Cabling : Structured, Network , Data & Voice Cabling
Structured Cabling is a set of standards that determine how to wire a data center, office or building for data or voice communications, typically using Category 5 or Category 6 cable and modular sockets. These standards define how to lay the cabling in a star formation, such that all outlets terminate at a central patch panel (which is normally 19 inch rack-mounted), from where it can be determined exactly how these connections will be used. Each outlet can be 'patched' into a data network switch (normally also rack mounted alongside), or patched into a 'telecom patch panel' which forms a bridge into a Private Branch Exchange (PBX) telephone system, thus making the connection a voice port.
Lines patched as data ports into a network switch require simple straight-through patch cables at the other end to connect a computer. Voice patches to PBXs in most countries require an adapter at the remote end to translate the configuration on 8P8C modular connectors into the local standard telephone wall socket. In the U.S., no adapter is needed, as the 6P6C plug used with RJ11 telephone connections is physically compatible with the larger 8P8C socket and the wiring of the 8P8C is compatible with RJ11.
It is normal to see different color patch cables used in the patch panel to help identify which type of connection is being carried, though the structured cabling standards do not require this, except in the demarcation wall field.
The TIA/EIA standards demand that all eight connectors in the Cat6 cable are connected, resisting the temptation to 'double-up' or use one cable for both voice and data. This is generally a good thing as it means that they fully support features such as Power over Ethernet which require the so-far unused brown cables.
INL Communication'sstructured cabling division specializes in providing both commercial and industrial cabling. Our depth of experience with technology and project management allows us to provide the highest levels of service and quality at extremely competitive rates.
From the design of the structured cable system to installation, testing and documentation, our technical engineers can provide the services you need for a successful installation. Additionally, our technicians receive on-going education through classes and seminars, in order to keep pace with our rapidly changing environment. Certifications from major manufacturers enable INL Communicationto have experienced technicians with up to 10 years of experience!
INL Communicationis a full-service technology Company committed to the highest quality craftsmanship and complete customer satisfaction. Our attention to detail and best practices for installation services allow us the ability to deliver world-class turnkey systems in virtually any type of installation environment. We have created a successful business model with the emphasis on being the company behind the company whcih leads to our success.
Basic types of Computer Cabes
There are several basic types of networks cables appropriate for connecting computers, printers, and other devices in a small area such as a home or small office building:
Cable is the medium through which information usually moves from one network device to another. There are several types of cable which are commonly used with LANs. In some cases, a network will utilize only one type of cable, other networks will use a variety of cable types. The type of cable chosen for a network is related to the network's topology, protocol, and size. Understanding the characteristics of different types of cable and how they relate to other aspects of a network is necessary for the development of a successful network.
The following sections discuss the types of cables used in networks and other related topics.
The quality of UTP may vary from telephone-grade wire to extremely high-speed cable. The cable has four pairs of wires inside the jacket. Each pair is twisted with a different number of twists per inch to help eliminate interference from adjacent pairs and other electrical devices. The EIA/TIA (Electronic Industry Association/Telecommunication Industry Association) has established standards of UTP and rated five categories of wire.
Categories of Unshielded Twisted Pair
Voice Only (Telephone Wire)
Data to 4 Mbps (LocalTalk)
Data to 10 Mbps (Ethernet)
Data to 20 Mbps (16 Mbps Token Ring)
Data to 100 Mbps (Fast Ethernet)
One difference between the different categories of UTP is the tightness of the twisting of the copper pairs. The tighter the twisting, the higher the supported transmission rate and the greater the cost per foot. Buy the best cable you can afford; most schools purchase Category 3 or Category 5. Category 5 cable is highly recommended.
If you are designing a 10 Mbps Ethernet network and are considering the cost savings of buying Category 3 wire instead of Category 5, remember that the Category 5 cable will provide more "room to grow" as transmission technologies increase. Both category 3 and category 5 UTP have a maximum segment length of 100 meters. In Florida, Category 5 cable is required for retrofit grants. 10BaseT refers to the specifications for unshielded twisted pair cable (category 3, 4, or 5) carrying Ethernet signals.
Unshielded Twisted Pair Connector
The standard connector for unshielded twisted pair cabling is an RJ-45 connector. This is a plastic connector that looks like a large telephone-style connector (See fig. 2). A slot allows the RJ-45 to be inserted only one way. RJ stands for Registered Jack, implying that the connector follows a standard borrowed from the telephone industry. This standard designates which wire goes with each pin inside the connector.
Fig.2. RJ-45 connector
Shielded Twisted Pair (STP) Cable
A disadvantage of UTP is that it may be susceptible to radio and electrical frequency interference. Shielded twisted pair (STP) is suitable for environments with electrical interference; however, the extra shielding can make the cables quite bulky. Shielded twisted pair is often used on networks using Token Ring topology.
Coaxial cabling has a single copper conductor at its center. A plastic layer provides insulation between the center conductor and a braided metal shield (See fig. 3). The metal shield helps to block any outside interference from fluorescent lights, motors, and other computers
Fig.3. Coaxial cable
Although coaxial cabling is difficult to install, it is highly resistant to signal interference. In addition, it can support greater cable lengths between network devices than twisted pair cable. The two types of coaxial cabling are: thick coaxial and thin coaxial.
