Understanding Priority Disconnect; Setting Priority Disconnect Status - Alcatel-Lucent OmniSwitch 6860 Hardware User's Manual

Understanding Priority Disconnect

Understanding Priority Disconnect
The priority disconnect function differs from the port priority function described on
applies only to the addition of powered devices (PDs) in tight power budget conditions. Priority discon-
nect is used by the system software in determining whether an incoming PD will be granted or denied
power when there are too few watts remaining in the PoE power budget for an additional device. For
example, if there are only 2 watts available in the current PoE power budget and a user plugs a 3.5W
powered device into a PoE port, the system software must determine whether the device will be powered
on. Based on priority disconnect rules, in some cases one or more existing devices may be powered down
in order to accommodate the incoming device. In other cases, the incoming device will be denied power.
Priority disconnect rules involve the port priority status of an incoming device (i.e., low, high, and criti-
cal), as well as the port's physical port number (i.e., 1–24). Understanding priority disconnect rules is
especially helpful in avoiding power budget deficits and the unintentional shutdown of mission-critical
devices when PDs are being added in tight power budget conditions. For detailed information on how
priority disconnect uses port priority and port number criteria for determining the power status of incom-
ing PDs, refer to the illustrated examples on pages
Reminder. Priority disconnect applies only when there is inadequate power remaining in the power
budget for an incoming device.
Note. For OS6860 switches using 920W power supplies, priority disconnect supports up to a maximum of
780W of PoE power (per power supply installed). For switches using 600W power supplies, priority
disconnect supports up to a maximum of 450W of PoE power (per power supply installed).
For information on setting the priority disconnect status, refer to the section below. For information on
setting the port priority status (a separate function from priority disconnect), refer to
Levels" on page 5-7.

Setting Priority Disconnect Status

By default, priority disconnect is enabled in the switch's system software. For information on changing the
priority disconnect status, refer to the information below.
Disabling Priority Disconnect
When priority disconnect is disabled and there is inadequate power in the budget for an additional device,
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).
To disable priority disconnect, use the
-> lanpower slot 2/1 priority-disconnect disable
Enabling Priority Disconnect
To enable priority disconnect, use the
-> lanpower slot 2/1 priority-disconnect enable
page 5-8
5-9 through 5-10.
lanpower slot priority-disconnect
lanpower slot priority-disconnect
OmniSwitch 6860 Hardware Users Guide
Managing Power over Ethernet (PoE)
page 5-7 in that it
"Setting Port Priority
command. For example:
command. For example:
May 2014