Dynamic reconfiguration can be used to logically move physical and logical units (the station to be reconnected using switched network backup) to an alternate line. The alternate, physical, switched line is generated in the NCP as a nonswitched line. When a line to a multipoint station fails, the affected station can be deleted from its position as originally generated in the NCP and added to the switched link through dynamic reconfiguration or with the MODIFY DR command. It can then be physically connected by an operator dialing the remote modem. If several stations are attached by a remote "fan out" modem, all the physical units on that modem can be added to the same backup link with the DR ADD command.

The physical units and logical units can have the same names, so no changes to application programs are needed.

Figure 1 illustrates dynamic reconfiguration without "fan out" modems.

Figure 1. Line backup through dynamic reconfiguration