QTech QSR-2830, User Manual

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2. Configuring Dialup 26
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Command Function
Qtech# show pppoe { tunnel | session }
Shows the PPPoE configuration.
Qtech# show interfaces dialer dialer-number Shows the logical interface configuration.
Qtech# debug pppoe { datas | errors | events | packets }
Turns on the PPPoE debug switch.
2.2
Callback
2.2.1
Callback Overview
2.2.1.1 Introduction
The callback needs the client/server relation between the two parties of the dialup. One remote callback client dials
to connect the callback server, and the callback server performs authentication for the dial-in user. If the
authentication passes, the callback server uses the related information of the remote host for callback.
If the callback fails due to busy line, no reply, or other reasons, no redialing is done. If the callback server has no
available interface for callback, no retry will be done.
Callback client : remote device or host that requests the callback
Callback server : the device that accepts the callback request, and if the authentication passes,
disconnects the current connection and locally initiates the dialing to the remote client.
2.2.1.2 Purposes
The callback is generally used in the following three scenarios:

Save cost: The call charge may be different for different areas. For example, the dialing from village to city may
be more expensive than the reverse direction, so it is possible to save cost by calling back from the city to
village.

Unified call charge: An organization may have quite a lot of branches. It is possible to call back from the center
to the branches so that the calls are all paid by the center to facilitate the financial management and statistics.

Security considerations: The callback numbers set for the callback server are the reliable and valid numbers
that have been configured. This helps ensure the location of the callback client is valid, forbidding the invalid
dialing from the range out of control.
2.2.1.3 Callback configuration tasks
Before configuring the callback, make sure the global DDR configuration preparations are completed. The callback
configuration tasks involve:

Configure the callback client

Configure the callback server
Configuring the callback client
Use the following commands to configure the callback client for the device in global configuration mode.
Command Function
Qtech(config)# interface type number
Specifies the interface and enters the interface
configuration mode.
Qtech(config-if)# dialer in-band
Enables DDR.
Qtech(config-if)# encapsulation ppp Encapsulates PPP.
Qtech(config-if)# ppp authentication { chap | pap }
Configures the PPP authentication.
Qtech(config-if)# dialer map protocol next-hop-address
name hostname dial-string
Maps the callback server hostname, address and
telephone number.