Where are all the PoE switches?

[AndyC_772]

Hi,

In my loft I have a Netgear GS105PE, which is a 5 port managed switch that can derive its own power via PoE. It needs to be PoE capable because there's no convenient mains power supply up there. I've been using it via an 802.3af PSE port on another switch, and it's been working fine for years.

I'd like to add another wired device to it, but it has no free ports. No problem, I thought, I'll just get a slightly bigger switch. It has to be a managed switch with VLAN support.

I bought a TP-link TL-RP108GE, which is one of the very few models I could find. It turns out, however, that this device only supports "passive PoE", and simply doesn't work when plugged into an 802.3af or .3at port. (WTF?  )

I had thought that a switch that's capable of being a PD would be a completely commonplace, everyday, commodity item that every manufacturer would have in their range, but that appears not to be the case.

Before I send it back, I'd like to know if there's a better option. I could:

- buy a "passive PoE injector", and run the TP-link off that. Ugly, but not overly expensive.

- buy a second GS105PE and either hope that its PoE passthrough works (some reviews say not), or run another cable from my PSE-capable switch into the loft

- buy some other make / model of switch which has 8 ports and which receive its own power via PoE

It seems really odd to me that PD capable switches seem all but extinct. Does anyone know of any I might have missed?

[jonpaul]

lots on eapy, used.

Have  100 base T 57V POE 5 port for $15, 1GB are easy to find

j

[pcprogrammer]

Found this one: https://intellinetsolutions.com/products/intellinet-en-poe-powered-8-port-gigabit-ethernet-poe-switch-with-poe-passthrough-561679

Don't think it is managed, but a search for "8 port switch powered from poe source" gave me that link, so try a search with these terms and more of what you need.

[AndyC_772]

Thanks. Seems odd that they're not more common, though.

I did find a solution in the end - get one of these, and plug it into any compatible switch that has a dc inlet:

https://www.tp-link.com/us/business-networking/accessory/tl-poe10r/

I've also ordered a TL-SG608E which is a standard, managed, 8 port Gbit switch with a 5V dc power input. Should plug straight in to the adapter, and when one day I want to redeploy it elsewhere, it's just an ordinary switch that I can power from the supplied wall wart. Much more future proof than some passive PoE oddball.

[pcprogrammer]

Looks like a nice solution. 

Reasonable price too. Have not looked at prices lately but years back I was looking into wireless access points or routers powered with poe and they were rather expensive. With your solution is possible to reuse what I have. My POE switch is currently not powering anything since I stopped with VOIP.

[coppice]

Seems odd that they're not more common, though.

Are little ones (3 or 5 port) more common? 8 ports is quite a lot for pass through PoE. The upstream side will need quite a high power capability. PoE is mostly a business solution, and for anything more than an expander in someone's office cubicle, businesses usually like to keep all their switches as rack mount units in a wiring closet.

[AndyC_772]

Actually no, they're not all that common. Even the GS105PE seems quite hard to get hold of, maybe discontinued.

D-Link DGS-1100-05PD is the only alternative I came across, also just 5 ports.

Basic PoE is 13W which I'd have thought was plenty to run at least an 8 port Gbit switch. 802.3at should power 16 ports easily.

It's surprising to me that I seem to be doing something unusual. My home isn't huge but it's big enough to need at least 2 wireless access points for good coverage. I have wired connections where I need reliability and/or maximum bandwidth - my office PC in one room, a PS5 in another, and so on. Nothing strange about that, I wouldn't have thought.

To that end I have a single Ethernet port in each room where there's fixed equipment. These connect to the switch in the loft, which in turn connects to a PoE (PSE) capable switch that sits alongside my router, NAS and a few other boxes.

Is it a lot for a home network? Sure, but I'm a nerd, and that's not uncommon.

If I didn't have the switch in the loft, I'd need to run multiple cables from my main switch, up the wall and into the loft space. Feeding them up behind the plasterboard is tricky, plus the cable length could start to become an issue. The switch means I can get away with a single run of Cat 5e per room, and each run is shorter so less danger of the port failing to sync up at 1 Gbit.

