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 | Caution This chapter describes the Cisco MC3810 Voice over Frame Relay implementation for versions prior to Cisco IOS Release 12.0(4)T. The configuration procedures were updated in that release; for more information, see the 12.0(4)T online document Voice over Frame Relay Using FRF.11 and FRF.12, or the Cisco IOS 12.1 Multiservice Applications Configuration Guide. Additional configuration changes were made in Cisco IOS Release 12.1(2)T; for more information, see the 12.1(2)T online document Voice over Frame Relay Using FRF.11 and FRF.12 Configuration Updates. |
This chapter describes how to configure Voice over Frame Relay (VoFR) on the Cisco MC3810 multiservice access concentrator and includes the following sections:
VoFR enables a Cisco MC3810 concentrator to carry voice traffic (for example, telephone calls and faxes) over a Frame Relay network. VoFR on the Cisco MC3810 is supported on serial ports 0 and 1, as well as on the T1/E1 trunk.
This chapter describes the commands to specifically configure VoFR on the Cisco MC3810. It is assumed you have already configured your Frame Relay backbone network. As part of your Frame Relay configuration, you need to configure the map class, and the Local Management Interface (LMI) among other Frame Relay functionality. For more information about Frame Relay configuration, see the Wide Area Networking Configuration Guide.
You can perform any of these procedures, depending on your application.
Before configuring a Frame Relay data-link connection identifier (DLCI) for voice traffic, you can configure a Frame Relay map class to assign traffic shaping properties to a group of DLCIs. If you have a large number of permanent virtual circuits (PVCs) to configure, you can assign the PVCs the same traffic shaping properties without statically defining the values for each PVC.
Configuring a Frame Relay map class is optional. You can create multiple map classes, with different variables for each map class. If you want to skip this task, proceed to the next section.
To configure a Frame Relay map class for a group of DLCIs, complete the following steps from configuration mode:
| Step | Command | Purpose |
|---|---|---|
| 1 | router(config)# map-class frame-relay map-class-name | Create a map-class name you will assign to a group of PVCs. The map-class name must be unique. |
| 2 | router(config-map-class)# frame-relay bc out bits | Configure the outgoing committed burst size for this group of PVCs. Configure the bits value to a minimum of 1000 for voice traffic. Configure the committed burst size to match your carrier to prevent the carrier from discarding discard eligible (DE) bits on ingress. This command is required. |
| 3 | router(config-map-class)# frame-relay be out bits | Configure the outgoing excess burst size for this group of PVCs. Configure the outgoing excess burst size to match your carrier to prevent the carrier from discarding discard eligible (DE) bits on ingress. This command is required. |
| 4 | router(config-map-class)# frame-relay cir out bits | Configure the outgoing excess CIR for this group of PVCs. Configure the CIR size to match your carrier to prevent the carrier from discarding discard eligible (DE) bits on ingress. This command is required. |
| 5 | router(config-map-class)# frame-relay bc in bits | (Optional) Configure the incoming committed burst size for this group of PVCs. Note This command and the frame-relay be in and frame-relay cir in commands are not required because the Cisco MC3810 normally does not police incoming traffic. However, you can set these values to aggregate incoming traffic as needed. |
| 6 | router(config-map-class)# frame-relay be in bits | (Optional) Configure the incoming excess burst size for this group of PVCs. |
| 7 | router(config-map-class)# frame-relay cir in bits | (Optional) Configure the incoming CIR size for this group of PVCs. |
| 8 | router(config-map-class)# frame-relay adaptive-shaping becn | |
| 9 | router(config)# exit | Exit map-class configuration mode. |
Proceed to the next section.
When configuring a Frame Relay PVC to support voice traffic, you must ensure that the carrier can accommodate the traffic rate or profile transmitted on the PVC. If too much traffic is sent at once, the carrier may discard frames, which causes disruptions to real-time voice traffic. Or, the carrier may deal with traffic bursts by queuing up the bursts and delivering them at a metered rate. Excessive queuing also causes disruption to real-time voice traffic.
To compensate for this, it is recommended that you configure Frame Relay traffic shaping, and that you configure the traffic profile parameters specified with the map class. For more information on configuring the map class, see the previous section.
