User guide

Internetworking Primer A-51
Asynchronous Protocols
Configuring Asynchronous Ports
Cisco 2500 series access servers have 8 or 16 asynchronous ports (plus an asynchronous
auxiliary port). These ports use RJ-45 connectors and the EIA/TIA-232 signaling standard.
In the access server configuration, there are two configuration submodes associated with
any asynchronous port—lines and asynchronous interfaces.
Asynchronous Lines
The line configuration subcommands are used to configure the asynchronous port for many
options, including the following:
• Physical layer options
• EXEC security
• Autoselect
• ARA protocol
Asynchronous Interfaces
Asynchronous interfaces are created and configured in Cisco IOS software to support PPP
and SLIP connections. The creation of an interface structure also allows Cisco IOS
software to use routing functions on the lines as it would with other interfaces. To support
SLIP or PPP on a given port, you must create and configure an asynchronous interface with
the same number as the line. Typically, the asynchronous interface would be configured for
the following features:
• Network protocol support (IP, IPX, or AppleTalk)
• Encapsulation support (PPP or SLIP)
• IP client addressing options (default and/or dynamic)
• IPX network addressing options
• PPP authentication (SLIP has no protocol security)