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2.2.2
UTP 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
2-3. Cable routing, connector attenuation, noise, and crosstalk can
adversely affect the maximum lobe length.
UTP
Category
3
4
5
*for cable with NEXT loss
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 Mbps,
Token Ring performance requirements demand a NEXT loss of at least
30.5 dB. When using Category 3 cables, consider safeguarding against
worst case conditions (running at 16 Mbps and using category 3 cable with
the category's lowest qualifying NEXT loss—23 dB) by keeping lobe
lengths shorter than the recommended maximum to keep crosstalk
interference within acceptable levels.
2.3 STP Cabling Specifications
The TDRMIM-42A supports 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.
2.3.1
STP Cable Categories
The supported STP cable types meet the following specifications:
Table 2-3. UTP Maximum Lobe Lengths.
@ 4 Mbps
meters
200
225
250
STP Cabling Specifications
Maximum Lengths
@ 16 Mbps
(feet)
meters
(656)
100*
(738)
110
(820)
120
30.5 dB per 100m
(feet)
(328)*
(360)
(393)
Page 2-5
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