Cabletron Systems 100BASE-FX, Руководство по кабельной продукции

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Ethernet Media
4-4 Cabling Types
Thick coaxial cable is a media used exclusively in Ethernet installations,
commonly as a backbone media. Transceivers are connected to the cable at
specified distances from one another, and standard transceiver cables connect
these transceivers to the network devices.
Due to the extensive shielding, thick coaxial cable is highly resistant to electrical
interference by outside sources such as lighting, machinery, etc. Because of the
bulkiness (typically 0.405 inch in diameter or thicker) and limited flexibility of the
cable, thick coaxial cable is primarily used as a backbone media and is placed in
cable runways or laid above ceiling tiles to keep it out of the way.
Thick coaxial cable is designed to be accessed as a shared media. Multiple
transceivers can be attached to the thick coaxial cable at multiple points on the
cable itself. A properly installed length of thick coaxial cable can support up to
100 transceivers.
Figure 4-3. Annular Rings
Multiple transceivers on a thick coaxial cable must be spaced at least 2.5 meters
from any neighboring transceivers or terminators. Thick coaxial cable is often
bright yellow or orange in color. The outer jacket will frequently be marked with
annular rings, dark red or black sections of jacketing that are spaced 2.5 meters
from one another. These annular rings are a useful guide for ensuring that
terminators and transceivers are spaced not less than 2.5 m from one another.
Thin Coaxial Cable
Thin coaxial cable (also known as thin Ethernet cable, “thinnet,” “cheapernet,”
RG-58 A/U, BNC or 10BASE2 cable) is a less shielded, and thus less expensive,
type of coaxial cabling. Also used exclusively for Ethernet networks, thin coaxial
cable is smaller, lighter, and more flexible than thick coaxial cable. The cable itself
resembles (but is not identical to) television coaxial cable.
Thin coaxial cable is made up of a single outer copper shield that may be braided
or foil, a layer beneath that of non-conductive dielectric material, and a stranded
center conductor. This shielding makes thin coaxial cable resistant to
electromagnetic interference as the shielding of thick coaxial cable does, but does
not provide the same extent of protection. Thin coaxial cable, due to its less
extensive shielding capacity, can be run to a maximum length of 185 meters
(606.7 ft).
2.5 m
(10BASE5)
Annular Rings
N-Type
Connector
Coaxial Cable
1845n03