Chapter 1: Introduction

Transcription

1 Chapter 1: Introduction The concept of global village in today s world is based on networking system. Today, we can never imagine our lives without networking. In networking system, data communication or the process of sending data from one location to another location is done electronically. Again, we can never imagine our surroundings at homes or offices without the installation of AC power lines. Because, we all use different electronic and electrical appliances and instruments for the requirements of our modern life styles. Modern life-styles and business world heavily depend upon electrical and electronic services utilizing different electrical/electronic instruments/ devices. For the operation of these electrical/electronic instruments/devices, installation of power lines and power supplies are needed. This implies that today we are surrounded by power lines at our homes, schools/colleges and offices for smooth running of our daily lives and services. Again, for networking which has become a fundamental fact of today s life, installation of networking cable is also essential. Therefore, at our homes or office buildings there are two types of cable installations- one is power line or power cable installation and the other is network cable installation. Currently, Unshielded Twisted Pair (UTP) cable is the most popularly used copper-based cable for networking supporting 10G Ethernet. Ethernet is the most commonly used LAN technology. Although UTP is widely used for networking, the main disadvantage with UTP cable is that it is the most sensitive cable to Electromagnetic Interference (EMI) than any other networking A Study on Effect of AC Power Lines on UTP cable: A Thesis Page 2

2 cables, such as shielded twisted pair (STP) or co-axial cables. The reason behind it is UTP cable offers low cost, ease of installation and supports high speed of data transmission with high bandwidth, low attenuation, low cross-talk. Electromagnetic Interference (EMI) is an undesirable phenomenon, which creates electromagnetic disturbance in the response of electrical or electronic systems. EMI degrades the performance of a system due to the electromagnetic fields making up an electromagnetic environment. Since all electric signals are electromagnetic waves, we are living in an electromagnetic environment. Effect of electromagnetic interference or noise has become an exceptionally crucial issue in the design of modern electronic system. Some of the very common examples of EMI sources are-different types of lightings, electric hand drill, Transceiver set, Fluorescent light, Microwave oven, generators, elevator motors, different medical equipments. Generally most electronic equipments are associated with EMI filters on the front end of their power supplies, which are used to prevent interference or noise conducted from power lines through the power supplies. But noise can couple into the system through the metallic enclosures or through the data lines. UTP cable is very much prone to electromagnetic interference. The probability to be effected by EMI becomes high, when the cable run close to the source of EMI or grounding system is inadequate. The EMI from the source can go through the unshielded cable very easily and can affect the data transmission quality, which may result in shutting down the communication system also. Shielded cables are basically designed to protect the signal transmission through it from sources of EMI powerful enough to generate Electromagnetic Interference. The basic functions A Study on Effect of AC Power Lines on UTP cable: A Thesis Page 3

3 of the shield are to prevent signal loss due to interference and to prevent electromagnetic radiations to interfere with devices. In modern day building structure, some very basic sources of EMI are found close to communication cables. It is not always possible to avoid networking cables from running close to EMI affected area produced by those sources. In this case, shielded cables are advised to use instead of unshielded cables. Shielded cables are costlier than unshielded cables. Therefore, if UTP is the first choice to be used by the users, the first point to note is to maintain an appreciable separation gap between UTP cable and sources of EMI to avoid interference, which may not be always possible. Then the only option is to use shielded cables. High speed data transmission supported by modern systems is getting faster and faster day by day. Therefore, design of systems are becoming harder and harder. During the process of design the things to be considered are power dissipation, data transmission speed, memory capacity and off course, protection against effect of electromagnetic interference which may result in even failure of operations for excessive effect of EMI. During the last years, there has been a rapid increase in the number of electromagnetic emissive sources. Our life is quite comfortable with the uses of cellular phones, digital pagers, fax machine and different medical instruments. Power line, which we found at our surroundings for the operations of different electronic and electrical systems/ devices, is a source of Electromagnetic Interference (EMI) also. Distance between the EMI source and the victim plays an important role in the intensity of effects of EMI. During installation of unshielded cable with the installation of AC power lines A Study on Effect of AC Power Lines on UTP cable: A Thesis Page 4

4 within the same building structure, careful consideration has to be taken regarding all factors, which may affect the data transmission through the networking cable. 1.1 Networking When two or more individual systems with data are interconnected to share services and to interact with each other by means of a shared communication link, a network is created. For example, suppose three s are connected together with a network cable and each of them are also connected to a laser printer to use. Therefore, they create a network and each of them are a part of the network. The size of a network depends upon the need and the necessity of the users. To form networks, all networks must have the following [1]: Data to share A physical pathway, called transmission medium Rules of communication, called protocols Advantages of networking The following are the advantages of networks: Sharing of files, resources and programs. Enhanced Communication between users through and groupware applications. Ease of Connectivity of s throughout the whole world A Study on Effect of AC Power Lines on UTP cable: A Thesis Page 5

5 Improved price and performance ratios because of rapidly decreasing cost of personal s and related hardware. Improved person-to-person communication through , On-line discussion and video conferencing Disadvantages of networking Computer networking has some disadvantages also. They include: Lack of data security and privacy because of unauthorized users or multiuser. High-speed network connection is expensive and has complex wiring. New developed reliable network software are complicated and costly. Crashing of the server on a server-based network because of irregular backups Basic Components of Networking The key Network Components with examples are: Media: Examples are- Twisted pair wire, coaxial cable, fiber optic cable, microwave satellites, Cellular radio and transceivers. Processors: Examples are-modems, multiplexers, concentrators, routers, bridges, Gateways, Front-end processors and client and server s. Software: Examples are- Communication software, network operating system, Netware, Point-to-Point Protocol (PPP), Post Office Protocol A Study on Effect of AC Power Lines on UTP cable: A Thesis Page 6

