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CCNA Voice Lab Manual: Establishing Network Connectivity and Understanding IP Phone Registration

Chapter Description

This chapter shows how to set up a voice network for a fictitious company and establish network connectivity and configure needed services.

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CCNA Voice Lab Manual

CCNA Voice Lab Manual

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In both Cisco Unified Communications Manager Express (CUCME) and Cisco Unified Communications Manager (CUCM) environments, phones need to connect to the network to receive services such as IP addresses from DHCP, VLAN assignments for voice traffic, IP information on where to register, and Network Time Protocol (NTP) packets. This chapter focuses on establishing those services.

In this chapter, you will set up a voice network for the fictitious company Shiny Objects Incorporated (SOI). Before phones are connected, you must establish network connectivity and configure needed services.

Lab 3-1: Network Connectivity

Equipment Required

This lab uses the following equipment:

  • Cisco router
  • Switch that supports voice VLANs
  • PC for testing
  • Cisco IP Phone (optional, but useful if switch supports Power over Ethernet [PoE])

Learning Objectives

Upon completion of this lab, you will be able to

  • Perform basic router and switch configuration
  • Configure VLANs to support data, voice, and network management traffic
  • Configure VLAN trunking between a router and a switch using subinterfaces
  • Configure router-based DHCP pools for voice and data devices


SOI would like to establish its new data network with the expectation of using VoIP in the near future.

These instructions refer to the Pod Addressing Table in Appendix A to determine the IP addresses and VLAN numbers used for your pod. Wherever an x is shown, substitute the pod number.

Task 1: Clear and Cable Devices

Because the CCNA is a prerequisite for the CCNA-Voice certification exam, this book assumes that you are familiar with clearing prior configurations.

Step 1-1: Clear Prior Configurations

Clear any prior configuration on the router and switch, and delete the vlan.dat file before reloading both devices.

Step 1-2: Cable Router and Switch

Cable router interface Fast Ethernet 0/0 to switch port Fast Ethernet 0/1, as shown in Figure 3-1. The PC will be connected later.

Figure 3-1

Figure 3-1. Topology Diagram

Task 2: Configure Basic Setup

This task establishes the basic configuration commands on both the router and switch.

Step 2-1: Configure Basic Setup on the Router

Router(config)# hostname RtrPodx

For example, Pod 8 would use hostname RtrPod8.

RtrPodx(config)# no ip domain-lookup
RtrPodx(config)# enable secret class
RtrPodx(config)# line con 0
RtrPodx(config-line)# logging synchronous
RtrPodx(config-line)# exec-timeout 120 0
RtrPodx(config-line)# password cisco
RtrPodx(config-line)# login
RtrPodx(config-line)# line vty 0 15
RtrPodx(config-line)# password cisco
RtrPodx(config-line)# login
RtrPodx(config-line)# exit

Step 2-2: Configure Basic Setup on the Switch

Switch(config)# hostname SwPodx

For example, Pod 3 would use hostname SwPod3

SwPodx(config)# no ip domain-lookup
SwPodx(config)# enable secret class
SwPodx(config)# line con 0
SwPodx(config-line)# logging synchronous
SwPodx(config-line)# exec-timeout 120 0
SwPodx(config-line)# password cisco
SwPodx(config-line)# login
SwPodx(config-line)# line vty 0 15
SwPodx(config-line)# password cisco
SwPodx(config-line)# login
SwPodx(config-line)# exit

Task 3: Configure the Switch

For the purposes of security and ease of implementing quality of service (QoS), use VLANs to keep voice traffic separate from other traffic.

Step 3-1: Create the VLANs

Create and name VLANs for data, voice, and network management.

SwPodx(config)# vlan x0
SwPodx(config-vlan)# name Data
SwPodx(config-vlan)# vlan x1
SwPodx(config-vlan)# name Management
SwPodx(config-vlan)# vlan x5
SwPodx(config-vlan)# name Voice
SwPodx(config-vlan)# exit

Step 3-2: Configure the Trunk Port

Configure the trunk port that connects the switch to the router. Layer 3 switches (such as the Cisco Catalyst 3560) require that the trunking protocol be specified with the switchport trunk encapsulation command before the interface can be set as a trunk. If you are using a Layer 2 switch (such as a Cisco Catalyst 2950 or 2960), the command is not needed and will be rejected.