[ejeffrey]

Another option is to use a PoE splitter like the TP-Link TL-PoE10R then use the switch of your choosing.  It's standards compliant PoE not passive and it has a built in step down converter to get you 12V.  That's what I use to power my fiber ONT that is located in a box outside the host but doesn't natively support PoE.

[ejeffrey]

As to why it's not more common, I think it's probably a bit uncommon to have a switch located somewhere without power but have power available for all the devices connected to it.  That becomes increasingly unlikely as the switch gets larger, and passthrogh PoE also becomes less sensible for larger switches.

I have a similar setup to you but all the Ethernet runs go all the way back to the closet with the main router, so I don't need an auxiliary switch in our attic.  Even if I did, the attic is where all the power runs for the rest of the house, it would be easy enough to install a junction box with an outlet.

[Nominal Animal]

Here in Finland, TP-Link TL-SG2008 costs 81€-100€, but vendors don't seem to have them in stock, with some claiming stock on Feb 2, others 4+ weeks lead time.

However, TL-POE10R 802.3af-compliant gigabit splitter with 5V/2A, 9V/1A or 12V/1A output, is easily available immediately for 17€.
So is the 8-port TP-Link TL-SG108E, for 36€ here.  Its power supply is 9V/0.6A, so well suited for use with TL-POE10R.
The combo would cost here 53€ + shipping (typically 5€); good value for money in my opinion.

[AndyC_772]

I did end up ordering exactly that, the TL-POE10R. Seems like that's the obvious solution, and I'm glad others came to the same conclusion I did.

The TL-SG2008 is probably overkill in terms of features in my case. I need VLAN support for a couple of devices that plug in to it directly, but that's all - most ports connect to other managed switches anyway. The TL-SG608E seems to be a newer version of the TL-SG108E and is just £24.99 at Amazon UK right now - £10 less than the 108E, which just about pays for the PoE adapter.

[David Hess]

Microtik has a few which meet those requirements and also have extra SFP or SFP+ ports.

https://mikrotik.com/product/css610_8g_2s_in
https://mikrotik.com/product/CRS112-8G-4S-IN

https://mikrotik.com/products/group/switches?filter&s=c&f=[%22poe_in%22]

[Nominal Animal]

Microtik has a few which meet those requirements and also have extra SFP or SFP+ ports.

https://mikrotik.com/product/css610_8g_2s_in
https://mikrotik.com/product/CRS112-8G-4S-IN

https://mikrotik.com/products/group/switches?filter&s=c&f=[%22poe_in%22]

They use "passive POE", which is not 802.3at/802.3af compliant, as it does not do the negotiation.  They do not work with a gigabit 802.3at POE PSE's (power sourcing equipment).

[themadhippy]

there's no convenient mains power supply up there.

no lighting circuit to tap into? an before anybody questions the practice of using the lighting circuit to power a switch,its common practice to have aerial amplifiers ,door bell transformers, extractor fans and even shower pumps   hanging off  the lighting circuit,and since weve moved over to led lamps theirs plenty of capacity on the circuit to deal with the little bit of extra load.

[David Hess]

Microtik has a few which meet those requirements and also have extra SFP or SFP+ ports.

https://mikrotik.com/product/css610_8g_2s_in
https://mikrotik.com/product/CRS112-8G-4S-IN

https://mikrotik.com/products/group/switches?filter&s=c&f=[%22poe_in%22]

They use "passive POE", which is not 802.3at/802.3af compliant, as it does not do the negotiation.  They do not work with a gigabit 802.3at POE PSE's (power sourcing equipment).

Sorry, I did not see that.  Given your requirements I would accept passive PoE in this one case.

[Monkeh]

Microtik has a few which meet those requirements and also have extra SFP or SFP+ ports.

https://mikrotik.com/product/css610_8g_2s_in
https://mikrotik.com/product/CRS112-8G-4S-IN

https://mikrotik.com/products/group/switches?filter&s=c&f=[%22poe_in%22]

They use "passive POE", which is not 802.3at/802.3af compliant, as it does not do the negotiation.  They do not work with a gigabit 802.3at POE PSE's (power sourcing equipment).

