Now that you have learned the basic Frame Relay operations, you can
use the following steps, which are illustrated in the following two
Figures
to implement Frame Relay:
Step 1
Order Frame Relay service from a
service provider, or create a private Frame Relay cloud.
Step 2
Connect each router, either directly
or through a channel service unit/digital service unit (CSU/DSU), to
the Frame Relay switch.
Step 3
When the CPE router is enabled, it
sends a Status Inquiry message to the Frame Relay switch. The
message notifies the switch of the router's status, and asks the
switch for the connection status of the other remote routers.
Step 4
When the Frame Relay switch receives
the request, it responds with a Status message that includes the
DLCIs of the remote routers to which the local router can send data.
Step 5
For each active DLCI, each router
sends an Inverse ARP request packet, introducing itself and asking
for each remote router to identify itself by replying with its
network-layer address.
Step 6
For every DLCI that the router learns
about through an Inverse ARP message, a map entry is created in the
router's Frame Relay map table. This includes the local DLCI,
the remote router's network-layer address, as well as the state of
the connection. Note that the DLCI is the router's locally configured
DLCI, not the DLCI that the remote router is using. Three possible
connection states appear in the Frame Relay map table:
Active state-Indicates that the
connection is active and that routers can exchange data.
Inactive state-Indicates that
the local connection to Frame Relay switch is working, but the
remote router's connection to Frame Relay switch is not
working.
Deleted state-Indicates that no
LMI is being received from the Frame Relay switch or no
service between the CPE router and Frame Relay switch is
occurring.
Step 7
Every 60 seconds, the routers
exchange Inverse ARP messages.
Step 8
By default, every 10 seconds the CPE
router sends a keepalive message to the Frame Relay switch, the CPE router sends a keepalive message to the Frame
Relay switch. The purpose of the keepalive message is to verify that
the Frame Relay switch is still active.