Title:
Category 6 Cable: A Category above the Rest!
Word Count:
842
Summary:
Today's bandwidth expectations mean that Category 5 is strategically
dead. What is a category 6 cable? Despite the fact that the Category 6
standards are only at draft stage, manufacturers are offering a host of
products and claiming that these products comply with the draft
proposals.
Keywords:
Category 6 Cable, Cat-6
Article Body:
Today's bandwidth expectations mean that Category 5 is strategically
dead. The Category 5 Enhanced (5e) standards, which should have been
ratified in August and may be finalized at November's committee meeting,
specify new measurements that provide more margins for 100BaseTX and ATM-
155 traffic. Critically, Category 5e standards make reliable Gigabit
Ethernet connections possible. But many structured cabling suppliers
argue that Category 5e is only an interim solution on the road to
Category 6, which will support at least 200 MHz; in the interests of
sufficient operating margin, the IEEE is requesting a 250-MHz Category 6
specification. Despite the fact that the Category 6 standards are only at
draft stage, manufacturers are offering a host of products and claiming
that these products comply with the draft proposals.
What is a category 6 cable? Out of the three cable categories (Cat-5,
Cat-5e & Cat-6), Category 6 is the most advanced and provides the best
performance. Just like Cat 5 and Cat 5e, Category 6 cable is typically
made up of four twisted pairs of copper wire, but its capabilities far
exceed those of other cable types because of one particular structural
difference: a longitudinal separator. This separator isolates each of the
four pairs of twisted wire from the others, which reduces crosstalk,
allows for faster data transfer, and gives Category 6 cable twice the
bandwidth of Cat 5! Cat 6 cable is ideal for supporting 10 Gigabit
Ethernet, and is able to operate at up to 250 MHz. Since technology and
standards are constantly evolving, Cat 6 is the wisest choice of cable
when taking any possible future updates to your network into
consideration. Not only is Category 6 cable future-safe, it is also
backward-compatible with any previously-existing Cat 5 and Cat 5e cabling
found in older installations.
Category 6, (ANSI/TIA/EIA-568-B.2-1) is a cable standard for Gigabit
Ethernet and other network protocols that is backward compatible with the
Category 5, category 5e and Category 3 cable standards. Cat-6 features
more stringent specifications for crosstalk and system noise. The cable
standard is suitable for 10BASE-T / 100BASE-TX and 1000BASE-T (Gigabit
Ethernet) and is expected to suit the 10000BASE-T (10Gigabit Ethernet)
standards. It provides performance of up to 250 MHz.
The cable contains four twisted copper wire pairs, just like earlier
copper cable standards. Although Cat-6 is sometimes made with 23 gauge
wire, this is not a requirement; the ANSI/TIA-568-B.2-1 specification
states the cable may be made with 22 to 24 AWG gauge wire, so long as the
cable meets the specified testing standards. When used as a patch cable,
Cat-6 is normally terminated in 8P8C often incorrectly referred to as
“RJ-45" electrical connectors. Some Cat-6 cables are too large and may be
difficult to attach to 8P8C connectors without a special modular piece
and are technically not standard compliant. If components of the various
cable standards are intermixed, the performance of the signal path will
be limited to that of the lowest category. As with all cables defined by
TIA/EIA-568-B, the maximum allowed length of a Cat-6 horizontal cable is
90 meters (295 feet). A complete channel (horizontal cable plus cords on
either end) is allowed to be up to 100 meters in length, depending upon
the ratio of cord length: horizontal cable length.
The cable is terminated in either the T568A scheme or the T568B scheme.
It doesn't make any difference which is used, as they are both straight
through (pin 1 to 1, pin 2 to 2, etc). Mixed cable types should not be
connected in serial, as the impedance per pair differs and would cause
signal degradation. To connect two Ethernet units of the same type (PC to
PC, or hub to hub, for example) a cross over cable should be used, though
some modern hardware can use either type of cable automatically.
Return loss measures the ratio of reflected-to-transmitted signal
strength and is the single most difficult test to repeat with consistent
results; at Category 6 levels, the difference between a pass and a fail
can be the amount of bend in a test cord. Return loss is also causing
headaches for connector manufacturers, because the RJ-45 system isn't up
to the job. The final stumbling block with Category 5e ratification
concerns the RJ-45 hardware; Category 6 is committed to RJ-45 for
backward compatibility, but the ISO's proposed Category 7 system will
have a new and as-yet-unspecified connector to accompany its revised
cabling. Today, the return loss problem explains why manufacturers of
Category 6 hardware, which is supposed to be interoperable, claim
Category 6 performance only if you use the manufacturers' matched parts
throughout a channel link.
The Telecommunications Industry Association (TIA) is working to complete
a new specification that will define enhanced performance standards for
unshielded twisted pair cable systems. Draft specification ANSI/TIA/EIA-
568-B.2-10 specifies cable systems, called "Augmented Category 6" or more
frequently as "Category 6a", that operates at frequencies up to 500 MHz
and will provide up to 10 Gbit/s bandwidth. The new specification has
limits on alien crosstalk in cabling systems.
Augmented Category 6 specifies cable operating at minimum frequency of
500 MHz, for both shielded and unshielded. It can support future 10 Gb/s
applications up to the maximum distance of 100 meters on a 4-connector
channel.