User's Manual

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BCM50a Integrated Router Configuration — Advanced
Appendix B
Triangle Route
The Ideal Setup
When the firewall is on, your BCM50a Integrated Router acts as a secure gateway
between your LAN and the Internet. In an ideal network topology, all incoming
and outgoing network traffic passes through the BCM50a Integrated Router to
protect your LAN against attacks.
Figure 110 Ideal Setup
The Triangle Route Problem
You can have more than one connection to the Internet (through one or more
ISPs). If an alternate gateway is on the LAN (and its IP address is in the same
subnet as the BCM50a Integrated Router LAN IP address), the triangle route (also
called asymmetrical route) problem can occur. The steps below describe the
triangle route problem.
A traffic route is a path for sending or receiving data packets between two
Ethernet devices. Some companies have more than one alternate route to one or
more ISPs. If the LAN and ISPs are in the same subnet, the triangle route problem
can occur. The steps below describe the triangle route problem.
BCM50a Integrated Router