6 (POP), Simple Mail Transfer Protocol (SMTP), Internet Explorer or Netscape Navigator and middleware. Channels: Examples are -Analog/ digital, switched/non-switched, circuit/massage/packet switching, simplex / duplex, synchronous/asynchronous. Topology: Examples are- Bus, star, ring, mesh and Ethernet. Architecture: Examples are- OSI, Institute of Electrical and Electric Appliances (IEEE), Integrated Services Digital Network (ISDN) and Public Switched Telephone Network (PSTN) Network Topology In a network, each or device, say printer is called a node. Network topology defines how nodes are connected to each other. It is the geometrical arrangement of nodes and cable links in a LAN [1, 2]. Following are the different network topologies: Bus Network Bus network provides the connectivity of each to other s through a single communication cable, so that every can directly communicate with every other or device in the network (fig 1.1). Fig 1.1: Bus Network. A Study on Effect of AC Power Lines on UTP cable: A Thesis Page 7

7 Ring Network In a ring network, a single communication cable is used to connect several s or devices in a closed loop (fig 1.2). Fig 1.2: Ring Network Star Network In a star network, all the devices or s are connected to one common central. Information exchange is done by first sending to the central from the source, which in turn sends them to the destination (fig 1.3). central Fig 1.3: Star Network A Study on Effect of AC Power Lines on UTP cable: A Thesis Page 8

8 Tree Network In a tree network, all the s and devices are linked in a hierarchical fashion as shown in the fig 1.4. Mainframe Fig 1.4: Tree Network Mesh Network In a mesh network, every or device has point-to-point connections between them (fig 1.5). Fig 1.5: Mesh Network A Study on Effect of AC Power Lines on UTP cable: A Thesis Page 9

9 1.1.5 Network Protocols A network protocol is a set of rules and standards for communication between s [1]. Without protocols, the s can only be connected but there will be no communication between them. Because, protocols govern the format of data, the timing, sequencing and error control Network Models A network model is a network architecture. Network models are classified into three categories: The peer-to-peer network where, each of a group is equal in terms of authority and usage (fig 1.6). Each is called a peer, which can share its resources on the net work. Each peer is both a client and a server. There is no specialized servers exist. peer peer peer peer Fig 1.6: Peer-to-peer network. The client/server network, where communication takes place between the client and the server s (fig 1.7). The client requests for services and the server responds to these requests from the client. A Study on Effect of AC Power Lines on UTP cable: A Thesis Page 10

10 . server client client client client Fig 1.7: Client/server network. The Hybrid Network, which is a combination of two or more networks topologies. For example, several star LANs can be connected by a bus or a ring, or a bus that connects several ring networks (fig1.8). Combinations of server-based and peer-to-peer networking models constitute many networking environments. compute compute HUB HUB compute compute compute r Fig 1.8: Hybrid network Hardware and Software of Networks Different hardware and software are needed for establishment of a network. The hardware includes the network interface card (NIC), networking cables and A Study on Effect of AC Power Lines on UTP cable: A Thesis Page 11

11 network devices. The software includes the protocols and the network operating system The Network Interface Card (NIC) A NIC is a device which is integrated into the system motherboard. It enables a to send and receive data across the network by providing an interface between the data bus and the networking medium. Every NIC has a 48-bit long binary address called Media Access Control Address (MAC) and which is used uniquely to identify each node of a Networking Devices Different networking devices are Hubs A hub is used to connect multiple s together. A hub has a number of ports and the different s can be connected to these ports to form a network (fig1.9). HUB Fig: 1.9: Hub. A Study on Effect of AC Power Lines on UTP cable: A Thesis Page 12

12 Switches A switch is used to join multiple s in a network. A switch and a hub are identical, but a switch is much more efficient. Switches are more suitable for use in areas of high network traffic (fig1.10). SWITCH Fig 1.10: Switch Repeaters A repeater is a networking hardware device, which regenerates the transmitted attenuated information carrying signal to its original strength. Bridges A bridge is a network hardware device, whose function is to regenerate the weak signals it receives and to check the physical address of the source and destination nodes (fig 1.11). Bridge Fig 1.11: Bridge A Study on Effect of AC Power Lines on UTP cable: A Thesis Page 13

13 Routers A router (fig1.12) is used to connect LANS and WANs on the internet. It contains a routing table which takes decision about the route of a data packet. The router, when receives a data packet from a source network, checks for the Internet Protocol address of the destination and transfers the data packet to its appropriate destination. Network 2 Network 1 Router Network 3 Fig 1.12: Router Networking Cables Networking cables are the transmission media which carry data from a source to the destination. The data is transmitted though the networking cables in the form of electrical signals or optical signals. Different types of networking cables are: * The twisted pair cable * The coaxial cable * The fiber optical cable Types of Networks The different types of network available are: LAN, WAN and MAN. A Study on Effect of AC Power Lines on UTP cable: A Thesis Page 14

