Power Negotiation Over Lldp; Network Protocols - Cisco 7800 Series Administration Manual

Power Negotiation Over LLDP

Power Negotiation Over LLDP
The phone and the switch negotiate the power that the phone consumes. Cisco IP Phone operates at multiple
power settings, which lowers power consumption when less power is available.
After a phone reboots, the switch locks to one protocol (CDP or LLDP) for power negotiation. The switch
locks to the first protocol (containing a power Threshold Limit Value [TLV]) that the phone transmits. If the
system administrator disables that protocol on the phone, the phone cannot power up any accessories because
the switch does not respond to power requests in the other protocol.
Cisco recommends that Power Negotiation always be enabled (default) when connecting to a switch that
supports power negotiation.
If Power Negotiation is disabled, the switch may disconnect power to the phone. If the switch does not support
power negotiation, disable the Power Negotiation feature before you power up accessories over PoE. When
the Power Negotiation feature is disabled, the phone can power the accessories up to the maximum that the
IEEE 802.3af-2003 standard allows.
Note When CDP and Power Negotiation are disabled, the phone can power the accessories up to 15.4W.

Network Protocols

Cisco IP Phones support several industry-standard and Cisco network protocols that are required for voice
communication. The following table provides an overview of the network protocols that the phones support.
Table 12: Supported Network Protocols on the Cisco IP Phone
Network Protocol
Bootstrap Protocol (BootP)
Cisco IP Phone 7800 Series Administration Guide for Cisco Unified Communications Manager
12
Set up each phone to enable or disable the EnergyWise settings. If EnergyWise is enabled, configure a
sleep and wake time, as well as other parameters. These parameters are sent to the phone as part of the
phone configuration XML file.
Purpose
BootP enables a network device,
such as the Cisco IP Phone, to
discover certain startup
information, such as its IP address.
About the Cisco IP Phone
Usage Notes
We recommend that you use DHCP
custom option 150. With this
method, you configure the TFTP
server IP address as the option
value. For additional supported
DHCP configurations, see the
documentation for your particular
Cisco Unified Communications
Manager release.