Cisco routers support the following three LMI types:
?– Cisco: LMI type de?¬?ned jointly by Cisco, StrataCom, Northern Telecom (Nortel), and
Digital Equipment Corporation
?– ANSI: ANSI T1.617 Annex D
?– Q.933A: ITU-T Q.933 Annex A
You can also manually con?¬?gure the appropriate LMI type from the three supported types
to ensure proper Frame Relay operation.
When the router receives LMI information, it updates its VC status to one of the following
three states:
?– Active: Indicates that the VC connection is active and that routers can exchange data
over the Frame Relay network.
?– Inactive: Indicates that the local connection to the Frame Relay switch is working, but
the remote router connection to the remote Frame Relay switch is not working.
?– Deleted: Indicates that either no LMI is being received from the Frame Relay switch
or that no service exists between the router and local Frame Relay switch.
PVC
CSU/DSU
DLCI: 500
DLCI: 400
10.1.1.1
PVC
Keepalive
LMI
500 = Active
400 = Inactive
Establishing a WAN Connection with Frame Relay 333
The following is a summary of how Inverse ARP and LMI signaling work with a Frame
Relay connection:
1.
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