PoE switch and PD questions.

[Apathetik]

  I'm looking in to setting up a few IP Cameras and came to the conclusion that PoE was going to be the more viable option for powering the cameras in the locations they will be installed. But I've never actually dealt with any PoE devices in all my years, so I've been doing a lot of research and think I have an answer to my question, but have yet to find a definitive yes/no confirmation. So I was hoping someone on here with more experience with these could let me know if I'm correct or need to rethink some things.

 

  My main issue right now is that I'm looking at replacing a 4 port gbit switch on my network with an 8 port (4 PoE+, 4 Non-PoE) gbit switch. To avoid additional clutter and having to chain switches together unnecessarily. In my research I know now that PoE is delivered in multiple ways over different sets of pairs depending on the connection type. Generally, from my understanding. Gbit switches supply power over all of the pairs. But the cameras I'm looking at are 100mbit PD's. Which I know only use 2 pairs for power in a PoE setup. While I know proper 802.3af and 802.3at compliant devices can negotiate their power requirements with the switch. I don't know if the switch and PD will also negotiate how the power is delivered. So that the gbit switch (which afaik, should normally supply power on all pairs to a gbit device) can deliver power across just 2 pairs as per what the PD is built to accept?

 

Sorry if the question seems silly or obvious. I think it should work. But I learned a long time ago it's better not to assume I've come to the correct conclusion regarding things I'm not familiar with. So I'd greatly appreciate any input from you all. Thanks in advance.

[Lurick]

What switch are you looking at getting?

If it's passive PoE then it won't negotiate at all but if it's active PoE then it should negotiate properly assuming it's been properly implemented of course

[Apathetik]

3 minutes ago, Lurick said:

What switch are you looking at getting?

If it's passive PoE then it won't negotiate at all but if it's active PoE then it should negotiate properly assuming it's been properly implemented of course

It's a Linksys LGS108P. Was looking at it because it seemed to be a relatively good deal for my situation. I already have a 4 port switch being used that can be switched over to the non-poe ports on this one. And for now I only need 2 PoE ports. But it's likely I'll end up with one or two more IP cameras at some point. Which is why I decided to go for a switch rather than injectors. 

[Lurick]

41 minutes ago, Apathetik said:

It's a Linksys LGS108P. Was looking at it because it seemed to be a relatively good deal for my situation. I already have a 4 port switch being used that can be switched over to the non-poe ports on this one. And for now I only need 2 PoE ports. But it's likely I'll end up with one or two more IP cameras at some point. Which is why I decided to go for a switch rather than injectors. 

On the product page it mentions that the switch is backwards compatible PoE+ to PoE so I assume that it auto negotiates the power correctly.

 

https://www.linksys.com/us/p/P-LGS108P/