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Configuring Voice over IP for the
Cisco 3600 Series
This chapter shows you how to configure Voice over IP (VoIP) on the Cisco 3600 series. For a
description of the commands used to configure Voice over IP, refer to the "Voice-Related
Commands" chapter in the Voice, Video, and Home Applications Command Reference.
VoIP enables a Cisco 3600 series router to carry voice traffic (for example, telephone calls and faxes)
over an IP network. Voice over IP is primarily a software feature; however, to use this feature on a
Cisco 3600 series router, you must install a voice network module (VNM). The VNM can hold either
two or four voice interface cards (VICs), each of which is specific to a particular signaling type
associated with a voice port. For more information about the physical characteristics, installing or
configuring a VNM in your Cisco 3600 series router, refer to the Voice Network Module and Voice
Interface Card Configuration Note that came with your VNM.
Voice over IP offers the following benefits:
Toll bypass
Remote PBX presence over WANs
Unified voice/data trunking
POTS-Internet telephony gateways
How Voice over IP Processes a Telephone Call
Before configuring Voice over IP on your Cisco 3600 series router, it helps to understand what
happens at an application level when you place a call using Voice over IP. The general flow of a
two-party voice call using Voice over IP is as follows:
The user picks up the handset; this signals an off-hook condition to the signaling application part
1
of Voice over IP in the Cisco 3600 series router.
The session application part of Voice over IP issues a dial tone and waits for the user to dial a
2
telephone number.
The user dials the telephone number; those numbers are accumulated and stored by the session
3
application.
After enough digits are accumulated to match a configured destination pattern, the telephone
4
number is mapped to an IP host via the dial plan mapper. The IP host has a direct connection to
either the destination telephone number or a PBX that is responsible for completing the call to
the configured destination pattern.
Configuring Voice over IP for the Cisco 3600 Series VC-13

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   Summary of Contents for Cisco 3600 Series

  • Page 1

    Configuring Voice over IP for the Cisco 3600 Series This chapter shows you how to configure Voice over IP (VoIP) on the Cisco 3600 series. For a description of the commands used to configure Voice over IP, refer to the “Voice-Related Commands”...

  • Page 2: List Of Terms

    FXO—Foreign Exchange Office. An FXO interface connects to the PSTN’s central office and is the interface offered on a standard telephone. Cisco’s FXO interface is an RJ-11 connector that allows an analog connection to be directed at the PSTN’s central office. This interface is of value for off-premise extension applications.

  • Page 3

    IP network. VoIP peers point to specific VoIP devices. Prerequisite Tasks Before you can configure your Cisco 3600 series router to use Voice over IP, you must first: • Establish a working IP network. For more information about configuring IP, refer to the “IP Overview,”...

  • Page 4

    Voice over IP Configuration Task List Voice over IP Configuration Task List To configure Voice over IP on the Cisco 3600 series, you need to complete the following tasks: Configure IP Networks for Real-Time Voice Traffic Configure your IP network to support real-time voice traffic. Fine-tuning your network to adequately support VoIP involves a series of protocols and features geared toward Quality of Service (QoS).

  • Page 5

    (Optional) Voice over IP can be used with Microsoft NetMeeting (Version 2.x) when the Cisco 3600 series router is used as the voice gateway. Refer to the 'Configure Voice over IP for Microsoft NetMeeting” section for more information about configuring Voice over IP to support Microsoft NetMeeting.

  • Page 6

    The important thing to remember is that QoS must be configured throughout your network—not just on the Cisco 3600 series devices running VoIP—to improve voice network performance. Not all QoS techniques are appropriate for all network routers. Edge routers and backbone routers in your network do not necessarily perform the same operations;...

  • Page 7

    This is only applicable if you have not configured RSVP. The ip rtp reserve command can be used instead of configuring RSVP. If you configure Note RSVP, this command is not required. Configuring Voice over IP for the Cisco 3600 Series VC-19...

  • Page 8: Figure 4

    Configure IP Networks for Real-Time Voice Traffic For more information about Multilink PPP, refer to the “Configuring Media-Independent PPP and Multilink PPP” chapter in the Dial Solutions Configuration Guide. Multilink PPP Configuration Example The following example defines a virtual interface template that enables Multilink PPP with interleaving and a maximum real-time traffic delay of 20 milliseconds, and then applies that virtual template to the Multilink PPP bundle: interface virtual-template 1...

