Cisco pre-draft Power over Ethernet

arlis · ‎01-30-2007

I'm considering purchasing a 3750-24PS and noticed PoE was classified as "pre-draft". What are the limitations in terms of device support and/or functionality?

lujohnso · ‎01-30-2007

The IEEE 802.3af standard is implemented on various phone vendors, whereas the Cisco pre-standard power is Cisco proprietary. So, it will limit you to using Cisco phones. This isn't really a problem, but if for some reason you have an access point or some other device that requires 802.3af power to function you will be out of luck. There are other flavors of the 3750 switch that do indeed support the 802.3af standard.

epardio · ‎01-31-2007

I just found the following detail about this catalyst. I'm not sure if it is the one you want to buy...

WS-C3750-24PS-S

? 24 Ethernet 10/100 ports with IEEE 802.3af and Cisco prestandard PoE

? 2 SFP-based Gigabit Ethernet ports

? 32-Gbps, high-speed stacking bus

? Innovative stacking technology

? 1 RU stackable, multilayer switch

? Enterprise-class intelligent services delivered to the network edge

? IP Base image installed

? Basic RIP and static routing, upgradable to full dynamic IP routing

According to the first line, this supports both the pre-standard, and the IEEE 802.3af standard

Hope that helps

mbalasko · ‎01-31-2007

Typically the switch that provide Cisco inline power, a.k.a pre-draft, do not supply as much power as the AF standard calls for. Additionally the detection method for checking to see if a device needs the power is different.

http://www.cisco.com/en/US/netsol/ns340/ns394/ns147/ns412/networking_solutions_white_paper09186a008026641c.shtml#wp43581

We've bumped into a few issues on our 6500's that are Cisco inline power vs. af power.

Mike