SwPodx(config)# interface fastethernet 0/1
SwPodx(config-if)# switchport trunk encapsulation dot1q
SwPodx(config-if)# switchport mode trunk
SwPodx(config-if)# exit

Step 3-3: Configure the Access Ports

Almost all Cisco IP Phones are designed with a three-port switch built inside (one physical port connected to the production switch, one physical port for a PC to connect to the phone, and one internal port for the phone itself). This built-in switch saves money in wiring costs, as existing phone cabling might not meet networking standards. This enables an existing computer to be plugged into the phone, and the phone connects to the switch in the wiring closet.

Prior to the introduction of voice VLANs, a trunk connected an IP Phone to the switch to keep the voice and data traffic separate. Current best practice configures the ports connected to phones and PCs to use access mode but adds a secondary voice VLAN. The switch ports use the access VLAN to send data traffic as untagged frames. However, if the switch detects a Cisco IP Phone using Cisco Discovery Protocol (CDP), it will inform the phone of the VLAN used for voice traffic, which will be tagged using 802.1q. This creates a pseudotrunk that allows only the data and voice VLANs on the link.

Use the interface range command to assign settings. This is the fastest way to assign settings to more than one switch port at a time.

SwPodx(config)# interface range fastethernet 0/2 – 24
SwPodx(config-if-range)# switchport mode access
SwPodx(config-if-range)# switchport access vlan x0
SwPodx(config-if-range)# switchport voice vlan x5
SwPodx(config-if-range)# exit

Example 3-1. Verify That spanning-tree portfast Is Created by the Voice VLAN Assignment

SwPod11# show run

<output omitted>

interface FastEthernet0/1
 switchport trunk encapsulation dot1q
 switchport mode trunk
interface FastEthernet0/2
 switchport access vlan 110
 switchport mode access
 switchport voice vlan 115
 spanning-tree portfast

<output omitted>

Step 3-4: Configure the Switch Management Interface

Set up an interface to manage the switch remotely.

SwPodx(config)# interface vlan x1
SwPodx(config-if)# ip address 10.x1.0.2
SwPodx(config-if)# exit
SwPodx(config)# ip default-gateway 10.x1.0.1

Task 4: Configure the Router Subinterfaces

Subinterfaces allow the VLANs to cross a trunk link to the router. Each subinterface will be the default gateway for a paired subnet. When using subinterfaces on a router, it is necessary to assign the correct VLAN to the subinterface before an IP address can be entered. Because there are three VLANs, you need three subinterfaces.

Step 4-1: Configure the Data VLAN Subinterface

RtrPodx(config-if)# interface fastethernet 0/0.x0
RtrPodx(config-subif)# encapsulation dot1Q x0
RtrPodx(config-subif)# description Data VLAN
RtrPodx(config-subif)# ip address 10.x0.0.1

Step 4-2: Configure the Management VLAN Subinterface

RtrPodx(config-subif)# interface fastethernet 0/0.x1
RtrPodx(config-subif)# encapsulation dot1Q x1
RtrPodx(config-subif)# description Management VLAN
RtrPodx(config-subif)# ip address 10.x1.0.1

Step 4-3: Configure the Voice VLAN Subinterface

RtrPodx(config-subif)# interface fastethernet 0/0.x5
RtrPodx(config-subif)# encapsulation dot1Q x5
RtrPodx(config-subif)# description Voice VLAN
RtrPodx(config-subif)# ip address 10.x5.0.1
RtrPodx(config-subif)# exit

Step 4-4: Activate the Router Interface

RtrPodx(config)# interface fastethernet 0/0
RtrPodx(config-if)# no shutdown

Task 5: Verification

Check the configuration to determine whether it matches what you expect. This will help to avoid future problems.

Step 5-1: Verify Switch VLAN Configuration

Use the show vlan brief command to verify the VLAN configuration. This output is from Pod 11; your output will have different VLAN numbers. Notice that Fa0/1 is a trunk port and as such does not have a VLAN assigned to it, so it will not show in the output.