Thin coaxial cable is also referred to as thinnet. 10Base2 refers to the specifications for thin coaxial cable carrying Ethernet signals. The 2 refers to the approximate maximum segment length being 200 meters. In actual fact the maximum segment length is 185 meters. Thin coaxial cable is popular in school networks, especially linear bus networks.
Thick coaxial cable is also referred to as thicknet. 10Base5 refers to the specifications for thick coaxial cable carrying Ethernet signals. The 5 refers to the maximum segment length being 500 meters. Thick coaxial cable has an extra protective plastic cover that helps keep moisture away from the center conductor. This makes thick coaxial a great choice when running longer lengths in a linear bus network. One disadvantage of thick coaxial is that it does not bend easily and is difficult to install.
Coaxial Cable Connectors
The most common type of connector used with coaxial cables is the Bayone-Neill-Concelman (BNC) connector (See fig. 4). Different types of adapters are available for BNC connectors, including a T-connector, barrel connector, and terminator. Connectors on the cable are the weakest points in any network. To help avoid problems with your network, always use the BNC connectors that crimp, rather than screw, onto the cable
Kevlar fiber helps to strengthen the cable and prevent breakage.
A plastic coating is used to cushion the fiber center.
Center (core) is made of glass or plastic fibers.
Fiber Optic Connector
The most common connector used with fiber optic cable is an ST connector. It is barrel shaped, similar to a BNC connector. A newer connector, the SC, is becoming more popular. It has a squared face and is easier to connect in a confined space.
Ethernet Cable Summary
Unshielded Twisted Pair
Not all networks are connected with cabling; some networks are wireless. Wireless LANs use high frequency radio signals or infrared light beams to communicate between the workstations and the file server. Each workstation and file server on a wireless network has some sort of transceiver/antenna to send and receive the data. Information is relayed between transceivers as if they were physically connected. For longer distance, wireless communications can also take place through cellular telephone technology or by satellite.
Wireless networks are great for allowing laptop computers or remote computers to connect to the LAN. Wireless networks are also beneficial in older buildings where it may be difficult or impossible to install cables.
Wireless LANs also have some disadvantages. They are very expensive, provide poor security, and are susceptible to electrical interference from lights and radios. They are also slower than LANs using cabling.
When running cable, it is best to follow a few simple rules:
Always use more cable than you need. Leave plenty of slack.
Test every part of a network as you install it. Even if it is brand new, it may have problems that will be difficult to isolate later.
Stay at least 3 feet away from fluorescent light boxes and other sources of electrical interference.
If it is necessary to run cable across the floor, cover the cable with cable protectors.
Label both ends of each cable.
Use cable ties (not tape) to keep cables in the same location together.
Data & Voice Cabling
The installation, material, quality of cable and testing procedures are all much more critical in data wiring. 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.
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) -Impedance 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.
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
When discussing voice cable, different applications and cable grades can come into play. With the advent of Voice over Internet Protocol (VoIP) the future of telephone cabling may change dramatically. But the fact of the matter is, we are still seeing over 90% of companies wiring for voice the same way it's been done for the last 20 years: using voice grade wire and standard RJ11 jacks at the user end. In most wiring closet, the terminations of choice are still 66 blocks, 110 style terminal blocks, Bix blocks and Krone fields.
Cat 3 Solution Still Has Longevity
These configurations give companies, and the majority of phone vendors, all the flexibility they need at a very reasonable cost. When voice cable is being installed in conjunction with your network cabling, the labor cost is greatly reduced. The cost of Category 3 cable, whether plenum rated or non-plenum, is very reasonable in relation to Category 5, and the jacks, usually 6 conductor USOC, are inexpensive. We generally split the 4 pair voice cable at the user end, and install 2 RJ11 jacks. This is possible because the large majority of phone systems on the market today require only 1 pair of wires, some others require 2 pairs. This gives our customers the option and flexibility to install any combination of phones, modems and analog lines at any location.
Description / Technical Information
Category 3 cable, commonly known as Cat 3, is an unshielded twisted pair (UTP) cable designed to reliably carry data up to 10 Mbit/s, with a possible bandwidth of 16 MHz. It is part of a family of copper cabling standards defined jointly by the Electronic Industries Alliance and the Telecommunications Industry Association. Category 3 was a popular cabling format among computer network administrators in the early 1990s, but fell out of popularity in favor of the very similar, but higher performing, Cat 5 standard. Presently, most new structured cable installations are built with Cat 5e or Cat 6 cable. Cat 3 is currently still in use in two-line telephone systems, although Cat 5 or higher could do the same work while facilitating a transition to VOIP.
Cat 3 & Cat 5
Dual-Purpose Jacks For some customers we will install multiple Category 5 or 5E cables to each user. Their intention is to use one or more of these cables for their telephones and/or modems. Obviously this configuration lends itself to great flexibility, because if they need a third or fourth network connection the network cable is already in place, but at a lesser cost. Each cable is Category 5 rated and needs a separate CAT 5 jack at the user end and a separate port on a rated patch panel in the wiring closet, all more costly than the Category 3 alternative. Unless the individual company has many heavy network users (those with more than 2 networked computers on their desk) we usually recommend the Category 3 solution.