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danletkeman
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802.3af power and 532aR5

Tue Jun 26, 2007 7:09 pm

Hello,

I'm having some trouble powering on a 532aR5 board with this power supply.

http://www.wlanparts.com/product/PSA16U-480

I have tried every combination imaginable and this is the only combination that does not work.

Is there a compatibility issue with 802.3af?
 
babyface
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Re: 802.3af power and 532aR5

Tue Jun 26, 2007 10:46 pm

802.3af isn't fully supported in Routerboards. The power supply mentioned is useless with RB, because it must detect 802.3af device to work.

I have the same problem with PoE switches and I have asked for a solution, but nobody seems to be interested.

MT should think in give us a little solution, maybe a little adapter.

PD: This is the only thing from MT that have dissapointed me. They must remove 802.3af from the board references and put "Passive Power over Ethernet (802.3af not compliant)".
 
danletkeman
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Re: 802.3af power and 532aR5

Wed Jun 27, 2007 2:38 am

Thank you.

I agree this is quite a disappointment. I now have to send back a box full of power supplies.

Do you know where I can get a power supply like this one that has the poe and power supply built in?
 
babyface
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Re: 802.3af power and 532aR5

Wed Jun 27, 2007 2:43 am

You only need a passive PoE inyector (about 9 euros) and a 48 power supply. MT has both products in her portfolio.
 
jo2jo
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Re: 802.3af power and 532aR5

Wed Jun 27, 2007 7:25 am

ive complained about this issue as well..from what i understand, i think the RB532 supports, TRUE 802.1AF , or what MT calls power OVER data Lines
 
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normis
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Re: 802.3af power and 532aR5

Wed Jun 27, 2007 3:18 pm

There are two types of PoE, one which uses the data lines for power, and one that uses 'spare lines'. RB153 supports both, rest of devices support only over 'spare lines'. Most PoE switches support only 'over datalines.
 
babyface
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Re: 802.3af power and 532aR5

Fri Jun 29, 2007 1:07 pm

Yes, there are two types of PoE devices, but both can work with a PoE switch without problems if they are 802.3af compliant.
 
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stephenpatrick
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Re: 802.3af power and 532aR5

Fri Jun 29, 2007 4:51 pm

Have a read here:
a good summary of the 802.3af standard

http://en.wikipedia.org/wiki/802.3af

"Two modes, A and B, are available. In mode A, pins 1-2 (pair #2 in T568B wiring) form one side of the 48 volt DC supply, and pins 3-6 (pair #3 in T568B) provide the 48 V return. 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.

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 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 power sourcing equipment (PSE) decides whether power mode A or B is to be used, not the powered device (PD).
The PSE can implement mode A or B or both (but must not supply power in both modes at the same time)."

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