Case Study 1

Configure ISDN
Connectivity between
Remote Sites

Cisco Networking Academy Program

CCNP 2: Remote Access v3.0

2-5

CCNP 2: Remote Access v3.0

Copyright

 2003, Cisco Systems, Inc.

Objectives

In this case study, the following concepts are covered:

■

Asynchronous Dialup Connection AUX

■

PPP (multilink and authentication)

■

ISDN (PRI and BRI)

■

Dialer Profiles

■

Map Class

Copyright

 2003, Cisco Systems, Inc.

Case Study 1: Configure ISDN Connectivity between Remote Sites 3-5

Scenario

The Air Guitar Company wants to connect three remote sites via ISDN links. In
addition they have asked that dialup access be enabled for remote users to access
the Air Guitar network.

Initial Configurations

■

Physically connect the network devices according the network diagram. Be
sure that the cables are connected to the appropriate Adtran ports as labeled
in the diagram.

■

The Air Guitar Company has decided to use the private address 10.0.0.0 /8
network. Configure Fa0/0 interface of R1, R2, and R3 to belong to the
10.x.x.x /24 network. The “x” refers to the router number. For example, the
Fa0/0 interface of R1 should be IP address 10.1.1.1 /24, R2 should be
10.2.2.1, and R3 should be 10.3.3.1.

■

Configure all three routers to use the password cisco to support Telnet
services and privilege EXEC mode.

■

Configure all three routers with a local username and password database
where the username will be the remote router names and the password cisco.
For example, the R1 router would include username R2 password
cisco

.

4-5

CCNP 2: Remote Access v3.0

Copyright

 2003, Cisco Systems, Inc.

Asynchronous

■

Configure an asynchronous dialup connection on the AUX port of R1, so that
Host A can dial up R1 to access the Air Guitar corporate network.

■

Configure the asynchronous interface so that it will share the Fa0/0 IP
address of R1.

■

Configure PPP dedicated mode on R1. The EXEC prompt should not appear
and the router will not be available for EXEC mode access unless the user
Telnets from the host.

■

Configure R1 to always assign Host A the IP address 10.1.1.10.

■

Configure a local database entry to authenticate Host A with the username
HostA and password letmein.

■

Configure the router to automatically discover the modem type and configure
it.

■

Configure Host A to dial 555-6001 to access the Air Guitar network.

ISDN

■

Configure ISDN PRI on R1. The ISDN switch type for the ISDN PRI
connection is primary-ni.

■

Configure the T1 controller on R1 to use esf framing, b8zs line coding, and
set the T1 controller to use all timeslots.

■

R1 belongs to the 10.1.2.0 /29 subnet. Configure the first valid IP address to
R1.

■

Configure the PRI channel on R1 for Dial-on-Demand Routing (DDR) to
establish a call to both R2 and R3. Be sure to correctly map the dialer string
to the appropriate IP address.

■

Configure the PRI channel on R1 to use PPP multilink.

■

Configure ISDN BRI on R2 and R3 to use the SPID information from the
network diagram. The ISDN switch type for the ISDN BRI connection is
basic-ni.

■

Configure a pair of dialer interfaces (Dialer 0 and Dialer 1) on R2 and R3 for
Dial-on-Demand Routing (DDR) to establish a call to R1 (Dialer 0) or
between both BRI interfaces (Dialer 1).

■

Configure Dialer 0 on both R2 and R3 to connect to the PRI interface of R1
by calling 555-5000.

■

Configure the R2 and R3 Dialer 0 interface so that they belong to the same
subnet as R1, 10.1.2.0 /29. All IP packets should be able to initiate an ISDN
call.

■

Configure Dialer 1 on both R2 and R3 to establish an ISDN connection
between the two routers.

Copyright

 2003, Cisco Systems, Inc.

Case Study 1: Configure ISDN Connectivity between Remote Sites 5-5

■

Configure the R2 and R3 dialer 1 interface so that they belong to the
10.1.2.16 /30 VLSM subnet. All IP packets should be able to initiate an
ISDN call.

■

Configure R2 and R3 to aggregate both ISDN B-channels when incoming or
outgoing traffic exceeds a threshold of 3.

■

Create a map class on R2 and R3 that will aggressively disconnect the ISDN
connection when the link is not used. Set the idle-timeout to 30 seconds, fast-
idle timer to 10 seconds, and carrier wait time to 25 seconds.

■

Configure R1, R2 and R3 to secure the ISDN connections with PPP CHAP.

■

Configure static routes on all routers so that each router knows how to reach
its neighbor remote LAN.

■

Test the ISDN connection.

■

Ping the R2 and R3 dialer 0 interface from R1 and vice versa. If the pings
fail, troubleshoot as necessary.

■

Ping the R2 dialer 1 interface from R3. If the pings fail, troubleshoot as
necessary.

Check List

■

R1 should query its local username and password database to authenticate
remote login attempts.

■

Host A should be able to reach the entire Air Guitar network after a
successful asynchronous connection is established to R1.

■

R1 should be able to initiate an ISDN DDR connection with R2 and R3.

■

R2 and R3 should use an aggressive map class to timeout the ISDN
connection.

■

R2 and R3 should be able to initiate a DDR connection using dialer profiles
with R1 and with each other.