To configure a Frame Relay DLCI to support voice traffic, complete the following steps from configuration mode:
| Step | Command | Purpose |
|---|---|---|
| 1 | router(config)# controller {t1 | e1} number | If you will configure VoFR over the T1/E1 trunk (T1/E1 0), enter the controller configuration mode. If you will configure VoFR over serial port 0 or 1, proceed to step 5. The number should be 1 if the controller is for the interface to the local phone device or PBX (through the DVM). The number should be 0 for the interface to the WAN (through the MFT). |
| 2 | router(config-controller)# channel-group channel-no timeslots timeslot-list speed {56 | 64} | Configure the channel group number and the timeslot list for the controller. The channel group is a number from 0 to 23. The timeslot-list is a number from 1 to 24. The channel group number must be unique, and cannot be the same as a configured Channel Associated Signaling (CAS) group or voice group. |
| 3 | router(config-controller)# exit | Exit controller configuration mode. |
| 4 | router(config)# interface serial 0:x | If configuring VoFR over the T1/E1 trunk, enter interface configuration mode by specifying serial 0:x, where x is the channel group number you configured in the previous step. Note In Cisco IOS Release 11.3(1) MA, serial port 2 was a valid port number. Beginning with Release 12.0, serial 2 is not a valid designation on the Cisco MC3810. You must enter the channel group number.Proceed to step 6. |
| 5 | router(config)# interface serial number | If configuring VoFR over serial port 0 or 1, enter interface configuration mode and configure the serial interface. You can specify serial port 0 or 1 for traffic over the universal input/output (UIO) serial ports. |
| 6 | router(config-if)# encapsulation frame-relay | Set the encapsulation type to Frame Relay on the serial port. |
| 7 | router(config-if)# clock rate network rate | If configuring back-to-back Frame Relay, set the network clock rate in kbps for the data communications equipment (DCE) side on serial ports 0 and 1 only. The valid range is from 56-2048 kbps, and the value must be a multiple of the value set using the network-clock base-rate command. |
| 8 | router(config-if)# dce terminal-timing enable | If configuring back-to-back Frame Relay, configure the DCE port to use its own clock signal to prevent phase shifting of the data with respect to the clock. |
| 9 | router(config-if)# frame-relay traffic-shaping | If a Frame Relay map class was not configured and assigned to this DLCI, enable Frame Relay traffic shaping on the interface. Make sure to use Frame Relay traffic shaping only; do not use generic traffic shaping. Note Frame Relay traffic shaping should be enabled on the interface if sending voice and data traffic over a single Frame Relay PVC over a public Frame Relay network. If sending voice and data traffic over a back-to-back Frame Relay configuration, or on a private Frame Relay network, traffic shaping is not required. |
| 10 | router(config-if)# frame-relay interface-dlci dlci voice-encap size voice-cir CIR |
You must configure the voice encapsulation option to support voice traffic. Set the data segmentation size to match the line rate, or the port access rate. Configure the same data segmentation size value on both Cisco MC3810 concentrators on the voice connection. For more information about recommended data segmentation sizes, see Table 5-1. The voice-cir option is used to configure the voice CIR for the DLCI. The default is the CIR configured for the Frame Relay map class. Do not configure this option to be higher than the physical link speed. If Frame Relay traffic shaping is enabled for a PVC sharing voice and data, do not configure the voice-cir option to be higher than the value set with the frame-relay mincir command. When the voice-encap option is configured, all priority queuing, custom queuing, and weighted fair queuing is disabled on the interface. Note The voice encapsulation option applies only to the transmit DLCI side. This option sends the Frame Relay stream through a segmentation engine that is similar to FRF.12. |
| 11 | router(config-dlci)# class name | Associate the DLCI with a map class that you configured in the previous section. The traffic shaping properties associated with the map class will be assigned to the DLCI. |
| 12 | router(config-dlci)# exit | Exit DLCI configuration mode. |
| 13 | If the serial interface was configured for multipoint operation, repeat steps 10 through 12 for each subinterface. | |
| Access Rate | Recommended Data Segmentation Size1 |
|---|---|
64 kbps | 80 bytes |
128 kbps | 160 bytes |
256 kbps | 320 bytes |
512 kbps | 640 bytes |
1536 kbps (full T1) | 1600 bytes |
2048 kbps (full E1) | 1600 bytes |
| 1The data segmentation size is based on back-to-back Frame Relay. If sending traffic through an IGX with standard Frame Relay, subtract 6 bytes from the recommended data segmentation size. |
When configuring VoFR in back-to-back hard-wired configurations, make sure one side of the voice connection is configured as data communications equipment (DCE) and the other side is configured as data terminal equipment (DTE). The VoFR configuration must be performed on the Cisco MC3810 concentrators on both sides of the voice connection.
