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T568B or T568A cabling with POE on Ubiquiti

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Fri, 11/30/2018 - 14:57
#1
ka9mot
ka9mot's picture
T568B or T568A cabling with POE on Ubiquiti

Hello,
My apology to everyone...  This question may not be related directly to AREDN but to RJ45 cabling or wiring that powers an AREDN device..
I have a nanostation M2 loaded with AREDN and on antenna outside.
I crimped a Cat6 cable and  used a cable-tester that shows that all pairs line up.
I  wired the RJ45  following this way: T568B
The distance between the POE power supply and the radio is of 0.038 miles or 60 meters..
The problem:  I am having problems reaching the router interface using " http://localnode:8080/ "..
it is irresponsive but the radio is on....  From other nodes I can see the radio..
I read somewhere that wiring cable for a POE radio should be ok for a cable of 3 to 8 meters length but above 50 meters it should be T568A since it tends to work better than T568B on POE devices..
Can you guys share your experience with cabling cat6 for a POE device located more than 50 meters from the power adapter ?
Thanks

Steve
..

 

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Fri, 11/30/2018 - 18:46
AJ6GZ
A/B
T568A and T568B are electrically identical. Only the colors of the wire pairs change, the signals are in the same locations on the RJ45. There is no performance difference. You just want to make sure you use the same one on each end of the cable and through any patch panels and patch cables. If you mix them, you have created an ethernet crossover cable and would flip the polarity in PoE mode A. The only thing at 50m would be to make sure you're using a 24V power supply. 12V won't cut it at that distance. It seems the radio is up and running so we would want to look at what it is plugged into. A laptop, a switch? Have you refreshed your DHCP on the laptop since flashing? Also make sure you are on the Main port of the radio. Ian
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Sat, 12/01/2018 - 05:10
(Reply to #2)
ka9mot
ka9mot's picture
Hello Ian,

Hello Ian,
thanks for your advice.. I am using 24V power supply and the radio  LAN cable is plugged  into a switch...
But I will double check the radio port being used as well...
the other thing that I am going to do is to recheck rj45 connectors to see if I did not with good intention create an ethernet crossover cable with regards to cable polarity...
thanks a lot
Steve..

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Sat, 12/01/2018 - 12:35
(Reply to #3)
AJ6GZ
Computer
Try plugging directly into a laptop or PC (with DHCP on) and see if you can access it. Then we can look at the switch config. Ian
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Tue, 12/04/2018 - 19:13
N7JYS
Cabling
I'm using cat6 cable and T568 wiring. I have no problems with a 284 foot run up my 305 ft tower using a NSM2 and Ubiquiti 5POE tough switch.

Eric

N7JYS
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Wed, 12/05/2018 - 07:10
KX5DX
You can use either A to A, B to B, or A to B.

You can use either A to A, B to B, or A to B. Besides the color code the other change is the TX/RX pairs are flipped when going from A to B to form a cross-over cable, the passive PoE power pairs stay the same.

Back 10 years ago it was mandatory to have the proper cable termination, straight-thru or cross-over. The easy way to remember when to use which cable, "like devices" (switch to switch) use cross-over, "unlike devices" (switch to PC) use straight-thru. 

Today, this is not an issue as most devices support auto MDIX and will auto detect if the TX/RX pairs need to be flipped due to an incorrect cable standard. This usually works fine but even Cisco still recommends to use the proper standard for the application.

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