1.1.1 IP address. Therefore, when the router must
send data to 10.1.1.1, it uses DLCI 500.
Figure 8-25 Frame Relay Address Mapping
Instead of using Inverse ARP to automatically map the local DLCIs to the remote router
network layer addresses, you can manually con?¬?gure a static Frame Relay map in the
map table.
Frame Relay signaling is required between the router and the Frame Relay switch.
Figure 8-26 shows how the signaling is used to get information about the different DLCIs.
IP (10.1.1.1)
PVC
10.1.1.1
Inverse ARP or
Frame Relay Map
Frame Relay DLCI (500)
CSU/DSU
DLCI: 500
332 Chapter 8: Extending the Network into the WAN
Figure 8-26 Frame Relay Signaling
The LMI is a signaling standard between the router and the Frame Relay switch. The LMI
is responsible for managing the connection and maintaining the status between the devices.
Although the LMI is con?¬?gurable, beginning in Cisco IOS Release 11.2, the Cisco router
tries to autosense which LMI type the Frame Relay switch is using. The router sends one
or more full LMI status requests to the Frame Relay switch. The Frame Relay switch
responds with one or more LMI types, and the router con?¬?gures itself with the last LMI
type received.
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