14 Local Area Network (LAN) A LAN is used to connect two or more s within a small area [1, 2]. The area may be a room, an office building or a campus. The range of a LAN is limited to a few kilometers only. Use of LAN enables the users to have a shared access to devices and applications, file exchange between connected users and communication between users. Main benefit of a LAN is that it reduces hardware and software costs because users can share several s and peripheral devices. A LAN generally consists of two or more s, different peripheral devices like modems, printers, plotters etc, networking cables, required software for the operation of the s and a plug-in board to handle the data transmissions. Characteristics of LAN are: high speed data transfer limited range less expensive technology than MAN and WAN. Although LAN works over limited distance, it allows a large number and a variety of computing devices to exchange information among them at high speeds. The number of s in LAN varies widely from small LANs to large LANs. A small LAN can connect 2 to 25 s while a large LAN can connect more than 10,000 s. The data transmission rate for LAN technologies is up to 10Gbit/s. A Study on Effect of AC Power Lines on UTP cable: A Thesis Page 15

15 Wide Area Network (WAN) A WAN is used to connect s with communication facilities covering a wide geographical area [1, 2]. WAN connects different metropolitans, countries and national boundaries. WANs can be interconnected with LANs. A WAN connection may be entirely within a state or country or it may have interconnection around the world. Different available Protocols for WAN are X.25, TCP/IP, Frame Relay. The transfer rate of these protocols is around 1Mbit/s or less. WAN is involved with a public telecommunication authority. The use of WAN is limited by the large organizations and government agencies. Characteristics of WAN are: WAN interconnects multiple LANs, covers an unlimited geographical area, but susceptible to errors due to the distances involved. WAN technology is expensive, more sophisticated and complex than LANs. Categories of WANs are: Enterprise WANs: Used to connect all LANs of a single organization those are located at great distances. Global WANs: Used to interconnect the networks of several corporations and organizations. Internet is the most common example of WAN. A Study on Effect of AC Power Lines on UTP cable: A Thesis Page 16

16 Metropolitan Area Network (MAN) MANs technology is similar to LAN but it is a bigger version of LAN [1, 2]. Its network coverage is between LAN and WAN. MAN generally connects two or more LANs or Campus Area Networks (CANs). MAN acts as a backbone to connect several LANs of an organization. Apart from these three main types of networks namely, some other types of networks are also available. They are Personal Area Network (PAN), Campus Area Network (CAN), Global Area Network (GAN), Value Added Network (VAN), Virtual Private Network (VPN), Wireless /Mobile Network LAN Technologies Various existing LAN technologies to help to establish LAN are Ethernet, Token Ring, Token Bus and FDDI. Ethernet Today, the most widely accepted and commonly used LAN technology is Ethernet [1, 3]. Ethernet is developed by DIX (Dec, Intel and Xerox corporation) and is a registered trademark name with Xerox corporation. Ethernet is standardized as IEEE Ethernet transmission data rate is million bits per second or Mbps. Ethernet has gone through four generations based on the speed of data transfer. They are: Standard Ethernet, Fast Ethernet, Gigabit Ethernet and Ten-Gigabit Ethernet. A Study on Effect of AC Power Lines on UTP cable: A Thesis Page 17

17 Standard Ethernet The data transfer rate of Standard Ethernet is 10Mbps. The original Standard Ethernet is divided into following types: 10Base5: Thick Ethernet or Thicknet. 10Base2: Thin Ethernet or Chipernet. It is more economical than 10Base5. 10Base-T: Twisted Pair Ethernet. It grows in popularity because of its reliability and flexibility and easy installation than the previous two. 10Base-F: Fiber Ethernet. It consists of three types, namely, 10BaseFL, 10BaseFB and 10BaseFP. The following table1.1 shows Standard Ethernet implementations with media and lengths. Table 1.1: Standard Ethernet implementations Characteristics 10Base5 10Base2 10Base-T 10Base-F Media Thick coaxial Thin coaxial 2 UTP 2 Fiber cable cable Maximum 500 m 185 m 100 m 2000m length Fast Ethernet Fast Ethernet transfers data 10 times faster than the Standard Ethernet. Its data transfer rate is 100Mbps. Fast Ethernet is divided into following types: A Study on Effect of AC Power Lines on UTP cable: A Thesis Page 18

18 100BaseT4: It uses all the four pairs of wires in the cable. It was the first type to be introduced as of Fast Ethernet. 100BaseTX: It uses two pairs of twisted pairs of cable. It is generally used in office networks. 100BaseFX: It uses two pairs of optical fiber cable. It is generally used as a backbone for networks. The following table1.2 shows Fast Ethernet implementations with media and lengths. Table 1.2: Fast Ethernet implementations Characteristics 100Base-T4 100Base-TX 100Base-FX Media Cat 4 UTP Optical Fiber Cat 5 UTP or STP Number of wires Maximum length 100m 100m 100m Gigabit Ethernet The data transfer rate of the Gigabit Ethernet is 1Gbps or 1000Mbps which is 100 times faster than the original Standard Ethernet. Gigabit Ethernet is divided into following different types: 1000Base-T: Refers to a standard type of four-wire implementation of Gigabit Ethernet.Uses UTP CAT5 cable, but CAT5e or CAT6 is preferred. A Study on Effect of AC Power Lines on UTP cable: A Thesis Page 19

