T1 AND E1 REMOTE ACCESS CONCENTRATORS
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6. Applications
There are several ways to establish a remote connection to the Remote Access Concentrator. This chapter
describes these four remote-access applications, including illustrations and examples of configuration
parameters:
• Windows Dial-up Networking and a modem (in
Section 6.1
)
• ISDN IP router running NAT (example includes switch-type and LBO changes; see
Section 6.2
)
• ISDN IP router not running NAT (in
Section 6.3
)
• ISDN bridge (in
Section 6.4
)
6.1 Windows 95/98/2000/NT Dial-up Networking
In this example, a single PC end station (that is, a “remote user”) needs to connect to the local network using
IP protocol through an analog modem or an ISDN terminal adapter (a “remote device”). This configuration is
commonly used by telecommuters with a Windows Dial-up Networking client and is often referred to as IP Host
mode. The remote device has no Layer 2 address. Rather, it is a Layer-3-only device connected to the end
station typically through a serial port. The Remote Access Concentrator and the IP Host share a common IP
address range; the Concentrator uses Layer 3 intelligence to determine what packets to send to the remote
device. The Concentrator provides a proxy ARP to the local network for any remote devices connected this way.
PSTN
Internet
Intranet
Concentrator
Router 1
Modem
From pool:
An address from
2.2.2.11 to 2.2.2.25
2.2.2.6
Server
Running
CSM
2.2.2.5
2.2.2.3
2.2.2.1
2.2.2.2
2.2.2.4
Local Network
Remote Site
