PD Disconnect Precedence

Summit X430, X440-24p, X460-24p, X460-48p, X460-G2, X440-8p, X440-48p and Modular PoE Switches Only

After a PD is discovered and powered on a Summit X440-24p, X460-24p, X460-48p or a modular PoE switch, the actual power drain is continuously measured.

If the usage for power by PDs is within the guard band, the system begins denying power to PDs.

To supply power to all PDs on a modular switch, you can reconfigure the reserved power budget for the switch or slot, so that enough power is available to power all PDs. You reconfigure the reserved power budget dynamically; you do not have to disable the device to reconfigure the power budget.

You can configure the switch to handle a request for power that exceeds the power budget situation in one of two ways, called the disconnect precedence:
  • Disconnect PDs according to the configured PoE port priority for each PD.
  • Deny power to the next PD requesting power, regardless of that port‘s PoE priority.

On modular switches, this is a switchwide configuration that applies to each slot; you cannot configure this disconnect precedence per slot.

The default value is deny-port. So, if you do not change the default value and the switch‘s or slot‘s power is exceeded, the next PD requesting power is not connected (even if that port has a higher configured PoE port priority than those ports already receiving power). When you configure the deny-port value, the switch disregards the configured PoE port priority and port numbering.

When the switch is configured for lowest-priority mode, PDs are denied power based on the individual port‘s configured PoE priority. If the next PD requesting power is of a higher configured PoE priority than an already powered port, the lower-priority port is disconnected and the higher-priority port is powered.