Cabletron Systems SEHI-22 User Manual

Also see for SEHI-22: User guide Addendum

Contents

SEHI OVERVIEWSEHI USER’S GUIDE1-31.3 SEHI OVERVIEWThe 10BASE-T SEHI-22 and SEHI-24 are intelligent repeater hubs. TheSEHI-22 has 12 RJ45 ports and one Ethernet Port Interface Module(EPIM) port on the front panel for network connections while theSEHI-24 has 24 RJ45 ports and two EPIM ports on the front panel fornetwork connections. Both models have one rear panel HubSTACKInterconnect Bus port for stackable connections. The SEHI is designed tomanage the Cabletron SEH series of non-intelligent stackable hubs.1.4 SEHI FEATURESRepeater FunctionalityThe SEHI fully conforms to the IEEE 802.3 Repeater, AUI, and10BASE-T specifications, and provides the flexibility to connectnetworks using IEEE 802.3, Ethernet Version 1 or Version 2 equipment.The SEHI transmits retimed data packets, regenerates the preamble,extends fragments, and arbitrates collisions.The SEHI automatically partitions problem segments, and reconnectsrepaired segments to the network. This feature minimizes the impact onnetwork operation resulting from a problem on one segment by isolatingthe problem segment. Only devices on the problem segment are affected.When the problem is solved, the SEHI automatically reconnects theisolated segment to the network.Polarity Detection and CorrectionEach twisted pair port on the SEHI incorporates a Polarity Detection andCorrection feature that allows the SEHI to pass data regardless of thepolarity of the twisted pair segment’s receive link. Cabletron does notrecommend operating in this condition. When this condition is detected,remove the segment from the network and wire it correctly to reduce thepotential for problems if equipment changes are made.Flash EEPROMsThe SEHI uses Flash EEPROMs that allow the downloading of new andupdated firmware in conjunction with Cabletron’s Remote LANVIEW/Windows, version 2.3 or later or any device utilizing BOOTP or TFTPprotocols.