Priority Disconnect Is Enabled; Same Priority Level On All Pd; Priority Disconnect Is Enabled; Incoming Pd Port Has Highest Priority Level; Priority Disconnect Is Enabled; Incoming Pd Port Has Lowest Priority Level - Alcatel-Lucent OmniSwitch 6850-48 Hardware User's Manual

Understanding Priority Disconnect

Priority Disconnect is Enabled; Same Priority Level on All PD

Reminder. Priority disconnect examples are applicable only when there is inadequate power remaining to
power an incoming device.
When a PD is being connected to a port with the same priority level as all other in the slot, the physical
port number is used to determine whether the incoming PD will be granted or denied power. Lower-
numbered receive higher priority than higher-numbered. In other words, a PD connected to
Port 1 will have a higher power priority than a PD connected to Port 2; a PD connected to Port 23 will
have a higher power priority than a PD connected to Port 24. In order to avoid a power budget deficit,
another port in the slot is disconnected. In determining which port to power off, the system software
disconnects the port with the highest physical port number.

Priority Disconnect is Enabled; Incoming PD Port has Highest Priority Level

Reminder. Priority disconnect examples are applicable only when there is inadequate power remaining to
power an incoming device.
When a PD is being connected to a port with a higher priority level than all other in the slot, the incoming
PD will automatically be granted power over the other devices, regardless of its physical port number.
In order to avoid a power budget deficit, another port in the slot is disconnected. In determining which port
to power off, the system software first selects the port with the lowest configured priority level. For exam-
ple, if a critical priority device is being added to a slot in which five existing devices are attached to high
priority and one device is attached to a low priority port, the low priority port is automatically discon-
nected, regardless of its physical port number.
If all existing devices are attached to with the same lower priority level, the system software disconnects
the port with both the lowest priority level and the highest physical port number. For example, if a critical
priority device is being added to a slot in which six existing devices are attached to high priority, the high
priority port with the highest physical port number is automatically disconnected.

Priority Disconnect is Enabled; Incoming PD Port has Lowest Priority Level

Reminder. Priority disconnect examples are applicable only when there is inadequate power remaining to
power an incoming device.
When a PD is being connected to a port with a lower priority level than all other in the slot, the incoming
PD will be denied power, regardless of its physical port number. Devices connected to other higher-prior-
ity will continue operating without interruption.
page 3-10
Installing and Managing Power over Ethernet (PoE)
OmniSwitch 6850 Series Hardware Users Guide September 2009