A bridge is a device that separates two or more network segments
within one logical network (e.g. a single IP-subnet). A bridge
is usually placed between two separate groups of computers that
talk with each other, but not that much with the computers in
the other group. A good example of this is to consider a cluster
of Macintoshes and a cluster of Unix machines. Both of these
groups of machines tend to be quite chatty amongst themselves,
and the traffic they produce on the network causes collisions
for the other machines who are trying to speak to one another.
The job of the bridge is to examine the destination of the data
packets one at a time and decide whether or not to pass the
packets to the other side of the Ethernet segment. The result is
a faster, quieter network with less collisions. The bridging
code decides whether to bridge data or to drop it not by looking
at the protocol type (IP, IPX, NetBEUI), but by looking at the
MAC-address unique to each NIC. Important: It's vital to
understand that a bri