Frame Relay Addressing Facts

Frame Relay Addressing Facts

Frame Relay Addressing Facts

Most Frame Relay installations involve connecting to a Frame Relay network through a T-1 line. The router connects to a CSU/DSU, which is connected to the Frame Relay network. The Frame Relay network is made up of multiple switches for moving packets. You should be aware of the following Frame Relay concepts:

Concept	Description
Data-Link Connection Identifier (DLCI)	Like an Ethernet MAC address, a DLCI identifies each virtual circuit. The DLCI ranges between 16 and 1007. The DLCI represents the connection between two frame relay devices. The Frame Relay service provider assigns the DLCI when the virtual circuit is set up. Each DLCI is unique for the local network, but not for the entire WAN. In other words, the same DLCI number can be used multiple times in the entire network to identify different devices.
Local Management Interface (LMI)	Local Management Interface (LMI) is a set of management protocol extensions that automates many Frame Relay management tasks. LMI is responsible for managing the connection and reporting connection status. LMI can: Maintain the link between the router and the switch. Gather status information about other routers and connections on the network. Enable dynamic DLCI assignment through multicasting support. Make DLCIs globally significant for the entire network. Although DLCI numbers are only locally significant, through LMI these numbers can be globally significant (i.e. the same number is used throughout the entire network to identify a specific link). Cisco routers support three LMI types: Cisco, ANSI, and Q933a.