19 1000Base-SX: Refers to a type of Gigabit Ethernet using optical fiber. It is a short wave two-wire implementation. 1000Base-LX: Refers to a type of Gigabit Ethernet using optical fiber. It is a long wave two-wire implementation. 1000Base-CX: Refers to a type of Gigabit Ethernet using STP cable. It is a two wire implementation. The following table 1.3 shows Gigabit Ethernet implementations with media and lengths. Table 1.3: Gigabit Ethernet implementations Characteristics 1000Base-T 1000Base- 1000Base- 1000Base- SX LX CX Media Cat 5 UTP Fiber short wave Fiber long wave STP Number of wires Maximum 100m 550m 5000m 25m length Ten-Gigabit Ethernet Ten-Gigabit Ethernet is called as Standard 802.3ae created by IEEE committee. It is designed to upgrade the data rate to 10Gbps. It is designed A Study on Effect of AC Power Lines on UTP cable: A Thesis Page 20

20 using fiber optic cable over long distances. The most common implementations are: 10GBase-S, 10GBase-L and 10GBase-E. The following table 1.4 shows Ten-Gigabit Ethernet implementations with media and lengths. Table1.4: Ten-Gigabit Ethernet implementations. Characteristics 10GBase-S 10GBase-L 10GBase-E Media Short-wave Long-wave Extended 1550-nm 850-nm 1310-nm single mode multimode Single mode Maximum 300 m 10 km 40 km length Token Ring Token Ring is a LAN technology based on ring topology (fig1.13). It is developed by International Business Machines (IBM) and is standardized as IEEE Token Ring transfers data at a rate from 4Mbps to 16Mbps. It uses UTP cable and two of four pairs of cable wires. Token Bus Token Bus is another type of LAN technology based on bus topology (fig 1.14). It is standardized as IEEE802.4 and is designed for large organizations. A Study on Effect of AC Power Lines on UTP cable: A Thesis Page 21

21 Token ring Fig 1.13: Token Ring Fig 1.14: Token Bus Fiber Distributed Data Interface Fiber Distributed Data Interface (FDDI) is a standard LAN technology using fiber optic cable. Its data transfer rate is 100Mbps. FDDI is based on the ring topology. It uses a dual ring model of a primary ring and a secondary ring. The flow of data in primary ring and secondary ring are in opposite directions. A Study on Effect of AC Power Lines on UTP cable: A Thesis Page 22

22 Basic model of Ethernet The fig 1.15 shows a very simple model of Ethernet network design for a small office consisting of UTP cabling that runs from a file server to several workstations with a printer. For UTP cabling the combined cable length connecting workstations and printer should not exceed 100 meters. printer S E R V E R Fig 1.15: A simple Ethernet network with a printer. 1.2 Cabling Cabling can be classified into following types [4]: Campus cabling: Campus cabling is used to connect and integrate the network within an overall area containing more than one building. Campus cabling is usually optical fiber based and connects the main wiring closets on different buildings. Riser/Backbone cabling: Riser or backbone cabling uses screened or unscreened pair cables and used for data and telephones. It connects A Study on Effect of AC Power Lines on UTP cable: A Thesis Page 23

23 the house central wiring closet to wiring closets on different building floors. Horizontal cables: Horizontal twisted pair (UTP and FTP) cables provide the communication link between and into specific work areas for high speed networks. These cables can be used in lengths of up to 90 meters. 24AWG is the most commonly used thickness for fixed wiring. Work area cabling: High performance flexible work area cables are available unscreened or Foil Screened and used for localized linking from a wall connection to networked equipment. Patch cables: Patch cables are generally available unscreened or foil screened. These cables are used to interconnect different communication equipment Types of Networking Cables Data with information moves from one network device to another device through networking cable. Networking cable is the transmission medium to transmit data from one end to another end. Different types of cables are available, which are commonly used with LANs. Selection of the type of cable for a network depends upon the network s topology, size, protocol and expenditure also. Networking cables are broadly divided into two types copper and fiber. Different types of networking cables offer different levels of performance. They are: A Study on Effect of AC Power Lines on UTP cable: A Thesis Page 24

24 Twisted Pair (TP) cable Co-axial cable Fiber Optic cable Twisted Pair (TP) and co-axial cables are copper based cables. Copper cabling has been used for decades to provide communication. Copper is a good conductor of electricity. The signals through copper cable are electric signals. Fiber optic cables are made of glass or plastic. The signals through fiber cables are optical signals Twisted Pair Cables A Twisted Pair (TP) consists of two copper wires, twisted together, each with its own plastic insulation [4-8]. When electric current flows through a copper wire, a small circular magnetic field is created around the wire. When two current carrying wires of an electrical circuit are in close proximity, the two magnetic fields are the exact opposite of each other. Hence they cancel each other out. They also cancel out any outside magnetic fields. This cancellation effect is enhanced when the two wires are twisted. Cable designers provide a self-shielding technique against signal noise and cross-talk for wire pairs using the cancellation effects together with twisting the wires. There are two types TP cables. They are: Unshielded Twisted Pair (UTP) cable Shielded Twisted Pair (STP) cable. A Study on Effect of AC Power Lines on UTP cable: A Thesis Page 25

25 Unshielded Twisted Pair (UTP) Cabling Types of UTP cable vary from telephone wire cable to extremely high speed data supporting cable.utp cable contains 8 wires, each 2 wires twisted together into 4 pairs with a plastic jacket. The characteristic impedance of each pair is 100 Ohms +/- 15%. Copper conductors of 24 gauge ( mmdiameter) or optionally 22 gauge ( mm diameter) are used. Depending on the number of twisted pairs and the application, each pair of UTP cable performs different function. EIA/TIA-568 standard specifies the electrical and physical requirements for all types of cables. This standard also specifies the color coding, cable diameter and electrical characteristics for cables. UTP cable must follow precise specifications about the number of twists permitted per meter of cable. Categories of UTP Cabling EIA/TIA-586 has categorized 6 different categories of UTP cables by the number of twists/foot. UTP cable with higher category number has more twists/foot with better signal quality. Higher category number UTP cables are technically more advanced than lower category number UTP cables. Table 1.5 shows different categories of UTP cable with their data rates, transmission frequency and uses. A Study on Effect of AC Power Lines on UTP cable: A Thesis Page 26

