Versatile Interface Processor-Based Distributed FRF.12
Feature Overview, Configuration Tasks, and Configuration Examples
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Versatile Interface Processor-Based FRF.12

Table Of Contents

Versatile Interface Processor-Based FRF.12

Feature Overview

Benefits

Restrictions

Supported Platforms

Prerequisites

Supported MIBs, Standards, and RFCs

List of Terms and Acronyms

Functional Description

Cisco Switched Voice over Frame Relay

Dynamic Switched Calls

Cisco-Trunk (Private Line) Calls

Frame Relay Fragmentation

End-to-End FRF.12 Fragmentation

Frame Relay Fragmentation Using FRF.11 Annex C

Cisco Proprietary Voice Encapsulation

Frame Relay Fragmentation Conditions and Restrictions

Configuration Tasks

Preliminary Frame Relay Configuration for Voice

Configuring a Map Class to Support Voice over Frame Relay

Configure a Frame Relay Map Class to Support Voice Traffic (Required)

Configure a Frame Relay Map Class to Support FRF.12 Fragmentation (Required)

Configure a Service Policy for Traffic-Shaping Parameters for Use on a Map Class (Optional)

Creating a Service Policy for FRF.11 or FRF.12 (Optional)

Verifying Your Frame Relay Configuration

Configuration Examples

Two Routers Using Frame Relay Fragmentation

Tandem Configuration with Three Routers for Switched Calls

Tandem Configuration with a Cisco MC3810 Endpoint Node for Cisco-Trunk (Private Line) Calls


Versatile Interface Processor-Based FRF.12


Feature Overview

The Voice over Frame Relay (VoFR) capabilities that were introduced on the Cisco MC3810 Multiservice Access Concentrator beginning with Cisco IOS Release 11.3 were eventually extended to the Cisco 2600 series, 3600 series, and 7200 series router platforms. These capabilities are now available for Cisco 7500 series routers with a Versatile Interface Processor (VIP).

When VoFR is configured on a Cisco router, the router is able to carry voice traffic such as telephone calls and faxes over a Frame Relay network.

This document describes how to configure VoFR on the Cisco routers that support this feature. 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 elements of Frame Relay functionality. For more information about basic Frame Relay configuration, see the Wide-Area Networking Configuration Guide.

Benefits

The Cisco implementation of Voice over Frame Relay provides the following benefits to existing Frame Relay networks:

Enables real-time, delay-sensitive voice traffic to be carried over slow Frame Relay links

Allows dedicated 64-kbps time-division multiplexing (TDM) telephony circuits to be replaced by more economical Frame Relay permanent virtual circuits

Allows voice-enabled routers from multiple remote sites to be multiplexed into a central site router through Frame Relay links

Utilizes voice compression technology that conforms to ITU-T specifications

Enables Cisco 7500 series routers with a VIP to support Frame Relay fragmentation, allowing scalability across multiple VIPs.

Restrictions

The following restrictions and limitations apply to Voice over Frame Relay:

In order for VoFR on the Cisco 7500 series router with a VIP to interoperate with VoFR on the Cisco MC3810, the Cisco MC3810 must be running Cisco IOS Release 12.0(3)XG or 12.0(4)T or later.

Cisco 7500 series routers with a VIP cannot terminate calls initiated by a Cisco MC3810 using VoFR implementations prior to Cisco IOS Release 12.0(3)XG or 12.0(4)T.

It is currently not possible to translate from the VoIP transport protocol to other protocols such as VoFR. As a result, a call coming in on a VoIP connection might not be (tandem) switched to a VoFR connection.

Hookflash for dial tone recall from the router is not supported. However, the router can pass-through hookflash on FXO-FXS permanent connections using the connection trunk voice-port configuration command.

For Cisco 7500 series routers with a VIP, distributed Cisco Express Forwarding (dCEF) must be enabled to run Voice over Frame Relay using FRF.12.

When using the shape command, the cir value needs to be a multiple of 8000. The bc/cir and be/cir must be multiples of 4 ms.

A VIP with 128MB of memory can support up to 500 service policies. Cisco Systems can not guarantee support for possible problems caused by VIPs using more than 500 service policies at one time.

Supported Platforms

Cisco 7500 series routers with a VIP2-40 or higher

Cisco 7500 series routers with a VIP4

Prerequisites

Before you can configure a Cisco router to use Voice over Frame Relay, you must do the following:

Complete your company's dial plan.