  • Page 9

    25 For more information about RTP header compression, see the “Configuring IP Multicast Routing” chapter of the Network Protocols Configuration Guide, Part 1. Configuring Voice over IP for the Cisco 3600 Series VC-21...

  • Page 10

    Real-time voice traffic is carried on UDP ports ranging from 16384 to 16624. This number is derived from the following formula: 16384 = 4(number of voice ports in the Cisco 3600 series router) Custom Queuing and other methods for identifying high priority streams should be configured for these port ranges.

  • Page 11

    We recommend FRF.12 fragmentation setup rules for Voice over IP connections over Frame Note Relay. FRF.12 was implemented in the Cisco IOS Release 12.0(4)T. For more information, refer to the Cisco IOS Release 12.0(4)T “Voice over Frame Relay using FRF.11 and FRF.12” feature module.

  • Page 12

    Configure Number Expansion • Fair-queuing is enabled. • IP RTP header compression is enabled. The subinterface has been configured as follows: • MTU size is inherited from the main interface. • IP address for the subinterface is specified. • Bandwidth is set to 64 kbps. •...

  • Page 13

    After you have configured dial peers and assigned destination patterns to them, you can verify number expansion information by using the show dialplan number command to see how a telephone number maps to a dial peer. Configuring Voice over IP for the Cisco 3600 Series VC-25...

  • Page 14: Source

    Configure Dial Peers Configure Dial Peers The key point to understanding how Voice over IP functions is to understand dial peers. Each dial peer defines the characteristics associated with a call leg, as shown in Figure 6 and Figure 7. A call leg is a discrete segment of a call connection that lies between two points in the connection.

  • Page 15: Table Of Contents

    For more information about stripping and adding digits, see the “Outbound Dialing on POTS Peers” section. Figure 9 shows how to complete the end-to-end call between dial peer 1 and dial peer 4. Configuring Voice over IP for the Cisco 3600 Series VC-27...

  • Page 16: Voice Port

    Configure Dial Peers Figure 9 Outgoing Calls from the Perspective of POTS Dial Peer 2 Destination Source IP cloud Dial peer 2 Dial peer 3 Dial peer 4 Dial peer 1 Voice port Voice port 10.1.2.2 1/0/0 1/0/0 10.1.1.2 (408) 555-4000 (310) 555-1000 POTS call leg VoIP call leg...

  • Page 17

    As shown in Figure 10, incoming means from the perspective of the router. In this case, it is the call leg coming into the access server to be forwarded through to the appropriate destination pattern. Configuring Voice over IP for the Cisco 3600 Series VC-29...

  • Page 18: Figure 10

    Configure Dial Peers Figure 10 Incoming and Outgoing POTS Call Legs Cisco 3600 Cisco 3600 cloud Incoming Outgoing call leg call leg Unless otherwise configured, when a call arrives on the access server, the server presents a dial tone to the caller and collects digits until it can identify the destination dial peer. After the dial peer has been identified, the call is forwarded through the next call leg to the destination.

  • Page 19: Dial Peer

    For additional VoIP dial-peer configuration options, refer to the “Voice-Related Commands” section of the Voice, Video, and Home Applications Command Reference. For examples of how to configure dial peers, refer to the section, “Voice over IP Configuration Examples.” Configuring Voice over IP for the Cisco 3600 Series VC-31...

  • Page 20: Router

    Optimize Dial Peer and Network Interface Configurations Validation Tips You can check the validity of your dial-peer configuration by performing the following tasks: • If you have relatively few dial peers configured, you can use the show dial-peer voice command to verify that the data configured is correct.

  • Page 21

    In this example, every time a connection is made through VoIP dial peer 108, an RSVP reservation request is made between the local router, all intermediate routers in the path, and the final destination router. Configuring Voice over IP for the Cisco 3600 Series VC-33...

  • Page 22

    Optimize Dial Peer and Network Interface Configurations To generate an SNMP trap message if the reserved QoS is less than the configured value for a selected VoIP peer, use the following commands, beginning in global configuration mode: Step Command Purpose dial-peer voice number voip Enter the dial-peer configuration mode to configure a VoIP peer.

