Lab
3.3.3: Configuring Callback with PAP authentication
Objectives:
Decrease the toll charges of your remote office by enabling
callback.
Scenario:
The Atlanta Bread Company is reviewing the costs incurred by the
Macon office for dialin access to the core router. A lower telephone
rate has been established for your Atlanta office to call to the
Macon office. You will configure callback services between the
Atlanta core router and the Macon remote office.
Notes:
Lab Tasks:
Log into the Atlanta router and
enter global configuration mode.
Configure the serial interface for
callback server mode. The commands to configure the serial
interface are:
Below is a brief description of each
of the above commands:
dialer in-band
Allows us to
dial multiple numbers if necessary
ppp callback
accept
Allows the router to
operate as a callback server.
dialer
callback-secure
Specifies that the
router is to disconnect the initial call, and call back only
if it has a dialer map command with a defined class for the
remote router
dialer
idle-timeout 300
Drops connection if
there is no traffic for 5 mins.
dialer
wait-for-carrier-time 60
Allows up to 1 min.
for the connection to occur
dialer
hold-queue
Holds up to 50
packets while the call is being setup
dialer-group 1
Places this
interface in group #1. This is the same as the access-group
command for dialers.
Exit
Move you out of
interface configuration
Create a chat script for your Hayes
56K modem to call the Macon remote office. The command to do this
is:
The final step on the Atlanta router
is to map the IP address to the Macon phone number with the "dialback"
map class.
Atlanta(config)#interface
serial 0/1
Atlanta(config)#dialer map ip 10.1.1.2 name macon class dialback
modem-script hayes56k broadcast 555600X
Write the configuration to memory.
Log into the Macon router and enter
global configuration mode.
Configure the serial interface to
request callback services. The command to configure the serial
interface is:
Macon(config)#interface serial 0/1
Macon(config-if)#ppp callback request
Write the configuration to memory.
Configure the Macon modem to answer
incoming calls by doing a reverse Telnet to the modem. A reverse Telnet
is a way to open a terminal session on a modem through the
router. It is used to issue commands and save the configuration to
the NVRAM of the modem. The following commands can be used to
reverse Telnet to the modem on line 2.
Macon#telnet modem2 or "telnet
192.168.0.1 2002"
Enter the "cisco" password
at the prompt.
Type "AT" and then press
the Enter key. You are now in the modem!
The modem should respond with "OK"
Type "AT&F" and then press the Enter key.
This command will reset the modem to default factory standards.
Type "ATS0=1" and then press the Enter key. This is a
"ZERO" not an "O"
This command tells the modem to answer on the first ring.
On the Hayes Accura 56K modem, answer on the first ring, is the only
initialization string that we must program on the modem.
Type "AT&W" and then press the Enter key.
This command saves the configuration to the modem's NVRAM
Finally, press Control,Shift, 6 at
the same time and then press "X"
This will suspend your reverse Telnet session.
Issue the following command to kill your reverse telnet session on
the router:
Macon# disconnect
Turn off both modems. The modems may
not get past the LCP negotiation process unless they were powered
off and then on. Don't forget to turn the modems back on.
From the Macon router issue the
following commands:
Macon#debug dialer events
Macon#ping atlanta
Record your findings about the
callback process below:
Save your configurations and turn
off all debugging.
Congratulations! You now have callback
service on your Atlanta core router and the Macon remote router.