Specifications

Overview of Modem Interfaces
Logical Constructs in Modem Configurations
DC-55
Cisco IOS Dial Technologies Configuration Guide
Logical Constructs in Modem Configurations
A logical construct stores core protocol characteristics to assign to physical interfaces. No data packets
are forwarded to a logical construct. Cisco uses three types of logical constructs in its access servers and
routers. These constructs are described in the following sections:
• Asynchronous Interfaces
• Group Asynchronous Interfaces
• Modem Lines and Asynchronous Interfaces
Asynchronous Interfaces
An asynchronous interface assigns network protocol characteristics to remote asynchronous clients that
are dialing in through physical terminal lines and modems. (See Figure 15.)
Use the interface async command to create and configure an asynchronous interface.
Figure 15 Logical Construct for an Asynchronous Interface
To enable clients to dial in, you must configure two asynchronous components: asynchronous lines and
asynchronous interfaces. Asynchronous interfaces correspond to physical terminal lines. For example,
asynchronous interface 1 corresponds to tty line 1.
Commands entered in asynchronous interface mode configure protocol-specific parameters for
asynchronous interfaces, whereas commands entered in line configuration mode configure the physical
aspects for the same port.
Contains core protocol
characteristics for
incoming asynchronous
clients
Asynchronous interface
Modem 1
Modem
14054
Line 1
PSTN/ISDN
Remote PC
negotiating parameters
with the asynchronous
interface