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STP Cabling Specifications
IBM
Operational
Type
Frequency
1 & 2
4 MHz
16 MHz
6 & 9
4 MHz
16 MHz
IBM Type 1 consists of two shielded twisted pairs (STP) of 22 AWG solid
wire for data. It is often used for the longest cable runs within the walls of
buildings.
IBM Type 2 consists of six pairs of unshielded twisted pairs of 24 AWG
solid wire and a shield casing. The two pairs carried within the shield
casing are used to carry Token Ring data. The four pairs carried outside of
the shield casing are typically used for voice communication. Type 2 is
frequently used to wire cable runs within the walls of buildings.
IBM Type 6 consists of two STP of 26 AWG stranded wire for data.
Because of its high attenuation, Type 6 is used only in patch panels or to
connect devices to/from wall jacks. Attenuation for Type 6 cable is 3/2 x
Type 1 cable (attenuation for 66 m of Type 6 = attenuation for 100 m of
Type 1).
IBM Type 9 is similar to Type 1, but uses 26 AWG solid wire. Like Type 6,
because of its high attenuation, Type 9 is used only in patch panels or to
connect devices to/from wall jacks. Attenuation for Type 9 cable is 3/2 x
Type 1 cable (66 m of Type 9 = 100 m of Type 1).
2.3.2
STP Cable Lengths to Stations
The physical length of the cable connecting a station to a TCU port on the
concentrator is referred to as the lobe length. The maximum lobe length
attainable with the concentrator, under ideal conditions, is shown in Table
2-5. Cable routing, connector attenuation, noise and crosstalk can
adversely affect the maximum lobe length.
Page 2-6
Table 2-4. STP Cable Type Specifications.
Impedance
150
150
150
150
Attenuation per...
1000 m
15%
22 dB
15%
45 dB
15%
33 dB
15%
66 dB
(1000 ft)
(
6.7 dB)
( 13.7 dB)
( 10.0 dB)
( 20.0 dB)
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