REQUIREMENTS & SPECIFICATIONS
This chapter describes network guidelines, power requirements, and
operating speciﬁcations for the STH. Before installing the STH, read this
chapter and conﬁrm that the network meets the requirements and
conditions speciﬁed in this chapter. Failure to follow these guidelines
could result in poor network performance.
.1 Ge ne ra l Consid e ra tions
All devices connected to the STH must meet IEEE 802.5 Token Ring
Ma xim um Num b e r of Sta tions on a Ring
The maximum stack composed of four 24-port STH hubs and one 24-port
intelligent hub offers a total of 120 TCU ports, but the number of ports
available on the LAN may be increased by the use of passive Multi-
station Access Units (MAUs) (refer to Section 1.2.4, Su p p or t for
P a ssive MAU Wor k gr ou p s). The recommended maximum number of
stations in a single ring is 250 stations when using STP lobe cabling and
150 stations when using UTP cabling anywhere on the ring.
Crosstalk is interference caused by signal coupling between different
cable pairs contained within a multi-pair cable bundle. Multi-pair cables
should not be used for UTP lobe cabling. Avoid mixing Token Ring
signals with other applications (voice, etc.) within the same cable.
Noise can be caused by either crosstalk or externally induced impulses.
Outside systems (motors, switching equipment, ﬂuorescent lighting, high
amperage equipment) may produce electrical interference causing noise.
The number and quality of cable connections also contribute considerably
to noise levels. If noise induced errors are suspected, it may be necessary