Establish a working Frame Relay network. For more information about configuring Frame Relay, refer to the Cisco IOS Wide-Area Networking Configuration Guide.

Establish a working telephony network based on your company's dial plan:

Integrate your dial plan and telephony network into your existing Frame Relay network topology. Make routing or dialing transparent to the user—for example, avoid secondary dial tones from secondary switches, where possible.

Contact your PBX vendor for instructions about how to reconfigure the appropriate PBX interfaces.

After you have analyzed your dial plan and decided how to integrate it into your existing Frame Relay network, you are ready to configure your network devices to support Voice over Frame Relay.

Supported MIBs, Standards, and RFCs

Standards for FRF.12

Frame Relay Implementation Agreement - December 1997

List of Terms and Acronyms

ABCD signaling—4-bit telephony line signaling coding in which each letter of "ABCD" represents one of the 4 bits. This is often associated with channel-associated signalling (CAS) or robbed-bit signaling on a T1 or E1 telephony trunk.

ADPCM—Adaptive differential pulse code modulation. A process by which analog voice samples are encoded into high-quality digital signals.

Call leg—A logical connection between the router and either a telephony endpoint over a bearer channel, or another endpoint using a session protocol.

CELP—Code excited linear prediction. A compression algorithm used in low bit-rate voice encoding. CELP is used in ITU-T Recommendations G.728, G.729, and G.723.1.

CEPT—Conférence Européenne des Postes et des Télécommunications. Association of the 26 European PTTs that recommends communication specifications to the ITU-T.

CID—Channel ID. Designates the Frame Relay subchannel ID for Voice over Frame Relay.

CIR—Committed information rate. The average rate of information transfer a subscriber (for example, a network administrator) has stipulated for a Frame Relay PVC.

Cisco-trunk (private line) call—A Cisco-trunk (private line) call is established by the forced connection of a dynamic switched call. A Cisco-trunk call is established during configuration of the trunk and stays up for the duration of the configuration. It optionally provides a pass-through connection path to pass signaling information between the two telephony interfaces at either end of the connection.

codec—Coder-decoder. (i) An integrated circuit device that typically uses pulse code modulation to transform analog signals into a digital bit stream and digital signals back into analog signals. (ii) In Voice over IP, Voice over Frame Relay, and Voice over ATM, a DSP software algorithm used to compress or decompress speech or audio signals.

CS-ACELP—Conjugate structure algebraic code excited linear prediction. A CELP voice compression algorithm specified in ITU-T Recommendation G.729, providing 8 kbps, or 8:1 compression.

DLCI—Data-link connection identifier. Value that specifies a PVC or SVC in a Frame Relay network. In the basic Frame Relay specification, DLCIs are locally significant (connected devices might use different values to specify the same connection). In the LMI extended specification, DLCIs are globally significant (DLCIs specify individual end devices).

Dial peer—An addressable call endpoint that contains configuration information, including voice protocol, codec type, and telephone number associated with the call endpoint. There are five kinds of dial peers: POTS, VoIP, VoFR, VoATM, and VoHDLC.

DS0—A 64-kbps B channel on an E1 or T1 WAN interface.

DTMF—Dual tone multifrequency. Use of two simultaneous voice-band tones for dial (such as touch tone).

DTMF relay—Enables the generation of FRF.11 Annex A frames for a VoFR dial peer. The DSP generates Annex A frames instead of passing a DTMF tone through the network as a voice sample.

Dynamic switched call—A telephone call dynamically established across a packet data network based on a dialed telephone number. In the case of VoFR, a Cisco proprietary session protocol similar to Q.931 is used to achieve call switching and negotiation between calling endpoints. The proprietary session protocol runs over FRF.11-compliant subchannels.

E&M—Stands for recEive and transMit (or Ear and Mouth). E&M is a trunking arrangement generally used for two-way switch-to-switch or switch-to-network connections. The Cisco analog E&M interface is an RJ-48 connector that allows connections to PBX trunk lines (tie lines). E&M is also available on E1 and T1 digital interfaces.

FIFO—First-in, first-out. In data communication, FIFO refers to a buffering scheme in which the first byte of data entering the buffer is the first byte retrieved by the CPU. In telephony, FIFO refers to a queuing scheme in which the first calls received are the first calls processed.

FRF—Frame Relay Forum. An association of corporate members consisting of vendors, carriers, users, and consultants committed to the implementation of Frame Relay in accordance with national and international standards. Refer to the web site http://www.frforum.com.

