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This section provides information that might be helpful for individual using the Voice over Frame Relay Using FRF.11 and FRF. 12 for the VIP feature. This Appendix includes the following sections:
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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. You can use a back-to-back configuration to test your VoFR and dial-peer configuration to determine if you can make a voice connection. Then, when you place both peers on the network, failure to make a voice connection will isolate the cause as a network problem. |
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.
Figure 1 shows a diagram of a small voice network in which router No. 1 connects a small sales branch office to the main office through router No. 2. Only two devices in the sales branch office that need to be established as dial peers: a telephone and a fax machine. Router No. 2 is the primary gateway to the main office; as such, it needs to be connected to the company's PBX. Two telephones and one fax machine connected to the PBX need to be established as dial peers in the main office.
Table 1 shows the peer configuration table for the example illustrated in Figure 1.
| Dial Peer | Extension | Prefix | Destination Pattern | Type | Voice Port | Session Target |
|---|---|---|---|---|---|---|
| Router No. 1 |
|
|
|
|
| |
1 | 61111 |
| 13107661111 | POTS | 1/0/0 |
|
2 | 62222 |
| 13107662222 | POTS | 1/0/1 |
|
10 |
|
| 1310767.... | VOFR |
| S0/0 150 |
| Router No. 2 |
|
|
|
|
| |
11 |
|
| 1310766.... | VOFR |
| S0/0 150 |
3 | 73333 | 7 | 1310767.... | POTS | 1/0/0 |
|
4 | 74444 | 7 | 1310767.... | POTS | 1/0/0 |
|
5 | 75555 | 7 | 1310767.... | POTS | 1/1 |
|
The dial plan shown in Table 1 lists a simple dial-peer configuration table. No configuration for forwarding digits to a PBX is shown. Additional configuration for this is required.
Two different kinds of dial peers pertain to VoFR configurations:
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 both to send and receive calls.
For tandem voice nodes, POTS dial peers are not configured.
Establishing two-way communication using VoFR requires establishing a specific voice connection between two defined endpoints. As shown in Figure 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 telephone number with a specific Frame Relay DLCI.
In the example, the destination pattern 14085554000 string maps to a U.S. telephone number 555-4000, with the digit 1 plus the area code (408) preceding the number. When you configure 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 3.
When you configure dial peers, ensure that you 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 router at the other end of the Frame Relay connection. Figure 4 and Figure 5 show the relationship between the destination pattern and the session target, as seen from the perspective of both routers in a VoFR configuration. These examples show a topology for switched calls only.
The following sections describe how to configure POTS peers and VoFR peers.
Depending on your dial plan configuration, you might 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 VoFR dial peer configuration procedures, refer to the following section:
Figure 6 shows an example of a Frame Relay network with switched calls. In the example, there are two routers (Routers No. 1 and No. 2) with telephone devices at the endpoints. In between the two endpoint routers are tandem routers (Routers A, B, and C) with switched connections in between. Standard VoFR dial peers are configured on the intermediate nodes in the Frame Relay network. Support for switched calls are configured on the dial peers on both Router No. 1 and Router No 2.
In this example, different types of VoFR dial peers have to be configured on the different routers.
VoFR dial peers for switched connections must be configured between Router No. 1 and Router No. 2 (the endpoints for the voice connection)
On the tandem routers (Routers A, B, and C) VoFR dial peers for switched calls must be configured for the following:
You configure standard VoFR dial peers for switched calls on the tandem routers in the network topology. Tandeming is not allowed when the call type is an FRF.11 trunk call.
You can configure VoFR dial peers for tandem routers on the Cisco MC3810 and on Cisco 7500 series routers.
