B. Network Components and Cabling
55
THICK ETHERNET CABLING
Thick Ethernet communications interface the female 15-pin D connector, designated J3,
to an external Attachment Unit Interface (AUI) drop cable. Refer to the figure
"
Frontplane Connectors
". Connector J3 provides a slide latch retention system in
accordance with the IEEE 802.3 standard. The other side of the AUI drop cable
connects to a Media Attachment Unit (MAU), which is directly tapped off the thick type
coaxial cable trunk. Refer to the "
Thick Ethernet Cable Segment
" figure following. The
MAU has a built-in transceiver that links the driver/receiver with the solid conductor thick
coaxial trunk cable.
The AUI drop cable is twisted-pair, which typically consists of four individually shielded
twisted wire pairs with an overall shield covering these individually shielded pairs. The
AUI signal pairs must have a differential characteristic impedance of 78 ohms and can
be up to 50 meters (165 feet) in length. The AUI cable must have a male 15-pin D
connector on one end, preferably with locking posts (IEEE 802.3 standard), and a
female 15-pin D connector on the other end, preferably with a slide latch (also an
IEEE 802.3 standard). The male end of the AUI drop cable connects to the female
connector (J3) on the ZT 8995-D2. The female end connects to the MAU, which is
tapped off the Thick Ethernet cable.
Unlike Thin Ethernet, the Thick Ethernet trunk generally does not use point-to-point
cables to connect each of the components on the network segment. Instead, it uses
continuous lengths of coaxial cable that have tap-in markings every 2.5 meters (8 feet)
to designate the minimum separation between MAU connections. However, some
manufacturers can supply a MAU that uses T connectors to splice point-to-point cables.
The thick coax is a double-shielded, 0.4 inch diameter cable with a solid and tinned
copper conductor, 2.5 meter tap-in markings, 50 ohm nominal impedance, and N-type
connectors. Belden cable part number 9901 or equivalent can be used.
Call Ziatech's
Technical Support
for information regarding where to purchase
interconnecting components and products described in this appendix.
Each Thick Ethernet segment can be a maximum of 500 meters (1640 feet) in length,
and can support up to 100 nodes, less one for each repeater on the segment.
If the ZT 8995 is used in a Thick Ethernet configuration, jumper
W10
must be removed
to disable the Thin Ethernet section of the board.
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