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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.