|
Definitions + Information |
| Category 5 Cable (UTP) (Unshielded
Twisted Pair) |
A multipair (usually 4
pair) high performance cable that consists of twisted
pair conductors, used mainly for data transmission.
Note: The twisting of the pairs gives the cable a
certain amount of immunity from the infiltration of
unwanted interference. category-5 UTP cabling systems
are by far, the most common (compared to SCTP) in the
United States. Basic cat 5 cable was designed for
characteristics of up to 100 MHz. Category 5 cable is
typically used for Ethernet networks running at 10 or
100 Mbps. |
| Category 5 E Cable (enhanced) |
Same as Category 5, except that it is made to
somewhat more stringent standards. The Category 5 E
standard is now officially part of the 568A standard.
Category 5 E is recommended for all new installations,
and was designed for transmission speeds of up to 1
gigabit per second (Gigabit Ethernet). |
| Category 6 |
Same as Category 5 E, except that
it is made to a higher standard. The Category 6 standard
is now officially part of the 568A standard. |
| Category 7 |
Same as Category 6, except that it is made to a
higher standard. The Category 7 standard is still in the
works (as of this writing) and is not yet part of the
568A standard. One major difference with category 7's
construction (as compared with category 5, 5 E, and 6)
is that all 4 pairs are individually shielded, and an
overall shield enwraps all four pairs. Category 7 will
use an entirely new connector (other than the familiar
RJ-45). |
| Category 5 Cable (SCTP) (Screened Twisted Pair) |
Same as above, except that the
twisted pairs are given additional protection from
unwanted interference by an overall shield. There is
some controversy concerning which is the better system (UTP
or SCTP). Category 5 SCTP cabling systems require all
components to maintain the shield, and are used almost
exclusively in European countries. |
Category 5E, RJ45 jack
(Work Area Outlet) |
An 8 conductor, compact, modular, female jack that
is used to terminate category-5E cable at the user (or
other) location. The jack is specifically engineered to
maintain the performance of cat 5E cabling. |
| Category 5E Patch Panel |
A Category 5E Patch Panel is
basically just a series of many category-5E jacks,
condensed onto a single panel. Common panel
configurations are 12, 24, 48, and 96 ports. Patch
panels are typically used where all of the horizontal
cable sections meet, and are used to connect the
segments to the Network Hub. |
| Category 5E Patch Cable |
A Category 5E Patch Cable consists a length of cat
5E cable with an RJ-45 male connector, crimped onto each
end. The cable assembly is used to provide connectivity
between any two category-5E female outlets (jacks). The
two most common are from hub to patch panel, and work
area outlet (jack) to the computer. |
| EIA/TIA 568A Standard |
This standard was published in
July of 1991. The purpose of EIA/TIA 568A, was to create
a multiproduct, multivendor, standard for connectivity.
Prior to the adoption of this standard, many
"proprietary" cabling systems existed. This was very bad
for the consumer. Among other things, the standard set
the minimum requirements for category 5E cable and
hardware. The 568 "standard" is not to be confused with
568A or 568B wiring schemes, which are themselves, part
of the "568A standard". |
| 568A and 568B Wiring Schemes |
When we refer to a jack or a patch panel's wiring
connection, we refer to either the 568A, or 568B wiring
scheme, which dictates the pin assignments to the pairs
of cat 5E cable. It is very important to note that there
is no difference, whatsoever, between the two wiring
schemes, in connectivity or performance when connected
form one modular device to another (jack to Patch
panel, RJ-45 to RJ-45, etc.), so long as they (the two
devices) are wired for the same scheme (A or B). The
only time when one scheme has an advantage over the
other, is when one end of a segment is connected to a
modular device, and the other end to a punch block. In
which case, the 568A has the advantage of having a more
natural progression of pairs at the punch block side.
More on 568 A&B later on. |
| Four Pairs |
| Pair 1: White
/ Blue |
Pair 3: White
/ Green |
| Pair 2: White
/ Orange |
Pair 4: White
/ Brown |
|
| Wiremap |
This is the most basic test that can be performed on
a category-5E segment. Wiremap tests for the basic
continuity between the two devices. In 568A or B, all
eight pins of each device should be wired straight
through (1 to 1, 2 to 2, 3 to 3, etc.). A wiremap
(continuity) test, should also test for absence of
shorts, grounding, and external
voltage. |
| Crosstalk |
Crosstalk is the "bleeding" of
signals carried by one pair, onto another pair through
the electrical process of induction (wires need not make
contact, signals transferred magnetically). This is an
unwanted effect, that can cause slow transfer, or
completely inhibit the transfer of data signals over the
cable segment. The purpose of the wire twists, in
category 5E cable is to significantly reduce the
crosstalk, and it's effects. Two types are: NEXT (Near
End Crosstalk), and FEXT (Far End Crosstalk). Fiber
Optic cable is the only medium that is 100% immune to
the effects of crosstalk. |
| Ambient Noise or
Electromagnetic Interference (EMI) |
Similar to crosstalk, in that it is an unwanted
signal that is induced into the cable. The difference is
that ambient noise (or EMI) is typically induced from a
source that is external to the cable. This could be an
electrical cable or device, or even an adjacent
category 5E cable. |
| Attenuation |
Attenuation is the loss of signal
in a cable segment due to the resistance of the wire
plus other electrical factors that cause additional
resistance (Impedance and Capacitance for example). A
longer cable length, poor connections, bad insulation, a
high level of crosstalk, or ambient noise, will all
increase the total level of attenuation. The 568A
standard, specifies the maximum amount of attenuation
that is acceptable in a category-5E cable segment. |