Today, your network cabling system carries the lifeblood of your organization - INFORMATION.
Cabling is the veins carrying the lifeblood of your organization
The installation, material, quality of cable and testing procedures are all much more critical in data wiring than in voice. The main reason for this is that networks today are designed to carry large amounts of information at incredible speeds. To accomplish this over unshielded twisted pair cable (UTP), many different criteria must be met.
Who sets the criteria and standards for network cabling?
The three major players are The Institute of Electrical and Electronics Engineers (IEEE - commonly called I-triple-E ) who work on developing new protocols, the American National Standards Institute (ANSI), and the Telecommunications Industry Association / Electronic Industry Alliance (TIA/EIA) who issue the standards and testing procedures.
Suffice it to say that these people have been busy over the past 12 years - as we've seen network speeds increase from 10 million bits of information per second, over Category 3 wire, back in 1991 to 1 billion bits (called Gigabit Ethernet) today. With bandwidth increasing and reliance on the network at an all time high, getting information to where it needs to be is becoming more challenging than ever. Ask any IT Manager what their most common network problem is and you will most likely hear them rant about cabling issues. In fact, cabling problems, which account for over 50% of network problems, cost companies millions annually. The most common problems are:
- Low attenuation
- Poor NEXT (near-end crosstalk)
- Poor ACR (attenuation-to-crosstalk ratio)
- Poor delay skew (data arrives at different times)
- Poor return loss (also known as "echo")
- Poor ELFEXT (equal-level far-end crosstalk) numbers for cable, connecting hardware and channel
- Splices in cable
Cat5, Cat 5E
Category 5 cable, commonly known as Cat 5, is an unshielded twisted pair cable type designed for high signal integrity. Category 5 has been superseded by the Category 5e specification. This type of cable is often used in structured cabling for computer networks such as Ethernet, although it is also used to carry many other signals such as basic voice services, token ring, and ATM (at up to 155 Mbit/s, over short distances).
The original specification for category 5 cable was defined in ANSI/TIA/EIA-568-A, with clarification in TSB-95. These documents specified performance characteristics and test requirements for frequencies of up to 100 MHz.
Category 5 cable includes four twisted pairs in a single cable jacket. It is most commonly used for 100 Mbps networks, such as 100BASE-TX Ethernet, although IEEE 802.3ab defines standards for 1000BASE-T - Gigabit Ethernet over category 5 cable. Cat 5 cable typically has three twists per inch of each twisted pair of 24 gauge copper wires within the cable.
The twisting of the cable reduces electrical radio frequency interference which causes crosstalk. Also, the wires are insulated with a plastic (FEP) that has low optical dispersion, that is, the dielectric constant of the plastic does not depend greatly on frequency. Special attention also has to be paid to minimizing impedance mismatches at connection points.
Cat 5e cable is an enhanced version of Cat 5 that adds specifications for far end crosstalk. It was formally defined in 2001 in the TIA/EIA-568-B standard, which no longer recognizes the original Cat 5 specification. Although 1000BASE-T was designed for use with Cat 5 cable, the tighter specifications associated with Cat 5e cable and connectors make it an excellent choice for use with 1000BASE-T. Despite the stricter performance specifications, Cat 5e cable does not enable longer cable distances for Ethernet networks: horizontal cables are still limited to a maximum of 90m (295ft) in length. Cat 5e cable performance characteristics and test methods are defined in TIA/EIA-568-B.2-2001.
Cat 6 & Cat 6a
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 5/5e 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) connections. 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 gauge wire, so long as the cable meets the specified testing standards. When used as a patch cable, Cat-6 is normally terminated in RJ-45 electrical connectors, although some Cat-6 cable may be difficult to attach RJ-45 connectors without a special modular piece and is technically not standards 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 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, frequently referred to as "Category 6a", that operate at frequencies up to 500 MHz and will provide up to 10 Gbit/s throughput.
Cat 7 – Commonly used in Europe
Category 7 cable (CAT7), (ISO/IEC 11801:2002 category 7/class F), is a cable standard for Ethernet and other interconnect technologies that can be made to be backwards compatible with traditional CAT5 and CAT6 Ethernet cable. CAT7 features even more stringent specifications for crosstalk and system noise than CAT6. To achieve this, shielding has been added for individual wire pairs and the cable as a whole.
The CAT7 cable standard has been created to allow 10 gigabit Ethernet over 100 meters of copper cabling. The cable contains four twisted copper wire pairs, just like the earlier standards. CAT7 can be terminated either with RJ-45 compatible GG45 electrical connectors which incorporate the RJ-45 standard or with TERA connectors. When combined with GG-45 or TERA connectors, CAT7 cable is rated for transmission frequencies of up to 600 MHz.