Cabletron Systems STHI 44 STHI-44 - Manual (Page 20)

UTP Lobe Lengths
Page 2-5
UTP cabling to any non-Token Ring network conductors
(telephone, etc.) or ground. If in doubt, test wiring before using.
2.3.2 UTP Lobe Lengths
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
2-2. Cable routing, connector attenuation, noise, and crosstalk can
adversely affect the maximum lobe length.
Some UTP category 3 cables fail to meet the performance minimums
required to support a Token Ring network. Whereas category 3 allows for
near end crosstalk (NEXT) loss as low as 23 dB per 100 m at 16 Mb/s,
Token Ring performance requirements demand a NEXT loss of at least
30.5 dB. To safeguard against worst case conditions (running at 16 Mb/s
and using category 3 cable with the category’s lowest qualifying NEXT
loss—23 dB), the recommended maximum lobe length should be reduced
to keep crosstalk interference within acceptable levels when using
category 3 cable.
2.4 STP Cabling Specifications
Both STP concentrator modules (STH-42 / 44) support all STP cables
classified as IBM Types 1, 2, 6, and 9. All cables meeting the criteria for
classification as IBM Type 1, 2, 6, or 9 meet Token Ring network
performance requirements.
Table 2-2. UTP Maximum Lobe Lengths.
UTP
Category
@ 4 Mb/s @ 16 Mb/s
meters (feet) meters (feet)
3 200 (656) 100* (328)*
4 225 (738) 110 (360)
5 250 (820) 120 (393)
* for cable with NEXT loss
≥
30.5 dB per 100m