This completes the preliminary Frame Relay configuration to prepare for voice traffic. Proceed to the "Configuring Dial Peers" section. If you have questions or need assistance, see "Additional Documentation".
To configure switched Frame Relay to support voice traffic, complete the following steps in configuration mode:
| Step | Command | Purpose |
|---|---|---|
| 1 | router(config)# frame-relay switching | Enable PVC switching on the Cisco MC3810. |
| 2 | router(config-if)# frame-relay route in-dlci out-interface out-dlci [voice-encap size] | Configure the Frame Relay static route for PVC switching. If the Frame Relay DLCI will be used for voice traffic, specify the voice-encapsulation option and specify the data segmentation size. The range for the data segmentation size is from 8-1600. For recommended data segmentation sizes, see Table 5-1. |
This completes the preliminary Frame Relay switch configuration to support voice traffic. Proceed to the "Configuring Dial Peers" section. If you have questions or need assistance, see "Additional Documentation".
 | TimeSaver If possible, you might want to configure the Frame Relay dial peers in a back-to-back configuration before separating them across the Frame Relay network. Using a back-to-back configuration, you can test your VoFR and dial-peer configuration to see if you can successfully make a voice connection. Then, when you place both peers on the network, if you cannot make a voice connection, you can isolate the cause as a network problem. For an example of a back-to-back VoFR configuration, see the "Voice over Frame Relay Configuration Examples" section. |
After you have configured your Frame Relay network, you should collect all of the data directly related to each dial peer by creating a peer configuration table to prepare for configuring VoFR.
There is specific information relative to each dial peer that needs to be identified before you can configure VoFR. One way to do this is to create a peer configuration table.
Figure 5-1 shows a diagram of a small voice network in which Cisco MC3810 No. 1 connects a small sales branch office to the main office through Cisco MC3810 No. 2. There are only two devices in the sales branch office that need to be established as dial peers: a telephone and a fax machine. Cisco MC3810 No. 2 is the primary gateway to the main office; as such, it needs to be connected to the company's private branch exchange (PBX). There are two telephones and one fax machine connected to the PBX that need to be established as dial peers in the main office.
Table 5-2 shows the peer configuration table for the example illustrated in Figure 5-1.
| Dial Peer | Extension | Prefix | Destination Pattern | Type | Voice Port | Session Target |
|---|---|---|---|---|---|---|
| Cisco MC3810 No. 1 |
|
|
|
|
| |
1 | 61111 |
| 13107661111 | POTS | 1/1 |
|
2 | 62222 |
| 13107662222 | POTS | 1/2 |
|
10 |
|
| 1310767.... | VOFR |
| S0 150 |
| Cisco MC3810 No. 2 |
|
|
|
|
| |
11 |
|
| 1310766.... | VOFR |
| S0 150 |
3 | 73333 | 7 | 1310767.... | POTS | 1/1 |
|
4 | 74444 | 7 | 1310767.... | POTS | 1/1 |
|
5 | 75555 | 7 | 1310767.... | POTS | 1/1 |
|
The dial plan shown in Table 5-2 lists a simple dial-peer configuration table, with no special configuration for how you forward or playout excess digits. For more information on other options for designing your dial plan and configuring your dial peers to connect with PBXs, see "Voice Dial Plan Considerations."