FRF.11—Frame Relay Forum implementation agreement for Voice over Frame Relay (v1.0 May 1997). This specification defines multiplexed data, voice, fax, DTMF digit-relay, and CAS/robbed-bit signaling frame formats, but does not include call setup, routing, or administration facilities. Refer to the website http://www.frforum.com.

FRF.11 Annex C—See FRF.12.

FRF11-trunk—A point-to-point permanent voice connection (private line) conforming to the FRF.11 specification.

FRF.12—The FRF.12 Implementation Agreement (also known as FRF.11 Annex C) was developed to allow long data frames to be fragmented into smaller pieces and interleaved with real-time frames. In this way, real-time voice and non-real-time data frames can be carried together on lower-speed links without causing excessive delay to the real-time traffic. Refer to the web site http://www.frforum.com.

FXO—Foreign Exchange Office. An FXO interface connects to the Public Switched Telephone Network's (PSTN) central office and is the interface offered on a standard telephone. The Cisco FXO interface is an RJ-11 connector that allows an analog connection to be directed at the PSTN central office or to a station interface on a PBX.

FXS—Foreign Exchange Station. An FXS interface connects directly to a standard telephone and supplies ring, voltage, and dial tone. The Cisco FXS interface is an RJ-11 connector that allows connections to basic telephone service equipment, keysets, and PBXs.

G.711—Describes the 64-kbps PCM voice coding technique. In G.711, encoded voice is already in the correct format for digital voice delivery in the PSTN or through PBXs. Described in the ITU-T standard in its G-series recommendations.

G.723.1—Describes a compression technique that can be used for compressing speech or audio signal components at a very low bit rate as part of the H.324 family of standards. This codec has two bit rates associated with it: 5.3 and 6.3 kbps. The higher bit rate is based on ML-MLQ technology and provides a somewhat higher quality of sound. The lower bit rate is based on CELP and provides system designers with additional flexibility. Described in the ITU-T standard in its G-series recommendations.

G.726—Describes ADPCM coding at 40, 32, 24, and 16 kbps. ADPCM-encoded voice can be interchanged between packet voice, PSTN, and PBX networks if the PBX networks are configured to support ADPCM. Described in the ITU-T standard in its G-series recommendations.

G.728—Describes a 16-kbps low-delay variation of CELP voice compression. CELP voice coding must be translated into a public telephony format for delivery to or through the PSTN. Described in the ITU-T standard in its G-series recommendations.

G.729—Describes CELP compression where voice is coded into 8-kbps streams. Two variations of this standard (G.729 and G.729 Annex A) that differ mainly in computational complexity; both provide speech quality similar to 32-kbps ADPCM. Described in the ITU-T standard in its G-series recommendations.

hookflash—A short on-hook period usually generated by a telephone-like device during a call to indicate that the telephone wishes to perform dial-tone recall from a PBX. Hookflash is often used to perform call transfer.

LD-CELP—Low-delay CELP. A CELP voice compression algorithm specified in ITU-T Recommendation G.728, providing 16 kbps, or 4:1 compression.

MEL CAS—Mercury Exchange Limited (MEL) channel associated signaling. A voice signaling protocol used primarily in the United Kingdom.

OOS—Out-of-Service signaling.

PBX—Private branch exchange. Privately owned central switching office.

Permanent calls—Permanent calls are private line calls used for fixed point-to-point calls, connections between PBXs (E&M to E&M), or for remote telephone extensions (FXO to FXS).

PLAR—Private line, automatic ringdown. A leased voice circuit that connects two single endpoints together. When either telephone handset is taken off-hook, the remote telephone automatically rings.

POTS—Plain old telephone service. Basic telephone service supplying standard single line telephones, telephone lines, and access to the PSTN.

POTS dial peer—Dial peer connected through a traditional telephony network. POTS peers point to a particular voice port on a voice network device.

PSTN—Public Switched Telephone Network. PSTN refers to the local telephone company.

PVC—Permanent virtual circuit.

SVC—Switched virtual circuit.

Switched calls—Switched calls are normal telephone calls in which a user picks up a telephone, hears dial tone and enters the destination telephone number to reach the other telephone. Switched calls can also be private line auto-ringdown (PLAR) calls, or tie-line calls for fixed E&M to E&M fixed point-to-point connections.

Tandem switching—The dynamic switching of voice calls between VoFR, VoATM, or VoHDLC PVCs and subchannels; also called tandeming. Tandem switching is often encountered in multihop VoFR call connection paths.

