Information Technology Reference
In-Depth Information
TABLE 1.1
Cabling Recommendations for Various Applications
Minimum cable performance categories
Application
Cat 2
Cat 3*
Cat 5e
Analog phone only
Yes
Yes
Yes
LAN/4/10/16 Mbps only
Yes (for runs
Yes (for runs
Yes (for runs
under 100 ft)
under 290 ft)
under 350 ft)
Yes
†
(if 4
Yes
†
(if 4
Yes
†
(if 4 LAN
Shared analog phone and
4/10/16 Mbps
pair cable)
pair cable)
pair cable)
Digital phone only
Not
Yes
Yes
recommended
Shared digital phone and
No
Not
Not
LAN/4/10/16 Mbps
recommended
recommended
Yes/no
‡
LAN 100/1000 Mbps only
No
Yes
Shared digital phone and
No
No
No
LAN 100/1000 Mbps
*Category 5e is required for 100BaseTX and 1000BaseT.
†May not operate at extended distances, particularly with Token-Ring 16 Mbps networks. Higher performance cat-
egory cables will provide better isolation between the phone and data signals.
‡Some 100 Mbps technologies are designed to operate on a minimum of Category 3 cable.
tible to problems from crosstalk, signal balance, interfering signals, magnetic cou-
pling, and noise sources.
The danger of interference from telephone pairs is probably less for the analog
signals of conventional telephones, because they limit transmitted frequencies to 4
kHz or less. However, both analog and digital telephones may use extra wire pairs
for power. This power connection is unbalanced and may serve to increase the unde-
sired coupling effects between pairs in the cable.
Some cabling designers feel that data and telephone wiring should never be
mixed. There is some support for this view from the standards, when interpreted
strictly. None of the standards provide guidelines for the application of two or more
signals to the same cable, although some users simply ignore the issue. The most
widely used standard, TIA/EIA-568-C, simply suggests two cables to each telecom-
munications outlet and recommends that each be used for only one application. If
you are going to provide separate cables for phone and data, you can easily run
them to totally separate areas of a wiring closet, or even to separate wiring closets.
You will never cause a technical problem with either LAN or telephone systems
by separating data and voice cables. On the other hand, you can expect the instal-
lation cost to be higher in almost all cases.
VoIP is a relatively new method of digitizing and transporting voice signals as
conventional IP packets. Voice connections to desk phones can now be made using
