Ethernet Cabling Types
Ethernet can be deployed over three types of cabling:
• Coaxial cabling – almost entirely deprecated in Ethernet networking
• Twisted-pair cabling
• Fiber optic cabling
Coaxial cable, often abbreviated as coax, consists of a single wire
surrounded by insulation, a metallic shield, and a plastic sheath. The shield
helps protect against electromagnetic interference (EMI), which can cause
attenuation, a reduction of the strength and quality of a signal. EMI can be
generated by a variety of sources, such as florescent light ballasts,
microwaves, cell phones, and radio transmitters.
Coax is commonly used to deploy cable television to homes and businesses.
Two types of coax were used historically in Ethernet networks:
• Thinnet
• Thicknet
Thicknet has a wider diameter and more shielding, which supports greater
distances. However, it is less flexible than the smaller thinnet, and thus more
difficult to work with. A vampire tap is used to physically connect devices
to thicknet, while a BNC connector is used for thinnet.
Twisted-pair cable consists of two or four pairs of copper wires in a plastic
sheath. Wires in a pair twist around each other to reduce crosstalk, a form of
EMI that occurs when the signal from one wire bleeds or interferes with a
signal on another wire. Twisted-pair is the most common Ethernet cable.
Twisted-pair cabling can be either shielded or unshielded. Shielded twistedpair
is more resistant to external EMI; however, all forms of twisted-pair
suffer from greater signal attenuation than coax cable.
There are several categories of twisted-pair cable, identified by the number
of twists per inch of the copper pairs:
• Category 3 or Cat3 - three twists per inch.
• Cat5 - five twists per inch.
• Cat5e - five twists per inch; pairs are also twisted around each other.
• Cat6 – six twists per inch, with improved insulation.
An RJ45 connector is used to connect a device to a twisted-pair cable. The
layout of the wires in the connector dictates the function of the cable.
While coax and twisted-pair cabling carry electronic signals, fiber optics
uses light to transmit a signal. Ethernet supports two fiber specifications:
• Singlemode fiber – consists of a very small glass core, allowing only
a single ray or mode of light to travel across it. This greatly reduces
the attenuation and dispersion of the light signal, supporting high
bandwidth over very long distances, often measured in kilometers.
• Multimode fiber – consists of a larger core, allowing multiple modes
of light to traverse it. Multimode suffers from greater dispersion than
singlemode, resulting in shorter supported distances.
Singlemode fiber requires more precise electronics than multimode, and thus
is significantly more expensive. Multimode fiber is often used for high-speed
connectivity within a datacenter.
Ethernet can be deployed over three types of cabling:
• Coaxial cabling – almost entirely deprecated in Ethernet networking
• Twisted-pair cabling
• Fiber optic cabling
Coaxial cable, often abbreviated as coax, consists of a single wire
surrounded by insulation, a metallic shield, and a plastic sheath. The shield
helps protect against electromagnetic interference (EMI), which can cause
attenuation, a reduction of the strength and quality of a signal. EMI can be
generated by a variety of sources, such as florescent light ballasts,
microwaves, cell phones, and radio transmitters.
Coax is commonly used to deploy cable television to homes and businesses.
Two types of coax were used historically in Ethernet networks:
• Thinnet
• Thicknet
Thicknet has a wider diameter and more shielding, which supports greater
distances. However, it is less flexible than the smaller thinnet, and thus more
difficult to work with. A vampire tap is used to physically connect devices
to thicknet, while a BNC connector is used for thinnet.
Twisted-pair cable consists of two or four pairs of copper wires in a plastic
sheath. Wires in a pair twist around each other to reduce crosstalk, a form of
EMI that occurs when the signal from one wire bleeds or interferes with a
signal on another wire. Twisted-pair is the most common Ethernet cable.
Twisted-pair cabling can be either shielded or unshielded. Shielded twistedpair
is more resistant to external EMI; however, all forms of twisted-pair
suffer from greater signal attenuation than coax cable.
There are several categories of twisted-pair cable, identified by the number
of twists per inch of the copper pairs:
• Category 3 or Cat3 - three twists per inch.
• Cat5 - five twists per inch.
• Cat5e - five twists per inch; pairs are also twisted around each other.
• Cat6 – six twists per inch, with improved insulation.
An RJ45 connector is used to connect a device to a twisted-pair cable. The
layout of the wires in the connector dictates the function of the cable.
While coax and twisted-pair cabling carry electronic signals, fiber optics
uses light to transmit a signal. Ethernet supports two fiber specifications:
• Singlemode fiber – consists of a very small glass core, allowing only
a single ray or mode of light to travel across it. This greatly reduces
the attenuation and dispersion of the light signal, supporting high
bandwidth over very long distances, often measured in kilometers.
• Multimode fiber – consists of a larger core, allowing multiple modes
of light to traverse it. Multimode suffers from greater dispersion than
singlemode, resulting in shorter supported distances.
Singlemode fiber requires more precise electronics than multimode, and thus
is significantly more expensive. Multimode fiber is often used for high-speed
connectivity within a datacenter.
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