Power Negotiation Over Lldp; Obtaining Additional Information About Power - Cisco 8961 Administration Manual

Providing Power to the Cisco Unified IP Phone

Power Negotiation over LLDP

The phone and the switch negotiate the power that the phone can consume. Cisco Unified IP Phone 8961,
9951, and 9971 operate at multiple power settings, which lowers their consumption when less power is
available.
After a phone reboots, the switch locks to one protocol (CDP or LLDP) for power negotiation. It 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, it 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 disabled, the switch may disconnect power to the phone. If the switch does not support power
negotiation, then 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
allowed by the IEEE 802.3af-2003 standard.
When CDP and Power Negotiation are disabled, the phone can power the accessories up to 15.4W.
Note
To enable or disable power negotiation, see
Phone".

Obtaining Additional Information About Power

For related information about power, see the documents shown in
information about the following topics:
•
•
•
Table 2-2
Document Topics
Cisco Unified IP Phone Power
Injector
PoE Solutions
Cisco Catalyst Switches
Integrated Service Routers
Cisco IOS Software
Cisco Unified IP Phone 8961, 9951, and 9971 Administration Guide for Cisco Unified Communications Manager 8.6 (SIP)
2-6
Cisco switches that work with Cisco Unified IP Phones
Cisco IOS releases that support bidirectional power negotiation
Other requirements and restrictions regarding power
Related Documentation for Power
Chapter 2 Preparing to Install the Cisco Unified IP Phone on Your Network
Table 8-1, "Telephony Features for the Cisco Unified IP
URL
http://www.cisco.com/en/US/products/ps6951/index.html
http://www.cisco.com/en/US/netsol/ns340/ns394/ns147/ns412/net
working_solutions_package.html
http://cisco.com/en/US/products/hw/switches/index.html
http://www.cisco.com/en/US/products/hw/routers/index.html
http://www.cisco.com/en/US/products/sw/iosswrel/products_ios_
cisco_ios_software_category_home.html
Table 2-2. These documents provide