User`s guide

120 XSR User’s Guide
Overview Chapter 7
Configuring Frame Relay
Relay switch are processed by the DLCI in three ways: frames are checked for
integrity, their associated DLCI is looked up in the DLCI table, and they are
relayed to their destination through the port specified in the table. If the
checks reveal errors or do not find the DLCI in the table, frames are discarded.
The
frame-relay interface-dlci command maps a DLCI to a specified
Frame Relay sub-interface.
Figure 14 Frame Relay Network Topology
From the perspective of the OSI reference model, Frame Relay is a high-
performance WAN protocol suite that operates at the physical and data link
layers (1 and 2). Starting from a source site, variable-length packets are
switched between the various network segments until the destination is
reached.
Devices attached to a Frame Relay WAN fall into two categories: Data
Terminal Equipment (DTE) and Data Circuit-terminating Equipment (DCE).
New York
Toronto
Minneapolis
Frame Relay
(Packet Switching Network)
DLCIs
DLCIs
Boston