Cabletron Systems 24 User Manual

UTP Lobe LengthsPage 2-5UTP cabling to any non-Token Ring network conductors(telephone, etc.) or ground. If in doubt, test wiring before using.2.3.2 UTP Lobe LengthsThe physical length of the cable connecting a station to a TCU port on theconcentrator is referred to as the lobe length. The maximum lobe lengthattainable with the concentrator, under ideal conditions, is shown in Table2-2. Cable routing, connector attenuation, noise, and crosstalk canadversely affect the maximum lobe length.Some UTP category 3 cables fail to meet the performance minimumsrequired to support a Token Ring network. Whereas category 3 allows fornear 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 least30.5 dB. To safeguard against worst case conditions (running at 16 Mb/sand using category 3 cable with the category’s lowest qualifying NEXTloss—23 dB), the recommended maximum lobe length should be reducedto keep crosstalk interference within acceptable levels when usingcategory 3 cable.2.4 STP Cabling SpecificationsBoth STP concentrator modules (STH-42 / 44) support all STP cablesclassified as IBM Types 1, 2, 6, and 9. All cables meeting the criteria forclassification as IBM Type 1, 2, 6, or 9 meet Token Ring networkperformance requirements.Table 2-2. UTP Maximum Lobe Lengths.UTPCategory@ 4 Mb/s @ 16 Mb/smeters (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