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1-34
Chapter 1
Planning a Network Topology
Furniture location can also be significant, as can the cable color if you
are attempting
to match it to the walls.
Finally, the diagram should contain a sufficient number of additional cable
runs to pro-
vide for future expansion of the network.
Locating Connectivity Devices
Before you can create a diagram of your network’s cable runs, you must
decide where
your hubs and patch panels will be located. A patch panel is a cabling
nexus, a termi-
nus for multiple cable runs that enables you to connect each cable to a hub
port, which
joins the cables to a network. The number of patch panels and hubs you need
and
their locations depend on the size of your network and of the installation
site.
The main limiting factor in the patch panel and hub locations is the maximum
allow-
able length of your network cables. UTP cable runs can be up to 100 meters
long,
meaning that you have to choose a location for your patch panel that is no
more than
100 meters from your most distant workstation. In most office sites, this is
not a big
problem. However, don’t forget that the maximum cable length includes the
lengths of
all patch cables (which are the individual cables running from the wall
plate to the
computer and from the patch panel to the hub). In addition, cable runs are
frequently
longer than they appear because of the need to run around obstacles and up
and down
inside walls. For this reason, network plans should always specify ceiling
heights and
exact locations of wall plates.
If the building in which the network will be installed is small enough, you
can run all
the cables to patch panels in a single location. However, this might require
you to run
large numbers of cables between floors. If the building does not have
conduits
between floors that provide sufficient space for the cables, this
alternative might not be
practical.
A common configuration in buildings with several floors is to have all the
cable runs
for each floor terminate in a single location, such as a utility closet. You
can then con-
nect the individual floors using relatively few cables. Depending on the
size and con-
figuration of the network and the protocols you decide to use, you can
connect the
floors using hubs or switches, creating one single LAN, or using routers,
creating an
internetwork. In the latter case, the individual LANs on each floor are
called horizontal
networks, and the LAN running between the floors and connecting the
horizontal net-
works is called a backbone network, as shown in Figure 1-7.
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