26 Table1.5: Different categories of UTP cable Category of UTP cable Data Rate, Frequency Uses Category 1(CAT1) Up to 1Mbps Traditional Telephone and ISDN-Modem Category 2(CAT2) Up to 4Mbps Token Ring, ARCnet Category 3(CAT3) Up to 10Mbps,16MHz Token Ring and 10Base-T Category 4(CAT4) Up to 16 Mbps, 20MHz Token Ring Category 5(CAT5) Up to 100 Mbps,100MHz Ethernet (10Mbps), Token Ring (16Mbps) and Fast Ethernet (100Mbps) Category 5e(CAT5e) Up to 1000 Gigabit Ethernet Category 6(CAT6) Mbps,100MHz Up to 1000Mbps,250MHz Gigabit Ethernet CAT5, CAT5e, CAT6 cables are popularly utilized for structured cabling system in the modern building s communication infrastructure. They can support any voice, imaging and data applications. Performance of UTP cables are guaranteed up to 100 meters between devices. Technically, the distance limitation is 90 meters for structured cabling and a total of 10 meters for patch cords on either end. A Study on Effect of AC Power Lines on UTP cable: A Thesis Page 27

27 UTP Connector The most common UTP connector is RJ-45 (RJ stands for registered jack) [9]. It is an 8-position, 8-contact (8P8C) modulator plug and jack. The RJ-45 is a keyed connector, meaning the connector can be inserted in only one way. RJ-45 was originally patented in 1975 by Western Electric Company. Since that time, RJ-45 has gone through many technical improvements to overcome cross-talk as data rates have evolved from 16MHz for CAT3 to 500MHz for the latest Category 6a standard. Advantages of UTP cable Advantages of UTP cable system are: UTP cable is a thin, flexible cable which is easy to string between walls. Again, since UTP is small, it does not quickly fill up wiring ducts. UTP uses two wires rather than one for each signal. Use of two wires allows the use of differential signaling. Differential signaling is more immune to the effects of external electrical noise. In UTP cable, each pair is twisted. Twisting keeps the wires of a signal s pair as close as possible and hence periodically exposes the opposite side of the pair to the noise which helps to cancel out the effects of outside interference. Again, each pair has a different twist pitch and therefore the pairs also appear twisted to each other which helps to reduce cross talk between the pairs. A Study on Effect of AC Power Lines on UTP cable: A Thesis Page 28

28 Since UTP cable is with no shielding, it reduces the cost, size and installation time of the cable and connectors. It also eliminates the possibility of ground loops. Disadvantages of UTP cable UTP cable is more prone to electrical noise and interference than other types of networking media. The distance between signal boosts is shorter for UTP than it is for coaxial and fiber optic cable. Shielded Twisted Pair (STP) Cable STP is a version of the twisted pair cable created by IBM. It is an insulated cable which includes bundled pairs wrapped in a foil shield. This type shielding protects the cables from external electromagnetic interferences and crosstalk [2, 3, 8]. STP is more difficult to install than UTP or coaxial cable.stp costs more than UTP but is less expensive than thick coaxial cable or fiber optic cable. The biggest difference between UTP and STP is the reduction of interference of EMI provided by STP s shielding. However, STP still suffers from relatively low immunity from interference. STP suffers from attenuation at a rate similar to UTP. Current technology restricts the effective range of STP to 100 meters for supporting Fast Ethernet (100 Base TX). But when used to support 10G Ethernet (1000 Base CX), the effective range is limited to 25m only. A Study on Effect of AC Power Lines on UTP cable: A Thesis Page 29

29 New Generation Cabling Category7 (Cat7) is the new generation cabling supporting 10G Ethernet Standard [5]. Cat7 is also called SSTP (Shielded Screen Twisted Pair). It also consists of 4pairs of twisted wires like UTP cable, each pair of wires is individually wrapped in a helical metallic foil followed by a metallic foil shield in addition to the outside sheath. Use of shielding reduces the effect of crosstalk and supports a data rate up to 600MHz Co-axial cable A coaxial cable consists of two concentric conductors. The inner conductor is of solid copper, which is also called the core conductor. The outer conductor, which serves as a second conductor, also serves as a shield against noise. Between the two conductors, there is an insulating material and the whole cable is covered with a cable jacket. The cover shields the cable from electromagnetic interference as well as from physical danger [2, 3]. Coaxial cables bandwidth potential increases with the diameter of the inner conductors. The cost of coaxial cable also increases with the diameter and composition of the conductors. The cost of thin coaxial cable is less than UTP and STP and the cost of thick coaxial cable is more than UTP and STP cable. Coaxial cable suffers from high attenuation, but at a much lower rate than twisted pair cables. While copper wire generally is a poor resistor to EMI, the shielding provided by coaxial cable greatly reduces its effects. A Study on Effect of AC Power Lines on UTP cable: A Thesis Page 30

