Catalyst 6500 Release 12.2SX Software Configuration Guide
Cisco IP Phone Support
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Configuring Cisco IP Phone Support

Table Of Contents

Configuring Cisco IP Phone Support

Understanding Cisco IP Phone Support

Cisco IP Phone Connections

Cisco IP Phone Voice Traffic

Cisco IP Phone Data Traffic

Other Cisco IP Phone Features

Default Cisco IP Phone Support Configuration

Cisco IP Phone Support Configuration Guidelines and Restrictions

Configuring Cisco IP Phone Support

Configuring Voice Traffic Support

Configuring Data Traffic Support


Configuring Cisco IP Phone Support


This chapter describes how to configure support for Cisco IP phones on the Catalyst 6500 series switches. This information may be helpful in configuring support for non-Cisco IP phones, but we recommend that you see the manufacturer's documentation for those devices.


NoteCisco ME 6500 Series Ethernet switches are not typically used to support Cisco IP phones.

For complete syntax and usage information for the commands used in this chapter, see the Cisco IOS Master Command List, at this URL:

http://www.cisco.com/en/US/docs/ios/mcl/allreleasemcl/all_book.html



Tip For additional information about Cisco Catalyst 6500 Series Switches (including configuration examples and troubleshooting information), see the documents listed on this page:

http://www.cisco.com/en/US/products/hw/switches/ps708/tsd_products_support_series_home.html

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This chapter consists of these sections:

Understanding Cisco IP Phone Support

Default Cisco IP Phone Support Configuration

Cisco IP Phone Support Configuration Guidelines and Restrictions

Configuring Cisco IP Phone Support

Understanding Cisco IP Phone Support

These sections describe Cisco IP phone support:

Cisco IP Phone Connections

Cisco IP Phone Voice Traffic

Cisco IP Phone Data Traffic

Other Cisco IP Phone Features

Cisco IP Phone Connections

The Cisco IP phone contains an integrated 3-port 10/100 switch. The ports are dedicated connections to these devices:

Port 1 connects to the switch.

Port 2 is an internal 10/100 interface that carries the Cisco IP phone traffic.

Port 3 connects to a PC or other device.

Figure 15-1 shows a Cisco IP phone connected between a switch and a PC.

Figure 15-1 Cisco IP Phone Connected to a Switch

Cisco IP Phone Voice Traffic

The Cisco IP phone transmits voice traffic with Layer 3 IP precedence and Layer 2 CoS values, which are both set to 5 by default. The sound quality of a Cisco IP phone call can deteriorate if the voice traffic is transmitted unevenly.

You can configure Layer 2 access ports on the switch to send Cisco Discovery Protocol (CDP) packets that configure an attached Cisco IP phone to transmit voice traffic to the switch in any of the following ways:

In the voice VLAN, tagged with a Layer 2 CoS priority value

In the access VLAN, tagged with a Layer 2 CoS priority value

In the access VLAN, untagged (no Layer 2 CoS priority value)


Note In all configurations, the voice traffic carries a Layer 3 IP precedence value (the default is 5 for voice traffic and 3 for voice control traffic).


To provide more predictable voice traffic flow, you can configure QoS on the switch to trust the Layer 3 IP precedence or Layer 2 CoS value in the received traffic (see Chapter 43 "Configuring PFC QoS").

Release 12.2(33)SXI1 and later releases support the trusted boundary device verification feature, which can configure ports on the switch to apply configured QoS port trust commands only when the Cisco Discovery Protocol (CDP) verifies that the device attached to the port is a Cisco IP phone. See the "Configuring Trusted Boundary with Cisco Device Verification" section.

You can configure a Layer 2 access port with an attached Cisco IP phone to use one VLAN for voice traffic and another VLAN for data traffic from a device attached to the Cisco IP phone.

Cisco IP Phone Data Traffic


NoteThe ability to either trust or mark tagged data traffic from the device attached to the access port on the Cisco IP phone is called the "trusted boundary (extended trust for CDP devices)" feature.

You cannot use Cisco IOS software commands to configure the frame type used by data traffic sent from a device attached to the access port on the Cisco IP phone.

Untagged data traffic from the device attached to the Cisco IP phone passes through the Cisco IP phone unchanged, regardless of the trust state of the access port on the Cisco IP phone.


To process tagged data traffic (traffic in 802.1Q or 802.1p frame types) from the device attached to the access port on the Cisco IP phone (see Figure 15-1), you can configure Layer 2 access ports on the switch to send CDP packets that instruct an attached Cisco IP phone to configure the access port on the Cisco IP phone to either of these two modes:

Trusted mode—All traffic received through the access port on the Cisco IP phone passes through the Cisco IP phone unchanged.

