Cisco 8851, Administration Manual

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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.
When CDP and Power Negotiation are disabled, the phone can power the accessories up to 15.4W.
Note
Network Protocols
Cisco IP Phone 8800 Series support several industry-standard and Cisco network protocols required for voice
communication. The following table provides an overview of the network protocols that the phones support.
Table 6: Supported Network Protocols on the Cisco IP Phone 8800 Series
Usage notes Purpose Network protocol
Cisco IP Phones 8845, 8865, and
8851 support Bluetooth 4.1.
Cisco IP Phone 8861 support
Bluetooth 4.0.
Cisco IP Phone 8811 and 8841 do
not support Bluetooth.
Bluetooth is a wireless personal area network (WPAN)
protocol that specifies how devices communicate over short
distances. Bluetooth
— BootP enables a network device, such as the Cisco IP Phone,
to discover certain startup information, such as the IP address. Bootstrap Protocol (BootP)
The Cisco IP Phones use CDP to
communicate information such as
auxiliary VLAN ID, per port power
management details, and Quality
of Service (QoS) configuration
information with the Cisco Catalyst
switch. CDP is a device-discovery protocol that runs on all
Cisco-manufactured equipment.
Using CDP, a device can advertise its existence to other
devices and receive information about other devices in the
network.
Cisco Discovery Protocol (CDP)
Cisco IP Phone 8800 Series Multiplatform Phones Administration Guide
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Network Protocols