-2 Open 72m
3-6 Open 70m
4-5 Open 73m
7-8 Open 70m
5 1-2 Open 63m
3-6 Open 61m
4-5 Open 64m
7-8 Open 61m
6 1-2 Open 64m
3-6 Open 61m
4-5 Open 64m
7-8 Open 61m
Is this an Ethernet port?
I received a temperature sensor with an RJ45 port. I was assured it was an Ethernet POE powered IOT gadget, but I had my doubts.
Well it didn't work, and the cable-diagnostic was able to provide the evidence why.
Cable Diagnostic Status - Copper Ports
MDI Cable Cable Length or
Port Pair Status Distance to Fault
---- ------ ----------- ---------------------
13 1-2 Inter-Short 2m
3-6 Inter-Short 1m
4-5 Short 1m
7-8 Inter-Short 1m