Is passive PoE basically garbage?

Networking & Firewalls
1

I’ve been a Unifi/pfSense guy for a good while now but I wanted to give Mikrotik a shot as I’ve heard an awful lot of good things about their equipment. I’ve got a Unifi 24p switch(not the pro, not the PoE). Works great, but I really dislike the concept of PoE injectors - just seems messy to me. Rather than upgrade to Unifi’s $699 24p PoE unit, I instead bought this Mikrotik switch after seeing the price tag AND “PoE” all under the same tag.

First of all wow. I more or less don’t even know what to do with this. I’ve been so spoiled by Unifi. I guess I’m going to have to break out the ole’ console cable and putty into this pig Cisco style.

The biggest thing though is that I really don’t know much about PoE and this purchase proves that because apparently it has “passive” PoE which I gather in 2021 is way behind the times? I thought if a switch had PoE, then you can plug whatever you desire - AP, IP phone, etc- in and boom, Bob’s your uncle. So this is not the case? Is this a decent unit or did I hastily and ignorantly just part with $175?

Thanks!

2

All of Ubiquiti’s Edge line is passive POE. Passive is preferred in the WISP space where they know what they are plugging in where, and just want the power to be output for as low cost as possible.

The issue for powering common POE devices isn’t so much the active vs passive, its that passive POE is almost always just 24V while Active POE is “48V” (anything between 46 and 58V on the output side is within spec, and higher voltage is preferred for handling long cable runs). The reason is that almost all consumer electronics (laptops, desktops) would handle 24V passive but may be damaged by a higher passive voltage. They wouldn’t be using this power, so it would just be wasted heating up the transformers in the client device.

Depending on which switch you bought, it will be running one of two possible OS’s, and the means to access them are different.

The CRS326 you linked runs RouterOS by default. This is fine, and is actually the more feature rich of the two, but more features means more things to learn and possibly mess up. The preferred way to configure RouterOS is by downloading WinBox from Mikrotik, which can connect either by IP (layer 3) or even by just the MAC (layer 2). It includes a discovery probe on the login screen that shows all found Mikrotik devices, if you want to connect to your switch via layer 2 just click on the MAC for it to be auto-entered. The other methods to program the switch are by going to its IP in your browser, like a consumer router, this is called WebFig (web config). The third method is SSH/telnet. The fourth as you stated is console cable.

That switch can be swapped over to SwitchOS as well. SwitchOS is more focused on the essentials of what a L2 switch needs. It can only be configured via the browser. SSH/telnet won’t work, and connecting by console won’t allow you to see or change very much.

You linked the CRS326-24G-2S+RM - this is not a POE-Out switch. Its only POE feature is that the switch itself can be powered via POE, like an AP or Phone.

The closest POE-Out switch is the MikroTik Routers and Wireless - Products: CRS328-24P-4S+RM - this has both Active48V and Passive 24V POE on all 24 ethernet ports. Meaning you don’t have to worry about what type of device you’re connecting, it will either be detected by Active POE or you can enable passive 24V on that single port.

Like almost everything from Mikrotik, the value of the hardware and software (price to features) is unbeatable. But the cost is a high learning curve and sometimes a lack of polish around new features.

5 Likes
3

Wow. Thank you so much for taking that much time to explain all of this which I fully and completely now understand. Also thank you for linking that switch. For whatever reason I did not see that in their lineup. What you linked is what I want so I’m going to pursue that. As far as a learning curve, hey, I use pfSense so…

Speaking of which, I would describe pfSense as “highly complicated but highly configurable”. It amazes me the knowledge Tom has (and I’m certain you as well) on these low/no-polish GUI’s and how quickly you get around them.

4

Many people find PFSense easier to grasp than Mikrotik, for routing setups at least. And the Switch config in RouterOS before the CRS3xx series was horrendous - you were basically programming the switch chip directly, meaning something that should be a single command or setting would take multiple non-obvious steps. With CRS3xx it is hugely improved, but still a little more difficult than a dedicated switch system (which isn’t going to change, the point of keeping all of RouterOS is that you have swiss-army-knife levels of options, and they built SwitchOS for people who want it streamlined). Stick to this page mostly: CRS3xx series switches - RouterOS - MikroTik Documentation if you keep the device in RouterOS mode. If you go to SwitchOS mode then its fairly obvious and straightforward. See the “Dual Boot” section of the above page for instructions on that.

2 Likes
5

You Sir, are a prince among men. Thank you for this. I guess I’ll just keep this one to kick around with and order the other one in the meantime. Never can have too many switches.

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Why not Look for a POE switch ? If you have devices that are poe & hate Injectors all over the place like me. Take the plunge and go POE. I went with Aruba AIO ( Aruba Instant On ) and haven’t looked back. Their Ap’s and switches with life time warranty is just Perfect !

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Passive PoE supports 10/100 Mbps only.

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You’re wrong.

Firstly, there isn’t a fundamental reason that it can’t work. Yes, if you’re talking about naive passive POE that uses the non-data wires. But passive POE can be done the same way that 802.3af/at works - via a center tap on the transformers.

Secondly, they exist. Just search for “gigabit passive POE injector” and you’ll see options from Mikrotik, Ubiquiti (in fact all of their POE injectors are passive, even the one named “af”, and even those that run at 48V), POE Texas, and more.

9

Never heard of em! Thanks for the mention.

10

LETS GET READY TO RUUUUUUMBLE! lol

Hey I just wanted to say I followed your instructions and have the switch up and running using RouterOS. Although I don’t need it, I actually decided to stick with RouterOS in the interest of challenging myself and furthering education. I have to say, despite what many opinions echo, I find the UI quite intuitive. I’m rather liking it a lot!

11

Glad you’ve got it working! The learning curve with RouterOS, once you have WinBox, is really the rough edges where features that are simple on other platforms are not on Mikrotik. With the CRS3xx series doing most of the switch config through the bridge menu, there isn’t a lot of that left for switches, but with the older switches (which are still the only options for some variants, like the only 8 port POE being a CRS1xx) and with non-switching config, there is a lot of gotchas.