Nortel BayStack 820, Installation And Reference Manual

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Introduction
206901-A
1-9
Figure 1-6 illustrates how two BayStack 820 ISDN Routers installed in two
different locations support a private company network and highlights an important
feature of the router. Both public and private devices can physically reside on the
same LAN. Both of the routers are connected to the Internet and are also
connected to each other through the ISDN network, forming a private company
network.
Figure 1-6. Two Private Networks with Internet Access
In this illustration, all devices on both LANs (except for the Web server) are
configured to obtain their IP addresses automatically from the built-in DHCP
server in the BayStack 820 ISDN Router. Because these IP addresses are used
only in the local LAN environment, these devices naturally form a private
network with default network IP addresses of 192.168.168.xxx, and cannot be
accessed from the Internet. For a server to be accessible from the Internet, it must
be mapped to a TCP/UDP port in the BayStack 820 ISDN Router Manager
software using Network Address Translation.
To enable LAN-to-LAN communications, you need to change the default private
network address (192.168.168.0) for one of the routers (for example, to
192.168.170.0 as illustrated in
Figure 1-6 ). The traffic between these two
networks is secure because data is sent across the ISDN network through a direct
phone call.
BayStack 820
ISDN Router
ISDN
ISDN
The
internet
Your LAN #1
Your LAN #2
Private:
192.168.170.xxx
Private:
192.168.170.230
Private:
192.168.168.xxx
Private:
192.168.168.230
Public:
206.112.113.6
Web server
Public:
206.112.113.xxx
BayStack 820
ISDN Router
9437FA