Trunk—Service that allows quasi-transparent connections between two PBXs, a PBX and a local extension, or some other combination of telephony interfaces with signaling passed transparently through the packet data network.

UIO—Universal I/O serial port (Cisco router).

VAD—Voice activity detection. When VAD is enabled on voice port or a dial peer, silence is not transmitted over the network, only audible speech. When VAD is enabled, the sound quality is slightly degraded but the connection monopolizes much less bandwidth.

VoFR—Voice over Frame Relay.

VoFR dial peer—Dial peer connected through a Frame Relay network. VoFR peers point to specific VoFR devices.

Voice over Frame Relay—Voice over Frame Relay enables a router to carry voice traffic (for example, telephone calls and faxes) over a Frame Relay network. When voice traffic is sent over Frame Relay, the voice traffic is segmented and encapsulated for transit across the Frame Relay network using FRF.12 encapsulation.

Voice over IP—Voice over IP enables a router to carry voice traffic (for example, telephone calls and faxes) over an IP network. In Voice over IP, the DSP segments the voice signal into frames, which are then coupled in groups of two and stored in voice packets. These voice packets are transported using IP in compliance with ITU-T specification H.323.

VoIP—Voice over IP.

Functional Description

The Cisco VoFR implementation allows the following types of VoFR calls:

Switched VoFR calls:

Dynamic switched calls

Cisco-trunk (private line) calls

This section describes the setup of Cisco VoFR calls. In addition, the following functionality is described:

FRF.12-based end-to-end fragmentation under Frame Relay

Permanent trunks over dynamic switched calls

Tandem switching of calls from one VoFR dial peer to another VoFR dial peer

With dynamic switched calls, the VoFR system includes dial-plan information that is used to process and route the calls based on the telephone numbers dialed by the callers. The dial-plan information is contained within dial-peer entries.

Cisco Switched Voice over Frame Relay

A tandem node is an intermediate router node within the Frame Relay call path. Its purpose is to switch the frames from one PVC subchannel to another (from one VoFR dial peer onto another VoFR dial peer) as the frames traverse the network. Use of tandem router nodes also avoids the need to have complete dial-plan information present on every router.

Dynamic Switched Calls

Dynamic switched calls are regular telephone calls in which the dial-plan-based call switching is performed by the Cisco router. The destination endpoint of the call is selected by the router based on the telephone number dialed and the dial-plan information contained in the dial-peer configuration entries. Contrast this implementation with permanent calls (Cisco-trunk calls), where the call endpoints are permanently fixed at configuration time.

The dial peer is configured using the session protocol cisco-switched dial-peer configuration command, which uses the Cisco proprietary session protocol.

Cisco-Trunk (Private Line) Calls

A Cisco-trunk (private line) call is basically a normal dynamic switched call of indefinite duration that uses a fixed destination telephone number and includes optional transparent end-to-end signaling. The telephone number of the destination endpoint is permanently configured into the router so that it always selects a fixed destination. Once established, either at bootup or when configured, the call stays up until one of the voice ports or network ports is shut down, or until a network disruption occurs.

The connection trunk voice-port command is used to establish a Cisco-trunk call; the dial peer is configured using the session protocol cisco-switched command, which invokes the Cisco proprietary session protocol.

Cisco 7500 series routers with a VIP can only be used for tandem switching. Cisco 7500 series routers can not be used as end nodes.

Frame Relay Fragmentation

Cisco has developed the following three methods of performing Frame Relay fragmentation:

End-to-End FRF.12 Fragmentation

Frame Relay Fragmentation Using FRF.11 Annex C

Cisco Proprietary Voice Encapsulation

These Frame Relay fragmentation methods are briefly described in the following sections.

Frame Relay fragmentation can be configured in conjunction with Voice over Frame Relay or independently of it.

End-to-End FRF.12 Fragmentation

FRF.12 fragmentation is defined by the FRF.12 Implementation Agreement. The FRF.12 Implementation Agreement was developed to allow long data frames to be fragmented into smaller pieces and interleaved with real-time frames. In this way, real-time voice and non-real-time data frames can be carried together on lower-speed links without causing excessive delay to the real-time traffic. As a result, FRF.12 is the recommended fragmentation to be used by VoIP.


Note VoIP packets should not be fragmented. However, VoIP packets can be interleaved with fragmented packets.
If some PVCs are carrying voice traffic, enable fragmentation on all PVCs. The fragmentation header is only included for frames that are greater than the fragment size configured.


