| |
| HOME > INFORMATION
CENTER > FAQ |
| | |
FAQ
| Q: |
What is the
difference between 568A and 568B wiring schemes? |
| A: |
8-Position Modular Jack Pair Assignments
for UTP Application Specific Pair Assignment for 8-Position
|
T568A Pin # / Conductor
Color Code
1 white/green
2 green
3 white/orange
4 blue
5 white/blue
6 orange
7 white/brown
8 brown |
|
T568B Pin # / Conductor
Color Code
1 white/orange
2 orange
3 white/green
4 blue
5 white/blue
6 green
7 white/brown
8 brown
TOP |
|
| Q: |
What
are the EIA/TIA Specifications for Category 5, 5e and
the proposed Category 6? |
| A: |
EIA/TIA Proposed Specs |
| Specification |
Category 5 |
Category 5E |
Category 6(Proposed) |
| Frequency Range |
1-100 MHz |
1-100 MHz |
1-200 MHz (250?) |
| Attenuation |
24 dB |
24 dB |
21.7 dB |
| NEXT |
27.1dB |
30.1 dB |
39.9 dB |
Power sum NEXT |
N/A* |
27.1 dB |
37.1 dB |
| ACR |
3.1 dB |
6.1 dB |
18.2 dB |
| Power sum ACR |
N/A* |
3.1 dB |
15.4 dB |
| ELFEXT |
17 dB* |
17.4 dB |
23.2 dB |
| Power sum ELFEXT |
14.4 dB* |
14.4 dB |
20.2 dB |
| Return Loss |
8 dB* |
10 dB |
12.0 dB |
| Propagation Delay |
548 ns* |
548 ns |
548 ns |
| Delay Skew |
50 ns* |
50 ns |
50 ns * |
| Not specified
for Category 5. Shown only for comparison. - TOP
|
| Q:
|
Can I use Cat
5 to connect different buildings? |
| A: |
Fiber is highly recommended, this
will eliminate ground loops, mismatched ground potentials,
and the possibility of a power surge affecting both building
via the network cable. - TOP
|
| Q: |
Where should
I Use Fiber? |
| A: |
The use of fiber only needs to be
considered for use in the backbone (the connect between
telecommunications closets) to retain electrical isolation
between buildings or additions or where distances exceed
that of traditional cable. - TOP
|
| Q: |
How far can
I run 10BaseT? |
| A: |
10BaseT is 10MHz Ethernet running
over unshielded, twisted-pair cabling. 10BaseT is accepted
to have a maximum run of 100-115 meters, but is based
on signal loss in Dbs (11.5db maximum loss source to destination).
10BaseT networks are star-wired, so there is no minimum
distance requirement between devices as described in this
document because devices cannot be connected serially.
- TOP |
| Q: |
How many cables
should be run to an office location? |
| A: |
The standards specify that two jacks
should be placed at each outlet location. The jacks can
be on the same wall plate. A separate Category 5 wire
should be run from the telecommunications closet to each
jack. If one jack and wire system fails at the location,
there is a second as a reserve. This avoids the need for
immediate repair to maintain service at that location.
It is recommended that a minimum of two wall outlet locations
be installed in each office. One telecommunications outlet
can be associated with voice and/or video; the other can
be associated with data. As a result, a normal office
location would have a minimum of two voice and two data
cables. More would be required for special devices such
as faxes, system printers or other network devices. -
TOP |
| Q: |
What is the
difference between plenum or nonplenum? |
| A: |
Plenum or nonplenum wire refers to
the outside insulation used on the wire. Nonplenum wire
uses a standard PVC plastic for the insulation; plenum
wire has special plastic insulation around it which, in
case of a fire, has special nontoxic fume characteristics.
Plenum wire typically is double the cost of nonplenum
wire. Safety considerations, as well as building and fire
codes, will determine the use of plenum or nonplenum wire.
- TOP |
| Q: |
What is Near-End
Crosstalk (NEXT)? |
| A: |
Near-End Crosstalk is easiest to
understand if you imagine yourself speaking into a telephone.
Normally, as you speak you can hear the person on the
other end and also hear yourself through the handset.
Imagine how it would sound if your voice was amplified
so it was louder than the other person's. Each time you
spoke you'd be deaf to anything coming from the other
end. A cable with inadequate immunity to NEXT couples
so much of the signal being transmitted back onto the
receive pair (or pairs) that incoming signals are unintelligible.
