R0106-HP MSR Router Series Layer 2 - WAN Configuration Guide(V7)

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Configuring PPP callback
PPP callback uses the client/server model where the calling party is the callback client and the called
party is the callback server. The client first originates a call, and the server decides whether to place a
return call. If a return call is needed, the callback server disconnects the call and places a return call
according to the username or callback number.
PPP callback has the following benefits:
• Enhanced security—The server places a return call to the locally configured number, which prevents
caller number spoofing.
• Reduced charges—The charge payer can be changed when the charge rates are different in the
two directions.
When you configure PPP callback on an interface, follow these restrictions and guidelines:
• PPP callback requires authentication. Configure PAP or CHAP authentication on both physical and
dialer interfaces on the callback client and server.
• To provide enough time for a server to call back, the holddown timer configured by using the dialer
timer enable command on the client must be at least 10 seconds longer than that on the server. HP
recommends setting the holddown timer to 5 seconds (the default) on the server and to 15 seconds
on the client.
• Do not configure dynamic route backup on the interface. Otherwise, the interface does not accept
incoming calls or outgoing calls other than those that are initiated for the dynamic route backup
feature.
Configuring the callback client
The callback client can place calls to the remote end (which can be a router or Windows NT server with
the callback server function), and receive return calls from the remote end.
You can configure the callback client to use traditional DDR or bundle DDR.
Configuring the callback client by using traditional DDR
Ste
p
Command Remarks
1. Enter system view.
system-view N/A
2. Enter dialup interface view.
interface interface-type
interface-number
N/A
3. Enable the interface to send
callback requests.
ppp callback client
By default, an interface does not
send callback requests.
4. (Optional.) Configure the dial
string for a Windows NT server
to call back.
ppp callback ntstring dial-number
By default, no dial string is
configured for a Windows NT
server to call back.
Configure this command if the
Windows NT server requires
callback clients to send callback
numbers.