Cabletron Systems SEH-24 User Manual

Also see for SEH-22: User guide

INSTALLATION REQUIREMENTS/SPECIFICATIONSPage 2-22.1.2 UTP and STP Cable Specifications for the Network Portsand EPIM-T ModuleThe device at the other end of the twisted pair segment must meetIEEE 802.3 10BASE-T specifications. When you connect a 10BASE-TTwisted Pair Segment to the SEH’s 10BASE-T Twisted Pair NetworkPorts and EPIM-T module, your network must meet the followingrequirements: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 determinesmaximum link length. If you use high quality, low attenuation cable,you can achieve link lengths of up to 200 meters. Cable delay limitsmaximum link length to 200 meters, regardless of the cable type.Insertion LossThe maximum insertion loss allowed for a 10BASE-T link is 11.5 dBat all frequencies between 5.0 and 10 MHz. This includes theattenuation of the cables, connectors, patch panels, and reflectionlosses due to impedance mismatches in the link segment.ImpedanceCabletron Systems 10BASE-T Twisted Pair products will work ontwisted pair cable with 75 to 165 ohms impedance. Unshielded twistedpair cables typically have an impedance of between 85 to 110 ohms.Shielded twisted pair cables, such as IBM Type 1 cable, can also beused. You should remember that the impedance of IBM Type 1 cable istypically 150 ohms. This increases the signal reflection caused by thecable, but since the cable is shielded, this signal reflection has littleeffect on the received signal’s quality due to the lack of crosstalkbetween the shielded cable pairs.JitterIntersymbol interference and reflections can cause jitter in the bit celltiming, resulting in data errors. A 10BASE-T link must not generatemore than 5.0 nsec. of jitter. If your cable meets the impedancerequirements for a 10BASE-T link, jitter should not be a concern.