The Cisco 7500 series routers with a VIP support end-to-end fragmentation on a per-PVC basis. Fragmentation is configured through a map class, which can apply to one or many PVCs, depending on how the class is applied.

Frame Relay Fragmentation Using FRF.11 Annex C

When Voice over Frame Relay (FRF.11) and fragmentation are both configured on a PVC, the Frame Relay fragments are transmitted in the FRF.11 Annex C format.

This fragmentation is used when FRF.11 voice traffic is transmitted on the PVC and it uses the FRF.11 Annex C format for data.

With FRF.11, all data packets contain fragmentation headers regardless of size. This form of fragmentation is not recommended for use with Voice over IP.

Cisco Proprietary Voice Encapsulation

Cisco proprietary voice fragmentation was implemented on earlier releases of the Cisco MC3810 Multiservice Access Concentrator. This fragmentation type is used on data packets on a PVC that is also used for voice traffic. When the vofr cisco command is configured on a DLCI and fragmentation is enabled on a map class, the Cisco 7500 series router with a VIP can interoperate with Cisco 2600 series, 3600 series, 7200 series, and other 7500 series routers as tandem nodes (but cannot perform call termination) with Cisco MC3810 concentrators running Cisco IOS releases earlier than 12.0(3)XG or 12.0(4)T.

On Cisco 7500 series routers, entering the vofr cisco command is the only method for configuring Cisco proprietary voice encapsulation.

Frame Relay Fragmentation Conditions and Restrictions

When Frame Relay fragmentation is configured, the following conditions and restrictions apply:

Hardware compression is not currently supported.

Voice over Frame Relay frames are never fragmented, regardless of size.

When FRF.12 fragmentation is used end-to-end, the voice packets do not include the FRF.12 header, provided the size of the voice packet is smaller than the fragment size configured. However, when FRF.11 Annex C or Cisco proprietary fragmentations are used, voice packets will include the fragmentation header.

If fragments arrive out of sequence, packets are dropped.


Note Fragmentation is performed after frames are removed from the weighted fair queue.


Configuration Tasks

This section describes how to configure VoFR, including the Cisco implementations for FRF.12. The following major tasks are covered and are divided into the following sections:

Configuration Tasks, page 1

Preliminary Frame Relay Configuration for Voice

This section specifically describes the commands to configure VoFR applications. It is assumed you have already configured your Frame Relay backbone network, including the map class and the LMI. For more information about Frame Relay configuration, see the Wide-Area Networking Configuration Guide.

Preliminary Frame Relay Configuration for Voice

This section describes preliminary Frame Relay configuration tasks that are necessary to support VoFR:

Configuring a Map Class to Support Voice over Frame Relay

Verifying Your Frame Relay Configuration

Configuring a Map Class to Support Voice over Frame Relay

Before configuring a Frame Relay DLCI for voice traffic, you must create a Frame Relay map class and configure it to support voice traffic. Configuring a Frame Relay map class is required because the voice bandwidth and fragmentation size attributes are configured on the map class. These attributes are required for sending voice traffic on the PVC.

This section is divided into the following procedures:

Configure a Frame Relay Map Class to Support Voice Traffic (Required)

Configure a Frame Relay Map Class to Support FRF.12 Fragmentation (Required)

A map class applies to a single DLCI or to a group of DLCIs, depending on how the class has been applied to the virtual circuit. If you have a large number of PVCs to configure, you can assign the PVCs the same traffic-shaping properties without statically defining the values for each PVC. You can create multiple map classes with different variables for each map class.

Configure a Frame Relay Map Class to Support Voice Traffic (Required)

To configure a Frame Relay map class to support voice traffic on a single DLCI or a group of DLCIs, use the following commands, beginning in global configuration mode:

 
Command
Purpose

Step 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.

Step 2 

router(config-map-class)# frame-relay voice bandwidth 
bps reserved

(FRF.11 only) Sets the bandwidth (in kpbs) reserved for voice traffic. This amount determines the number of voice calls allowed on the DLCIs associated with this map class. Set this value to no higher than the minimum CIR if you want to preserve voice quality when a burst is being transmitted. The valid range is from 8000 to 45,000,000 bps.

This command must be configured for voice calls to take place. The default for this command is 0, which disables all voice calls.

