Specifications

Overview of Modem Interfaces
Logical Constructs in Modem Configurations
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Cisco IOS Dial Technologies Configuration Guide
Specifically, you configure asynchronous interfaces to support PPP connections. An asynchronous
interface on an access server or router can be configured to support the following functions:
• Network protocol support such as IP, Internet Protocol Exchange (IPX), or AppleTalk
• Encapsulation support such as PPP
• IP client addressing options (default or dynamic)
• IPX network addressing options
• PPP authentication
• ISDN BRI and PRI configuration
For additional information about configuring asynchronous interfaces, see the “Overview of Dial
Interfaces, Controllers, and Lines” chapter.
Group Asynchronous Interfaces
A group asynchronous interface is a parent interface that stores core protocol characteristics and projects
them to a specified range of asynchronous interfaces. Asynchronous interfaces clone protocol
information from group asynchronous interfaces. No data packets arrive in a group asynchronous
interface.
By setting up a group asynchronous interface, you also eliminate the need to repeatedly configure
identical configuration information across several asynchronous interfaces. For example, on a
Cisco AS5300 one group asynchronous interface is used instead of 96 individual asynchronous
interfaces. (See Figure 16.)
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
To configure multiple asynchronous interfaces at the same time (with the same parameters), you can
assign each asynchronous interface to a group and then configure the group. Configurations throughout
this guide configure group asynchronous interfaces, rather than each interface separately.
If you want to configure different attributes on different asynchronous interfaces, do not assign them to
the group or assign different interfaces to different groups. After assigning asynchronous interfaces to a
group, you cannot configure these interfaces separately. For example, on a Cisco AS5300 access server
in a T1 configuration, you could assign asynchronous interfaces 1 to 48 as part of one group (such as
group-async1) and asynchronous interfaces 49 to 96 as part of another group (group-async2). You can
also use the member command to perform a similar grouping function.