| Engineering Journal 6.3.4: Frame relay operation summary 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.