Sorry, I did not see that.  Given your requirements I would accept passive PoE in this one case.

Which means you then have to supply passive PoE.. defeating the purpose of having a real PSE available.

[David Hess]

Which means you then have to supply passive PoE.. defeating the purpose of having a real PSE available.

Passive PoE could be used to supply a switch which has 802.3at/802.3af compliant outputs except it would exceed any possible supply, which may explain why such a switch with more than 5 ports is not available.

[Nominal Animal]

TL-POE10R splitter is 802.3af compliant, supports GbE –– it doesn't just limit the connection to 10/100Base-T, it can source power from a 1000Base-T Cat-5/5e/6 cable ––, and has a small slide switch to select between the 5V/2A, 9V/1A, and 12V/1A outputs.  It is a darned good splitter for its price!

If AndyC_772 did not already have a switch supplying power, then a "passive gigabit POE" injector (like MikroTik RBGPOE) and a matching POE-powered switch or splitter would work, sure!

The gigabit ones work by biasing one of the twisted pairs relative to another pair, via the center tap in the magnetics.  (In comparison, the 10/100Base-T ones use the "spare" pair of twisted pairs for power supply only.)  On the supply side, there are chokes to ensure the bias has no high-frequency components to mess with the data transfers, so if properly implemented, it does not affect 1000Base-T at all.  The difference between "passive" gigabit and 802.3af/802.3at on 1000Base-T is the lack of negotiation, and that 802.3af/at requires powered devices (PD) to support either pair of twisted pairs (the supply decides which pair it uses); the passive ones just skip all that and use either pair of pairs.  MikroTik RBGPOE biases the 4-5 pair 18-57 volts higher than the 7-8 pair (using center taps on the transformers), as that is what its POE-powered devices expect.

802.3af/at is not expensive to implement on the powered device side, though.  For example, two TI TPS2378 (lots in stock at Mouser, about 2€ apiece in singles, 1€ in reels), a smattering of passives, and two full bridge rectifiers: all four twisted pairs are connected, but only two are used (chosen by the supply).  Cisco uses a nonstandard variant that uses all pairs (doubling the power budget), but you can do that too with two TPS2378, as described in the TI SLVA625A Application Report.

[AndyC_772]

Upd: the new switch and PoE dongle arrived.

Helpfully, the dongle comes packaged with a stumpy little dc-dc "suicide cable", which can be connected between itself and the switch. Or at least it could, if TP-link actually used the same connector on the (otherwise compatible!) switch. Instead of just plugging it straight in I spent over an hour rifling through my box of old tech and cables looking for something with the right plug that I could snip off and turn into a suitable power cable.

Thanks, TP-link. Would adding a few 10p cables to the package really have been such a big deal?

The PoE dongle also comes with an RJ45 patch cable, which is nice - except it's much, much longer than the power lead. (Why?)

So, two custom cables later, the switch is configured with all the right VLAN settings and it's installed in my loft. It seems to be working fine, except I can't see its management interface now it's somewhere inaccessible.

Turns out that, when it has multiple ports configured, it seemingly randomly chooses a VLAN for its own management interface - which affects the IP address it's allocated and the other ports on my network from which it can be accessed. 

First it's on the VLAN I reserve for wireless access points, then after a reboot it's on the trusted VLAN for servers. Disable most of its ports and it then chooses the 'untrusted' VLAN, reserved for devices that get to see the internet but nothing on the local network; that was fun to recover from.

Eventually I set a static IP and it seems OK, but now it's the one device in the whole house not using DHCP.

How do 'normal' folks cope with this stuff...?

[tszaboo]

Large switches would need to be able to source quite a bit of power to be compliance with the PoE standard. So they u rely on injectors.

[ejeffrey]

How do 'normal' folks cope with this stuff...?

I've never used a managed switch that had that behavior, and wouldn't find it acceptable.  Normally I would expect either that you can configure the management interface to be on any VLAN or that the management interface would always be on the untagged network accessible via a trunk port.  I'd say that either the switch is misconfigured or defective by design.

