Digital Audio Interfacing and Networking 1491about. A hub has ports that connect either to stations or
other hubs. Any data that comes in a port is immediately
sent out all the other ports except the port it came in on,
Fig. 39-29. An audio analogy would be a mix-minus
system.
One of the factors keeping the size of the network
from growing is that all of these star and star of stars
topologies still have the same network diameter limita-
tion. One way to build a bigger network is to isolate
data in one star from that in another, and only pass
between stars packets that need to reach stations in the
other star. Collisions that occur in a given star are not
passed to the other stars since only complete packets
addressed to a station in the other star are passed on.
This isolates each star into a collision domain of its
own, so the network diameter limitation only applies
within a given collision domain.
The device that provides this function between a pair
of collision domains is called a bridge. As the tech-
nology became cheaper multiport bridges started to
appear that were called switches. As switches become
popular and bridges fade from use, you will sometimes
see a bridge referred to as a two-port switch, Fig.39-30.Figure 39-26. Ethernet star topology.
nodenodenodehub nodeFigure 39-27. Ethernet star of stars topology examples.