Infrastructure Hardware

Category 7/Class F (ISO/IEC 11801:2002) specifies a frequency range of 1–600 MHz over 100 meters of fully shielded twisted-pair cabling. It encompasses four individually shielded pairs inside an overall shield, called Shielded/Foiled Twisted Pair (S/FTP) or Foiled/ Foiled Twisted Pair (F/FTP). There is a pending class Fa, based on the use of S/FTP cable to 1000 MHz. It can support 10GBASE-T transmissions.

With both types of cable, each twisted pair is enclosed in foil. In S/FTP cable, all four pairs are encased in an overall metal braid. In F/FTP, the four pairs are encased in foil.

Category 7/Class F cable can be terminated with two interface designs as specified in IEC 6063-7-7 and IEC 61076-3-104. One is an RJ-45 compatible GG-45 connector. The other is the more common TERA connector, which was launched in 1999.

Category 7/Class F is backwards compatible with traditional CAT6 and CAT5 cable, but it has far more stringent specifications for crosstalk and system noise. The fully shielded cable virtually eliminates crosstalk between the pairs. In addition, the cable is noise resistant, which makes the Category 7/Class F systems ideal for high EMI areas, such as industrial and medical imaging facilities.
Category 7/Class F cable can also increase security by preventing the emission of data signals from the cable to nearby areas.

The news on bandwidth
The need for increased bandwidth never ceases—the more you have, the more you need. Applications keep getting more complex, and files keep getting bulkier. It won’t be long before you need to increase the speed of your network.

Don’t worry. Black Box experts are ready 24 hours a day to answer your questions. When you click on “Talk to a Tech,” you’ll be talking to a trained expert in seconds. If you need help installing a network, or adding an additional drop, contact us.

Because unshielded twisted-pair UTP cable is by far the most common networking cable, let’s take a brief look at where UTP is headed.

The limits of Category 5
Category 5 (CAT5) cabling is good, solid cable for 100-Mbps LANs. The Category 5 standard has been around since 1991, so it’s well established. You’ll find existing Category 5 installations everywhere. What can Category 5 cable do, and what can’t it do?

If you still have a lot of 10-Mbps equipment, CAT5 cabling will serve your needs. It also handles 100-Mbps Fast Ethernet transmissions very well.

But if you’re running up against the performance limits of a 100-Mbps network, you’ll probably want to upgrade at least parts of your system fairly soon to Category 5e (CAT5e) or higher.

Category 5e: the improved Category 5
Category 5e, also known as Enhanced Category 5, or CAT5e, was ratified in 1999. It’s an incremental improvement designed to enable cabling to support full-duplex Fast Ethernet operation and Gigabit Ethernet.

The main differences between CAT5 and CAT5e can be found in the specifications. The performance requirements have been raised slightly in the new standard.

CAT5e has stricter specifications for Power Sum Equal-Level Far-End Crosstalk (PS-ELFEXT), Near-End Crosstalk (NEXT), Attenuation, and Return Loss (RL) than those for CAT5. Like CAT5, CAT5e is a 100-MHz standard, but it has the capacity to handle bandwidth superior to that of CAT5. With these improvements, you can expect problem-free, full-duplex, 4-pair Ethernet transmissions over your CAT5e UTP.

Category 6
The next level in the cabling hierarchy is Category 6 (CAT6) (ANSI/TIA/EIA-568-B.2-1), which was ratified by the TIA/EIA in June 2002. CAT6 provides higher performance than CAT5e and features more stringent specifications for crosstalk and system noise.

The quality of the data transmission depends upon the performance of all the components of the channel. So to transmit according to CAT6 specs, the jacks, patch cables, patch panels, cross-connects, and cabling must all meet CAT6 standards. (The channel includes everything from the wallplate to the wiring closet.) The CAT6 components are tested individually, and they are also tested together for performance. In addition, the standard calls for generic system performance so that CAT6 components from any vendor can be used in the channel.

CAT6 channel transmission requirements should result in a Power-Sum Attenuation-to-Crosstalk Ratio (PS-ACR) that’s greater than or equal to zero at 200 MHz.

In addition, all CAT6 components must be backward compatible with CAT5e, CAT5, and CAT3. If different category components are used with CAT6 components, then the channel will achieve the transmission performance of the lower category. For instance, if CAT6 cable is used with CAT5e jacks, the channel will perform at a CAT5e level.

Industry standards
The advantage of sticking to the industry standards is the knowledge that your cabling will be compatible with standards applications. But the standards are always being improved upon, and it takes time to ratify a new standard. Often, as with CAT6, the final standard may be different from the proposed standard. For the latest information, contact our FREE Tech Support.

Twisted-Pair Cable Specifications Comparison
Frequency — CAT5, CAT5e: 100 MHz;
CAT6: 250 MHz;
CAT7 (Proposed): 600 MHz
Attenuation (min. at 100 MHz) — CAT5, CAT5e: 22 dB;
CAT6: 19.8 dB;
CAT7 (Proposed): 20.8 dB
Characteristic Impedance — All: 100 ohms ± 15%
NEXT (min. at 100 MHz) — CAT5: 32.3 dB;
CAT5e: 35.3 dB;
CAT6: 44.3 dB;
CAT7 (Proposed): 62.1 dB
PS-NEXT (min. at 100 MHz) — CAT5: no specification;
CAT5e: 32.3 dB;
CAT6: 42.3 dB;
CAT7 (Proposed): 59.1 dB
ELFEXT (min. at 100 MHz) — CAT5: no specification;
CAT5e: 23.8 dB;
CAT6: 27.8 dB;
CAT7 (Proposed): not yet specified
PS-ELFEXT (min. at 100 MHz) — CAT5: no specification;
CAT5e: 20.8 dB;
CAT6: 24.8 dB;
CAT7 (Proposed): not yet specified
Return Loss (min. at 100 MHz) — CAT5: 16 dB;
CAT5e: 20.1 dB;
CAT6: 20.1 dB;
CAT7 (Proposed): 14.1 dB
Delay Skew (max. per 100 m) — CAT5: no specification;
CAT5e: 45 ns:
CAT6: 45 ns;
CAT7 (Proposed): 20 ns