Power Over Ethernet Interoperability Guide

1-Finger or 2-Finger Classification for Type 2 PSEs?

This is a commonly asked question. We have discussed it previously, but we will highlight and summarize it here.

Assuming PDs are compliant: Despite the added software-based complexity, the LLDP approach (after a 1-finger classification) may be considered preferable, as compared to 2-finger classification for a couple of reasons:

1.  When the data link comes up, the PSE will use LLDP protocol to communicate to the PD that it is a Type 2 PSE and is thus able to provide more than 13 W to it. But adding to this statement: LLDP classification actually allows the PSE to tell the PD not only that it can provide more than 13 W, but how much more! Maybe it does not need the PSE to provide full 30 ...