Power Over Ethernet - HP MSM317 Deployment Manual

Power over Ethernet

Power over Ethernet has many advantages over AC wiring for powering IP phones and other devices.
It is cheaper, has a smaller carbon footprint than AC, and is not subject to the same code compliance
as AC installations. PoE devices also do not require standard power outlets, helping to contain the
cost of large deployments.
The MSM317 receives PoE power through its uplink port (either via the RJ-45 connector or
punch-down block). The uplink port must be connected to an 802.3af or 802.3at compliant power
source. The Ethernet connection to this port must be a standard 10/100 link delivered over
Category 5 (or better) structured cabling.
The MSM317 can supply PoE power on port 1. The power supply capability of port 1 is directly
related to the PoE source that powers it. The MSM317 requires about 6 watts for its own operation,
with the remaining power available to the port on the front of the unit.
Figure 10: External interfaces of the MSM317.
Before plugging a PoE device into this port, it is important to understand the device's power
requirements as these dictate the PoE source type you need. For example, the Avaya 9640G/9620
IP phone is a Class 2 device, requiring a standard PoE source. Two PoE power settings are available
on port 1 of the MSM317:
• If the MSM317 is powered from an 802.3af standard PoE source, then port 1 can support Class 1
(3.84 watts) or Class 2 (6.49 watts).
• If the MSM317 is powered from an 802.3at PoE+ source with an output power greater than
23 watts, or a PoE injector capable of delivering greater than 15.4 watts (as specified in the
802.3af standard), then port 1 can support Class 0 (15.4 watts) and Class 3 devices (15.4 watts).
Note:
For more information on PoE and PoE+ on the MSM317, see the
HP MSM317 Access Device Installation and Getting Started Guide.
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