Gigabit and PoE

[Michael]

Hello all,

Apologies if this is an obvious question, but here goes:

A lot of newer Access Points support 10/100/1000 connectivity and typically if you have a 10/100 switch with PoE it delivers data and power together.

Is it possible to take advantage of 10/100/1000 connectivity AND use PoE at the same time? So a single Cat5e Ethernet cable, operating at 1000Mbps and supplying PoE at the same time?

[CyberNerd]

Thats how our AP's work.

[plexer]

Yes gigabit networking and poe works fine.

Ben

[plexer]

NETGEAR GS110TP ProSafe 8-port Gigabit PoE Smart Switch with 2 Gigabit Fiber SFP Reviewed - SmallNetBuilder

Ben

[Michael]

My understanding was/is 2 pairs were used for 10/100 and another 2 pairs for upto 15w of power.

10/100/1000 uses all four pairs, so how does it deliver PoE as well?

[CyberNerd]

My understanding was/is 2 pairs were used for 10/100 and another 2 pairs for upto 15w of power.

10/100/1000 uses all four pairs, so how does it deliver PoE as well?

The DC is shared with the signal.

[Michael]

So something like a HP J9148A would work?

[MYK-IT]

Same situation here, we use the Ruckus POE Injectors with our Ruckus APs, and they work fine at 1Gbps.

Although alot of POE injectors won't.

[psydii]

While it can be a bit messy, consider separate injectors as they are way more cost effective than Gig PoE switches when you are looking to drive the high end features of 802.11n APs which often require more power than an average-price PoE switch can deliver.

[RobFuller]

We've had great success using these at 1Gbps with Netgear APs TP-Link PoE Injector Adapter (TL-PoE150S) - www.misco.co.uk

[Michael]

For everyone's reference, below are the differences in PoE standards:

The original PoE standard - IEEE 802.3af will operate at a maximum 10/100 as one pair of cables provide up to 15.4W of power.

A newer revised PoE standard - IEEE 802.3at will operate at 10/100/1000 and provide up to 25.5W of power. This is suitable for many Wireless 'N' access points and does not require any PoE injectors which can be messy and expensive.

So if you're on the lookout for a new gigabit switch, make sure it supports the IEEE 802.3at standard.

[tom_newton]

And make sure you carry your wallet in a wheelbarrow - still pretty expensive. If it is just a few devices i'd suggest those advising injectors may have a point - in terms of price, certainly, and also looking at our PoE kit, the 24 port 100 meg switches are deep, noisy and suck juice - not something that will be as much of a problem with a non-PoE gig switch and some injectors.

[Michael]

Further to what I wrote above, there's a small correction:

The original PoE standard - IEEE 802.3af-2003 will operate at 10/100 and provide up to 15.4W of power.

In 2005 there was a small revision to the specification which means a phantom power technique is used to deliver the full 1000Mbps and PoE. IEEE 802.3af-2005 will operate at 10/100/1000 and provide up to 15.4W of power.

A newer PoE+ standard - IEEE 802.3at-2009 will also operate at 10/100/1000 and provide up to 25.5W of power.

As above, when all four pairs are used to deliver the full 1000Mbps and PoE+ they're delivered using a phantom technique, however PoE+ delivers more power - 25.5W compared to 15.4W.