Understanding Priority Disconnect
Managing Power over Ethernet (PoE)
page 5-10
OmniSwitch 6850/6850E Series Hardware Users Guide
June 2011
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. Due to the
support of different PoE standards and PoE hardware on each platform the internal port priority is differ-
ent for each platform. The following tables should be used to determine PoE priority:
PoE Physical Port Priority
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 priority 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 lowest physical port priority 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.
OS6850 Physical Ports - 24 Port Models
1 (Highest) -> 24 (Lowest)
OS6850E Physical Port - 24 Port Models
24 (Highest) -> 1 (Lowest)
OS6850 Physical Ports - 48 Port Models
1 (Highest) -> 48 (Lowest)
OS6850E Physical Port - 48 Port Models
48 (Highest) -> 1 (Lowest)