To configure the map class to support FRF.12 fragmentation, see the "Configure a Frame Relay Map Class to Support FRF.12 Fragmentation (Required)" section. To configure the map class to support traffic shaping if you want to send both voice traffic and data traffic on the same PVC, see the "Configure a Service Policy for Traffic-Shaping Parameters for Use on a Map Class (Optional)" section.

Configure a Frame Relay Map Class to Support FRF.12 Fragmentation (Required)

To configure the map class to support FRF.12 fragmentation, use the following command in map-class configuration mode:

router(config-map-class)# frame-relay fragment fragment_size

This command configures Frame Relay fragmentation for the map class. The fragment_size defines the payload size of a fragment, and excludes the Frame Relay headers and any Frame Relay fragmentation header. The valid range is from 16 to 1600 bytes, and the default is 53.

The fragment_size should be less than or equal to the MTU size.

Set the fragmentation size such that the largest data packet is not larger than the voice packets.

To configure the map class to support traffic shaping if you want to send both voice traffic and data traffic on the same PVC, see the next section, "Configure a Service Policy for Traffic-Shaping Parameters for Use on a Map Class (Optional)" section of this document.

Configure a Service Policy for Traffic-Shaping Parameters for Use on a Map Class (Optional)

When you configure 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 might discard frames, which causes disruptions to real-time voice traffic. The carrier might also 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 condition, traffic shaping is required if you are sending both voice traffic and data traffic over the same PVC.


Note When you configure the outgoing Excess Burst size, the Committed Burst size, and the committed information rate (CIR) values, obtain the appropriate values from your carrier. The values configured on the router must match those of the carrier. Traffic shaping is necessary to prevent your carrier from discarding Discard Eligible (DE) bits on ingress or to prevent excessive burst data from affecting voice quality.


Use the following commands to configure shaping parameters for Cisco 7500 routers with a VIP:

 
Command
Purpose

Step 1 

Router(config)# policy-map policy-name

Specifies the name of the service policy to be created.

Step 2 

Router(config-pmap)# class class-default

Specifies the name of the default class to configure. Although the default class is not required to configure traffic-shaping parameters, Cisco Systems highly recommends that you configure traffic shaping on the default class.

Step 3 

Router(config-pmap-c)# shape {average | peak} 
mean-rate [burst-size [excess-burst-size]]

Shapes traffic to the indicated bit rate according to the algorithm specified.

Step 4 

router(config-pmap-c)# exit

Exits policy map class configuration mode.

Step 5 

router(config-pmap)# exit

Exits policy map configuration mode.

Step 6 

router(config)# map-class frame-relay map-class-name

Creates a map-class name you will assign to a group of PVCs. The map-class name must be unique.

Step 7 

router(config-map-class)# service-policy output 
policy-map-name

Specifies the name of the service policy to be attached to the interface. In this particular example, the name of the service policy was specified in Step 1.

For additional information on the shape command, see the Distributed Traffic Shaping feature module on CCO.

If your shape configuration is complete, see the "Verifying Your Frame Relay Configuration" section. To begin your dial peer configuration, see Appendix section of this document.

Creating a Service Policy for FRF.11 or FRF.12 (Optional)

To create a service policy for FRF.11 or FRF.12, enter the following commands:

 
Command
Purpose

Step 1 

Router(config)# class-map class-name

Specifies the name of the traffic class to configure.

Step 2 

Router(config-cmap)# match match-criterion

Specifies the match criterion. IP precedence matching is the most commonly used match criterion for FRF.12. For FRF.11, the match protocol vofr command is the required match criterion.

Step 3 

Router(config-cmap)# exit

Exits class map configuration mode.

Step 4 

Router(config)# policy-map policy-name

Specifies the name of the service policy to configure.

Step 5 

Router(config-pmap)# class class-name

Specifies the name of a predefined class, which was defined with the class-map command, included in the service policy. In this example, the class-name was defined in Step 1.

Step 6 

Router(config-pmap-c)# priority bandwidth

Reserves a priority queue for CBWFQ traffic.

For information on the priority command, see the Low Latency Queueing for the Versatile Interface Processor document on CCO.

Step 7 

Router(config-pmap-c)# exit

Exits policy map class configuration mode.

Step 8 

Router(config-pmap)# exit

Exits policy map configuration mode.

Step 9 

Router(config)# policy-map policy-name

Specifies the name of the service policy to configure.

Step 10 

Router(config-pmap)# class class-name

Specifies the name of a predefined class, which was defined with the class-map command, included in the service policy.
In this example, the class-name was defined in step 1.