There are two different kinds of dial peers:
POTS peers associate a telephone number with a particular voice port so that incoming calls for that port can be received. VoFR peers point to specific voice-network devices (by associating destination telephone numbers with a specific Frame Relay DLCI) so that outgoing calls can be placed. Both POTS and VoFR dial peers are needed to establish VoFR connections if you want to both send and receive calls.
For tandem voice nodes, POTS dial peers are not required.
Establishing two-way communication using VoFR requires establishing a specific voice connection between two defined endpoints. As shown in Figure 5-2, for outgoing calls (from the perspective of the voice-telephony dial peer 1), the voice-telephony dial peer establishes the source (the originating telephone number and voice port) of the call. The voice-network dial peer establishes the destination by associating the destination phone number with a specific Frame Relay DLCI.
In the example, the destination pattern 14085554000 string maps to a U.S. phone number 555-4000, with the digit 1 plus the area code (408) preceding the number. When configuring the destination pattern, set the dial string to match the local dial conventions.
To complete the two-way communications loop, you need to configure VoFR dial peer 4 as shown in Figure 5-3.
The only exception to this is when both POTS dial peers are connected to the same concentrator, as shown in Figure 5-4. In this circumstance, you would not need to configure a VoFR dial peer.
When configuring dial peers, you need to understand the relationship between the destination pattern and the session target. The destination pattern is the telephone number of the voice device attached to the voice port. The session target represents the route to a serial port on the peer Cisco MC3810 at the other end of the Frame Relay connection. Figure 5-5 and Figure 5-6 show the relationship between the destination pattern and the session target, as seen from the perspective of both Cisco MC3810 concentrators in a VoFR configuration.
The following sections describe how to configure POTS peers and VoFR peers.
Depending on your dial plan configuration, you may need to consider how to configure voice networks with variable-length dial plans, number expansion, excess digit playout, forward digits and default voice routes, or use hunt groups with dial-peer preferences. For more information on these topics, see "Voice Dial Plan Considerations."
To configure POTS dial peers, complete the following steps from configuration mode:
| Step | Command | Purpose |
|---|---|---|
| 1 | router(config)# dial-peer voice tag pots |
The tag value identifies the dial peer and must be unique on the Cisco MC3810. Do not duplicate a specific tag number. |
| 2 | router(config-dialpeer)# destination-pattern string | Configure the dial peer's destination pattern. The string is a series of digits that specify the E.164 or private dialing plan telephone number. Valid entries are the digits 0-9 and the letters A-D. The following special characters can be entered in the string:
The plus symbol (+) is not a valid character in the string. |
| 3 | router(config-dialpeer)# port slot/port | Associate this voice-telephony dial peer with a specific logical dial interface. Enter the slot/port number of the voice port connected to the POTS dial peer. |
When you configure the dial plan, you have different options for how the dial plan is designed. For more information about dial plan strategies, see "Voice Dial Plan Considerations."
To configure dial plan options, complete one or more of the following steps from dial-peer configuration mode:
| Step | Command | Purpose |
|---|---|---|
| 1 | router(config-dialpeer)# num-exp extension-number extension-string | (Optional) If using the number expansion feature, define how to expand an extension number into a particular destination pattern. |
| 2 | router(config-dialpeer)# forward-digits {num-digit | all | implicit} | (Optional) If using the forward-digits feature, configure the digit-forwarding method that will be used on the dial peer. The valid range for the number of digits forwarded (num-digit) is from 0-32. The default value is implicit, in which the exactly matched digits are not forwarded. Only digits matched by the wildcard pattern are forwarded. For more information about the forward-digits feature, see the "Forward Digits and Voice Default Routes" section. |
| 3 | router(config-dialpeer)# prefix string | (Optional) If the forward-digits feature was not configured in the last step, assign the dialed digits prefix for the dial peer. |
| 4 | router(config-dialpeer)# preference value |
For more information about hunt groups and preferences, see the "Hunt Groups and Preference Configuration" section. |
To configure the next POTS dial peer, exit dial-peer configuration mode by entering exit, and repeat the previous steps. To configure VoFR dial peers, see the next section "Configuring Voice over Frame Relay Dial Peers."
