•
The current VLANs might be configured on an IP subnet basis. However, an additional IP address might
not be available to assign the phone to the same subnet as other devices connect to the same port.
•
Data traffic present on the data/native VLAN may reduce the quality of VoIP traffic.
•
Network security may indicate a need to isolate the VLAN voice traffic from the VLAN data traffic.
Resolve these issues by isolating the voice traffic onto a separate VLAN. The switch port to which the phone
connects would be configured to have separate VLANs for carrying:
•
Voice traffic to and from the IP phone (auxiliary VLAN, on the Cisco Catalyst 6000 series, for example)
•
Data traffic to and from the PC that connects to the switch through the access port of the IP phone (native
VLAN)
Isolation of the phones on a separate, auxiliary VLAN improves the quality of the voice traffic and allows a
large number of phones to be added to an existing network where not enough IP addresses exist for each
phone.
For more information, see the documentation included with a Cisco switch. You can also access related
documentation at this URL:
http://cisco.com/en/US/products/hw/switches/index.html
Related Topics
Phone Startup Process, on page 36
Network Configuration Menu, on page 66
Cisco Unified IP Phone Power
Cisco Unified IP Phone 7975G, 7971G-GE, 7970G, 7965G, and 7945G can be powered with external power
or with Power over Ethernet (PoE). A separate power supply provides external power. A switch through the
Ethernet cable that is attached to a phone provides PoE.
When you install a phone powered with external power, connect the power supply to the phone and to a
power outlet before you connect the Ethernet cable to the phone. When you remove a phone that is powered
with external power, disconnect the Ethernet cable from the phone before you disconnect the power supply.
Caution
The following sections provide more information about phone power:
Power Guidelines
The following table provides guidelines that apply to external power and to PoE power for Cisco Unified IP
Phone 7975G, 7971G-GE, 7970G, 7965G, and 7945G.
Cisco Unified IP Phone 7975G, 7971G-GE, 7970G, 7965G, and 7945G Administration Guide for Cisco Unified
Communications Manager 9.0 (SCCP and SIP)
31
Cisco Unified IP Phones and Telephony Networks
Cisco Unified IP Phone Power