USB Modem Interfaces

You configure two types of interfaces for USB modem connectivity: a physical interface and a logical interface called the dialer interface:

• The USB modem physical interface uses the naming convention umd0. The Services Router creates this interface when a USB modem is connected to the USB port.
• The dialer interface, dln, is a logical interface for configuring dialing properties for USB modem connections.

See the interface naming conventions in the J-series Services Router Basic LAN and WAN Access Configuration Guide.

The following rules apply when you configure dialer interfaces for USB modem connections:

• The dialer interface must be configured to use PPP encapsulation. You cannot configure Cisco High-Level Data Link Control (HDLC) or Multilink PPP (MLPPP) encapsulation on dialer interfaces.
• The dialer interface cannot be configured as a constituent link in a multilink bundle.
• If you are using the same dialer interface for ISDN connections and USB modem connections, the dialer interface cannot be configured simultaneously in the following modes:
  • As a backup interface and a dialer filter
  • As a backup interface and dialer watch interface
  • As a dialer watch interface and a dialer filter
  • As a backup interface for more than one primary interface