A properly installed network minimizes any Near-End Crosstalk.
- TOP |
| Q: |
What is Attenuation?
|
| A: |
A signal traveling on a cable becomes
weaker the further it travels. Each interconnection also
reduces its strength. At some point the signal becomes
too weak for the network hardware to interpret reliably.
Particularly at higher frequencies (10MHz and up) UTP
cable attenuates signals much sooner than does coaxial
or shielded twisted pair cable. Attenuation is the weakening
(or loss) of signal strength. Knowing the attenuation
(and NEXT) of a link allows you to determine whether it
will function for a particular access method, and how
much margin is available to accommodate increased losses
due to temperature changes, aging, etc. - TOP
|
| Q: |
What are the
basic types of Fiber Cable? |
| A: |
There are 5 basic types of fiber
cable, which include: |
1 - Multimode (MM) Fiber - Step index
or graded index fiber. In North America the most common size
is 62.5/125; in Europe, 50/125 is often used. These numbers
represent the diameter of the core (62.5) and diameter of the
cladding (125) in microns. Multimode fiber is typically used
in applications such as local area networks, at distances less
than 2 km.
2 - Single Mode (SM) Fiber - Single mode fiber has a very small
core. Typical values are 5-10 microns. Single mode fiber has
a much higher capacity and allows longer distances than multimode
fiber. Typically used for wide area networks such as telephone
company switch to switch connections and cable TV (CATV).
3 - Loose Buffer - The fiber is contained in a plastic tube
for protection. To give better waterproofing protection to the
fiber, the space between the tubes is sometimes gel-filled.
Typical applications are outside installations. One drawback
of loose buffer construction is a larger bending radius. Gel-filled
cable requires the installer to spend time cleaning and drying
the individual cables, and cleaning up the site afterwards.
4 - Tight Buffer - Buffer layers of plastic and yarn material
are applied over the fiber. Results in a smaller cable diameter
with a smaller bending radius. Typical applications are patch
cords and local area network connections. At least one mfr.
produces this type of cable for inside/outside use.
5 - Ribbon Cable - Typically 12 coated fibers are bonded together
to form a ribbon. There are higher density ribbons (x100) which
have the advantage of being mass-terminated into array connectors.
A disadvantage is that they are often harder, and require special
tools to terminate and splice. - TOP
| Q: |
What are the
common type of Fiber Connectors found in LAN/MAN/WAN installations? |
| A: |
There are four basic types used?
|
FSD - Fixed Shroud Device, such as the FDDI MIC dual-fiber connector.
SC - A push-pull connector. The international standard. The
SC connectors are recommended in SP-2840A. The SC connector
has the advantage (over ST) of being duplexed into a single
connector clip with both transmit/receive fibers.
SMA - Threaded connector, not much used anymore because of losses
that change with each disconnection and reconnection.
ST - Keyed, bayonet-style connector, very commonly used. - TOP
| Q: |
What is the
Minimum Bending Radius for a Cable? |
| A: |
According to EIA SP-2840A (a draft
version of EIA-568-x) the minimum bend radius for UTP
is 4 x cable outside diameter, about one inch. For multipair
cables the minimum bending radius is 10 x outside diameter.
|
SP-2840A gives minimum bend radii for Type 1A Shielded Twisted
Pair (100 Mb/s STP) of 7.5 cm (3-in) for non-plenum cable, 15
cm (6-in) for the stiffer plenum-rated kind.
For fiber optic cables not in tension, the minimum bend radius
is 10 x diameter; cables loaded in tension may not be bent at
less than 20 x diameter. SP-2840A states that no f/o cable will
be bent on a radius less than 3.0 cm (1.18-in).
The ISO DIS 11801 standard, Section 7.1 General specs for 100
ohm and 120 ohm balanced cable lists three different minimum
bend radii. Minimum for pulling during installation is 8x cable
diameter, minimum installed radius is 6x for riser cable, 4x
for horizontal.
Some manufacturers recommendations differ from the above, so
it is worth checking the spec sheet for the cable you plan to
use. - TOP
Return
To Services
|
| |
| New Line Communications,
Inc. | 901 South Bolmar St. | Suite B.
West Chester, PA 19382
©2008 New Line Communications, Inc.
|  | |
