Cisco MC3810 Multiservice Concentrator Configuration Guide
Configuring Frame Relay - ATM Interworking
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Table Of Contents

Configuring Frame Relay-ATM Interworking

Frame Relay-ATM Interworking Concepts

Configuring Frame Relay-ATM Interworking

Configuring Frame Relay-ATM Interworking for Voice

Frame Relay-ATM Interworking Configuration Examples

Frame Relay-ATM Interworking Example (Data Traffic Only)

Frame Relay-ATM Interworking Example (Data and Voice Traffic)


Configuring Frame Relay-ATM Interworking

The Cisco MC3810 multiservice access concentrator supports the FRF.5 Frame Relay-ATM Interworking function, which enables Frame Relay voice or data traffic to be encapsulated in Asynchronous Transfer Mode (ATM) cells. This chapter includes the following sections:

•Frame Relay-ATM Interworking Concepts

•Configuring Frame Relay-ATM Interworking

•Frame Relay-ATM Interworking Configuration Examples

Note The Cisco MC3810 provides only network interworking (FRF.5). The Cisco MC3810 can be used with service interworking (FRF.8), which is provided by the carrier's ATM network equipment.

Frame Relay-ATM Interworking Concepts

Using the FRF.5 Frame Relay-ATM Interworking function, you can transport Frame Relay traffic over an ATM cloud via a virtual interface within the Cisco MC3810. Using the encapsulation process, you can migrate from Frame Relay to ATM, or you can tunnel Frame Relay traffic across an ATM backbone to a second Cisco MC3810 or other Frame Relay device, and then extract the ATM traffic back to Frame Relay. The Frame Relay traffic is encapsulated in the ATM data cells.

You can transport either data or voice traffic using Frame Relay-ATM Interworking.

Figure 7-1 shows how the virtual interface in the Cisco MC3810 encapsulates Frame Relay traffic to ATM traffic.

Figure 7-1 Frame Relay-ATM Network Interworking Virtual Interfaces

Figure 7-2 shows an example of encapsulating Frame Relay traffic within ATM cells on the Cisco MC3810, tunneling it across the ATM backbone, and then extracting it back from ATM on a second Cisco MC3810.

Figure 7-2 Tunneling Frame Relay Traffic over ATM Using Frame Relay to ATM Interworking

Figure 7-3 shows an application of Frame Relay-ATM Interworking, in which the FRF.5 interworking function (IWF) takes place between a Frame Relay carrier network and an ATM carrier network.

Figure 7-3 Frame Relay-ATM Interworking between Frame Relay and ATM Carrier Networks

Configuring Frame Relay-ATM Interworking

When you configure Frame Relay-ATM Interworking, the working interface you are configuring is Frame Relay, not ATM.

To configure Frame Relay-ATM Interworking, complete the following steps in global configuration mode:

Step
Command
Purpose
1 
router(config)# interface 
fr-atmnumber

Create a Frame Relay-ATM Interworking interface. The number value is a number between 0 and 20. Repeat this step for each Frame Relay-ATM Interworking interface configured. The number assigned is unique on each Cisco MC3810. The default interface created is FR-ATM20.

Note Do not enter a space between fr-atm and the Frame Relay-ATM Interworking interface number.

The Frame Relay-ATM Interworking interface is a virtual interface that can be added dynamically. This interface does not have a physical interface, but can perform the operations similar to that of a physical interface. You can configure up to 21 Frame Relay-ATM interworking virtual interfaces.

2 
router(config-if)# encapsulation 
frame-relay

Configure the interface for Frame Relay encapsulation.

3 
router(config-if)# frame-relay 
interface-dlci dlci [voice-encap 
size]

Configure the Frame Relay data-link connection identifier (DLCI).

If the DLCI will be used for data traffic only, do not specify the voice encapsulation option. 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 80-1600. For recommended data segmentation sizes, see Table 7-1.

The DLCI must match on both sides of the ATM network because the DLCI is mapped on both sides.

4 
router(config-if)# frame-relay 
route in-dlci out-interface 
out-dlci

Configure the Frame Relay static route.

5 
router(config-if)# no keepalive

Turn off Frame Relay keepalive packets.

6 
router(config-if)# fr-atm  
connect dlci dlci atm0 pvc 
[name] [vpi/vci]

Map a Frame Relay DLCI to an ATM permanent virtual circuit (PVC) name or virtual path identifier/virtual channel identifier. The encapsulation type of the current interface must be Frame Relay or Frame Relay 1490 (IETF). The ATM interface on the Cisco MC3810 must be set to atm0.

This step can be repeated to define multiple DLCIs on the virtual interface. To connect DLCIs to different ATM PVCs, you must define separate Frame Relay-ATM Interworking interfaces.

7 
router(config-if)# exit

Exit interface configuration mode.

8 
router(config)# controller {t1 | 
e1} 0

Select the E1 or T1 controller 0. ATM is supported only on controller 0.

