ATL Telecom AM30 - Manual (Page 118)

118 ATL Telecom User Guide
AM30
Note
Bridges vs. Routers: The essential difference between a
bridge and a router is that a router uses a higher-level
protocol (such as IP) to determine how to pass data. IP
data packets contain IP addresses that specifically identify
the destination computer. Routers can read this
information and pass the data to the destination computer,
or determine which next router to send the data to if the
destination is not on a connected network.
Bridges cannot read IP information, but instead refer to the
hardware ID of the destination computer, which is also
included in data packets. Hardware IDs are unique numbers
that manufacturers assign to each piece of hardware they
sell. A bridge learns to recognize the hardware IDs
accessible through each of its ports. When it receives a
packet, the bridge simply forwards the packet through the
port it associates with the given hardware ID, or through all
its ports if it does not recognize the ID. The hardware ID is
often referred to as the Media Access Control (MAC)
address.
Routers are considered more intelligent and flexible devices
than bridges, and often provide a variety of security and
network administration services based on the IP protocols.
When to Use the Bridging Feature
Although the ROUTER is preconfigured to serve as a router for providing Internet
connectivity to you LAN, there are several instances in which you may also want to
configure bridging:
fYour ISP may use protocols that require bridging with
your LAN. The device can be configured to appear as
a bridge when communicating with your ISP, while
continuing to provide router functionality for your
LAN.
fYour LAN may include computers that communicate
using “layer-3” protocols other than the Internet
Protocol. These include IPX
® and AppleTalk ® . In this
case, the device can be configured to act as a bridge
for packets that use these protocols while continuing
to serve as a router for IP data.