Understanding Network Cabling
wired as described in Table 4-1. For instance, you cannot use a standard twisted-pair
patch cable to connect directly from a network server to a workstation, or between two
workstations, because those are all DTE devices. Instead, you must purchase or prepare
a crossover cable for this connection. For 10/100Base-T networks, Table 4-2 shows the
wiring needed for a crossover cable.
You can easily purchase all the tools and parts needed to make twisted-pair/RJ-45 cables,
and you should do so if you manage a network of any appreciable size (more than 50 workstations).
Knowing how to use these tools and parts to make patch cables or to replace a failed cable is
invaluable. This way, you can quickly make cables of any length you need. However, even though
you should be able to do this, and it can get you out of a jam quickly, you're better off purchasing
premade twisted-pair/RJ-45 cables to use with your network. Professionally made cables are more
reliable and should give you fewer problems than the ones that you make yourself. Make your own
cables when you're in a pinch.
What's All This About Cable Categories?
Twisted-pair network cables are rated in terms of their capability to carry network
traffic. These ratings are defined by the Electronic Industries Alliance (EIA) and the
Telecommunications Industry Association (TIA) and are referred to as Levels 1 and
2 and Categories 3, 4, 5, and 6. The different category levels are simply called Cat-3
through Cat-6. Table 4-3 shows the rated performance for each of these levels.
To achieve a particular performance rating in practice, you not only need cable
certified to that performance level, but you must observe other requirements, including
using connectors and patch cables that also meet that level of performance. For
example, for a Cat-5 installation, you must have Cat-5 cable, connectors, patch panels,
and patch cables. The entire circuit, from where the client computer connects to the hub
connection at the other end, needs to be tested and certified to the performance level
you need to achieve.
Twisted-Pair/RJ-45 Crossover Cable Wiring
Cable End 1
Cable End 2
Wire Base Color Wire Stripe Color
Wire Base Color
Wire Stripe Color