Networking involves connection of computers, workstations and peripheral devices. Networking hardware involves ail the peripheral devices, interface cards, and other equipments such as cables and wires that are used to establish a network connection. Wire is a single, cylindrical strand of metal conductor with low resistance to the current flow. Cable can be defined as a bunch of wires bound together which may be bare or insulated. A medium or channel is needed to link these devices. You can connect these devices either using physical transmission medium or using wireless transmission medium. Physical transmission media involves the use of wires and cables. Wireless transmission involves the use of radio wave, Infrared and Microwave technologies.
Characteristics of fiber optic Cables
Beforeselecting a cable for a network, you may have to consider various cable characteristics. Every cable has certain advantages and disadvantages. You may have to consider the following criteria before selecting and installing a network cable:
Segment length - Defines the length of a single wire. Every cable has a limitation to carry signals only to a particular distance after which the quality of the signal degrades and becomes corrupt. The capacity of I cable to carry signals to a certain distance till they can be regenerated using amplifiers or repeaters is known as the maximum segment length of that cable.
Attenuation - As the signals travel through copper cables, they lose their strength. This loss of signal strength in a cable is called as attenuation. With more attenuation, the signal strength arriving at destination decreases. As the operating frequency and cable length increases, attenuation also increases. Attenuation s measured in DB (decibels) and expressed as a negative value as it indicates a loss, for example -12 DB.
Bandwidth - It is the amount of digital data that a cable can carry. Each type of cable can carry only a certain amount of information or data over a given period of time. This capacity is measured in terms of bandwidth. It is measured in terms of bits or bytes the cable can carry at a certain time. It is an important factor while selecting a network.
Number of segments - Defines the maximum number of segments in a network. Every network cable is subject to a maximum number of segments it can have. The amount of time taken by a signal to traverse through the particular length of the cable is known as latency. Every cable is subject to latency. If the time taken to traverse is long, it is assumed that the signal will not reach the other end. Therefore cables are subject to a maximum number of segments so that there is no delay in receiving the signals from one end to the other.
Cost - Cables come in different quality. Depending on the length, size of the network, you may need to choose the right type of cable. Copper cables are the cheapest form of cable, whereas fiber optic cables are the most expensive. Installation costs of copper cables are cheap as compared to that of fiber optic cables.
Interference susceptibility - Explains the concept of electronic interference on cables. Each type of cable is susceptible to some interference such as internal or external noise. It depends on the environment where the cable is to be laid. External noise may consist of Electromagnetic interference (EMI) or Radio frequency interference (RFI). EMI refers to unwanted radiations or noise from external devices such as motors and relays. RFI refers to the radiation in the radio frequency range interfering with transmissions over copper cables. In case of shielded cable, if the shield is not grounded properly, then it acts as an antenna and picks up such interfering signals. Cables that consist of shielding are less susceptible to interference than the unshielded cables. Coaxial cables and shielded twisted pair cables are less susceptible to interference. Fiber optic cables are the least susceptible to interference.
Crosstalk - Explains the concept of interference generated when magnetic fields or current of one cable affects electrical currents of other cable. Cable crosstalk can result into signal distortion which leads towards network problems. Crosstalk can be reduced by twisting and shielding the wire pairs. In twisted pair cable the magnetic fields cancel each other to decrease the crosstalk.
Source: http://factoidz.com
Characteristics of fiber optic Cables
Beforeselecting a cable for a network, you may have to consider various cable characteristics. Every cable has certain advantages and disadvantages. You may have to consider the following criteria before selecting and installing a network cable:
Segment length - Defines the length of a single wire. Every cable has a limitation to carry signals only to a particular distance after which the quality of the signal degrades and becomes corrupt. The capacity of I cable to carry signals to a certain distance till they can be regenerated using amplifiers or repeaters is known as the maximum segment length of that cable.
Attenuation - As the signals travel through copper cables, they lose their strength. This loss of signal strength in a cable is called as attenuation. With more attenuation, the signal strength arriving at destination decreases. As the operating frequency and cable length increases, attenuation also increases. Attenuation s measured in DB (decibels) and expressed as a negative value as it indicates a loss, for example -12 DB.
Bandwidth - It is the amount of digital data that a cable can carry. Each type of cable can carry only a certain amount of information or data over a given period of time. This capacity is measured in terms of bandwidth. It is measured in terms of bits or bytes the cable can carry at a certain time. It is an important factor while selecting a network.
Number of segments - Defines the maximum number of segments in a network. Every network cable is subject to a maximum number of segments it can have. The amount of time taken by a signal to traverse through the particular length of the cable is known as latency. Every cable is subject to latency. If the time taken to traverse is long, it is assumed that the signal will not reach the other end. Therefore cables are subject to a maximum number of segments so that there is no delay in receiving the signals from one end to the other.
Cost - Cables come in different quality. Depending on the length, size of the network, you may need to choose the right type of cable. Copper cables are the cheapest form of cable, whereas fiber optic cables are the most expensive. Installation costs of copper cables are cheap as compared to that of fiber optic cables.
Interference susceptibility - Explains the concept of electronic interference on cables. Each type of cable is susceptible to some interference such as internal or external noise. It depends on the environment where the cable is to be laid. External noise may consist of Electromagnetic interference (EMI) or Radio frequency interference (RFI). EMI refers to unwanted radiations or noise from external devices such as motors and relays. RFI refers to the radiation in the radio frequency range interfering with transmissions over copper cables. In case of shielded cable, if the shield is not grounded properly, then it acts as an antenna and picks up such interfering signals. Cables that consist of shielding are less susceptible to interference than the unshielded cables. Coaxial cables and shielded twisted pair cables are less susceptible to interference. Fiber optic cables are the least susceptible to interference.
Crosstalk - Explains the concept of interference generated when magnetic fields or current of one cable affects electrical currents of other cable. Cable crosstalk can result into signal distortion which leads towards network problems. Crosstalk can be reduced by twisting and shielding the wire pairs. In twisted pair cable the magnetic fields cancel each other to decrease the crosstalk.
Source: http://factoidz.com
Kudos!!!!good work Sanjay...
ReplyDeleteRegards,
Anil Mishra
http://anilkmishra.blogspot.com