Cabletron Systems SEH-22 User Manual

Also see for SEH-22: User guide

Contents

CHAPTER 2: INSTALLATION REQUIREMENTS/SPECIFICATIONS2-2SEH USER’S GUIDE2.1.2 10BASE-T UTP and STP Cable SpecificationsThe devices and 10BASE-T Twisted Pair Segments connected to the SEH10BASE-T Twisted Pair Network Ports and EPIM-T module must meetthe IEEE 802.3 10BASE-T specifications shown below.LengthThe IEEE 802.3 10BASE-T standard requires that 10BASE-T devicestransmit over a 100 meter (328 foot) link using 22-24 AWG unshieldedtwisted pair wire. However, cable quality largely determines maximumlink length. With high quality, low attenuation cable, link lengths of up to200 meters are achievable. Cable delay limits maximum link length to200 meters, regardless of cable type.Insertion LossThe maximum insertion loss allowed for a 10BASE-T link is 11.5 dB atall frequencies between 5 and 10 MHz. This includes the attenuation ofthe cables, connectors, patch panels, and reflection losses due toimpedance mismatches in the link segment.ImpedanceCabletron Systems 10BASE-T Twisted Pair products work on twisted paircable with 75 to 165 ohms impedance. Unshielded twisted pair cablestypically have an impedance of between 85 to 110 ohms.Shielded twisted pair cables, such as IBM Type 1 cable, can also be used.The impedance of IBM Type 1 cable is typically 150 ohms. This increasesthe signal reflection caused by the cable, but because the cable is shielded,this signal reflection has little effect on the received signal’s quality due tothe lack of crosstalk between the shielded cable pairs.JitterIntersymbol interference and reflections cause jitter in the bit cell timing,resulting in data errors. A 10BASE-T link must not generate more than5.0 ns of jitter. If the cable meets the impedance requirements for a10BASE-T link, jitter should not be a concern.