Understanding How The Cisco Ip Phone Interacts With The Cisco Catalyst Family Of Switches - Cisco 7960G Administration Manual

Chapter 2 Preparing to Install the Cisco IP Phone on Your Network
Understanding How the Cisco IP Phone Interacts with the
Cisco Catalyst Family of Switches
Cisco IP Phone Administration Guide for Cisco CallManager 4.0, Cisco IP Phones 7960G/7940G
OL-4825-01
Related Topic
Configuring Telephony Features Using Cisco CallManager, page 5-2
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The Cisco IP Phone models 7960G and 7940G have an internal Ethernet switch,
enabling proper forwarding of appropriate packets to the phone, to the access port
(labeled 10/100 PC on the phone), and to the network port (labeled 10/100 SW on
the phone).
If a computer is connected to the access port, the computer and the phone share
the same physical link to the switch and share the same port on the switch. This
shared physical link has the following implications for the VLAN configuration
on the network:
The current VLANs might be configured on an IP subnet basis. However,
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additional IP addresses might not be available to assign the phone to the same
subnet as other devices connected to the same port.
Data traffic present on the VLAN supporting phones might reduce the quality
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of Voice-over-IP traffic.
You can resolve these issues by isolating the voice traffic onto a separate VLAN
on each of the ports connected to a phone. The switch port configured for
connecting a phone would have separate VLANs configured for carrying:
Voice traffic to and from the IP phone (auxiliary VLAN)
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Data traffic to and from the PC connected to the switch through the access
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port of the IP phone (native VLAN)
Isolating the phones on a separate, auxiliary VLAN increases the quality of the
voice traffic and allows a large number of phones to be added to an existing
network where there are not enough IP addresses.
For more information, refer to the documentation included with the
Cisco Catalyst switch.
Understanding Interactions with Other Cisco IP Telephony Products
2-3