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BlanketyBlank
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RB4011iGS+ PoE in seems to need a jump-start

Sun May 30, 2021 3:53 am

Hi there,

I have an RB4011 that I'd like to power from a Starlink power-brick using PoE. I connect them using an ethernet cable from the Starlink white port to the RB4011 ether1 but get no power. If I then connect the DC adapter to the RB4011 (Starlink still connected), the router powers on. Then after a minute or two I can remove the DC adapter and the router remains powered by Starlink (PoE). So it seems like I'm jumpstarting the PoE. Obviously this is not a great solution. :-)

Is there a configuration option that I'm missing? Is there something funky going on?

Thanks for your thoughts, let me know if you need more information!
 
UpRunTech
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Re: RB4011iGS+ PoE in seems to need a jump-start

Sun May 30, 2021 6:31 am


Is there a configuration option that I'm missing? Is there something funky going on?
Ohhh ohhhh nice humblebrag about having Starlink. :)

Well what are the specs for the powerbrick? What does it say it's voltage output is? Is it 802.3at/af or is it the more basic passive PoE like a lot of Mikrotik gear. The RB4011 only takes passive PoE.
 
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Re: RB4011iGS+ PoE in seems to need a jump-start

Sun May 30, 2021 6:53 am

I had to mention Starlink because I was hoping someone knew the PoE specs (can't find them published officially). Although I *am* very pleased to be participating in the beta. :-D

So... assuming the PoE out from Starlink is *not* passive, does that explain the observed behaviour? Presumably It's trying to negotiate and the RB4011 isn't talking. Why would it then start to provide power later? Or is that the RB4011 able to start negotiating once it's receiving DC power? Lots of question marks there, sorry. I'm not very familiar with the vagaries of PoE.
 
UpRunTech
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Re: RB4011iGS+ PoE in seems to need a jump-start

Sun May 30, 2021 7:10 am

I had to mention Starlink because I was hoping someone knew the PoE specs (can't find them published officially). Although I *am* very pleased to be participating in the beta. :-D

So... assuming the PoE out from Starlink is *not* passive, does that explain the observed behaviour? Presumably It's trying to negotiate and the RB4011 isn't talking. Why would it then start to provide power later? Or is that the RB4011 able to start negotiating once it's receiving DC power? Lots of question marks there, sorry. I'm not very familiar with the vagaries of PoE.

It's probably some kind of passive PoE. This pic of the label of the Starlink powerbrick suggests it might be the case. The 4011 takes up to 57V which is fine to use with this. Starlink might be using different resistors for the PoE sensing to what Mikrotik use which is why you are having startup issues. It's a nice idea to use the Starlink brick but don't rely on it.
 
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Re: RB4011iGS+ PoE in seems to need a jump-start

Sun May 30, 2021 7:52 am

Thank you for the information @UpRunTech and especially the links. I always appreciate references. :-)
 
UpRunTech
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Re: RB4011iGS+ PoE in seems to need a jump-start

Sun May 30, 2021 8:41 am

Thank you for the information @UpRunTech and especially the links. I always appreciate references. :-)
No worries. I was thinking just for shits and giggles you could try a GPER in line and see if that helps convince the Starlink brick to power up right away. Where in the world are you running your Starlink from?
 
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Re: RB4011iGS+ PoE in seems to need a jump-start

Sun May 30, 2021 9:09 am

Just residential so I probably won't bother with any more hardware. :-)

I'm in the far south of Ottawa, Canada. Best offering (other than paying through the nose for mobile data with cell phone company) is 10/1 mbps through fixed-wireless. Sorry, that's not quite true, there are two options available but I refuse to use the other company. They could offer "up to" 25/3 though. Starlink has been great for me. Happy to chat more about it but should probably take it out of this thread. :-)
 
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mkx
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Re: RB4011iGS+ PoE in seems to need a jump-start

Sun May 30, 2021 11:02 am

Only thinking aloud: starlink brick specifies output voltage at 56V. That might be nominal voltage while in reality (specially while unloaded) it might be a tad higher. Mikrotik OTOH might refuse to start when fed by voltage higger than exactly the upper limit (57V). If, after starting up, mikrotik starts to use PoE in, brick's voltage might drop (either due to internal workings or due to UTP cable length/resistance).
Another thought: starlink brick (judging from photograph) has three power outputs, one is low power (0.3A at 57V is 17W) which might be just too little for RB4011 to start (during initialization phase it might draw full rated power while during normal operation it might consume less than rated power). However, if this is the reason, you'd see bootloop on RB4011 (like blinking some LEDs but device reseting in few seconds). If you can, try connecting it to different ports of starlink brick (seems like the two high-power ports are intended for sat antenna though)..
 
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Re: RB4011iGS+ PoE in seems to need a jump-start

Sun May 30, 2021 7:26 pm

Oh yes, there are only two ethernet ports on the brick but the black port [Output 1] is confirmed to be a non-standard PoE extension to allow for upwards of 150W to the terminal (dish) over a 100' cable. I don't think I'll plug anything else into that port. :-)

There is no boot loop, no initial power at all (left it for a few minutes).

What I've done for now is connect the Starlink AC power brick to a UPS then connected the Starlink Output 2 [white PoE out] to RB4011 ether1 [PoE in]. Then connected DC power to the RB4011. Hopefully this will provide uninterrupted power if there is an outage.

Oh, and although I can't find a reference at the moment, I'm pretty sure that the Starlink white port [Output 2] offers 802.3af/at.

Again, this is residential so it's more for my own curiosity than a pressing problem.

Thanks for your thoughts!
 
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Re: RB4011iGS+ PoE in seems to need a jump-start

Sun May 30, 2021 8:12 pm

PoE standard 802.3 af/at defines some elaborate procedure when PSE (power source) applies power to port. And if PD (powered device) does not respond appropriately, PSE should assume that connected device is not 802.3 af/at compliant and should not enable full power. RB4011 supports only passive PoE and thus does not respond in proper 802.3 af/at manner while being powered up.

I wonder why it actually works after RB4011 is up&running.
 
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Re: RB4011iGS+ PoE in seems to need a jump-start

Mon May 31, 2021 2:17 am

I wonder why it actually works after RB4011 is up&running.
You can test the 802.3at/af theory if you have a CAPAC, WAP, WAPAC or MAP as they will run off both PoE modes.
 
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Re: RB4011iGS+ PoE in seems to need a jump-start

Mon May 31, 2021 2:27 am

I have an Audience but it exhibits behaviour similar to the RB4011.
 
UpRunTech
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Re: RB4011iGS+ PoE in seems to need a jump-start

Mon May 31, 2021 3:08 am

I have an Audience but it exhibits behaviour similar to the RB4011.
Yeah I checked it but it doesn't do 802.3at/af.

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