IEEE 802.3at LLDP Emulation & Analysis
With the 802.3at standard, PoE has moved in the direction of bypassing layer 1 PD classification in favor of a MAC (or Link) Layer PD classification that offers very high power distribution granularity and enables dynamic negotiation of power levels between PSE and PD.
The link layer scheme uses a PoE-specific Link Layer Discovery Protocol (LLDP) as specified in the new Clause 79 of IEEE 802.3 with additional protocol rules defined in Clause 33 (IEEE 802.3at). LLDP is a link (point-to-point) MAC protocol historically used to allow switches and routers to automatically "discover" what is around them and to populate and maintain a MIB that can be used for viewing and managing a network topology.
PSA-3000 and PSL-3000 platforms each offer a feature upgrade that enables flexible emulation and analysis for PoE "Plus" LLDP. The upgrade is available in the form of an instrument-specific license code that may be purchased from Sifos Technologies.