Enterasys sth-22 User Manual
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.
(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.
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.
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.
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