Power Over Ethernet Stackable Switch; Load Detection; How The P333T-Pwr Detects A Powered Device - Avaya P333T-PWR Installation And Configuration Manual

Chapter 13 Avaya P330 Layer 2 Features

Power Over Ethernet Stackable Switch

The P333T-PWR switch provides IEEE 802.3af-compliant "Inline" DC power over
the signal pairs in addition to switched Ethernet on the existing LAN infrastructure
for devices such as IP telephones and Wireless LAN access points. This allows you
to deploy devices in the network that require power without installing standard
power cables in hard to access areas. The P333T-PWR is pre-configured to supply
power according to the load detection criteria (see "Load Detection"), so you can
use it right out of the box. The P333T-PWR provides power over standard Category
3 and Category 5 cables.
Note: The P333T-PWR does not supply power to ports on Expansion Modules.

Load Detection

The P333T-PWR periodically checks all ports, powered and non-powered to check
their status and the power status of connected devices.
The P333T-PWR will supply power to a port only after it has detected a suitable PD
(powered device) is connected to the port. The check consists of the P333T-PWR
looking for a signature from the device that indicates it needs to supply power.

How the P333T-PWR Detects a Powered Device

The P333T-PWR uses two powered device signatures – specific resistance or
capacity between the power feed pairs – and PD connection verification to
determine whether to supply power to a give port. Figure 13.1 shows the process.
62 Avaya P333T-PWR User's Guide