3Com MSR 50 Series Configuration Manual page 743

Introduction to Terminal Access 743
Figure 222 Network diagram for terminal access
Source address binding
The principle of source IP address binding is to configure an IP address on a stable
interface (the loopback interface or dialer interface is recommended) and use this
address as the source IP address of the upstream TCP connection from the router
through IP unnumbered configuration.
If an FEP runs, the IP address of the router connected to the FEP needs to be
authenticated. Therefore, when the dial-up backup function is used in a wide area
network (WAN), if the primary link fails, the router begins to use the backup
interface. In that case, the IP address of the router is changed, and the
authentication fails if source IP address binding is not implemented. To avoid such
failures, configure source IP address binding on the router to use a fixed IP address
to establish a TCP connection with the FEP.
For security or some other reason, the actual IP address used in the upstream TCP
connection on the router may need to be hidden and another IP address needs to
be used. In that case, you also need to configure source IP address binding.
Make sure the FEP and the router's IP address is reachable to each other.
Terminal menu
Terminal menu allows you to bring up the menu interface by pressing the menu
hotkey at the terminal. The menu interface displays the services provided by each
VTY on the terminal. By entering a service option, you can switch to the
corresponding service display. The menu interface displays:
TTY ACCESS SYSTEM
VERSION 3.0