Step 11 

Router(config-pmap-c)# shape {average | peak}

mean-rate [burst-size [excess-burst-size]]

Shapes traffic to the indicated bit rate according to the algorithm specified.

Step 12 

Router(config-pmap-c)# service-policy

policy-name

Specifies the name of a previously configured service policy to use in the new service policy. For purposes of FRF.11 and FRF.12, the policy-name is specified in Step 10.

Step 13 

Router(config-pmap-c)# exit

Exits policy map class configuration mode.

Step 14 

Router(config-pmap)# exit

Exits policy map configuration mode.

Step 15 

router(config)# map-class frame-relay map-class-name

Creates a map class name you will assign to a group of PVCs. The map class name must be unique.

Step 16 

Router(map-class)#  service-policy [ input | output] policy-map-name

Specifies the name of the service policy to be attached to the interface.

Verifying Your Frame Relay Configuration

You can check the validity of your Frame Relay configuration by performing the following tasks:

To show the status of your PVCs, use the show frame-relay pvc command.

To show statistics and information on the open subchannels, use the show frame-relay vofr [[interface] [dlci[cid]] command.

To show the Frame Relay fragmentation configuration, use the show frame-relay fragment [interface number [dlci]] command.

If you are using Frame Relay traffic shaping, use the show policy-map interface command to display the traffic-shaping information.

Configuration Examples

This section provides specific configuration examples for different VoFR connections and call type scenarios. This section includes the following examples:

Two Routers Using Frame Relay Fragmentation

Tandem Configuration with Three Routers for Switched Calls


Note In the examples, some commands are shown with a boldface lowercase letter. These letters indicate command settings that must match on the different routers. For example, the frame-relay cir s value indicates that the committed information rate "s" must match on the routers as shown.


The examples do not provide complete configurations, but show the required commands to configure Voice over Frame Relay.

Two Routers Using Frame Relay Fragmentation

Figure 1 shows an example of Frame Relay fragmentation between two routers. This configuration uses FRF.12 fragmentation.

Figure 1 Two Routers Using Frame Relay Fragmentation

Router A (Cisco 3600)
Router B (Cisco 7500)
interface serial 0/0
interface serial 0/0/0
  encapsulation frame-relay
  encapsulation frame-relay
  frame-relay traffic shaping



interface serial 0/0.1 point-to-point
interface serial 0/0/0.1 point-to-point
frame-relay interface-dlci 100
frame-relay interface-dlci 100
  class frf12-class
class frf12-class


map-class frame-relay frf12-class
map-class frame-relay frf12-class
  frame-relay fragment y
frame-relay fragment y
  frame-relay cir s
service-policy output llq-shape 
  frame-relay bc u



Note The examples in this document assume that a map-class called frf12-class was previously configured.
The service-policy output llq-shape command used on the Cisco 7500 series router in the above example assumes that the service policy called llq-shape was configured using low latency queuing and distributed traffic shaping. For information on low latency queueing on the VIP, see the Low Latency Queueing for the VIP feature module on CCO. For information on distributed traffic shaping, see the Distributed Traffic Shaping feature module on CCO.
The Configuration Examples section of this document assumes that the frf12-class map-class and the llq-shape service policy were previously configured.


Tandem Configuration with Three Routers for Switched Calls

Figure 2 shows an example of a tandem configuration with a Cisco 3600 as one endpoint and a Cisco MC3810 as another endpoint. The Cisco 7500 series router with a VIP as a tandem node.

Figure 2 Tandem Configuration with Three Routers for Switched Calls

Router A (Cisco 3600) Endpoint
Router C (Cisco 7500)
Router B (Cisco MC3810) Endpoint
interface serial 0/0
interface serial 1/0/0
interface serial 0/1
  encapsulation frame-relay
  encapsulation 
frame-relay
  encapsulation frame-relay
  frame-relay traffic-shaping
interface serial 1/0/0.1 
point-to-point
  frame-relay traffic-shaping
  frame-relay interface-dlci 100
  frame-relay 
interface-dlci 100
  frame-relay interface-dlci 
200
  vofr data 4 call 5
  vofr data 4 call 5
  vofr cisco
  class voice
  class voice
  class voice