9 
router(config-controller)# mode 
atm

Specify that the controller will support ATM encapsulation, and create virtual ATM interface 0, which you will use to create ATM PVCs.

10 
router(config-controller)# no 
shutdown

Make sure the controller is activated.

11 
router(config-controller)# exit

Exit controller configuration mode.

12 
router(config)# interface atm 0 
point-to-point

Enter interface configuration mode to configure ATM interface 0 for a point-to-point network.

13 
router(config-if)# pvc [name] 
vpi/vci

Create an ATM PVC and enter virtual circuit configuration mode.

14 
router(config-if-atm-pvc)# 
encapsulation aal5mux frame

Set the encapsulation of the ATM PVC to support Frame Relay-ATM Interworking.

15

Configure one of the following commands to perform traffic shaping on the virtual circuit:

  
router(config-if-atm-pvc)# ubr 
output value [input value]

Assign the unspecified bit rate (UBR) peak cell rate in kbps for this virtual circuit.

  
router(config-if-atm-pvc)# ubr+ 
output-peak-value 
output-minimum-rate-value 
[input-peak-value] 
[input-minimum-rate-value]

Assign the UBR+ values in kbps for this virtual circuit.

  
router(config-if-atm-pvc)# 
vbr-nrt output-pcr output-scr 
output mbs [input-pcr] [input 
scr] [input mbs]

Assign the variable bit rate (VBR) - Non Real-Time (NRT) values for this virtual circuit.

  
router(config-if-atm-pvc)# 
vbr-rt peak-rate average-rate 
[burst]

Assign the variable bit rate (VBR) - Real-Time (RT) values for this virtual circuit if the virtual circuit will be supporting voice traffic.

Note The UBR, UBR+, VBR-NRT, and VBR-RT services are mutually exclusive. You can assign only one of these services on a virtual circuit at one time.


Table 7-1 Recommended Data Segmentation Sizes

Port 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

1 The 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.


Note When configuring the voice encapsulation data segmentation size, use the slower access rate of either the local or remote device to calculate which data segmentation size to use. If you configure a data segmentation size too high for either the local or remote device, the circuit rate will become throttled because the slower device cannot handle the larger data segmentation size. For example, if the access rate at the local device is 512 kbps and the access rate of the remote device is 256 kbps, configure the data segmentation size based on the slower 256-kbps circuit rate.

If you are configuring Frame Relay-ATM Interworking for data, this completes your configuration. If you are configuring Frame Relay-ATM Interworking for voice, then you also need to configure the Frame Relay-ATM Interworking voice network dial peers. Proceed to the next section.

Configuring Frame Relay-ATM Interworking for Voice

If you are configuring Frame Relay-ATM Interworking for voice traffic, then you need to configure the voice-network dial peers to support Frame Relay-ATM Interworking.

Prerequisite

Follow the steps in the "Preliminary Frame Relay Configuration for Voice" section.

Configure the POTS Dial Peers

Configure the POTS dial peers for the PBX or telephony devices attached to the local voice ports. For more information about the concept of dial peers, see the "Configuring Dial Peers" section.

To configure POTS dial peers, complete the following steps from configuration mode:

Step
Command
Purpose
1 
router(config)# dial-peer voice 
tag pots

Define a POTS peer and enter dial-peer configuration mode. The tag value of the command uniquely identifies the dial peer. All subsequent commands that you enter in dial-peer voice mode before you exit will apply to this dial peer.

2 
router(config-dialpeer)# 
destination-pattern string

Configure the dial peer's destination pattern.

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.

4 
router(config-dialpeer)# 
preference value

(Optional) Configure a preference for the POTS dial peer. The value is a number from 0-10 where the lower the number, the higher the preference. If POTS and voice-network (VoFR) peers are mixed in the same hunt group, POTS dial peers will be searched first, even if a voice-network peer has a higher preference number.

For more information about hunt groups and preferences, see the "Hunt Groups and Preference Configuration" section.

5 
router(config-dialpeer)# 
forward-digits {num-digit | all}

(Optional) If using the digit-forwarding feature, configure the digit-forwarding method that will be used on the dial peer.

6 
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.


Configuring the Voice over Frame Relay Dial Peers

To configure dial peers for Voice over Frame Relay (VoFR) (used for Frame Relay-ATM Interworking), complete the following steps from configuration mode:

Step
Command
Purpose
1 
router(config)# dial-peer voice 
tag vofr

Define a VoFR dial peer for VoFR and enter dial-peer configuration mode. The tag value uniquely identifies the dial peer.

This procedure is very similar to the standard VoFR dial-peer configuration, except you specify the Frame Relay-ATM Interworking session target in step 3 below.

2 
router(config-dialpeer)# 
destination-pattern string

Configure the dial peer's destination pattern.

3 
router(config-dialpeer)# 
session target FRATM number dlci 
dlci

Configure the Frame Relay-ATM Interworking session target for the dial peer.

Note Do not enter a space between FRATM and the Frame Relay-ATM Interworking interface number.

