TTYs are asynchronous connectionsbetween the router’s async interfaces and serialdevices (modems). If you are connecting modems to your router oraccess server for dial-up or dial-out connections, you will need toconfigure the TTY ports.
The TTY ports correspond directly to asyncinterfaces.Therefore, whenever you configure a TTY line, you will probably alsoconfigure the corresponding interface. If you plugged a modem intoasync port 1, you would use TTY1 to configure allthe hardware aspects of the connection between the router and themodem, and the interface Async1 would configurethe protocol. (The interface commands are defined in Chapter 5.) Figure 4-3 demonstratesthe possible modem configuration on a router or terminal server.
Here is an example of a modem configuration on TTY port 3:
! Select line 3line tty 3 ! Tell the router to use its local username list login local ! This line is for dial-in access only modem dialin ! The speed of the serial connection is 115200 bps speed 115200 ! Use hardware flow control flowcontrol hardware ! The type of modem is autoconfigured by the router modem autoconfigure discovery
The configuration isn’t difficult to read. The router, which issome sort of terminal server, maintains its own list of usernames andpasswords (login local); themodem is used only for dial-in; the serial connection between themodem and the router is set to 115200 baud; hardware flow control isused; and the modem is configured by the router.
