Cabletron Systems 24 User Manual

Page 2-1CHAPTER 2REQUIREMENTS & SPECIFICATIONSThis chapter describes network guidelines, power requirements, andoperating specifications for the STH. Before installing the STH, read thischapter and confirm that the network meets the requirements andconditions specified in this chapter. Failure to follow these guidelinescould result in poor network performance.2.1 General ConsiderationsAll devices connected to the STH must meet IEEE 802.5 Token Ringspecifications.Maximum Number of Stations on a RingThe maximum stack composed of four 24-port STH hubs and one 24-portintelligent hub offers a total of 120 TCU ports, but the number of portsavailable on the LAN may be increased by the use of passive Multi-station Access Units (MAUs) (refer to Section 1.2.4, Support forPassive MAU Workgroups). The recommended maximum number ofstations in a single ring is 250 stations when using STP lobe cabling and150 stations when using UTP cabling anywhere on the ring.CrosstalkCrosstalk is interference caused by signal coupling between differentcable pairs contained within a multi-pair cable bundle. Multi-pair cablesshould not be used for UTP lobe cabling. Avoid mixing Token Ringsignals with other applications (voice, etc.) within the same cable.NoiseNoise can be caused by either crosstalk or externally induced impulses.Outside systems (motors, switching equipment, fluorescent lighting, highamperage equipment) may produce electrical interference causing noise.The number and quality of cable connections also contribute considerablyto noise levels. If noise induced errors are suspected, it may be necessary