Specifications

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Catalyst 4224 Access Gateway Switch Software Configuration Guide
OL-2031-02
Chapter 3 Configuring Ethernet Switching
Configuring Ethernet Ports to Support IP Phones with Multiple Ports
Sample Configuration
The Catalyst 4224 supports the use of an 802.1p-only option when configuring
the voice VLAN. Use this option to allow the IP phone to tag VoIP packets with
a CoS of 5 on the native VLAN, while all PC data traffic is sent untagged.
The following example shows a single subnet configuration for the Catalyst 4224
switch:
interface FastEthernet5/2
description Port to IP Phone in single subnet
switchport access vlan 40
switchport voice vlan dot1p
spanning-tree portfast
The Catalyst 4224 instructs the IP phone to generate an 802.1Q frame with a null
VLAN ID value but with an 802.1p value (default is CoS of 5 for bearer traffic).
The voice and data vlans are both 40 in this example.
Configuring Ethernet Ports to Support IP Phones with
Multiple Ports
You might want to use multiple ports to connect the IP phones (option 2 in
Figure 3-1) if any of the following conditions apply to your Cisco IP telephony
network:
• You are connecting IP phones that do not have a second Ethernet port for
attaching a PC.
• You want to create a physical separation between the voice and data
networks.
• You want to provide in-line power easily to the IP phones without having to
upgrade the data infrastructure.
• You want to limit the number of switches that need UPS power.
IP Addressing
The recommended configuration for using multiple cables to connect IP phones
to the network is to use a separate IP subnet and separate VLANs for IP telephony.