Hello,
1) at what OSI layer this device work? at L1 like hub, or at L2 like switch?
2) what delay does this device add?
3) why distance is limited to 1500 m?

1) at what OSI layer this device work? at L1 like hub, or at L2 like switch?

Does that really matter for a two-port device?

3) why distance is limited to 1500 m?

That's because of the power drop. Check the official brochure for the details. You can build a link up to 3000m long if you provide power from both ends of the link (you will also need to adjust jumpers on GPeR devices in the center of the link).

1) Of course it matters (and two port has nothing to do with it)
2) ???
3) Ok

1) Of course it matters (and two port has nothing to do with it)

Really ... what's the big difference between 2-port ethernet hub and 2-port ethernet switch?
And yes, port count has everything to do with it.

Instead of forwarding frame to the other port because forwarding table (MAC address list) of the second port contains the destination MAC (or sending it to all one port other than ingress if dst-MAC address is not there) ... the hub just forwards the fscking frame to the other port. Without adding a microsecond delay needed to consult forwarding table.
The only case I can think of where the MAC table would be handy is if there was some switching problem elsewhere (so that GPeR would receife frame through one port and its own forwarding table said dst-MAC was accessible through ingress port ... so that switch would reject to forward such a frame. But then, is this duty of a range extender?

Look at it as a media converter. It only put out what came in and the other way and amplify the voltage to make the next leg of the cable.

Is a delay a big criteria? Before then it even never arrived.

The GPER is a passive device that connects wires together, you can call it Layer1. This is not really a hub.

Regarding second question, GPeR doesn't add any noticeable delay, for example, at 1500m you have 0ms ping response time and you still can push 1Gbps.

If GPER is just a passive device that connects wires together, then the price is perplexing (50% of Raspberry Pi 4 computer)

Can you name any other alternatives that allows to extend ethernet cable, without sacrificing PoE?

I can see a communication noise happening around here. How about MT guys writing a few lines of technical description about GPeR ... what is it, how it works. Doesn't really have to disclose some patented technology ... I guess it's about a fairly simple (electrical) signal shaper with some DC bypass (to allow PoE to pass), but still far more complex than a RJ45 coupler ...

It's an active device, product page mentions it already = Gigabit Passive Ethernet Repeater. repeater = 2-ports switch => datagram receiver and re-transmit.
I don't see how this would introduce noise.

Yes, there is a basic switch chip inside.

normis
Tue Jul 30, 2019 9:57 am
The GPER is a passive device that connects wires together, you can call it Layer1. This is not really a hub.

normis
Fri Aug 02, 2019 3:14 pm
Yes, there is a basic switch chip inside.


Two completely different answers.
You are Dr Jekyll and Mr Hyde??

Well, take it this way. Mikrotik is marketing this as "passive" since they are trying to compete with various passive optical solutions here. The whole GPEN product line is just about that. But technically, none of the products in this line are really passive, IMO.

Sorry about confusion. I meant to say that it's not a smart device, no software. Also, yes, "passive" is a bit confusing, as it does need the PoE power in to function. There is no delay though.

Why you're lying to us?
There is Marvell 88E6341 (6port) switch inside so it's not repeater, it's 2-port switch. And it's using store&forward so it add some delay (like any other switch).

Why you're lying to us?
There is Marvell 88E6341 (6port) switch inside so it's not repeater, it's 2-port switch. And it's using store&forward so it add some delay (like any other switch).

going back to the basics of networks:

what is a hub? is a multiport repeater, because that it can only work in half duplex, for obvious reasons

its a fact you can't do repeating in a full duplex gigabit ethernet segment, you have to do switching

i think its obvious gper is a switch because of the extended reach only achievable electrically regenerating the signal

this topic has become a very Byzantine discussion

a lot of questioning and criticisms for a 15 USD device you have not tried

i have tried it and works well, its a very useful and innovative device, its a matter of time to see it allow diverse and innovative solutions and designs

with the new GPeR IP67 Case, the possibilities are endless !!!

i think Mikrotik do a Good job whit this kind of disruptive devices, maybe too disruptive to be properly understood by some people

Who is lying to whom?

Passive means it is without configuration interface, just plug in and use it. There is no GUI to control it, it just works.

Hello,
1) at what OSI layer this device work? at L1 like hub, or at L2 like switch?
2) what delay does this device add?
3) why distance is limited to 1500 m?

1) L2 although think of it more like L1.
2) None
3) Voltage droop

It's actually incredible that the device is on the market. The closest I have seen to this is a Veracity Outreach extender which is often more than 10 times the price.

Who is lying to whom?

Passive means it is without configuration interface, just plug in and use it. There is no GUI to control it, it just works.

I think the misunderstanding is because "Passive" is referred usually to a device that DOESN'T require power to be supplied....

Good to know what the GPER really is - it was a valid question, and should be clearly answered in the documentation.
Actually it is possible to make a repeater without a switch chip, by connecting two PHY chips back-to-back.

https://e2e.ti.com/support/interface/f/138/t/675991

There is still some delay as the PHY chips have internal FIFOs to handle small differences between asynchronous clocks at both ends, but much less than whole frame time.
It is true that we are talking microseconds where which can be ignored in most cases, but these microseconds add up and could still make a difference in some special applications.

On the specs page for power it seems very odd and I suspect it's wrong!
https://mikrotik.com/product/gper
Max out per port output (input < 30 V) 0.7 A
Max out per port output (input > 30 V) 2 A

So at 48V it allows 2A to pass through, yet at 24V it only allows 700mA through??!!

Regards,
Bevan

Hi I am having a problem with gper here is my setup
Modem/router --) poe(46v 1a) --1m--) gper1 --90m--) gper2 --90m--)gper3--70m--) ubiquity switch.
My problem is that in number 2gper everything is fine good speed no data loss while in gper number 3i have disconnections and when I ping my router I have data loss and when I connect to the switch at the end everything is very slow and I have bad speed lots of disconnections and it's almost impossible to use the internet my cable is cat6 they are brand new and I changed them again to be sure. Also I have tested the gpers by plugging a laptop at every end. I first used a 46v 0,5a poe and then I changed it to what I have now. Please someone help me am I doing something wrong or do I need to do something else;

Did you solve? I need to install similar layout and I have bought several repeaters. Testing with 50 m we have problems, but may be because cable is partially rolled up. Same cable is working well connecting a switch (and my laptop to switch) to router/modem.