  • Page 23

    Voice over IP simulates a trunk connection by creating virtual trunk tie lines between PBXs connected to Cisco 2600 and 3600 series routers on each side of a VoIP connection. (See Figure 11.) In this example, two PBXs are connected using a virtual trunk. PBX-A is connected to Router A via an E&M voice port;...

  • Page 24

    • Configure both end routers for trunk connections. • The connected Cisco routers must be Cisco 2600 or Cisco 3600 series routers. The Cisco AS5300 does not currently support trunk connections. Note Because virtual trunk connections do not support number expansion, the destination patterns on each side of the trunk connection must match exactly.

  • Page 25

    Configure Voice over IP for Microsoft NetMeeting Voice over IP can be used with Microsoft NetMeeting (Version 2.x) when the Cisco 3600 or Cisco 2600 series router is used as the voice gateway. Use the latest version of DirectX drivers from Microsoft on your PC to improve the voice quality of NetMeeting.

  • Page 26

    Step 2 Enter the telephone number in the Address field. Step 3 Click Call to initiate a call to the Cisco 3600 series router from Microsoft NetMeeting. Step 4 Voice over IP Configuration Examples The actual Voice over IP configuration procedure you complete depends on the actual topology of your voice network.

  • Page 27

    ! Configure RTP header compression ip rtp header-compression ip rtp compression-connections 25 ! Enable RSVP on this interface ip rsvp bandwidth 48 48 fair-queue 64 256 36 Configuring Voice over IP for the Cisco 3600 Series VC-39...

  • Page 28

    Voice over IP Configuration Examples clockrate 64000 router igrp 888 network 10.0.0.0 network 20.0.0.0 network 40.0.0.0 VC-40 Voice, Video, and Home Applications Configuration Guide...

  • Page 29

    20.0.0.2 255.0.0.0 ! Configure RTP header compression ip rtp header-compression ip rtp compression-connections 25 ! Enable RSVP on this interface ip rsvp bandwidth 96 96 fair-queue 64 256 3 clockrate 128000 Configuring Voice over IP for the Cisco 3600 Series VC-41...

  • Page 30

    Voice over IP Configuration Examples ! Configure IGRP router igrp 888 network 10.0.0.0 network 20.0.0.0 network 40.0.0.0 Configuration for Router RLB-2 hostname r1b-2 ! Create pots dial peer 2 dial-peer voice 2 pots ! Define its associated telephone number and voice port destination-pattern +4155554000 port 1/0/0 ! Create voip dial peer 20...

  • Page 31: Dial Peer

    555..port 1/0/1 !Configure voip dial peer 3 dial-peer voice 3 voip destination-pattern 119..session target ipv4:172.16.65.182 !Configure the E&M interface voice-port 1/0/0 signal immediate operation 4-wire type 2 Configuring Voice over IP for the Cisco 3600 Series VC-43...

  • Page 32

    Voice over IP Configuration Examples voice-port 1/0/1 signal immediate operation 4-wire type 2 !Configure the serial interface interface serial 0/0 description serial interface type dce (provides clock) clock rate 2000000 ip address 172.16.1.123 no shutdown Configuration for Router SLC hostname saltlake !Configure pots dial peer 1 dial-peer voice 1 pots destination-pattern 119..

  • Page 33

    ! Configure voip dial peer 2 dial-peer voice 2 voip destination-pattern 9... session target ipv4:172.16.65.182 ! Configure the serial interface interface serial 0/0 clock rate 2000000 ip address 172.16.1.123 no shutdown Configuring Voice over IP for the Cisco 3600 Series VC-45...

  • Page 34

    Voice over IP Configuration Examples Configuration for Router SLC ! Configure pots dial peer 1 dial-peer voice 1 pots destination-pattern 9... port 1/0/0 ! Configure voip dial peer 2 dial-peer voice 2 voip destination-pattern +14085554000 session target ipv4:172.16.1.123 ! Configure serial interface interface serial 0/0 ip address 172.16.65.182 no shutdown...

  • Page 35

    2 voip destination-pattern +14085554000 session target ipv4:172.16.1.123 ! Configure the voice-port voice-port 1/0/0 connection plar 14085554000 ! Configure the serial interface interface serial 0/0 ip address 172.16.65.182 no shutdown Configuring Voice over IP for the Cisco 3600 Series VC-47...

  • Page 36

    Voice over IP Configuration Examples VC-48 Voice, Video, and Home Applications Configuration Guide...

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