10 votes
Accepted

Multiple POE over a single cable

I know this is an older question, hopefully you've solved it by now, but I wanted to toss in my two cents, for the benefit of future generations if nothing else. First of all, yes, ethernet and PoE ...
Soundy's user avatar
  • 116
6 votes

Is a 10/100 switch sufficient for Voice?

If only phones are connected to the switch, you should be fine. If you also have PCs connected in tandem (switch<->phone<->PC), then you need to worry about QoS capabilities on the switch.
Ron Trunk's user avatar
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6 votes
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POE injector to extend the number of devices

That looks pretty horrible - I don't think any reasonable network engineer would build something like that. Chaining switches is generally considered bad design[*1] and it's aggravated by using PoE. A ...
Zac67's user avatar
  • 84.4k
5 votes

Multiple POE over a single cable

If 100 Mbit/s is enough for camera to work, You can try split single 4-pairs cat5 cable in two 2-pairs links. It can be done by 2 Ethernet splitter or by proper cable crimping. "This adapter brings 4-...
mmv-ru's user avatar
  • 774
5 votes
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In practice, how much can the 100m ethernet limit be pushed?

The "100 m Ethernet limit" you refer to exists for twisted-pair copper only. Fiber Ethernet over single-mode fiber (SMF) easily reaches over many kilometers. 800 ft/240 m is far beyond the ...
Zac67's user avatar
  • 84.4k
4 votes

Enable PoE on Cisco non-PoE switches

You cannot convert switches so they become POE. But you can use special devices that are called "POE Injectors" in addition to the switch. They exist in 24 and 48 ports (and other size) versions.
JFL's user avatar
  • 19.7k
4 votes

Strange POE Behaviour

Patch cable has a smaller effective diameter (usually AWG 26-28) and a larger serial resistance than horizontal (rigid) cable (AWG 22-24). This causes a higher voltage drop from end to end. With 30+ m ...
Zac67's user avatar
  • 84.4k
4 votes
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Verifying 802.3 auto negotiation

With gigabit endpoints (1000BASE-T) your injector needs to be gigabit capable as well. Cheap injectors insert power on the pairs unused by 10BASE-T and 100BASE-TX while disrupting the data ...
Zac67's user avatar
  • 84.4k
4 votes

Feeding a PoE capable device with variable power supply over TIA568 A cable (DC spares)

The PSE decides on which pairs power is supplied. A compliant PD needs to be able to use either pairs. Connecting a power supply to the spare pairs (only possible with 10BASE-T and 100BASE-TX) is not ...
Zac67's user avatar
  • 84.4k
4 votes

HP ProCurve 2520G Switch not accepting HP transceiver SFP

The 468508-002 is a short-wave (850 nm) 8Gb SFP+ transceiver for Fibre Channel. It is not compatible with Ethernet switches and won't ever work in a 2520. Provision switches like the 2520 series ...
Zac67's user avatar
  • 84.4k
4 votes

PoE only data and power over network

IEEE PoE (Power over MDI) is the only standard for running power over a network cable, consisting of the original PoE 802.3af (12.95 W), the improved "PoE+" 802.3at (25.5 W) and the latest "4PPoE" 802....
Zac67's user avatar
  • 84.4k
4 votes
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Adapting 10GBaseT and NBaseT with a PoE Injector?

"NBASE-T" or "MGBASE-T" is any speed from 2.5GBASE-T or 5GBASE-T (sometimes including 10GBASE-T). The best speed in common between a 10/100/1000/10GBase-T and a 10/100/1000/NBase-T ...
Zac67's user avatar
  • 84.4k
3 votes
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PoE Query - IP Phones

Your question: We have been led to believe that BT Business Broadband blocks IP Phones other than their own. Is this true? is off topic here. You will need to ask BT, but it doesn't matter if ...
Ron Maupin's user avatar
  • 99.6k
3 votes
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Changing ethernet wiring for Cisco pre-standard PoE

It's your network, do whatever compromise is required by you, your management, and their budget. I agree with comment above: don't mess with hidden wire, do it close to the phone or in the patch ...
jonathanjo's user avatar
  • 16.2k
3 votes
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Mostly wireless campus vs. VoIP

While wireless is a good, convenient, possibly necessary thing for a company to have and use, you don't own the airwaves, and you must be willing to accept any interference that disrupts your Wi-Fi, ...
Ron Maupin's user avatar
  • 99.6k
3 votes
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POE - How does Mode A work?

