Copyright Goodheart-Willcox Co., Inc. 62 Networking Fundamentals RG-8 RG-8, or thicknet, is a very rigid coaxial cable with a solid copper conductor in the center. Th e copper conductor adds to its rigidity and to its overall thickness. RG-8 al- lows for longer segments than other copper-core cables, but because of the diffi culty in handling the cable and its wide diameter, it severely limits the number of cables that can be placed inside a conduit. Th icknet can be found in some network back- bones because of its capability to carry a network signal as far as 500 meters. RG-58 RG-58, or thinnet, is smaller in diameter and easier to work with than thicknet co- axial cable. However, it does not carry a signal as far. RG-58 is still permitted but not recommended for use in new network installations. Twisted Pair Twisted pair is a type of cable that consists of four pairs of twisted conductors. Twisted-pair cable has been available for many years and was fi rst used by telephone companies to carry voice transmissions. Today, twisted pair is the most common choice of network cable. AWG wire sizes range from 18 to 26. Th e AWG wire size 24 is used most often. Th ere are eight categories of twisted-pair cable: Category 1 through Category 8. Th e categories are based on the physical design, such as the number of pairs or twists per foot, and the capabilities of the cable, such as the maximum frequency rating and the data rate. Th e maximum frequency rating and data rate are only two of the mea- surements of a cable’s capabilities. Other measurements to consider are crosstalk, NEXT, and impedance. Twisted-pair cable can also be labeled as UTP (unshielded twisted pair) or STP (shielded twisted pair). Shielding can be applied over the entire cable assembly or over individual pairs of conductors. When shielding is applied to individual pairs of conductors, the shielding protects against crosstalk and outside sources of interfer- ence. Th e problem with shielding individual pairs of conductors is it makes the cable much harder to work with when applying connectors. Th is type of cable is also more expensive than unshielded twisted-pair cable. Two diff erent classifi cations of cable can have the same maximum frequency rating, but as a standard, they will support two diff erent data rates. An example of a cable having the same frequency rating is Category 5 and Category 5e. Both have a frequency rating of 100 MHz, but because Category 5e has a better refl ected loss rating based on NEXT and FEXT, it can be used in networks with a higher data rate standard. What makes this section so confusing is that information about cable Tech Tip You may see references to 10Base2 and 10Base5 in outdated materials located on the Internet. 10base2 and 10base5 were early implementations of network media created from RG-58 and RG-8 cables, respectively. Network+ Note The only RG type of cable listed in the CompTIA Network+ Exam objectives are RG-6 and RG-58. Tech Tip When referring to a category of twisted-pair cable, it is common to use the term Cat for short. For example, it is common to use the term Cat 5 instead of Category 5. 2.1 NET