SwPod11# show vlan
VLAN Name                             Status    Ports
---- -------------------------------- --------- -------------------------------
1    default                          active    Gi0/1, Gi0/2
110  Data                             active    Fa0/2, Fa0/3, Fa0/4, Fa0/5
                                                Fa0/6, Fa0/7, Fa0/8, Fa0/9
                                                Fa0/10, Fa0/11, Fa0/12, Fa0/13
                                                Fa0/14, Fa0/15, Fa0/16, Fa0/17
                                                Fa0/18, Fa0/19, Fa0/20, Fa0/21
                                                Fa0/22, Fa0/23, Fa0/24
111  Management                       active
115  Voice                            active    Fa0/2, Fa0/3, Fa0/4, Fa0/5
                                                Fa0/6, Fa0/7, Fa0/8, Fa0/9
                                                Fa0/10, Fa0/11, Fa0/12, Fa0/13
                                                Fa0/14, Fa0/15, Fa0/16, Fa0/17
                                                Fa0/18, Fa0/19, Fa0/20, Fa0/21
                                                Fa0/22, Fa0/23, Fa0/24
1002 fddi-default                     act/unsup
1003 token-ring-default               act/unsup
1004 fddinet-default                  act/unsup
1005 trnet-default                    act/unsup

Step 5-2: Verify Switch Port Assignment

Use the show interfaces switchport command to verify the configuration of trunk and access ports. This output is from Pod 11; your output will have different VLAN numbers. Notice that Fa0/1 is a trunk port, while Fa0/2 is a static access port and has a voice VLAN assigned to it.

SwPod11# show interfaces switchport
Name: Fa0/1
Switchport: Enabled
Administrative Mode: trunk
Operational Mode: trunk
Administrative Trunking Encapsulation: dot1q
Operational Trunking Encapsulation: dot1q
Negotiation of Trunking: On
Access Mode VLAN: 1 (default)
Trunking Native Mode VLAN: 1 (default)
Administrative Native VLAN tagging: enabled
Voice VLAN: none

<output omitted>

Name: Fa0/2
Switchport: Enabled
Administrative Mode: static access
Operational Mode: down
Administrative Trunking Encapsulation: negotiate
Negotiation of Trunking: Off
Access Mode VLAN: 110 (Data)
Trunking Native Mode VLAN: 1 (default)
Administrative Native VLAN tagging: enabled
Voice VLAN: 115 (Voice)

<output omitted>

Step 5-3: Verify Router Subinterface IP Assignment

Use the show ip interface brief command to verify that the trunk is assigned correctly. This output is from Pod 11; your output will have different subinterface and IP address numbers.

RtrPod11# show ip interface brief
Interface                  IP-Address      OK? Method  Status                Protocol
FastEthernet0/0            unassigned      YES unset   up                    up
FastEthernet0/0.110      YES manual  up                    up
FastEthernet0/0.111      YES manual  up                    up
FastEthernet0/0.115      YES manual  up                    up

Task 6: DHCP Services

While phones and PCs can be assigned IP addresses statically, DHCP can automatically assign IP address leases. Additionally, DHCP can provide additional information to clients, allowing them to locate necessary resources on the network at the same time they receive an IP address. Using the router as a DHCP server is a quick way to provide DHCP services to clients.

The DHCP option 150 tells Cisco IP Phones the IP address of the TFTP server with the initial configuration file. When using CUCME, the router is the TFTP server by default. This lab assigns the default gateway IP address as the option 150 address, as there is only one way to reach the call agent in this network.

Step 6-1: Configure DHCP Pools on the Router

Always enter the ip dhcp exclude address command before a DHCP pool is created. This avoids IP addresses that should be excluded from being assigned to devices. Enter the network statement as the last command in the pool. Otherwise, if devices are connected, they are assigned an IP address by DHCP right after the network statement is entered, even if the default gateway and option 150 are not configured. This can make troubleshooting difficult, as the PCs and phones will receive IP addresses, but the phones will not register and the PCs will not communicate outside their own subnet without the default router (gateway) address.