[pcprogrammer]

How do 'normal' folks cope with this stuff...?

Devices that need to be reachable on my internal net, like servers and routers, get a fixed IP address. The rest of the devices can use DHCP. That way I always know where a specific device can be reached. Otherwise you need some dynamic domain naming system. To much of a bother.

[bingo600]

Dooh ... Thought you looked for a replacement , not an extra.


I have use a HP-1820-8G 8-port gigabit switch , that can be fed via PoE on port 1.
Or DC power in the back.
Mine have been running for 8..10 years wo. issues .. Quite impressive that the external PSU hadn't died yet ..

Data:

hp 1820 8g - model j9979a
http://5.imimg.com/data5/SELLER/Doc/2021/8/UA/GP/PV/3895157/j9979a.pdf

Seems like there's some on ebay.

[ejeffrey]

What you are describing could be caused by the management processor trying to solicit IP addresses on every available VLAN but somehow they conflict and only one response sticks.

I could imagine this sort of thing being caused by an unintentional bridge between VLANs allowing traffic to cross without being routed.  That could happen due to configuration mismatch on the switch or any connected trunking devices, including another managed switch.

[David Hess]

How do 'normal' folks cope with this stuff...?

Devices that need to be reachable on my internal net, like servers and routers, get a fixed IP address. The rest of the devices can use DHCP. That way I always know where a specific device can be reached. Otherwise you need some dynamic domain naming system. To much of a bother.

I still use DHCP but the DHCP on my router can assign variable or fixed addresses to specific MAC addresses, and then add entries to its DNS resolver so whether the IP changes or not, my local DNS resolution points to it on my own custom domain which is not visible outside of my DNS.

[MarginallyStable]

Netgear GS108Tv3

[AndyC_772]

I've never used a managed switch that had that behavior, and wouldn't find it acceptable.  Normally I would expect either that you can configure the management interface to be on any VLAN or that the management interface would always be on the untagged network accessible via a trunk port.  I'd say that either the switch is misconfigured or defective by design.

I think it's just missing that essential configuration setting, ie. which VLAN to use for the management interface. I even went so far as to RTFM which is here.

I thought it was really odd not to have a simple setting for the management VLAN, so I even went so far as to check the manuals for some other competing switches. Zyxel GS1200-8 is very cheap indeed and supports setting the management VLAN:

https://download.zyxel.com/GS1200-8/user_guide/GS1200-8_V2.00_Ed2.pdf

So does D-Link DGS-1100-08V2/B

https://support.dlink.com/resource/products/DGS-1100-08V2/REVA/DGS-1100-08V2_REVA_MANUAL_v1.00_WW.pdf

My other 8 port managed switches are Netgear, GS108E and GS308E. They seem to default to VLAN 1 for management; it can't be set manually.

I also have a TP-link TL-SG1024DE which also seems to pick VLAN 1 even though it's clearly running the same basic firmware as the 608E. Maybe I just got lucky as it's plugged directly into the router and it's on a UPS so very rarely gets reset.

[coppice]

I still use DHCP but the DHCP on my router can assign variable or fixed addresses to specific MAC addresses, and then add entries to its DNS resolver so whether the IP changes or not, my local DNS resolution points to it on my own custom domain which is not visible outside of my DNS.

I think that's pretty much the norm for modern routers. The problem is the documentation is usually weak, and you have to figure out how to use that facility by trial and error. In a simple setup its the easiest way to have all the devices in your home reachable by a name.

[Halcyon]

- buy some other make / model of switch which has 8 ports and which receive its own power via PoE

For anyone playing along at home, Ubiquiti make a series of switches which can be powered via PoE: https://ui.com/us/en/switching/utility

Their Flex Mini, Flex and Flex 10 GbE can be powered by a downstream switch (or PoE adapter) and will also output PoE on all other ports. The downside is all of them only have 4 usable ports.
The Flex is a good little weatherproof switch if you need a few ports up a pole or outdoors somewhere.