Untrusted mode—All traffic in 802.1Q or 802.1p frames received through the access port on the Cisco IP phone is marked with a configured Layer 2 CoS value. The default Layer 2 CoS value is 0. Untrusted mode is the default.

Most IP phones have no ability to notify the switch of link state changes on the IP phone's access port. When a device attached to the access port is disconnected or disabled administratively, the switch is unaware of the change. Some Cisco IP phones can send a CDP message containing a host presence type length value (TLV) indicating the changed state of the access port link. To recognize the host presence TLV, the switch must be running Cisco IOS Release 12.2(33)SXI or a later release.

Other Cisco IP Phone Features

The Catalyst 6500 series switch provides support for authentication, authorization, and accounting (AAA) for Cisco IP phones, as described in Chapter 60 "Configuring IEEE 802.1X Port-Based Authentication."

The Catalyst 6500 series switch also supports automatic tracking for Cisco Emergency Responder (Cisco ER) to help you manage emergency calls in your telephony network. For further information, see this URL:

http://www.cisco.com/en/US/products/sw/voicesw/ps842/tsd_products_support_series_home.html

Default Cisco IP Phone Support Configuration

Cisco IP phone support is disabled by default.

When the voice VLAN feature is enabled, all untagged traffic is sent with the default CoS priority of the port.

The CoS is not trusted for 802.1P or 802.1Q tagged traffic.

Cisco IP Phone Support Configuration Guidelines and Restrictions

The following guidelines and restrictions apply when configuring Cisco IP phone support:

You must enable the Cisco Discovery Protocol (CDP) on the port connected to the Cisco IP phone to send configuration information to the Cisco IP phone.

You can configure a voice VLAN only on a Layer 2 LAN port.

You can configure the ports on WS-X6548-RJ-45 and WS-X6548-RJ-21 switching modules to trust received Layer 2 CoS values (QoS port architecture 1p1q0t/1p3q1t). The WS-X6548-RJ-45 and WS-X6548-RJ-21 switching modules cannot supply power to Cisco IP phones.

You cannot configure 10/100 Mbps ports with QoS port architecture 1p4t/2q2t to trust received Layer 2 CoS values. Configure policies to trust the Layer 3 IP precedence value on switching modules with QoS port architecture 1p4t/2q2t.

The following conditions indicate that the Cisco IP phone and a device attached to the Cisco IP phone are in the same VLAN and must be in the same IP subnet:

If they both use 802.1p or untagged frames

If the Cisco IP phone uses 802.1p frames and the device uses untagged frames

If the Cisco IP phone uses untagged frames and the device uses 802.1p frames

If the Cisco IP phone uses 802.1Q frames and the voice VLAN is the same as the access VLAN

The Cisco IP phone and a device attached to the Cisco IP phone cannot communicate if they are in the same VLAN and subnet but use different frame types, because traffic between devices in the same subnet is not routed (routing would eliminate the frame type difference).

You cannot use Cisco IOS software commands to configure the frame type used by traffic sent from a device attached to the access port on the Cisco IP phone.

If you enable port security on a port configured with a voice VLAN and if there is a PC connected to the Cisco IP phone, set the maximum allowed secure addresses on the port to at least 2.

You cannot configure static secure MAC addresses in the voice VLAN.

Ports configured with a voice VLAN can be secure ports (see Chapter 62 "Configuring Port Security").

In all configurations, the voice traffic carries a Layer 3 IP precedence value (the default is 5 for voice traffic and 3 for voice control traffic).

Configuring Cisco IP Phone Support

These sections describe how to configure Cisco IP phone support:

Configuring Voice Traffic Support

Configuring Data Traffic Support


Note Voice VLANs are referred to as auxiliary VLANs in the Catalyst software publications.


Configuring Voice Traffic Support

To configure the way in which the Cisco IP phone transmits voice traffic, perform this task:

 
Command
Purpose

Step 1 

Router(config)# interface fastethernet slot/port

Selects the port to configure.

Step 2 

Router(config-if)# switchport

Configures the LAN port for Layer 2 switching.

Note You must enter the switchport command once without any keywords to configure the LAN port as a Layer 2 port before you can enter additional switchport commands with keywords.

Step 3 

Router(config-if)# switchport voice vlan {voice_vlan_ID | dot1p | none | untagged}

Configures the way in which the Cisco IP phone transmits voice traffic.

Step 4 

Router(config)# end

Exits configuration mode.

Step 5 

Router# show interfaces fastethernet slot/port switchport

Router# show running-config interface fastethernet slot/port

Verifies the configuration.

