User guide

Internetworking Primer A-53
Asynchronous Protocols
Step 2 Enable IP and IPX (or other protocols) by assigning network numbers. (IP can be
configured by entering the command ip unnumbered rather than an IP subnet.)
This example enables PPP to support IP control protocol (ipcp) and IPX control
protocol (ipxcp). Enter the following interface subcommands to configure IP and
IPX (use your administered IPX network number):
Router(config-if)#ip unnumbered ethernet 0
Router(config-if)#ipx network B011
Step 3 Define PPP (or SLIP) encapsulation as the default:
Router(config-if)#encapsulation ppp
Step 4 Enter the following command to allow the port to support services other than PPP
(such as EXEC, SLIP, or ARA) (This step is optional):
Router(config-if)#async mode interactive
Step 5 Configure a default client IP address. This should be a valid, unique, and unused
IP address for a subnet on a connected LAN:
Router(config-if)#async default ip address 172.16.1.12
You can also enter the following additional configuration commands:
asynchronous dynamic address
(interface subcommand)
Allows you to dynamically select your own IP address
when dialing in. Use caution to ensure that only valid
IP addresses are used by the client.
ip tcp header compression passive
(interface subcommand)
Instructs the access server port to perform compression
of TCP headers if requested by the client.
autoselect ppp
(line subcommand)
Automatically launches a PPP session if the client
starts sending PPP packets after the modems have
connected. If you use autoselect, You should use PPP
authentications to prevent unauthorized access.
ppp authen chap
ppp authen pap
(interface subcommand)
Use CHAP or PAP to authenticate PPP sessions.
Recommended for use with autoselect.