30 Categories of Co-axial Cables The RG (radio government) ratings are used to categorize the co-axial cables. Different RG ratings denote different set of physical specifications and are used for different specialized function. The following table 1.6 shows different categories of co-axial cable. Table 1.6: Different categories of co-axial cable Category Impedance Use RG-59 75Ω Cable TV RG-58 50Ω Thin Ethernet (10Base 2) RG-11 50Ω Thick Ethernet (10 Base 5) Co-axial Cable Connectors The most common type co-axial cable connector is the BNC (Bayone-Neill- Concelman) connector. There are 3 types of BNC connectors: the BNC connectors, the BNC T connectors and the BNC terminator. For connection in Ethernet networking, the BNC T connector is used Other copper cables There are two main types of other copper cables. They are twinaxial ( twinax ) and single pair full-duplex [10]. A Study on Effect of AC Power Lines on UTP cable: A Thesis Page 31

31 Twinaxial copper cable Twinaxial cable is similar to co-axial cable, but it has two parallel conductors instead of one. It is an excellent choice for high speed data transmission, but is relatively expensive. Twinaxial copper cable has not been specified for deployment by the LAN or WAN standards bodies. It is used primarily in mainframe rooms to connect various peripherals to the or front-end processor. It provides a BER better than according to Cisco. Single-pair full duplex (POTS) cable POTS cable is an UTP cable with full-duplex (simultaneous transmit and receive) capability over a single pair of wires. Its use has been limited primarily to analog voice-band service applications Fiber Optical Cable In a fiber optical cable, the signal propagates in the form of light [1-3, 11].It has two concentric layers. The inner one is called the core, which is made up of glass or plastic. The outer one is called the cladding, which is also made up of glass or plastic, but it is less dense than the core. If the cladding is made of glass, then there is also a plastic protective jacket. The fiber optic cable has greater bandwidth than the copper cables. Due to greater bandwidth, current technology supports data rates from 100 Mbps to over 2Gbps, at distances from 2kms to 25kms. The supporting data rate of a fiber optic system depends upon the composition of the used fiber, the mode A Study on Effect of AC Power Lines on UTP cable: A Thesis Page 32

32 supported by the system and the wavelength of the transmitted light. Optical fiber transmits data at very high speed without errors. The transmitted signals through the optical fiber are in the form of light. Therefore, they are not subjected to electromagnetic interference (EMI). Fiber optic cables attenuate much less than any copper cable. They have extremely low attenuation rates. The transmitted light signal is well confined within the optical fiber cable, so no loss or leakage of light signal occurs. Optical fiber cable is ideal for hazardous, high voltage or eavesdropping-sensitive environments. Advantages of Optical Fiber cables are: Low cost Small size and light weight Immunity to interference Signal security Electrical isolation Low transmission loss and wide bandwidth There are two types of optical fibers: single mode fiber and multimode fiber. Light signal can transverse the multimode fiber in many modes. But single mode fiber allows only one mode of light propagation. The fiber diameter is 8.5 microns for single mode and 50 or 62.5 microns for multimode fiber. There are three operating wavelengths for fiber-optic systems: 850nm, 1300nm or 1550nm. The transmitted light signals are commonly referred to by their wavelength, expressed in nanometers (nm). Optical fiber signals are in the A Study on Effect of AC Power Lines on UTP cable: A Thesis Page 33

33 infrared portion of the spectrum, 850nm and 1300nm are the most common wavelengths. by type. The following table 1.7 gives [13] the specifications for optical fiber cable Table 1.7: Specifications for optical fiber cable Cable Type Cable Type Maximum Minimum Wavelength Attenuation Bandwidth 62.5 µm MM 850 nm 3.5 db/km 500 MHz-km 1300 nm 1.5 db/km 500 MHz-km 50 µm MM 850 nm 3.5 db/km 160 MHz-km 1300 nm 1.5 db/km 500 MHz-km 8.3 µm SM 1300 nm 1.0 db/km n/a 1550 nm 0.5 db/km n/a Installation of fiber optic cable is comparatively much more expensive than any type of copper cable. Special care has to be taken to ensure that the light path is not obstructed, at every fiber junction or connection. During installation, the optical fiber should not be excessively stretched or bended Comparison between all types of cables The following table 1.8 gives a comparison between all types of cable. A Study on Effect of AC Power Lines on UTP cable: A Thesis Page 34

34 Table 1.8: A comparison between all types of cable Cable Cost Installation Capacity Range EMI type Co-axial Less than Inexpensive/ 10Mbps 185 m Less Thinnet STP Easy typical sensitive than UTP Co-axial Greater than Easy 10Mbps 500 m Less Thicknet STP,less than typical sensitive fiber than UTP STP Greater than Fairly easy 16Mbps 100m Less UTP, less typical to typical sensitive Than thicknet 500Mbps than UTP UTP Lowest Inexpensive/ 10Mbps 100m Most Easy typical to typical sensitive 100Mbps Fiber Highest Expensive/ 100Mps 10s of Insensitive Optic difficult typical to as Km high as 200,00Mbps A Study on Effect of AC Power Lines on UTP cable: A Thesis Page 35

35 1.2.7 Cable Parameters of Interest There are six parameters of interest for twisted-pair cable [10], which can be determined from measurements using some special-purpose instruments. They are namely: Z 0, the characteristic impedance Length, the physical length of the cable Crosstalk, the coupling between adjacent pairs in the cable Resistance, the dc resistance of the copper conductors Attenuation, the signal loss at a specified frequency Wire map, the connector-to-connector wiring by pin numbers The measurements for coaxial cable are the same for twisted-pair cable except crosstalk and wire mapping Network Cabling Troubles One of the most common source of problems on a network is the network cabling. Cabling problems may result in many problems, such as disconnecting workstations, slow network services, packet errors and unreliable data transmission [3]. There are several things related to cabling structure resulting problems on a network. Some of them are as follows: Cable length: If a cable segment is overly long, that is if a network segment is extended beyond the IEEE specification, there will be communication problems affecting all nodes on that segment. Cable type: Use of non-standard cabling. A Study on Effect of AC Power Lines on UTP cable: A Thesis Page 36

