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About the TDRMIM
Repeater Circuitry
The Ring Port sets provide circuitry that completely retimes and repeats
all received signals before transmitting them to the next point on the ring.
This enhances signal integrity and makes adjusted ring length (ARL)
computations unnecessary: maximum trunk cable distances are extended
to 2 Km.
Ring Speed Fault Protection
TDRMIMs provide ring speed fault protection on each Ring Port to protect
against beaconing conditions caused by ring speed mismatches between
the host hub's ring and the ring on the externally connected hub. If there
is a mismatch between the ring speeds of the incoming signal and the
destination ring, the TDRMIM keeps the Ring Port looped back on itself to
protect the hub from the conflict. When the speed mismatch condition is
eliminated, the port comes out of loopback mode.
1.2.2
Lobe Ports
Each TDRMIM is equipped with 12 lobe ports—female RJ45 modular
connector jacks—for TCU (Trunk Coupling Unit) or Multi Ring Out
connections. TDRMIM-22A supports UTP cabling (Unshielded Twisted
Pair) and TDRMIM-42A supports STP (Shielded Twisted Pair). The RJ45
connectors used in the TDRMIM-42A (for STP cabling) provide a
grounded connection for the cabling shield.
Refer to Section 1.2.3, Cluster Switching, for details about port-to-FNB
Ring assignments.
TCU and Multi Ring Out Configurations
BY default, each lobe port on the TDRMIM operates as a TCU to support
the insertion of a Token Ring station into a ring; however the Local
Management (LM) application on a management module (such as
TRMM-4) may be used to reconfigure any of these TCU ports to function
as Multi Ring Out ports to support the connection of passive network
devices. See Section 1.2.5, Support for Passive MAU Workgroups.
Active Circuitry
Each lobe port provides circuitry which filters, equalizes, and amplifies all
received signals before transmitting them to the next point on the ring. The
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