interface serial 1/0/0.2 
point-to-point


frame-relay 
interface-dlci 200


vofr cisco


class voice




map-class frame-relay voice
map-class frame-relay 
voice
map-class frame-relay voice
  frame-relay fragment d
frame-relay fragment d
  frame-relay fragment d
  frame-relay voice bandwidth c
  frame-relay voice 
bandwidth c
  frame-relay voice bandwidth 
c
  frame-relay cir a
service-policy output 
llq-shape
  frame-relay cir a
  frame-relay min-cir t

  frame-relay min-cir t
  frame-relay bc b

  frame-relay bc b



dial-peer voice 1 pots
dial-peer voice 1 vofr
dial-peer voice 1 vofr
  destination-pattern 1001
  destination-pattern 
1001
  destination-pattern 1001
  port 1/0/0
  session target 
serial 1/0/0 200
  session target serial 0/1 
200



dial-peer voice 2 vofr
dial-peer voice 2 vofr
dial-peer voice 2 pots
  destination-pattern 2001
  destination-pattern 
2001
  destination-pattern 2001
  session target serial 0/0 100
session target serial 
1/0/0 200
port 1/0/0



voice-port 1/0/0

voice-port 1/0/0


Note The service-policy output llq-shape command used on the Cisco 7500 series router in the above example assumes that the service policy called llq-shape was configured using low latency queuing and distributed traffic shaping. For information on low latency queueing on the VIP, see the Low Latency Queueing for the VIP feature module on CCO. For information on distributed traffic shaping, see the Distributed Traffic Shaping feature module on CCO.
The Configuration Examples section of this document assumes that the frf-11 map-class and the llq-shape service policy were previously configured.


Tandem Configuration with a Cisco MC3810 Endpoint Node for Cisco-Trunk (Private Line) Calls

Figure 3 shows an example of a tandem configuration with a Cisco MC3810 acting as an endpoint node for Cisco-trunk (private line) calls.


Note When a Cisco MC3810 is on a VoFR network, the configuration for connections to and from the Cisco MC3810 is slightly different from that of other routers that support VoFR. The vofr cisco command is required for those connections.


Figure 3 Tandem Configuration with a Cisco MC3810 Endpoint Node for Permanent Switched Call

Router A (Cisco 3600) Endpoint
Router C (Cisco 7500)
Router B (Cisco MC3810) Endpoint
interface serial 0/0
interface serial 1/0/0
interface serial 0/1
  encapsulation frame-relay
  encapsulation frame-relay
  encapsulation frame-relay
  frame-relay traffic-shaping
interface serial 1/0/0.1 
point-to-point
  frame-relay traffic-shaping
  frame-relay interface-dlci 
100
  frame-relay 
interface-dlci 100
  frame-relay interface-dlci 200
  vofr data 4 call 5
  vofr data 4 call 5
  vofr cisco
  class voice
  class voice
  class voice







interface serial 1/0/0.2 
point-to-point


frame-relay interface-dlci 
200


vofr cisco


class voice




map-class frame-relay voice
map-class frame-relay voice
map-class frame-relay voice
  frame-relay fragment d
frame-relay fragment d
  frame-relay fragment d
  frame-relay voice bandwidth 
c
  frame-relay voice 
bandwidth c
  frame-relay voice bandwidth c
  frame-relay cir a
service-policy output 
llq-shape
  frame-relay cir a
  frame-relay min-cir t

  frame-relay min-cir t
  frame-relay bc b

  frame-relay bc b



dial-peer voice 1 pots
dial-peer voice 1 vofr
dial-peer voice 1 vofr
  destination-pattern 1001
  destination-pattern 1001
  destination-pattern 1001
  port 1/0/0
  session target 
serial 1/0/0 200
  session target serial 0/1 200



dial-peer voice 2 vofr
dial-peer voice 2 vofr
dial-peer voice 2 pots
  destination-pattern 2001
  destination-pattern 2001
  destination-pattern 2001
  session target serial 0/0 
100
session target serial 1/0/0 
200
port 1/0/0



voice-port 1/0/0

voice-port 1/1
connection trunk 2001A 
answer-mode

connection trunk 1001A


Note The service-policy output llq-shape command used on the Cisco 7500 series router in the above example assumes that the service policy called llq-shape was configured using low latency queuing and distributed traffic shaping. For information on low latency queueing on the VIP, see the Low Latency Queueing for the VIP feature module on CCO. For information on distributed traffic shaping, see the Distributed Traffic Shaping feature module on CCO.
The Configuration Examples section of this document assumes that the frf-12 map-class and the llq-shape service policy were previously configured.