36 Terminator: A defective or missing terminator on a network segment may result like a network segment that is too long. Distance between Connectors: Two nearby workstations may face network communication problems, if the distance between their connectors is less than the minimum distance according to the IEEE specifications. Grounding: Proper grounding is an important criteria during network cabling installation. Lack of proper grounding may result in network packet transmission with many Cyclic Redundancy (CRC) errors. Grounding problems can be dangerous for network analysts and users also. Cable impedance: Cable impedance must meet the required IEEE specifications on Ethernet cable. Use of inexpensive or non standard cable may cause data transmission problems. Opens and Shorts: An intermittent open or short on a cable segment may cause intermittent problems on that segment causing network errors and disconnection problems. RFI and EMI: Effect of RFI and EMI may result in noise on the data transmission of network cable. This problem arises when the cable is run close to the electrical field of an electric or electronic system. Connectors: A faulty connector may create problems causing a short or open on the cable. A Study on Effect of AC Power Lines on UTP cable: A Thesis Page 37

37 1.2.9 Network Troubleshooting Equipments Network troubleshooting equipments help to find the network problems and its solutions. Some of the commonly used network test equipments are listed below: Voltmeter, multimeter and optical power meter Transceiver monitor Cable scanner MAU analyzer Time domain reflectometer Protocol analyzer Remote network monitoring A voltmeter is used to measure the voltage on a network cable or to test signal strength on any network equipment. The multimeter has both a voltmeter and an ohm meter. Using multimeter, the cable resistance can also be determined as well as the voltage. An optical power meter is used to measure the signal strength on a fiber optic cable run. Transceivers are small devices, which are a part of the Attachment Unit Interface (AUI). The transceiver monitor is used to detect different transceiver problems which are related to power, signal reception and collision handing. Cable scanners are designed to test the different network cabling plants. Cable scanner can provide more information than a voltmeter or a multimeter. A Study on Effect of AC Power Lines on UTP cable: A Thesis Page 38

38 Multimeters are able to indicate only the presence of a short or open circuit. But scanners are able to show the location of problems also. Scanners can find out whether the cable is too long for IEEE specifications or not. A scanner can also indicate that whether the cable has radio frequency interference or electromagnetic interference or not. A MAU analyzer functions similar to a cable scanner. It is used in Token Ring networks. A Time Domain Reflectometer (TDR) functions similar to an oscilloscope. It can test various things of a network. They are line impedance, open, shorts, electrical interference, cable distances and connector and terminator problems. Protocol analyzers are the most comprehensive network monitoring devices. They are expensive and contain software that is designed to interpret specific protocol. Generally they are used in large network. 1.3 Current Trend of Cabling Structured Cabling System The term Structured Cabling System refers to all of the cabling and cabling components installed in a logical, hierarchical way [4]. Previously, each of the different data communications technology required its own type of wiring. Today, structured cabling system which is a single wiring technology, can support all the major existing data networking technologies. The design of structured cabling is relatively independent of the used network, so that it can be updated with a minimum of rework in future. A Study on Effect of AC Power Lines on UTP cable: A Thesis Page 39

39 Benefits of structured UTP cabling include: UTP cabling permits many communication protocols including voice, data, CCTV video and control to reside in the same wire bundle. UTP cabling is a Color-coded cabling. UTP cable is less expensive than co-axial or fiber cable. UTP cable is physically smaller than co-axial and other types of cables UTP cabling is very easy media to install, terminate and reconfigure. A good properly installed UTP system gives better interference rejection than co-axial cable system Unshielded Twisted Pair Cabling Unshielded Twisted Pair (UTP) cable is the most common cable used in networking. Ethernet, the most common data networking standard utilizes UTP cable. Despite of the disadvantage that UTP is the most sensitive cable to Electromagnetic Interference (EMI) than any other type of cable, it grows in popularity in networking world. Today, it is considered as the fastest copper based medium for most of the major networking architectures. The reason behind it is UTP cable offers low cost, ease of installation and supports high speed of data transmission with high bandwidth, low attenuation, low cross-talk. Therefore, today UTP is the most widely used networking cable for most of the structured cabling systems. During installation of UTP cable, careful considerations are taken to minimize the effect of EMI, by maintaining a proper separation gap between UTP cabling and the possible EMI sources. A Study on Effect of AC Power Lines on UTP cable: A Thesis Page 40