Depending on your dial plan configuration, you may need to consider how to configure voice networks with variable-length dial plans, number expansion, excess digit playout, forward digits and default voice routes, or use hunt groups with dial peer preferences. For more information on these topics, see "Voice Dial Plan Considerations."
To configure VoFR dial peers, complete the following steps from configuration mode:
| Step | Command | Purpose |
|---|---|---|
| 1 | router(config)# dial-peer voice tag vofr |
The tag value identifies the dial peer and must be unique on the Cisco MC3810. Do not duplicate a specific tag number. |
| 2 | router(config-dialpeer)# destination-pattern string | |
| 3 | router(config-dialpeer)# session target interface serial interface dlci | Configure the Frame Relay session target for the dial peer. |
| 4 | router(config-dialpeer)# preference value | (Optional) Configure a preference for the VoFR dial peer. The value is a number from 0 to 10 where the lower the number, the higher the preference. For more information about hunt groups and preferences, see the "Hunt Groups and Preference Configuration" section. |
| 5 | router(config-dialpeer)# alt-dial string | (Optional) Configure the alternate dial-out string when configuring on-net-to-off-net alternative dialing. |
To configure the next VoFR dial peer, exit dial-peer configuration mode by entering exit, and repeat the previous steps.
Verify that the voice connection is working by doing the following:
You can check the validity of your dial-peer and voice-port configuration by performing the following tasks:
If you are having trouble connecting a call, you can try to resolve the problem by performing the following tasks:
This section provides the following VoFR configuration examples:
Figure 5-7 shows a configuration example for two Cisco MC3810 concentrators configured back-to-back, with VoFR configured for both concentrators. This setup is useful to test your VoFR configuration locally to make sure voice connections can be made locally before configuring VoFR across a larger network. Following the figure are the commands required to configure the Cisco MC3810 concentrators in this example.
no service pad no service udp-small-servers no service tcp-small-servers hostname Frame-top frame-relay switching interface Ethernet0 ip address 10.1.10.1 255.0.0.0 interface Serial0 point-to-point ip address 12.0.0.3 255.0.0.0 encapsulation frame-relay no fair-queue clock rate network-clock 2000000 dce terminal-timing enable frame-relay class fr1 frame-relay map ip 12.0.0.1 231 broadcast frame-relay interface-dlci 231 voice-encap 1600 frame-relay intf-type dce map-class frame-relay fr1 frame-relay adaptive-shaping becn frame-relay cir 64000 frame-relay bc 1000
router rip redistribute connected network 12.0.0.0 voice-port 1/1 dial-peer voice 1 pots destination-pattern 10 port 1/1 dial-peer voice 101 vofr destination-pattern 2. session target Serial0 231 end
interface Ethernet0 ip address 10.1.20.1 255.0.0.0 router rip redistribute connected network 12.0.0.0 interface Serial0 point-to-point ip address 12.0.0.1 255.0.0.0 encapsulation frame-relay bandwidth 2000000 frame-relay class fr1 frame-relay map ip 12.0.0.3 231 broadcast frame-relay interface-dlci 231 voice-encap 1600 map-class frame-relay fr1 frame-relay adaptive-shaping becn frame-relay cir 64000 frame-relay bc 1000 voice-port 1/1 dial-peer voice 1 pots destination-pattern 20 port 1/1 dial-peer voice 101 vofr destination-pattern 1. session target Serial0 231 end
The following is a configuration example for a VoFR network, including configuration for voice ports and dial peers. Figure 5-8 shows the configuration for one Cisco MC3810 at a central site connected to two Cisco MC3810 concentrators at different remote sites across a Frame Relay network. Following the figure are the commands required to configure the Cisco MC3810 concentrators in this example.
