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STHI Overview
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1.2.2 TCU Ports
The four STHI models are functionally identical with the exception of the
number and type of network ports they offer:
Each STHI is equipped with TCU ports fitted with female RJ45 modular
connector jacks to support the attachment of either STP (shielded twisted
pair) or UTP (unshielded twisted pair) cabling with RJ45 connector plugs.
Models that support STP cabling use RJ45 connectors that provide a
grounded connection for the cabling shield. See Section 2.2.2,
TCU and
COM Ports
, for pinouts.
Lobe Port and Multiple Ring Out Port Configurations
1
Each TCU port on the STHI is internally defaulted to operate as a lobe
interface to support the insertion of a Token Ring station into a ring.
However, each TCU port may also be reconfigured via the Local
Management (LM) application (see Section 5.6.3,
Port Configuration
Fields
) to function as a Ring Out port which will support connections to
non-intelligent, passive MAU (Multi-Station Access Unit) workgroups.
Refer also to Section 1.2.6,
Support for Passive MAU Workgroups
.
Ring Speed Fault Protection
2
STHI hubs also provide Ring Speed Fault Protection on each TCU port to
protect against beaconing conditions caused by stations inserting at the
wrong ring speed. If a ring speed mismatch is detected, the STHI blocks
the port to keep the misconfigured station isolated from the ring and
provides a simple visible LED signal (blinking red at the port’s LED) to
indicate that Ring Speed Fault Protection is blocking the port. The port
remains blocked until the ring speed mismatch condition is removed or
resolved.
Table 1-1. TCUs and Media Types per Model
STHI-22 12 unshielded RJ45 ports
STHI-24 24 unshielded RJ45 ports
STHI-42 12 shielded RJ45 ports
STHI-44 24 shielded RJ45 ports