Specifications

Overview of Modem Interfaces
Logical Constructs in Modem Configurations
DC-57
Cisco IOS Dial Technologies Configuration Guide
Modem Lines and Asynchronous Interfaces
Modems attach to asynchronous lines, which in turn attach to asynchronous interfaces. Depending on
the type of access server you have, these components appear outside or inside the physical chassis.
Figure 16 shows the logical relationships among modems, asynchronous lines, asynchronous interfaces,
and group asynchronous interfaces. All these components work together to deliver packets as follows:
• Asynchronous calls come into the modems from the “plain old telephone service” (POTS) or Public
Switched Telephone Network (PSTN).
• Modems pass packets up through asynchronous lines.
• Asynchronous interfaces clone their configuration information from group asynchronous interfaces.
Note The number of interfaces and modems varies among access server product models.
Figure 16 Modems, Lines, and Asynchronous Interfaces
Use the interface group-async command to create and configure a group asynchronous interface. The
following example shows a group asynchronous configuration for a Cisco AS5300 access server loaded
with one 4-port ISDN PRI card and 96 MICA modems:
Router(config)# interface group-async 1
Router(config-if)# ip unnumbered loopback 0
Router(config-if)# encapsulation ppp
Router(config-if)# async mode interactive
Router(config-if)# peer default ip address pool dialin_pool
Router(config-if)# no cdp enable
Router(config-if)# ppp authentication chap pap dialin
Router(config-if)# group-range 1 96
Group asynchronous interface
Projects core protocol
characteristics out to
asynchronous
interfaces
Modem 1
14478
Modem 2 Modem 96
Interface async 1
Interface async 2 Interface async 96
Line 1 Line 2 Line 96
Asynchronous lines
and interfaces inside
the access server
Modems are inside or
outside the access
server, depending on
the
p
roduct model