40 UTP is a type of cable with twisted pairs of conductors and no shield [4-8]. Types of UTP cable vary from telephone wire cable to extremely high speed data supporting cable. Alexander Graham Bell first used UTP cable in his telephone system in The term UTP is specified in the EIA/TIA-568 Commercial Building Telecommunication Wiring Standard as Unshielded Twisted Pair cable. This standard specifies the electrical and physical requirements for all types of cables (UTP, STP, co-axial and optical fiber cables). EIA/TIA-568 standard also specifies the color coding, cable diameter and other electrical characteristics, such as cross-talk, attenuation etc for cables. The first EIA/TIA-568 specifications were released in 1991and revised time to time with being added to new defined categories. To limit the signal degradation caused by EMI and RFI effects, UTP cable designers rely solely on the cancellation effect produced by the twisted wire pairs. The number of twists in the wire pairs also varies for further reduction of cross talk between the pairs in UTP cable. UTP cable must follow precise specifications about the number of twists permitted per meter of cable. UTP cable contains 8 wires, each 2 wires twisted together into 4 pairs with a plastic jacket. The two wires of each twisted pair represent the negative and positive paths of a complete circuit. Each wire consists of stranded copper with own plastic color coded cover. The two wires of each twisted pair are called the tip wire and the ring wire. Depending on the number of twisted pairs and the application, each pair of UTP cable performs different function. Irrespective of the type of function, the cables carry only electrical signals between networking devices allowing communication. A Study on Effect of AC Power Lines on UTP cable: A Thesis Page 41

41 1.3.3 Self noise reduction technique of UTP cable In a twisted pair cable, the two conductor wires are twisted around each other. The transmitted signal is the difference voltage between the two conductor wires [12]. The directions of current flow in each wire of a pair are opposite to each other as shown in the fig 1.16 (a). Fig 1.16 (a): Current flow in a twisted-pair cable Since the two currents in a twisted pair are equal and opposite, the two magnetic fields produced by the two currents cancel each other. They cancel out any magnetic interference caused by outside noise sources. The twistedpair cable is therefore less prone to interference exhibiting a self shielding property {fig 1.16 (b)}. Fig 1.16 (b): Shielding of twisted pair cables A Study on Effect of AC Power Lines on UTP cable: A Thesis Page 42

42 Twisting of the wires in a pair reduces crosstalk between pairs to minimum. Twisting helps to reduce EMI and RFI. It also helps in balancing the mutual capacitance of the cable pair. The twist rate (also called pitch of the twist, usually defined in twists per meter) makes up part of the specification for a given type of cable Requirements of UTP The following are the main requirements of UTP cable [5]: UTP has four individually twisted pairs per cable. The characteristic impedance of each pair is 100 Ohms +/- 15%. Copper conductors of 24 Gauge ( mm-diameter) or optionally 22 Gauge ( mm diameter) are used. UTP cables are used for Ethernet, Token Ring, CDDI, ATM, ISDN, analog telephone and other types of communication. UTP cable is frequently referred to as Ethernet Cable also. Performance of UTP cables are guaranteed up to 100 meters between devices. Technically, the distance limitation is 90 meters for structured cabling and a total of 10 meters for patch cords on either end Most popularly used cables brief: Different most popularly used UTP cables [13-17] are described below in CAT5: CAT5 is a cable standard supporting Fast Ethernet speed. Its cable types, connector types and cabling topologies are defined A Study on Effect of AC Power Lines on UTP cable: A Thesis Page 43

43 bytia/eia-568-b. CAT5 is most commonly used for 100 Base-TX and 1000 Base-T. CAT5 usually comprises of 4 pairs of copper conductors, but Fast Ethernet utilizes only 2 pairs. Cable runs are limited to a maximum recommended length of 100m (328 feet). CAT5e: CAT5e is an Enhanced version of CAT5. It supports Gigabit Ethernet (speed up to 1000Mbps) operation over short distances. It utilizes all the 4 twisted pairs of the cable and it is backward compatible with ordinary CAT5. Both CAT5 and CAT5e have the same bandwidth specifications, 100MHz. The difference between CAT5 and CAT5e are in their transmission performance. CAT5e is with additional electrical characteristics such as power sum NEXT, equal level far-end cross talk, power sum equal level far-end cross-talk and return loss. CAT6: Cat6 is a cable standard for Gigabit Ethernet and other network protocols that are backward compatible with CAT5 and CAT5e. CAT6 specifications are more stringent for cross-talk and noise than CAT5/5e. CAT6 provides a performance up to 250MHz. It is an excellent choice for 10Base-T,100Base-Tx(Fast Ethernet),1000 Base-T/1000 Base- TX(Gigabit Ethernet) and 10GBase-T(10Gigabit Ethernet).CAT6 cable contains 4 twisted pairs, made of 22 to 24 AWG copper conductors to meet ANSI/TIA-568-B.2-1 performance specifications. CAT6 patch cables are normally terminated in 8P8C modular connectors (often referred as RJ-45). For CAT6 cable and connectors, the characteristics A Study on Effect of AC Power Lines on UTP cable: A Thesis Page 44

44 Attenuation, NEXT and PSNEXT are significantly lower than CAT5 and CAT5e. CAT6a: CAT6a cable or Augmented Category 6 provides a performance up to 500MHz, which is twice that of CAT6. CAT6a standard was defined in 2008 in ANSI/TIA/EIA-568-B-2-10 for enhanced performance standards for twisted pair cable. When compared with CAT6, CAT6a performs at improved specifications, especially for alien cross-talk. CAT6 exhibits high alien noise at high frequencies. Table 1.9 shows UTP cable specifications. Table 1.9: UTP cable specifications CAT5 CAT5e CAT6 Ratified Frequency 100MHz 100MHz 250MHz Attenuation 22dB 22dB 19.8dB Characteristic 100Ω±15% 100Ω±15% 100Ω±15% impedance NEXT 32.3dB 35.3dB 44.3dB PS-NEXT dB 42.3dB FLEXT dB 27.8dB PS-ELFEXT dB 24.8dB Return Loss dB 20.1dB Delay skew - 45ns 45ns A Study on Effect of AC Power Lines on UTP cable: A Thesis Page 45