802.3af power-over-data-lines

[dconn]

Hi,

Is there any way to use RocketM5s with 802.3af power-of-data-lines (rather than "passive PoE" power over blue & brown lines)?

I looked at the Ubiquiti instant 802.3af adapters but they said they were only for Rocket a/b/g equipment and I'm not sure if they are power over data lines either.

thanks for any info

D

[WHT]

I don't know where you read anything like that about the UBNT Instant PoE Adapters for only the Rocket.

Basically all it is is a "voltage step-down" adapter if you use standard 48 volts on you power pairs, the wht/blu & blu/wht, and wht/brn & brn/wht wires.

[dconn]

Hi WHT,

Thanks for getting back to my query,

I don't know where you read anything like that about the UBNT Instant PoE Adapters for only the Rocket.

Yes - you are right - it does say "...for Airmax and..." - I missed the "Airmax" bit.

Basically all it is is a "voltage step-down" adapter if you use standard 48 volts on you power pairs, the wht/blu & blu/wht, and wht/brn & brn/wht wires.

That's the bummer. I'm using 802.3af with power-over-datalines with Mikrotik RB600s right now and its great that I can have two boards powered up via a single CAT5 cable (or, rather, its a pity I don't have more cables installed.....)

D

[tagno25]

Basically all it is is a "voltage step-down" adapter if you use standard 48 volts on you power pairs, the wht/blu & blu/wht, and wht/brn & brn/wht wires.

If it is actually a 802.3af compliant device then it has to support power over datalines.

Two modes, A and B, are available.

Mode A has two alternate configurations (MDI and MDI-X), using the same pairs but with different polarities. In mode A, pins 1-2 (pair #2 in T568B wiring) form one side of the 48 V DC, and pins 3-6 (pair #3 in T568B) form the other side. These are the same two pairs used for data transmission in 10Base-T and 100Base-TX, allowing the provision of both power and data over only two pairs in such networks. The free polarity allows for patch cables and automatic RX/TX detection.

In mode B, pins 4-5 (pair #1 in both T568A and T568B) form one side of the DC supply and pins 7-8 (pair #4 in both T568A and T568B) provide the return; these are the "spare" pairs in 10BASE-T and 100BASE-TX. Mode B, therefore, requires a 4-pair cable.

The PSE decides whether power mode A or B shall be used, not the powered device (PD). PDs that implement only Mode A or Mode B are specifically not allowed by the standard.
backed up by http://grouper.ieee.org/groups/802/3/af/requirements.pdf #12

It should drop the data lines to a valid/safe power level, move the power to pins 4/5 7/8, and set the output power to 16v.

[WHT]

If it is actually a 802.3af compliant device then it has to support power over datalines.
True...but what I was referring to is how it supplies power to a UBNT radio, which of course is not "af" compliant.

[Ron]

I looked at the Ubiquiti instant 802.3af adapters but they said they were only for Rocket a/b/g equipment


I think you can use the adapter to power any ubnt or mikrotik device.
Mike will likely confirm power over data lines in the morning, but no one has complained about it not working - so far.

[dconn]

I think you can use the adapter to power any ubnt or mikrotik device.
Mike will likely confirm power over data lines in the morning, but no one has complained about it not working - so far.

Mikrotik RB600 and RB800 are 802.3af 48V power-over-datalines. It's good because you only need two pairs to supply both power and data.

I was wondering if the Ubiquiti 48V PoE 802.3af solution is power-over-datalines but I don't think so now...

Derek

[tagno25]

Mikrotik RB600 and RB800 are 802.3af 48V power-over-datalines. It's good because you only need two pairs to supply both power and data.

I was wondering if the Ubiquiti 48V PoE 802.3af solution is power-over-datalines but I don't think so now...

Derek

all PoE 802.3af compliant powered devices can take power over the data lines. And since the Ubuquti 802.3af converter is a compliant device, acording to the data sheet, the it should be able to support power over the data lines on input.

[UBNT-Mike.Ford]

Hey Guys,

The device is 802.3af compliant so it will support this.

Thanks,

Mike