PoE allocation

LLDP can negotiate power with a PD by using LLDP MED TLVs (disabled by default). This can be enabled using the int <port-list> PoE-lldp-detect [enabled|disabled] command, as shown below. LLDP MED TLVs sent by the PD are used to negotiate power only if the LLDP PoE+ TLV is disabled or inactive; if the LLDP PoE+ TLV is sent as well (not likely), the LLDP MED TLV is ignored.

Enabling PoE-lldp-detect allows the data link layer to be used for power negotiation. When a PD requests power on a PoE port, LLDP interacts with PoE to see if there is enough power to fulfill the request. Power is set at the level requested. If the PD goes into power-saving mode, the power supplied is reduced; if the need for power increases, the amount supplied is increased. PoE and LLDP interact to meet the current power demands.

Syntax:


int <port-list> poe-lldp-detect [enabled | disabled]

Allows the data link layer to be used for power negotiation between a PD on a PoE port and LLDP.

Default: Disabled

Example:

You can enter this command to enable LLDP detection:

switch(config) # int 7 PoE-lldp-detect enabled

or in interface context:

switch(eth-7) # PoE-lldp-detect enabled

NOTE:

Detecting PoE information via LLDP affects only power delivery; it does not affect normal Ethernet connectivity.

You can view the settings by entering the show power-over-ethernet brief command, as shown in Port with LLDP configuration information obtained from the device.

Port with LLDP configuration information obtained from the device

switch(config)# show power-over-ethernet brief

 Status and Counters - Port Power Status

  System Power Status  : No redundancy
  PoE Power Status     : No redundancy

  Available: 300 W Used: 0 W Remaining: 300 W

  Module A Power
  Available: 300 W Used: 5 W Remaining: 295 W

  POE   | Power   Power     Alloc Alloc  Actual Configured  Detection   Power
  Port  | Enable  Priority  By    Power  Power  Type        Status      Class
  ----- + ------- --------- ----- ------ ------ ----------- ----------- ----
  A1    | Yes     low       usage 17 W   0.0 W  Phone1      Delivering  1
  A2    | Yes     low       usage 17 W   0.0 W              Searching   0
  A3    | Yes     low       usage 17 W   0.0 W              Searching   0
  A4    | Yes     low       usage 17 W   0.0 W              Searching   0
  A5    | Yes     low       usage 17 W   0.0 W              Searching   0
  A6    | Yes     low       usage 17 W   0.0 W              Searching   0