When configuring the way in which the Cisco IP phone transmits voice traffic, note the following information:

Enter a voice VLAN ID to send CDP packets that configure the Cisco IP phone to transmit voice traffic in 802.1Q frames, tagged with the voice VLAN ID and a Layer 2 CoS value (the default is 5). Valid VLAN IDs are from 1 to 4094. The switch puts the 802.1Q voice traffic into the voice VLAN.

Enter the dot1p keyword to send CDP packets that configure the Cisco IP phone to transmit voice traffic in 802.1p frames, tagged with VLAN ID 0 and a Layer 2 CoS value (the default is 5 for voice traffic and 3 for voice control traffic). The switch puts the 802.1p voice traffic into the access VLAN.

Enter the untagged keyword to send CDP packets that configure the Cisco IP phone to transmit untagged voice traffic. The switch puts the untagged voice traffic into the access VLAN.

Enter the none keyword to allow the Cisco IP phone to use its own configuration and transmit untagged voice traffic. The switch puts the untagged voice traffic into the access VLAN.

In all configurations, the voice traffic carries a Layer 3 IP precedence value (the default is 5).

See Chapter 43 "Configuring PFC QoS," for information about how to configure QoS.

See the "Configuring a LAN Interface as a Layer 2 Access Port" section for information about how to configure the port as a Layer 2 access port and configure the access VLAN.

This example shows how to configure Fast Ethernet port 5/1 to send CDP packets that tell the Cisco IP phone to use VLAN 101 as the voice VLAN:

Router# configure terminal 
Router(config)# interface fastethernet 5/1 
Router(config-if)# switchport voice vlan 101 
Router(config-if)# exit 
 
   

This example shows how to verify the configuration of Fast Ethernet port 5/1:

Router# show interfaces fastethernet 5/1 switchport 
Name: Fa5/1
Switchport: Enabled
Administrative Mode: access
Operational Mode: access
Administrative Trunking Encapsulation: dot1q
Operational Trunking Encapsulation: dot1q
Negotiation of Trunking: off
Access Mode VLAN: 100
Voice VLAN: 101
Trunking Native Mode VLAN: 1 (default)
Administrative private-vlan host-association: none 
Administrative private-vlan mapping: 900 ((Inactive)) 901 ((Inactive)) 
Operational private-vlan: none 
Trunking VLANs Enabled: ALL
Pruning VLANs Enabled: 2-1001
Capture Mode Disabled
Capture VLANs Allowed: ALL

Configuring Data Traffic Support


Note The trusted boundary feature is implemented with the mls qos trust extend command.


To configure the way in which an attached Cisco IP phone transmits data traffic, perform this task:

 
Command
Purpose

Step 1 

Router(config)# interface fastethernet slot/port

Selects the port to configure.

Step 2 

Router(config-if)# mls qos trust extend [cos cos_value]

Configures the way in which an attached Cisco IP phone transmits data traffic.

Step 3 

Router(config)# end

Exits configuration mode.

Step 4 

Router# show interfaces fastethernet slot/port switchport

Router# show running-config interface fastethernet slot/port

Verifies the configuration.

When configuring the way in which an attached Cisco IP phone transmits data traffic, note the following information:

To send CDP packets that configure an attached Cisco IP phone to trust tagged traffic received from a device connected to the access port on the Cisco IP phone, do not enter the cos keyword and CoS value.

To send CDP packets that configure an attached Cisco IP phone to mark tagged ingress traffic received from a device connected to the access port on the Cisco IP phone, enter the cos keyword and CoS value (valid values are 0 through 7).

You cannot use Cisco IOS software commands to configure whether or not traffic sent from a device attached to the access port on the Cisco IP phone is tagged.

This example shows how to configure Fast Ethernet port 5/1 to send CDP packets that tell the Cisco IP phone to configure its access port as untrusted and to mark all tagged traffic received from a device connected to the access port on the Cisco IP phone with CoS 3:

Router# configure terminal 
Router(config)# interface fastethernet 5/1 
Router(config-if)# mls qos trust extend cos 3 
 
   

This example shows how to configure Fast Ethernet port 5/1 to send CDP packets that tell the Cisco IP phone to configure its access port as trusted:

Router# configure terminal 
Router(config)# interface fastethernet 5/1 
Router(config-if)# mls qos trust extend 
 
   

This example shows how to verify the configuration on Fast Ethernet port 5/1:

Router# show queueing interface fastethernet 5/1 | include Extend 
  Extend trust state: trusted

Tip For additional information about Cisco Catalyst 6500 Series Switches (including configuration examples and troubleshooting information), see the documents listed on this page:

http://www.cisco.com/en/US/products/hw/switches/ps708/tsd_products_support_series_home.html

Participate in the Technical Documentation Ideas forum