Twisted pair Ethernet is transformer isolated. To allow the signals to pass through the transformers (which block DC and low frequencies). the signal is transmitted at high frequency and coding ...
Peter Green's user avatar
  • 13.3k
3 votes
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Strange POE Behaviour

From the fact that Phone 2 works with long cable into port 10 but not 9, and that the switch doesn't enable power when plugged into port 9 ... It does indeed look like the cable. POE sensing is a ...
jonathanjo's user avatar
  • 16.2k
3 votes
Accepted

Join two PoE Splitters

No. This isn't possible. The switch itself negotiates the amount of power to be provided when it comes up, and beyond the obvious non-starter of two data lines being paralleled to each other (two ...
rnxrx's user avatar
  • 6,114
3 votes
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Why is there a warning on some PoE Switches, non-PoE might suffer damage?

There are some poorly designed or constructed devices. We experienced this with some devices that had pins shorted in a way that requested PoE from the switch, but the devices could not handle PoE, ...
Ron Maupin's user avatar
  • 99.6k
3 votes

Active POE Injector with passive POE Splitter

So-called "passive PoE" is really just power-over-cat5 and really isn't compatible at all with 802.3af PoE. Even the cheaper supposedly conforming PoE splitters can have issues with isolation and ...
jonathanjo's user avatar
  • 16.2k
3 votes
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PoE losses: Cat5e vs Cat6

The cable category defines the high-frequency parameters of the cable (mostly attenuation and crosstalk). For PoE, the serial resistance of the cable matters which isn't defined by category. Good ...
Zac67's user avatar
  • 84.4k
3 votes
Accepted

Is temperature sensor on zero enough to prove PoE Control Module is failed?

(converted from comments) The "Total Power" figure should show what the PSU can deliver, regardless of what's currently in use. The "0 W" pretty clearly shows there's something wrong. Possibly, the ...
Zac67's user avatar
  • 84.4k
3 votes

C3560CX-8PT-S UPOE

The Catalyst WS-C3560CX-8PT-S is a PD/PSE product, which means that the switch can behave like both a Power Device (PD) and Power Source Equipment (PSE). This switch will be powered on by the PoE ...
Cow's user avatar
  • 1,732
3 votes

In practice, how much can the 100m ethernet limit be pushed?

Unlike UL, there isn't any regulatory body that enforces, tests, and certifies ethernet hardware. So one is unfortunately on their own to find these sorts of issues. "In practice" ...
Ricky's user avatar
  • 32.2k
3 votes
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What does "inline" mean in the context of cable testing?

“Inline” refers to PoE, not to the position of the tester. So this with this tester you can check cables doing power over Ethernet. You would still place the tester at the ends of the cable.
Teun Vink's user avatar
  • 17.4k
3 votes

Why is a PoE circuit limited to 328 feet?

IEEE PoE is an option for IEEE 802.3 twisted-pair Ethernet which is generally limited to 100m in total - up to 90m of rigid, solid-core cable and up to 10m of flexible, stranded cable. If you use ...
Zac67's user avatar
  • 84.4k
3 votes
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Daisy Chaining POE switches

There are two kinds of PoE devices/ports: power-sourcing equipment/PSE (switches or injectors) and powered devices/PD which draw power from a PSE. PoE devices come in three generations: IEEE 802.3af (&...
Zac67's user avatar
  • 84.4k
3 votes
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How PoE interacts LLDP and LLDP-MED?

PoE power allocation can happen on the physical layer by signature resistance, or on the data link layer by LLDP TLV (PD→PSE). Which one takes precedence is a matter of configuration in your switches/...
Zac67's user avatar
  • 84.4k
2 votes
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Passive Power over Ethernet 802.3af Supported

Speaking from my experience, most devices indicating they are being powered by "passive PoE" means that the device does not support standards based PoE (802.3af or 802.3at). While standards based ...
YLearn's user avatar
  • 27.3k
2 votes

Can I auto-negotiate PoE class (brocade)?

Here is the brocade documentation. Brocade doc The ports will follow 802.3af and at standards on brocade when the inline power command is used . These standards will monitor and adjust power as ...
Fixitrod's user avatar
  • 938

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