Enabling PPP


Router(config-if)# encapsulation ppp

* Defines encapsulation type

© 2004 Cisco Systems, Inc. All rights reserved. BCRAN v2.1—3-2

PPP can be enabled on various types of interfaces, including synchronous, asynchronous, serial, ISDN BRI, and ISDN PRI interfaces. The syntax to enable PPP is the same, regardless of interface.

An example of configuring PPP on a synchronous interface would be: Router(config)# interface serial 0 Router(config-if)# encapsulation ppp

PPP Session and EXEC Session

This topic describes the concepts of initiating PPP via an in-band PPP session and an out-of band EXEC session.

© 2004 Cisco Systems, Inc. All rights re

© 2004 Cisco Systems, Inc. All rights re

You can use asynchronous connections as either an in-band PPP session or an out-of-band EXEC session.

An in-band PPP session is the most common type of connection because it provides users access to network resources such as web servers and mail servers. You can configure PPP inband as a dedicated session (dedicated mode) or an interactive session (interactive mode). In dedicated mode, an interface is automatically configured for PPP connections. In interactive mode, the user can choose between an in-band and an out-of-band session.

Generally, you will want to restrict the ability of remote users to start EXEC sessions with your router. Typical end users do not require access to the router interface. Instead, they need a Layer 3 protocol (IP and so on) connection to the corporate network or the Internet. In most cases, you should force the asynchronous interface to use PPP and not allow an EXEC connection.

To ensure that the dial-in user must run PPP on the specified line, use the async mode dedicated command:

Router(config-if)# async mode dedicated

An out-of-band EXEC session is typically configured to allow administrators and power users to access the router command-line interface (CLI). This feature allows remote users to log in to the router and issue commands as if the user were connected to the console port. IP addressing or PPP encapsulation is not necessary for this type of connection. Data is sent as asynchronous characters.

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