Cabletron Systems SEH-24, SEH-32, SEH-34

INTRODUCTION

Page 1-3

You can stack together up to ﬁve SEH hubs using Cabletron Systems’

external HubSTACK Interconnect cables. If you want to add

management to the stack, Cabletron Systems offers the MicroMMAC

and the SEHI intelligent hubs. You can stack up to four SEHs with

one intelligent hub. Stackable conﬁgurations let you maintain only

one IEEE repeater hop while providing up to 130 Ethernet ports.

The SEH-22/24 and SEH-32/34 are functionally identical with the

exception of the network ports:

•

SEH-22

, 12 RJ45 network ports and one EPIM port.

•

SEH-24

, 24 RJ45 network ports and two EPIM ports.

•

SEH-32

, one 50 pin Champ connector, providing 12 twisted

pair segments, and one EPIM port.

•

SEH-34

, two 50 pin Champ connectors, providing 24 twisted

pair segments, and two EPIM ports.

1.4 SEH FEATURES

Repeater Functionality

The SEH fully conforms to the IEEE 802.3 Repeater, AUI, and

10BASE-T speciﬁcations, and provides the ﬂexibility to connect

networks using IEEE 802.3, Ethernet Version 1 or Version 2

equipment. The SEH transmits re-timed data packets, regenerates the

preamble, extends fragments, and arbitrates collisions.

The SEH automatically partitions problem segments, and reconnects

repaired segments to the network. This feature minimizes the impact

on network operation by isolating the problem segment. Only devices

on the problem segment are affected. When the problem is solved, the

SEH automatically reconnects the isolated segment to the network.

Polarity Detection and Correction

Each twisted pair port on the SEH incorporates a Polarity Detection

and Correction feature that allows the SEH to pass data regardless of

the polarity of the twisted pair segment’s receive link. We do not

recommend operating in this condition. If you discover this condition,

remove the segment from the network and wire it correctly. This

reduces the potential for problems if equipment changes are made.