Create DHCP pools for both the data and voice networks. While it might seem that option 150 is irrelevant in data VLANs, with software on a PC able to emulate a phone (such as the Cisco IP Communicator software), it makes sense to include it for both DHCP pools.

RtrPodx(config)# ip dhcp excluded-address 10.x0.0.1 10.x0.0.10
RtrPodx(config)# ip dhcp pool Data
RtrPodx(dhcp-config)# default-router 10.x0.0.1
RtrPodx(dhcp-config)# option 150 ip 10.x0.0.1
RtrPodx(dhcp-config)# network 10.x0.0.0
RtrPodx(dhcp-config)# exit
RtrPodx(config)# ip dhcp excluded-address 10.x5.0.1 10.x5.0.10
RtrPodx(config)# ip dhcp pool Voice
RtrPodx(dhcp-config)# default-router 10.x5.0.1
RtrPodx(dhcp-config)# option 150 ip 10.x5.0.1
RtrPodx(dhcp-config)# network 10.x5.0.0
RtrPodx(dhcp-config)# exit

Task 7: Test and Cleanup

Step 7-1: Test Connectivity

Connect a PC to the switch. Verify that the PC is assigned an IP address from the 10.x0.0.0 /24 subnet. Verify that the PC can telnet to both the router and the switch management IP addresses. If not, troubleshoot the configuration.

Step 7-2: Save the Configurations

Save the configurations into a text file for both the router and switch. They will be needed for future labs.

Step 7-3: (Optional) Explore Power Over Ethernet on the Switch

If you have a switch that is PoE capable and a Cisco IP Phone or two, monitor the console port of the switch and connect the jack on the phone labeled SW to a switch port. See Figure 3-2 for an example.

Figure 3-2

Figure 3-2. Cisco IP Phone Connections

If you connect an older Cisco IP Phone (a 7960, for example) that supports only Cisco-proprietary inline power, you might see a message like this on the switch console line:

*Mar  1 05:23:55.900: %ILPOWER-7-DETECT: Interface Fa0/3: Power Device detected:
  Cisco PD
*Mar  1 05:23:55.976: %ILPOWER-5-POWER_GRANTED: Interface Fa0/3: Power granted

If you connect a newer Cisco IP Phone (a 7975, for example) that supports the IEEE 802.1af standard, you might see a message like this on the switch console line:

* Mar  1 05:23:55.858: %ILPOWER-7-DETECT: Interface Fa0/4: Power Device detected:
Mar  1 05:23:55.942: %ILPOWER-5-POWER_GRANTED: Interface Fa0/4: Power granted

When verifying PoE usage or troubleshooting phone power problems, you can see the existing PoE usage with the show power inline command. Knowing the remaining PoE capacity is important, as Cisco sells some switch models that do not have enough PoE to fully power all ports, such as the 24-port Catalyst 2960-24LT-L that supports only eight PoE devices at 15.4 watts.

In this output from Pod 11, there are two Cisco IP Phones attached, consuming 18.3 watts, with 351.7 watts of PoE capacity left on this switch. The 7960 phone (6.3 watts) does not have a PoE class, as it does not support 802.1af, while the 7975 phone (12.0 watts) shows as an IEEE PoE Class 3 device.

SwPod11# show power inline
Available:370.0(w)  Used:18.3(w)  Remaining:351.7(w)

Interface Admin  Oper       Power   Device              Class Max
--------- ------ ---------- ------- ------------------- ----- ----
Fa0/1     auto   off        0.0     n/a                 n/a   15.4
Fa0/2     auto   off        0.0     n/a                 n/a   15.4
Fa0/3     auto   on         6.3     IP Phone 7960       n/a   15.4
Fa0/4     auto   on         12.0    IP Phone 7975       3     15.4
Fa0/5     auto   off        0.0     n/a                 n/a   15.4
Fa0/6     auto   off        0.0     n/a                 n/a   15.4
<output omitted>

At this point, the phones should be attempting to register and will display a message such as “Registering” or “Configuring CM List” (the message will vary depending on the phone model and the version of firmware on the phone). If the phones show “Configuring IP” for more than a few seconds, the DHCP service is not functioning. The messages displayed on the phones are useful information when troubleshooting.

2. Lab 3-2: Network Time Protocol | Next Section