Compatible cable tester for MS-120 switches

[Craighaty7]

I've been using Fluke IQ Cable Qualifier kit for all my cable testing on our networks mainly of HP and Korenix PoE switches.

As we're in the process of migrating to Meraki switches, I'm finding that the network tester doesn't like when a Meraki switch is attached, warning 'voltage detected, disconnect cable'.

I understand the 802.3af standard that these switches support, and that there is a very small voltage on the pairs to negotiate whether or not to supply the full 48v. I do not experience this alert on our existing fleet of POE switches. This is the sort of fault I find on a passive POE injector. My POE tester does not record a full POE voltage, usually about 4VDC, from the Meraki switch until the tester's signature is triggered, emulating a PD request, then it records the full 48VDC.

I also understand that the best way to qualify a cable run is to disconnect from devices and connect the remote ID dongle. However, during our production periods, if there's a fault, time is critical and I usually disconnect the device and test back to the switch. I can't do this with the Meraki switches. It's almost like the Fluke Cable IQ is triggering the 25ohm POE request - yet I don't experience this with HP or Korenix switches.

Anyone else experience this?

Any suggestions for quality network tester?

[PhilipDAth]

I don't know the answer. 

Have you considered just using the cable tester built into the switch? 

[Craighaty7]

Philip, it's one of the reasons we're 'switching' to Meraki - our operations are spread over a large area and remote troubleshooting is a big plus. But when I'm on the ground and time is critical, if a device is not working I just unplug the device and throw the tester on the end and get a good head start where to look. Most of the old cabling in our sites is not referenced or labelled so I need to start from the device and work back. It's for this reason I can't test much from the switch to the device, unless I know the port it's supposed to be on or see a fault at the switch's console.

There must be cablers/installers out there who use a network tester on these switches. At this stage it looks like I need two testers, Fluke Microscanner2 which is POE friendly, to use on the Meraki networks, and the Cable IQ for non-Meraki sites (the Cable IQ gives a much greater picture of how the cable is performing).

[Adam]

To do a proper cable test don't you need to have it disconnected from the Meraki and have the probe ends on both sides?  Otherwise, you could just run the test from the Meraki switch.  

[Craighaty7]

Correct Adam. And when doing installs or repairs, I do that to certify the run. The issue I have is troubleshooting a fault when you don't know what port it's on. When I get a call that a device fails, and there's no obvious error on the Meraki switch, I go to site, disconnect the device and test the run. The good thing with doing this on HP and other switches is with my current tester I can flash the port lights and immediately know which port its on. When an install is by-the-book and all cables are labelled, I can talk to an on-site person and ask them 'what port is PLC-x on' and check that port's history/state. I need to get to that point.

I'm surprised no one has encountered using a network tester on a cable plugged into the Meraki switch. 

[GiacomoS]

Hey @Craighaty7, 

Do you normally have computers connected or a different type of device? You could potentially track down the ports easily by putting the mac address in the search field of the Clients page, then select the device and should tell you where it's connected.

Another possibility that might help with non-PoE devices could be to allocate a number of ports specifically for them and disable PoE on the ports configuration. This would obviously not help you in the case of PoE clients.

Hope this helps.

Giacomo

[Craighaty7]

Giacomo, your tips are practical and as you suggested, would not change those ports with POE devices on them. 

We have many POE devices, IP cameras, VoIP phones and wifi radios, as well as a plethora of other devices like PLCs, RFID readers, weight scales, touchscreen PCs and the usual computers and servers.

I've decided now to get a Netscout LinkRunner AT-2000 network tester which will fill this hole testing back to the switch and keep my Fluke Cable IQ for cable certification. 

[GiacomoS]

Awesome 🙂 It does sound like a rather complex setup...  

I wish you good luck with the rollout then! 🙂 

Giacomo