The following is the configuration for the central site Cisco MC3810 concentrator:
hostname central controller T1 0 framing esf linecode b8zs channel-group 1 timeslots 1-24 speed 64 interface Ethernet0 ip address 172.22.124.66 255.255.255.0 interface Serial 0:1 multipoint ip address 223.223.224.229 255.255.255.0 encapsulation frame-relay no fair-queue frame-relay traffic-shaping frame-relay interface-dlci 100 voice-encap 80 class fr1 frame-relay interface-dlci 200 voice-encap 160 class fr2 router igrp 1 network 172.22.0.0 network 223.223.224.0 no ip classless map-class frame-relay fr1 frame-relay adaptive-shaping becn frame-relay cir 64000 frame-relay bc 1000 map-class frame-relay fr2 frame-relay adaptive-shaping becn frame-relay cir 128000 frame-relay bc 1000 line con 0 exec-timeout 0 0 line aux 0 line vty 0 voice-port 1/1 voice-port 1/2 voice-port 1/3 voice-port 1/4 voice-port 1/5 voice-port 1/6 dial-peer voice 1 pots destination-pattern 3488801 port 1/1 dial-peer voice 2 pots destination-pattern 3488802 port 1/2 dial-peer voice 3 pots destination-pattern 3488803 port 1/3 dial-peer voice 4 pots destination-pattern 3488804 port 1/4 dial-peer voice 5 pots destination-pattern 3488805 port 1/5 dial-peer voice 6 pots destination-pattern 3488806 port 1/6 dial-peer voice 338 vofr destination-pattern 338.... session target Serial0:1 100 dial-peer voice 358 vofr destination-pattern 358.... session target Serial0:1 200 end
The following is the configuration for the Cisco MC3810 concentrator at remote site 1:
hostname remote1 controller T1 0 framing esf linecode b8zs channel-group 2 timeslots 1 speed 64 interface Ethernet0 ip address 172.22.125.66 255.255.255.0 interface Serial 0:2 multipoint ip address 223.223.224.227 255.255.255.0 encapsulation frame-relay no fair-queue frame-relay traffic-shaping frame-relay interface-dlci 100 voice-encap 80 class fr1 router igrp 1 network 172.22.0.0 network 223.223.224.0 no ip classless map-class frame-relay fr1 frame-relay cir 64000 frame-relay bc 1000 frame-relay adaptive-shaping becn line con 0 exec-timeout 0 0 line aux 0 line vty 0
voice-port 1/1 voice-port 1/2 voice-port 1/3 voice-port 1/4 voice-port 1/5 voice-port 1/6 dial-peer voice 1 pots destination-pattern 3388801 port 1/1 dial-peer voice 2 pots destination-pattern 3388802 port 1/2 dial-peer voice 3 pots destination-pattern 3388803 port 1/3 dial-peer voice 4 pots destination-pattern 3388804 port 1/4 dial-peer voice 5 pots destination-pattern 3388805 port 1/5 dial-peer voice 6 pots destination-pattern 3388806 port 1/6 dial-peer voice 2000 vofr destination-pattern 358.... session target Serial0:2 100 dial-peer voice 2001 vofr destination-pattern 348.... session target Serial0:2 100
The following is the configuration for the Cisco MC3810 concentrator at remote site 2:
hostname remote2 interface Ethernet0 ip address 172.22.126.66 255.255.255.0 interface Serial1 multipoint ip address 223.223.224.226 255.255.255.0 encapsulation frame-relay no fair-queue frame-relay traffic-shaping frame-relay interface-dlci 200 voice-encap 160 class fr1 clock rate 128000
router igrp 1 network 172.22.0.0 network 223.223.224.0 no ip classless map-class frame-relay fr1 frame-relay cir 128000 frame-relay bc 1000 frame-relay adaptive-shaping becn line con 0 exec-timeout 0 0 line aux 0 line vty 0 voice-port 1/1 voice-port 1/2 voice-port 1/3 voice-port 1/4 voice-port 1/5 voice-port 1/6 dial-peer voice 1 pots destination-pattern 3588801 port 1/1 dial-peer voice 2 pots destination-pattern 3588802 port 1/2 dial-peer voice 3 pots destination-pattern 3588803 port 1/3 dial-peer voice 4 pots destination-pattern 3588804 port 1/4 dial-peer voice 5 pots destination-pattern 3588805 port 1/5 dial-peer voice 6 pots destination-pattern 3588806 port 1/6 dial-peer voice 2000 vofr destination-pattern 348.... session target Serial1 200 dial-peer voice 2001 vofr destination-pattern 338.... session target Serial1 200 end
Posted: Mon Jun 12 18:34:47 PDT 2000
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