Powering cAP ax trough PoE

RouterOS Beginner Basics
1

Hello,

I am looking for help understanding the basics of powering devices trough PoE. I am currently in process of upgrading my home network and I was looking for powerful AP. Came over cAP ax, but I have one major problem. I have need for switch in place where I want to install the AP. So I need two devices there, but there are only two sockets, one will be permanently occupied. I started looking into the PoE and came over RB960PGS to power cAP ax trough PoE. They both have PoE 802.3af/at but I think the RB960PGS cannot output maximum the cAP ax might need.

I am not an electrician or fluent in power calculus but through what I could find, I deciphered that maximum output of RB960PGS is 26,65 W (0,45A * 57V) and max power consumption of cAP ax is 36 W.

How big of a problem that would be in household scenario?

Thanks for responses!

2

It all depends …
It might never be a problem during normal operations unless already at startup the device will exceed power budget of RB960 in which case it will never start.

You already took into account a separate power supply unit since you mention 57V?
Because default RB960 comes with 24V PSU. With 1A output that’s 24W.

However, since you mentioned it should be a switch, why use a router ?
I’m probably cursing here in the church but TP link SG105PE is a sweet managed switch suited for those needs.
30W on each POE port (it has 5 ports of which 4 are POE, 65W total output). I have it installed on a couple of installations with cAP AX and no issues (simple config, only AP and nothing more).

3

I took into account only specs mentioned on respective product pages. So this is where the 57V comes from.

As for switch/router. I was looking for switch that can satisfy my needs, but could not find anything from mikrotik that would be normal household switch with that requirements.. Maybe I am wrong and blind and the same time but really could not. I am trying to move away from TP-Link stuff I have at home, got burned by buying modem that went to hell in few months of use. But you are right that I should be looking for switch rather than router, there is no need for one as everything is managed by my hAP ax.

4

Dont’ worry. :slight_smile:

The cap Ax itself uses 11W:

Max power consumption without attachments 11 W

that is the absolute max, in real world you will see more like 6-7 W.

But you can daisy chain to it another device (i.e. using the PoE out of the cap Ax), this device can be roughly another 20 W, and this makes, considering losses and what not, the total stated:

Max power consumption 36 W

So you won’t have any problem in powering just the capAx from the RB960PGS.

The capAx (even if may be not clear from the specs) can be powered both with “old” 24 V PoE and with “new” 802.3af/at 48V PoE.

Personally I wouldn’t spend nowadays on a hex poe, however, because it has a limited amount of storage (16 Mb) that is already tight with the current 7.x Ros versions and it is basically a router, and you don’t need the SFP cage, you might probably be better served by a small switch like the RB260GSP (that runs SwOS ) and is much faster at switching.

The issue (or non issue) in this case would be that the RB260GSP uses only the “old” (passive) poe at 24 V, so while your capAX is compatible with that, if you want to change the AP the new one may support 802.3af/at only and you will have to change the switch also.

You would save some money, however, at list prices 90-56=34 $.

The power supply that comes with the both the hex Poe (RB960GSP) and the RB260GSP is a 24V 2.5A one (60 W) more than adequate to power both the switch and the capAx, but if you want to use the “new” 802.3af/at with the hex PoE you will need to buy additionally a 48 V power supply, such as:
https://mikrotik.com/product/48POW
another 18$
or this :
https://mikrotik.com/product/mt48_480095_11dg
only 12$

If you are confused, it is normal, the current situation of Mikrotik PoE is madness.

The TP-Link suggested should be around the same price as the Mikrotik switch, it is 802.3af/at and has the “right” 48V power, with some 65W total, so it would be a good alternative.

5

RB260GSP is the one I had selected before I noticed that cAP ax spec says that only 802.3 af/at PoE is able to power the device.

I think you saved me, I am getting RB260GS already for my second switch so I will get GSP to power this part of the network.

You are livesaver, I thought I was getting mad already reading all the specs :slight_smile:

Thank you!

6

Yep, that is exactly the kind of mess I was talking about, the specs:

PoE in 802.3af/at
PoE in input Voltage 18-57 V

say first 802.3af/at, but anything below 37 or 44V is not 802.3af/at, and the 18-57 V below means that it can also use the “old” 24V PoE.

The drawback (unlikely in your case unless you have an exceptionally large home) is that 24 V is much less efficient on long lengths of ethernet cable than 48 V.