Download Voice Over IP

Integrating Voice with Data
Over a Leased Line
Quick Start Guide
Wael Yousif @
Valencia Community College
1
Major Configuration Tasks
Step 1 Configure your IP network to support real-time voice traffic.
Before you move to the next step, ping the remote router to make
sure you have an IP connection.
Step 2 Configure your router to support voice ports: Foreign exchange
station (FXS). The default voice-port values are usually adequate
for FXS
Step 3 Enter configuration mode to configure your router for VoIP
traffic.
Step 4 Save the configuration.
Step 5 Establish a dial plan to determine how the call can be routed.
Use the dial-peer voice command to define dial peers and to
implement the dial plan.
Step 6 Fine-tune your network to adequately support VoIP by
configuring a series of protocols and features for quality of service
(QoS).
2
Voice and data on IP Networks
How to configure Cisco modular routers to carry
voice traffic such as telephone calls and faxes
over an IP network
3
Installing Voice Network Modules
•Two-Slot Voice Network Module
•Convert telephone voice signals into a from that can be transmitted over
an IP network
4
Installing Voice Network Modules
5
Voice Interface Cards
• There are three types of VICs:
– An FXS (Foreign Exchange
Station): Connects to
standard Phone or Fax
Machine.
– An FXO (Foreign Exchange
Office): Connects local calls
to a PSTN Central Office.
– E&M (Ear and Mouth):
Connects remote Calls from
an IP network to a PBX for
local Distribution
6
Connecting Voice Interface Cards
to the Network
RJ11
RJ11
RJ48S
7
Connecting a Voice Gateway to a
PBX Using E&M
• An Ear and Mouth (E&M) interface is used to support tieline facilities or signals between telephone switches. The
E&M voice interface card (VIC) is mostly used to
integrate VoIP with the legacy voice solution, connecting
the Cisco router to a PBX.
8
Voice Port Numbering
Example:
Suppose you install a two-slot voice network module in the upper right slot of a Cisco
3640 router, and install two VICs in the module. Each VIC has two ports. From right
to left, these ports would be numbered 2/0/0, 2/0/1, 2/1/0, and 2/1/1.
9
Configuring FXS Interfaces (West)
Local Dial Peers:
•Associating a telephone number to a voice port
•For instance, if a call comes in for 408 555-3737, the router needs to know that
this phone is connected to FXS VIC 2/0/0.
•Cisco IOS uses objects called dial peers to accomplish this task
•Configuring dial peers is similar to configuring static IP routes
•Dial peers are identified by numbers: 32-bit field
•Dial peer numbers are also known as dial peer tags
10
Configuring FXS Interfaces (West)
• This type of dial peer is called
POTS
• A POTS dial-peer associates a
physical voice port with a local
telephone device
• VoIP dial-peers will be
discussed later
• However, the dial-peer
command always takes the
argument voice
• Destination Pattern (dest-pat)
= telephone number, and
always begin with + sign
• A destination pattern can also
include other signs such as #,
or *. (coming up)
11
Configuring FXS Interfaces (East)
12
Configuring FXS Interfaces (East)
13
Checking the Configuration
• You should now be able to place calls
between telepnones connected to the
same router.
• Use the command: router# show dialpeer voice
– The above command verifies that the data
you configured is correct
14
Wild cards and Number Expansion
• Office PBXs are configured so a user can
dial a local call within the same PBX by
dialing the extension only
• For example dial five-digit extension
53737 instead of 1 408555-3737
• The same shortcut can be provided on a
VoIP network by using the numberexpansion command.
15
Wild cards and Number Expansion
• For instance, to expand 53737 into 408 5553737, enter the following command:
– West(config)# num-exp 53737 +4085553737
• Wild cards can also be used in number
expansion as follows:
– West(config)# num-exp 5…. +408555….
– The period (.) is used as a wild-card character
representing a single digit.
• Use the command: west# show num-exp to
verify your configuration.
• Now, you should be able to dial using the
extension number.
16
Calling between Routers
• West and East offices would like to send voice traffic over the same
IP network they use to send data traffic.
• IP routers know how to locate IP addresses on the network, but they
do not know how to locate telephone numbers.
• To route an outgoing voice call over this connection, the West router
has to associate a telephone number in the East office with the IP
address of the East router.
17
Remote Dial Peers/VoIP Dial Peers
• This goal is accomplished by configuring Voice
Over IP Dial Peers
• The term VoIP means that the dial peer
associates a telephone number with an IP
address.
• As opposed to POTS dial peers which
associates a physical voice port such as FXS
with a telephone number
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Remote Dial Peers/VoIP Dial Peers
Remote
Location
Phone #
Destination
Pattern
IP add
Dial Peer
Tag
East
919 958-8282
+19199588282 192.168.10.2
501
East
919 958-9595
+19199589595 192.168.10.2
502
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Remote Dial Peers with Wild Cards
Remote
Location
Phone #
Destination
Pattern
IP add
Dial Peer
Tag
East
919 958-xxxx
+1919958….
