Installing and Managing Power over Ethernet (PoE)
Understanding Priority Disconnect
OmniSwitch 7700/7800 Hardware Users Guide
April 2005
page 3-29
Priority Disconnect is Disabled
Reminder.
Priority disconnect examples are only applicable when there is inadequate power remaining to
power an incoming device.
When priority disconnect is disabled, power will be denied to
any
incoming PD, regardless of its port
priority status (i.e., low, high, and critical) or physical port number (i.e., 1–24).
In the example below, there are only 2 watts available in the current PoE power budget. An incoming PD
requiring 3.5W is being attached to a critical priority port. All existing PDs are attached to low priority
ports. If priority disconnect was enabled (the default setting), the incoming device would easily have
power priority over all other connected devices. However, because priority disconnect status is disabled in
this example, any incoming PD is denied power, regardless of its priority level. The incoming 3.5W
device remains powered off. The existing devices connected to low-priority ports continue operating with-
out interruption.
Priority Disconnect Example 4: Feature is Disabled
1x
3x
5x
7x
9x
11
x
13x
15x
17x
19x
21x
23x
OK1
OK2
24x
2x
!
Incoming Powered
Device (PD) requiring
approx. 3.5 watts
Critical
Low
Low
Low
Low
Low
Low
Port 24
Port 1
Existing Powered
Devices (PDs)
Current power budget
has 2 watts available
for incoming PDs
UPS
Power Shelf
UPS
