Cabletron Systems SEH-34 SEH Features, Repeater Functionality, Polarity Detection and Correction

INTRODUCTION

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.

1.4SEH 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.

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