Configuring Frame Relay DLCIs
When you are using Frame Relay encapsulation on an interface, each logical interface corresponds to one or more permanent virtual circuits (PVCs) or switched virtual circuits (SVCs). For each PVC or SVC, you must configure one data-link connection identifier (DLCI).
A Frame Relay interface can be a point-to-point interface or a point-to-multipoint (also called a multipoint non-broadcast multiaccess [NBMA]) connection.
To configure Frame Relay DLCIs, you can do the following:
Configuring a Point-to-Point Frame Relay Connection
To configure a point-to-point Frame Relay connection, include the dlci statement:
You can include this statement at the following hierarchy levels:
- [edit interfaces interface-name unit logical-unit-number]
- [edit logical-systems logical-system-name interfaces interface-name unit logical-unit-number]
The DLCI identifier is a value from 16 through 1022. Numbers 1 through 15 are reserved for future use. A point-to-point interface can have one DLCI.
 | Note: For information about Frame Relay DLCI limitations for channelized interfaces, see Data-Link Connection Identifiers on Channelized Interfaces. You configure the router to use DLCI sparse mode by including the sparse-dlcis statement at the [edit chassis fpc slot-number pic pic-number] hierarchy level. For more information about DLCI sparse mode, see the Junos OS Administration Library for Routing Devices. For more information about Frame Relay DLCIs, see Configuring a Point-to-Point Frame Relay Connection. |
When you are configuring point-to-point connections, the MTU sizes on both sides of the connection must be the same.
Configuring a Point-to-Multipoint Frame Relay Connection
To configure a point-to-multipoint Frame Relay connection (also called a multipoint NBMA connection), include the multipoint-destination statement:
You can include this statement at the following hierarchy levels:
- [edit interfaces interface-name unit logical-unit-number family family address address]
- [edit logical-systems logical-system-name interfaces interface-name unit logical-unit-number family family address address]
For each destination, include one multipoint-destination statement. address is the address of the remote side of the connection, and dlci-identifier is the DLCI identifier for the connection.
When you are configuring point-to-multipoint connections, all interfaces in the subnet must use the same MTU size.
If keepalives are enabled, causing the interface to send LMI messages during idle times, the number of possible DLCI configurations is limited by the MTU selected for the interface. For more information, see Configuring Frame Relay Keepalives.
Configuring a Multicast-Capable Frame Relay Connection
By default, Frame Relay connections assume unicast traffic. If your Frame Relay switch performs multicast replication, you can configure the connection to support multicast traffic by including the multicast-dlci statement:
You can include this statement at the following hierarchy levels:
- [edit interfaces interface-name unit logical-unit-number]
- [edit logical-systems logical-system-name interfaces interface-name unit logical-unit-number]
The DLCI identifier is a value from 16 through 1022 that defines the Frame Relay DLCI over which the switch expects to receive multicast packets for replication.
You can configure multicast support only on point-to-multipoint Frame Relay connections.
If keepalives are enabled, causing the interface to send LMI messages during idle times, the number of possible DLCI configurations is limited by the MTU selected for the interface. For more information, see Configuring Frame Relay Keepalives.
