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In this configuration example,
the central-site router has a PRI connection and internal modems.
The router is configured to receive both async and BRI calls. The
incoming async calls are sent to the internal modems. A dialer
interface has been configured to receive ISDN BRI calls from
the branch office. The following steps describe the commands used to
configure the central-site router.
Step 1
- Under the PRI D channel, the
following command will have analog calls sent to the internal
modem:
CentralA(config-if)#isdn
incoming-voice modem
The following links this serial
interface to the dialer pool:
CentralA(config-if)#dialer
pool-member 1
Step 2
- To configure an asynchronous
group:
CentralA(config)#interface
group-async 1
The following list shows the commands
for the Step Two configuration requirements:
- To have async lines 65 to 70
service this interface:
CentralA(config-if)#group-range
65 70
To make the interface not have its
own IP address, and instead borrow the interface E0 address:
CentralA(config-if)#ip
unnumbered e 0/0
To have the encapsulation be PPP
with CHAP authentication:
CentralA(config-if)#encapsulation
ppp
CentralA(config-if)#ppp authentication chap
To ensure that this interface will
be using DDR on its async lines:
CentralA(config-if)#dialer
in-band
To make incoming calls, start either
a PPP or an EXEC session:
CentralA(config-if)#async
mode interactive
To associate this interface with the
dialer list 1:
CentralA(config-if)#dialer-group
1
To have the incoming PPP session be
issued an IP address from the ASYNCLAB pool of addresses:
CentralA(config-if)#peer
default ip address pool lab
To make the disconnect take place
after 120 seconds without interesting traffic:
CentralA(config-if)#dialer
idle-timeout 120
Step 3
Configure the physical
characteristics of the lines that are associated with the async-group
interface. The following list shows the commands for the Step 3
configuration requirements:
- To have the EXEC, IP, or SLIP
session be automatically decided by the router upon receiving
the first byte of data of the incoming connection:
CentralA(config)#line 65 70
CentralA(config-line)#autoselect
during-login
CentralA(config-line)#autoselect
ppp
- To have the router consult the
local username database to authenticate callers:
CentralA(config-line)#login
local
- To ensure that the modem can
receive and place calls:
CentralA(config-line)#modem
inout
- To have the router autoconfigure
the MICA modem:
CentralA(config-line)#modem
autoconfigure type mica
- To make the lines authorized to
transport for input and output any traffic (Telnet, rlogin, lat,
and so on):
CentralA(config-line)#transport
input all
- To have the flowcontrol be done by
the modem signaling with one stopbit:
CentralA(config-line)#stopbits
1
CentralA(config-line)#flowcontrol
hardware
Step 4
The following shows how to configure
the dialer interface to be used for receiving calls from the branch
office. It also shows how to provide all the necessary commands for
an authenticated PPP session, for identifying interesting traffic,
and any other commands you should configure on a dialer interface:
CentralA(config)#interface
dialer 1
CentralA(config-if)#ip address 10.130.0.2 255.255.255.0
CentralA(config-if)#dialer
in-band
CentralA(config-if)#dialer
idle-timeout 60
CentralA(config-if)#dialer-group 1
CentralA(config-if)#no fair-queue
CentralA(config-if)#encapsulation ppp
CentralA(config-if)#ppp authentication chap
CentralA(config-if)#no peer default ip address
CentralA(config-if)#ppp multilink
CentralA(config-if)#dialer remote-name BranchA
CentralA(config-if)#dialer string 7782001
CentralA(config-if)#dialer
pool 1
Step 5
To assign a static route to reach
the branch office by using the dialer interface and to prevent
IGRP routing updates from going out of your interface dialer:
CentralA(config)#ip route
10.218.0.0 255.255.255.0 dialer 1
CentralA(config)#router igrp 100
CentralA(config-router) #passive-interface
dialer 1
The new configuration can be seen in
bold letters in Figure .
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