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Note Cisco 7500 series routers with a VIP can serve as tandem nodes in the VoFR network. |
To configure VoFR dial peers on tandem routers, use the following commands from configuration mode:
| Command | Purpose | |
|---|---|---|
Step 1 | router(config)# dial-peer voice number vofr |
The number value tag identifies the dial peer and must be unique on the router. Do not duplicate a specific number tag. |
Step 2 | router(config-dialpeer)# destination-pattern | |
Step 3 | router(config-dialpeer)# session target interface dlci | Configure the Frame Relay session target for the dial peer. |
Step 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 in hunt groups. |
Step 5 | To configure the next VoFR dial peer, exit dial-peer configuration mode by entering exit, and repeat the previous steps. On tandem nodes, at least two VoFR dial peers are required, one for each call leg in the router. | |
After you have configured the Frame Relay DLCI settings and you have configured your dial plan, you are ready to configure specific VoFR connections.
There are many different scenarios for VoFR connections. For information on the different connection types, see the next section, "Overview of Voice over Frame Relay Connection Types."
For procedures on how to configure the different connection types, see the following sections:
In addition, special consideration is required for configuring calls for tandem nodes. For more information, see "Configuring Connections for Tandem Nodes" section.
When you configure VoFR connections, there are many different connection types possible depending on the hardware platform, whether the call is to be a regular switched (user dialed or auto-ringdown) call, or whether the call is a permanent call (Cisco-trunk or FRF.11-trunk). You configure these specific connection types using combinations of several commands.
This section only details Voice Over Frame Relay connection types that are currently available with Cisco 7500 series routers with a VIP. Table 2 lists the different connection types for VoFR connections supported on the Cisco 7500 series with a VIP, and the combinations of commands to enter for each call type.
| Type of Call | Frame Relay DLCI interface Command to Enter | Data Fragmentation Supported by vofr Command | Session Protocol Command to enter in dial peer mode |
|---|---|---|---|
Switched call | vofr [data cid] | FRF.11 Annex C | session protocol cisco-switched2
|
Switched call | vofr cisco3
| Cisco proprietary4 | session protocol cisco-switched |
Tandeming is the switching of an incoming VoFR call on a Frame Relay DLCI to an outgoing VoFR enabled DLCI. Tandeming works for switched calls and Cisco-trunk permanent calls only. You cannot tandem FRF.11 trunk calls over a multihop network.
Tandeming is supported on the Cisco 7500 series routers with a VIP. The Cisco 7500 series router with a VIP can only act as a tandem router in a VoFR network.
Depending on which router is used as the end node and which router is used as the tandem node, you must use the correct Frame Relay PVC type when configuring your connections. Table 3 shows the different combinations of routers that can serve as end nodes and tandem nodes, and the Frame Relay PVC type required.
| End Node(s) | Tandem Node | vofr Command to Enter for the Frame Relay DLCI |
|---|---|---|
Cisco 2600/3600 | Cisco 2600, Cisco 3600, Cisco 7200, or Cisco 7500 | vofr call-control |
Cisco 2600/3600 and Cisco MC3810 | Cisco MC3810 or Cisco 7500 | vofr cisco |
Cisco MC3810 | Cisco 2600, Cisco 3600, Cisco 7200, or Cisco 7500 | vofr cisco |
When you configure a tandem node, you must configure two VoFR dial peers, one for each tandem connection.
Verify that the voice connection for switched calls is working by doing the following:
Verify that the voice connection for FXO-FXS trunk calls from a telephone to a remote PBX 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:
Use the following commands to monitor and maintain your Voice over Frame Relay configuration:
| Command | Purpose |
|---|---|
| Displays the active call table. |
| Displays the call history table. |
| Displays configuration information and call statistics for dial peers. |
| Displays information about the Frame Relay fragmentation taking place in your Cisco router. |
| Displays statistics about PVCs for Frame Relay interfaces. |
| Displays information about the FRF.11 subchannels being used on VoFR DLCIs. |
| Displays information about a serial interface. |
| Displays information about the contents on a service policy. |
| Displays information about the permanent calls on a voice interface. |
Posted: Fri Jun 23 18:26:04 PDT 2000
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