Passing the CCNA is tough, and one of the toughest parts is keeping all the acronyms straight! Frame Relay has plenty of those, and today we're going to examine what DLCIs do and how they're mapped on a Cisco router.

Frame Relay VCs use Data-Link Connection Identifiers (DLCI - pronounced "del-see") as their addresses. Unlike other Cisco technologies, VCs have only a single DLCI in their header. They do not have a source and destination.

DLCIs have local significance only. DLCI numbers are not advertised to other routers, and other routers can use the same DLCI numbers without causing connectivity issues.

Cisco uses the term global addressing to describe a technique by which a router in a frame relay network is reached via the same DLCI number from each router in the network. For example, in a 25-router network, the same DLCI number would be used to reach