11 CONFIGURING LOGICAL INTERFACE
This chapter contains information on the following topics:
■Logical Interface Introduction
■Dialer Interface
■Loopback Interface
■Null Interface
■Sub-Interface
■Standby Center Logic Channel
■Virtual-Template and Virtual Interface
Logical Interface
Introduction The logical interface refers to the interface that can exchange data, but does not
exist physically and needs to be established through configuration, including the
Dialer interface, loopback interface, null interface, sub-interface, standby center
logic channel and virtual-template.
Dialer Interface Dialer interface is used for dialup. Dial-supporting interfaces on the 3Com Router
series include synchronous serial interface, asynchronous serial interface, ISDN BRI
interface and ISDN PRI interface. The 3Com Router realizes the Bandwidth on
Demand Routing (BDR) function, and provides two BDR configuration methods:
Legacy BDR and BDR profiles. Please see Operation Manual - Dial-up for detailed
information.
Configure Dialer
Interface According to different BDR modes, configurations of Dialer interface are:
■Configure Dialer interface for Legacy BDR
■Configure Dialer interface for BDR profiles
Please see related chapters in Operation Manual - Dial-up for detailed description,
monitoring and maintenance, typical configuration example, fault diagnosis and
troubleshooting of the configurations of BDR.
Loopback Interface It is prescribed in TCP/IP that the network segment 127.0.0.0 is loopback address.
The interface with the loopback address is called loopback interface. The 3Com
Router series define interface Loopback0 as the loopback interface, which can
receive all the packets destined for this router. The addresses on the loopback
interfaces can neither be configured nor be advertised by routing protocols.