192.168.10.2
501
One Remote Dial Peer to reach all phones on the East Router
20
Even Better, Configure Number
Expansion
Remote
Location
Phone #
Destination
Pattern
IP add
Dial Peer
Tag
East
919 958-8282
+19199588282 192.168.10.2
501
East
919 958-9595
+19199589595 192.168.10.2
502
With Wild Cards
Remote
Location
Phone #
Destination
Pattern
IP add
Dial Peer
Tag
East
919 958-xxxx
+1919958….
192.168.10.2
501
West(config) # num-exp 8…. +1919958….
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Configuration Commands
1. Reset the router:
1. if your router displays this message: “would you like to enter the initial
configuration dialog? [ys]:” then it has already been reset. Just answer no and
move on to step 3.
2. If your router asks for a password try one of the following: conpass,
compass, cisco, or class (if configured, you have to enter a password for the
console and another to get to privileged mode)
1. West>enable
2. West#erase start
3. Westr#reload
3. Configure the serial interface with an IP address
1.
2.
3.
4.
5.
6.
7.
router> enable
Router# config t
Router(config) # hostname West
West(config) # int s0/0 (or S0/1, depending on where your cable is connected)
West(config-if) # i p address 192.168.10.1 255.255.255.0
West(config-if) # clock rate 56000 (if DCE)
West(config-if) # no shut
4. Save your config
1. West# copy run start
5. Verify that your interface is up:
1. West# show ip int brief
22
Configuration Commands
• Configure VoIP dial peers:
– West(config) # dial-peer voice 501 voip
– West(config-dial-peer) # dest-pat +1919958….
– West(config-dial-peer) # session-target ipv4:192.168.10.2
23
Apply the same config to East
router
Remote
Location
Phone #
Destination
Pattern
Phone #
Destination
Pattern
IP add
Dial Peer
Tag
West
West
Remote
Location
IP add
Dial Peer
Tag
East
West(config) # num-exp
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1.
Apply the same config to East
router
Reset the router:
1. if your router displays this message: “would you like to enter the initial
configuration dialog? [ys]:” then it has already been reset. Just answer no and
move on to step 3.
2. If your router asks for a password try one of the following: conpass,
compass, cisco, or class (if configured, you have to enter a password for the
console and another to get to privileged mode)
1. West>enable
2. West#erase start
3. Westr#reload
3. Configure the serial interface with an IP address
1.
2.
3.
4.
5.
6.
7.
router> enable
Router# config t
Router(config) # hostname West
West(config) # int s0/0 (or S0/1, depending on where your cable is connected)
West(config-if) # i p address _________________________
West(config-if) # clock rate 56000 (if DCE)
West(config-if) # no shut
4. Save your config
1. West# copy run start
5. Verify that your interface is up:
1. West# show ip int brief
2. Ping the remote Interface
25
Apply the same config to East
router
• West(config) # dial-peer voice
• West(config-dial-peer) # dest-pat
• West(config-dial-peer) # session-target ipv4:
26
Configuring the IP Network for
Real-Time Voice Traffic
• VoIP Commands require the IP Plus,
Desktop Plus, or Enterprise Plus image,
Cisco IOS Release 11.3(1)T or later
• Voice traffic is much more sensitive to
timing variations than data traffic
• You might need to configure your data
network so voice packets are not lost or
delayed
27
Configuring the IP Network for
Real-Time Voice Traffic
• Three important methods of improving
QoS (The level of network performance
needed for VoIP connections)
– Resource Reservation Protocol (RSVP)
– Multilink PPP Interleaving
– Real Time Transport Protocol header
compression (RTP header compression)
28
Do we Need QOS
PPP or HDLC Serial Links
Fast Ethernet
29
When to Use RSVP
• Serial links between
two routers using
HDLC or PPP
encapsulation (Such
as the case in leased
lines)
• Links Slower than 2
Mbps and with high
utilization
30
Requesting RSVP
• After configuring RSVP on the WAN interface as
we did back on slide 13,
• Configure each VoIP dial peer to request an
RSVP session, using the req-qos command:
– West(config) # dial-peer voice 501 voip
– West (config-dial-peer) # req-qos controlled-load
– Apply the same config to the VoIP dial peer at the East router
• Check and verify your configuration on both routers
using the command: west# show dial-peer voice
31
When to Use Multilink PPP
Interleaving?
• ISDN links BRI or PRI
• Links Slower than 2
Mbps
32
When to Use RTP Compression
• Can be combined with RSVP or with
Multilink PPP Interleaving
• Use when you are trying to save bandwidth
on slow serial links (less than 2 Mbps)
• Configuration:
– Router(config-if)# ip rtp header-compression
– Compression must be enabled at both ends of
the serial link.
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Converged Network Lab
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