4 
router(config-dialpeer)# 
alt-dial string

(Optional) Configure the alternate dial-out string when configuring on-net-to-off-net alternative dialing.

5 
router(config-dialpeer)# 
preference value

(Optional) Configure a preference for the dial peer. The value is a number from 0-10, where the lower the number, the higher the preference.


This completes the Frame Relay-ATM Interworking configuration.

Frame Relay-ATM Interworking Configuration Examples

This section describes the following examples of configuring Frame Relay-ATM Interworking:

•Frame Relay-ATM Interworking Example (Data Traffic Only)

•Frame Relay-ATM Interworking Example (Data and Voice Traffic)

Frame Relay-ATM Interworking Example (Data Traffic Only)

The following example shows a Frame Relay-ATM Interworking configuration for two Cisco MC3810 concentrators exchanging data traffic only. Figure 7-4 shows the network configuration.

Figure 7-4 Frame Relay-ATM Interworking Example for Data Traffic Only

Cisco MC3810 No. 1 


hostname Router


no aaa per-user


controller T1 0

 mode atm


interface Ethernet0

 ip address 172.22.124.239 255.255.0.0

 no ip mroute-cache

 no ip route-cache


interface ATM0 point-to-point

no ip mroute-cache

 no ip route-cache

 map-group atm1

 pvc 1 1 200 

 encapsulation aal5mux frame-relay

 pvc 26 26 200 

 encapsulation aal5snap


interface FR-ATM1

 ip address 223.223.201.1 255.255.255.0

 encapsulation frame-relay

 frame-relay map ip 223.223.201.2 200 broadcast

 fr-atm connect dlci 200 ATM0 1

interface FR-ATM20



no ip classless


map-list atm1

 ip 223.223.224.228 atm-vc 26 broadcast


end

Cisco MC3810 No. 2 

hostname Router


controller T1 0

 mode atm


interface Ethernet0

 ip address 172.22.124.247 255.255.0.0

 no ip mroute-cache

 no ip route-cache

 ipx network 123


interface Serial0 

 no ip address

 no ip mroute-cache


interface Serial1


interface ATM0 point-to-point

 ip address 223.223.224.228 255.255.255.0

 no ip mroute-cache

 encapsulation atm

 no ip route-cache

 map-group atm1

 pvc 1 1 200 

 encapsulation aal5mux frame-relay

 pvc 26 26 200 

 encapsulation aal5snap


interface FR-ATM2

 ip address 223.223.201.2 255.255.255.0

 encapsulation frame-relay

 frame-relay map ip 223.223.201.1 200 broadcast

fr-atm connect dlci 200 ATM0 1

interface FR-ATM20


no keepalive


map-list atm1

 ip 223.223.224.229 atm-vc 26 broadcast


end

Frame Relay-ATM Interworking Example (Data and Voice Traffic)

The following example shows a Frame Relay-ATM Interworking configuration for two Cisco MC3810 concentrators exchanging both data and voice traffic. Figure 7-5 shows the network configuration.

Figure 7-5 Frame Relay-ATM Interworking Example for Data and Voice Traffic

Cisco MC3810 No. 1 

hostname Router



controller T1 0

 mode atm


interface Ethernet0

 ip address 172.22.125.87 255.255.0.0

 no ip route-cache

 no ip mroute-cache

 no cdp enable


interface ATM0

 ip address 223.223.224.229 255.255.255.0

 no ip route-cache

 no ip mroute-cache

 map-group atm1

 atm enable-payload-scrambling

 pvc 1 1 200 

 encapsulation aal5mux frame-relay

 pvc 26 26 200 

 encapsulation aal5snap


interface FR-ATM 1

 ip address 223.223.201.1 255.255.255.0

 encapsulation frame-relay

 no ip mroute-cache

 frame-relay interface-dlci 200 voice-encap 512

 no keepalive

 frame-relay lmi-type ansi

 fr-atm connect dlci 200 ATM0 1

interface FR-ATM20


map-list atm1

 ip 223.223.224.228 atm-vc 26 broadcast

no cdp run



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 1001 vofr

 destination-pattern 338....

 session target FR-ATM1 200


end

Cisco MC3810 No. 2 


hostname Router



controller T1 0

 mode atm


interface Ethernet0

 ip address 172.22.125.87 255.255.0.0



interface ATM0

 ip address 223.223.224.228 255.255.255.0

 map-group atm1

 atm enable-payload-scrambling

 pvc 1 1 200 

 encapsulation aal5mux frame-relay

 pvc 26 26 200

 encapsulation aal5snap


interface FR-ATM 1

 ip address 223.223.201.1 255.255.255.0

 encapsulation frame-relay

 no ip mroute-cache

 frame-relay interface-dlci 200 voice-encap 512

 no keepalive

 fr-atm connect dlci 200 ATM0 1

interface FR-ATM20


ip classless



map-list atm1

 ip 223.223.224.229 atm-vc 26 broadcast



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 1001 vofr

 destination-pattern 348....

 session target FR-ATM1 200


end