Table of Contents
Advertisement
Prestige 623 Series Dual-link ADSL Router
Chapter 17
Configuring Bridging
This chapter describes how to configure the Prestige to operate as a bridge.
17.1 Introduction
You can configure your Prestige to act as a bridging device between your LAN and your ISP. Bridges are
devices that enable two or more networks to communicate as if they are two segments of the same physical
LAN.
Before changing your bridge configuration, make sure you know which of
connection your ISP uses to exchange data with their customer's DSL modems
(such as Ethernet bridging or IP routing).
17.2 Overview of Bridges
A bridge is a device used to connect two or more networks so they can exchange data. A bridge learns the
unique manufacturer-assigned hardware IDs of each computer or device on both (or all) networks. It learns
that some of the IDs represent computers attached via one of the device's interfaces and others represent
computers connected via other interfaces. It stores the ID list and the interfaces associated with each in its
bridge forwarding table.
When the bridge receives a data packet, it compares its destination hardware ID to the entries in the bridge
forwarding table. When the packet's ID matches one of the entries, it forwards the packet through the
interface that connects to the network where that device resides. Note that the bridge does not send the data
directly to the receiving computer, but broadcasts it to the receiving network, making it available to any
node on the network. On the receiving network, a LAN protocol such as Ethernet takes over, helping the
packet reaches its destination.
When the bridge does not recognize a packet's destination hardware ID, it broadcasts the packet through all
of its interfaces – to each network it is attached to.
17.3 Bridges vs. Routers
The essential difference between a bridge and a router is that a router uses a higher-level protocol (such as
the IP) to determine how to pass data. IP data packets contain IP addresses that specifically identify the
Configuring Bridging
17-1
Advertisement
Table of Contents
Troubleshooting
