Packet Tracer 5.3 - IP telephony basic configuration

Tutorial description

This tutorial is designed to help you to configure the new voice over ip (voip) features available in Packet Tracer 5.3. It will show you the steps required to :

• Configure Call Manager Express^TM on a 2811 router,
• Use the various telephony devices
• Setup dial peers
• Connect  Cisco^TM IP phones as well as analogue phone on the network.

Network diagram

Note : Connect only IP Phone 1 at the beginning of the lab. IP Phone 2 must be disconnected.

Tasks 1 : Configure interface FastEthernet 0/0 and DHCP server on RouterA (2811 router)

#Configure the FA 0/0 interface#

RouterA>enable

RouterA#configure terminal

RouterA(config)#interface FastEthernet0/0

RouterA(config-if)#ip address 192.168.10.1 255.255.255.0

RouterA(config-if)#no shutdown

The DHCP server is needed to provide an IP adress and the TFTP server location for each IP phone connected to the network.

RouterA(config)#ip dhcp pool VOICE #Create DHCP pool named VOICE

RouterA(dhcp-config)#network 192.168.10.0 255.255.255.0 #DHCP network network 192.168.10 with /24 mask#

RouterA(dhcp-config)#default-router 192.168.10.1 #The default router IP address#

RouterA(dhcp-config)#option 150 ip 192.168.10.1 #Mandatory for voip configuration.

After the configuration, wait a moment  and check that ‘IP Phone 1’ has received an IP address by placing your cursor over the phone until a configuration summary appears.

Tasks 2 : Configure the Call Manager Express telephony service on RouterA

You must now configure the Call Manager Express telephony service on RouterA  to enable voip on your network.

RouterA(config)#telephony-service #Configuring the router for telephony services#

RouterA(config-telephony)#max-dn 5 #Define the maximum number of directory numbers#

RouterA(config-telephony)#max-ephones 5 #Define the maximum number of phones#

RouterA(config-telephony)#ip source-address 192.168.10.1 port 2000 #IP Address source#

RouterA(config-telephony)#auto assign 4 to 6 #Automatically assigning ext numbers to buttons#

RouterA(config-telephony)#auto assign 1 to 5 #Automatically assigning ext numbers to buttons#

Task 4 : Configure a voice vlan on SwitchA

Apply the following configuration on SwitchA interfaces. This configuration will separate voice and data traffic in different vlans on SwitchA. data packets will be carried on the access vlan.

SwitchA(config)#interface range fa0/1 – 5 #Configure interface range#

SwitchA(config-if-range)#switchport mode access

SwitchA(config-if-range)#switchport voice vlan 1 #Define the VLAN on which voice packets will be handled#

Task 5 : Configure the phone directory for IP Phone 1

Although ‘IP Phone 1’ is already connected to SwitchA, it needs additionnal configuration before beeing able to communicate. You need to configure RouterA CME to assign a phone number to this IP phone.

RouterA(config)#ephone-dn 1 #Defining the first directory entry#

RouterA(config-ephone-dn)#number 54001 #Assign the phone number to this entry#

Task 5 : Verify the configuration

Ensure that the IP Phone receives an IP Address and a the phone number 54001 from RouterA  (this can take a short while).

Task 6 : Configure the phone directory for IP Phone 2

Connect IP Phone 2 to SwitchA and power the phone ON using the power adapter (Physical tab).

RouterA(config)#ephone-dn 2 #Defining the first directory entry#

RouterA(config-ephone-dn)#number 54002 #Assign the phone number to this entry#

Task 7 : Verify the configuration

Ensure that the IP Phone 2 receives an IP Address and a the phone number 54002 from RouterA  (this can take a short while). Same procedure as task n°5.

Dial 54001 and check if IP phone 1 correctly receives the call.

interface Ethernet0/1
ip address 12.1.2.3 255.255.255.0
ip nat outside
!
interface Ethernet0/0
ip address 192.168.101.1 255.255.255.0
ip nat inside
!
ip nat inside source list 101 interface Ethernet0/1 overload
ip nat inside source static tcp 192.168.101.2 1723 interface Ethernet0/1 1723
!
access-list 101 permit ip any any

In the above configuration, Ethernet 0/1 is connected to the public Internet with a static address of 12.1.2.3 and Ethernet 0/0 is connected to the inside network with a static address of 192.168.101.1. NAT outside is configured on E0/1 and NAT inside is configured on E0/0. Access-list 101 works in conjunction with the "ip nat inside source list 101 interface Ethernet0/1 overload" statement to permit all inside hosts to use E0/1 to connect to the Internet sharing whatever IP address is assigned to interface Ethernet E0/1.

The "overload" statement implements PAT (Port Address Translation) which makes that possible. (PAT allows multiple internal hosts to share single address on an external interface by appending different port numbers to each connection.)

The statement "ip nat inside source static tcp 192.168.101.2 1723 interface Ethernet0/1 1723" takes incoming port 1723 (PPTP) requests on Ethernet0/1 and forwards them to the VPN server located at 192.168.101.2.

You could do something similar with a Web server by changing port 1723 to port 80 or port 443. Here's what that would look like:

interface Ethernet0/1
ip address 12.1.2.3 255.255.255.0
ip nat outside
!
interface Ethernet0/0
ip address 192.168.101.1 255.255.255.0
ip nat inside
!
ip nat inside source list 101 interface Ethernet0/1 overload
ip nat inside source static tcp 192.168.101.2 80 interface Ethernet0/1 80
!
access-list 101 permit ip any any

In this example, the web server is located at 192.168.101.2 and instead of forwarding PPTP (port 1723) traffic, we're forwarding HTTP (port 80) traffic.

Obviously, you can configure your Cisco router in a similar manner to forward nearly any type of traffic from an outside interface to an internal host.