Cabletron Systems NBR-220 Installation Manual

Also see for NBR-220: Management guide

Contents

Appendix C: Network Planning and ConfigurationPage C-2NBR-SERIES Installation Guide• Insertion Loss - Between frequencies of 5.0 and 10.0 MHz, themaximum insertion loss must not exceed 11.5 dB. This includes theattenuation of the cables, connectors, patch panels, and reflectionlosses due to impedance mismatches in the link segment.• Impedance - Cabletron Systems 10BASE-T Twisted Pair productswork on twisted pair cable with 75 to 165 ohms impedance.Unshielded twisted pair cables typically have an impedance ofbetween 85 to 110 ohms. You can also use shielded twisted pair cables,such as IBM Type 1 cable, but keep in mind that this cable has animpedance of 150 ohms. The high impedance of the IBM Type 1 cableincreases signal reflection. However, due to cable shielding, and itssubsequent lack of crosstalk between shielded pairs, this signalreflection has little effect on the quality of the received signal.• Jitter - Intersymbol interference and reflections can cause jitter in thebit cell timing, resulting in data errors. 10BASE-T links must notgenerate more than 5.0 ns of jitter. Make sure your cable meets10BASE-T link impedance requirements to rule out jitter as a concern.• Delay - The maximum propagation delay of a 10BASE-T link segmentmust not exceed 1000 ns. This 1000 ns maximum delay limits themaximum link segment length to no greater than 200 meters.• Crosstalk - Signal coupling between different cable pairs within amulti-pair cable bundle causes crosstalk. 10BASE-T transceiverdesign alleviates concerns about crosstalk, providing the cable meetsall other requirements.• Noise - Crosstalk, or externally induced impulses, can cause noise.Impulse noise may cause data errors if the impulses occur at veryspecific times during data transmission. Generally, noise is not aconcern. If you suspect noise-related data errors, you may need toreroute the cable or eliminate the source of the impulse noise.NOTELosses introduced by connections at punch-down blocks andother equipment reduce total segment length. For eachconnector or patch panel in the link, subtract 12 meters fromthe total length of your cable.