Cabletron Systems STHI manual Shielded Twisted Pair STP, B.2.2 STP Lobe Lengths

Shielded Twisted Pair (STP)

Table B-3. STP Cable Type Specifications.

IBM	Operational		Attenuation per...
		Impedance
Type	Frequency		1000 m	(1000 ft)
1 & 2	4 MHz	≤ 150Ω ±15%	≤ 22 dB	(≤ 6.7 dB)
	16 MHz	≤ 150Ω ±15%	≤ 45 dB	(≤ 13.7 dB)
6 & 9	4 MHz	≤ 150Ω ±15%	≤ 33 dB	(≤ 10.0 dB)
	16 MHz	≤ 150Ω ±15%	≤ 66 dB	(≤ 20.0 dB)

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).

NOTE

IBM Types 6 & 9 are to be used only for lobe connections from station to wall jack and patch panels.

B.2.2 STP Lobe Lengths

The maximum lobe length attainable under ideal conditions, is shown in Table B-4. Cable routing, connector attenuation, noise and crosstalk can adversely affect the maximum lobe length.

B.2.3 Mixed STP Cable Types

If cable types are to be mixed in the LAN, compensations must be made for the different cable attenuations. For example, Type 6 & 9 cables can be run for only 2/3 the distance of Type 1: 100 meters of Type 1 ≈ 66 meters of Types 6 or 9)

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