frame-relay interface-dlci

To assign a data-link connection identifier (DLCI) to a specified Frame Relay subinterface on the router or access server, or to define a specific permanent virtual circuit (PVC) to a DLCI and apply a virtual template configuration for a PPP session, use the frame-relay interface-dlci interface configuration command. To remove this assignment, use the no form of this command.

frame-relay interface-dlci dlci [ietf | cisco] [voice-encap size] [voice-cir cir]
[ppp virtual-template-name]

no frame-relay interface-dlci dlci [ietf | cisco] [voice-encap size] [voice-cir cir]
[ppp virtual-template-name]

BOOTP server only

frame-relay interface-dlci dlci [protocol ip ip-address]
Syntax Description

dlci

DLCI number to be used on the specified subinterface.

ietf | cisco

(Optional) Encapsulation type: Internet Engineering Task Force (IETF) Frame Relay encapsulation or Cisco Frame Relay encapsulation.

voice-encap size

(Supported on the Cisco MC3810 only.) Specifies that data segmentation will be used to support Voice over Frame Relay. The voice encapsulation size denotes the data segmentation size. For a list of recommended data segmentation sizes, see the "Usage Guidelines" section.

voice-cir cir

(Optional; supported on the Cisco MC3810 only.) Specifies the upper limit on the voice bandwidth that may be reserved for this DLCI. The default is the CIR configured for the Frame Relay map class. For more information, see the "Usage Guidelines" section.

ppp

(Optional) Enables the circuit to use the PPP in Frame Relay encapsulation.

virtual-template-name

(Optional) Specifies which virtual template interface to apply the PPP connection to.

protocol ip ip-address

(Optional) Indicates the IP address of the main interface of a new router or access server onto which a router configuration file is to be automatically installed over a Frame Relay network. Use this option only when this device will act as the BOOTP server for automatic installation over Frame Relay.

Defaults

No DLCI is assigned.

Command Modes

Interface configuration

Command History
Release Modification

10.0

This command was introduced.

11.3(1)MA

The voice-encap option was added for the Cisco MC3810.

12.0(1)T

The ppp keyword and virtual-template-name argument were introduced.

12.0(2)T

The voice-cir option was added for the Cisco MC3810.

12.0(3)T

The keyword x25 profile was introduced.

12.0(4)T

Usage guidelines for the Cisco MC3810 were added.
Usage Guidelines

This command is typically used for subinterfaces; however, it can also be used on main interfaces. Using the frame-relay interface-dlci command on main interfaces will enable the use of routing protocols on interfaces that use Inverse ARP. The frame-relay interface-dlci command on a main interface is also valuable for assigning a specific class to a single PVC where special characteristics are desired. Subinterfaces are logical interfaces associated with a physical interface. You must specify the interface and subinterface before you can use this command to assign any DLCIs and any encapsulation or broadcast options. See the "Examples" section for the sequence of commands.

This command is required for all point-to-point subinterfaces; it is also required for multipoint subinterfaces for which dynamic address resolution is enabled. It is not required for multipoint subinterfaces configured with static address mappings.

Use the protocol ip ip-address option only when this router or access server will act as the BOOTP server for autoinstallation over Frame Relay.

By issuing the frame-relay interface-dlci interface configuration command, you enter Frame Relay DLCI interface configuration mode (see the first example below). This gives you the following command options, which must be used with the relevant class or X.25-profile names you previously assigned:

A Frame Relay DLCI configured for Annex G can be thought of as a single logical X.25/LAPB interface. Therefore, any number of X.25 routes may be configured to route X.25 calls to that logical interface.

When configuring the voice-encap option on the Cisco MC3810 to enable Voice over Frame Relay, set the data fragmentation size based on the port access rate. The table below lists recommended data fragmentation sizes for different port access rates. Note also that when the voice-encap option is configured on the Cisco MC3810, voice traffic is not shaped, and all priority queueing, custom queueing, and weighted fair queueing is disabled on the interface.

Note: On the Cisco MC3810 only, the voice-encap option performs the same function as the vofr cisco interface configuration command introduced in Cisco IOS Release 12.0(3)XG. Either command is required to enable Voice over Frame Relay. The voice-encap option and the vofr cisco command are mutually exclusive on the same interface; you must choose which command to use. The voice-encap option does not support any priority queueing function, which provides greater throughput. The vofr cisco command uses weighted fair queueing, which reduces throughput but provides a means of prioritizing traffic flows.

The voice-cir option on the Cisco MC3810 provides call admission control; it does not provide traffic shaping. A call setup will be refused if the unallocated bandwidth available at the time of the request is not at least equal to the value of the voice-cir option.

When configuring the voice-cir option on the Cisco MC3810 for Voice over Frame Relay, do not set the value of 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. Note that voice traffic is not shaped when the voice-encap option is configured; thus, in this case the frame-relay mincir command is irrelevant.

Note: On the Cisco MC3810 only, the voice-cir option performs the same function as the frame-relay voice bandwidth map-class configuration command introduced in Cisco IOS Release 12.0(3)XG.
Port Access Rate Recommended Data Segmentation Size*

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
* The data segmentation size is based for back-to-back Frame Relay. If sending traffic through an IGX with standard Frame Relay, add an extra 15 bytes to the recommended data segmentation size.

For more information about automatically installing router configuration files over a Frame Relay network, see the "Loading System Images and Microcode" chapter in the Cisco IOS Configuration Fundamentals Configuration Guide.

Examples

The following example assigns DLCI 100 to serial subinterface 5.17:

! Enter interface configuration and begin assignments on interface serial 5
interface serial 5
! Enter subinterface configuration by assigning subinterface 17
interface serial 5.17
! Now assign a DLCI number to subinterface 5.17
frame-relay interface-dlci 100

The following example specifies DLCI 26 over subinterface serial 1.1 and assigns the characteristics under virtual-template 2 to this PPP connection:

Router(config)# interface serial1.1 point-to-point
Router(config-if)# frame-relay interface-dlci 26 ppp virtual-template2

The following example shows an Annex G connection being created by assigning the X.25 profile "NetworkNodeA" to the Frame Relay DLCI interface 20 on interface serial 1 (having enabled Frame Relay encapsulation on that interface):

Router(config)# interface serial1
Router(config-if)# encapsulation frame-relay
Router(config-if)# frame-relay interface-dlci 20
Router(config-fr-dlci)# x25-profile NetworkNodeA

The following example assigns DLCI 100 to serial subinterface 5.17:

Router(config)# interface serial 5
Router(config-if)# interface serial 5.17
Router(config-if)# frame-relay interface-dlci 100

The following example assigns DLCI 100 to a serial interface, starting from global configuration mode: 

router(config)# interface serial 1/1
router(config-if)# frame-relay interface-dlci 100
router(config-fr-dlci)#

The following example enables Voice over Frame Relay on DLCI 100 on a Cisco MC3810 and sets the data fragmentation size to 80 bytes:

router(config)# interface serial0
router(config-if)# frame-relay interface-dlci 100 voice-encap 80
router(config-fr-dlci)#

The following example enables Voice over Frame Relay on DLCI 100 on a Cisco MC3810, sets the data fragmentation size to 80 bytes, and sets the voice CIR to 24000 bps:

router(config)# interface serial0
router(config-if)# frame-relay interface-dlci 100 voice-encap 80 voice-cir 24000
router(config-fr-dlci)#