Specifications
Functional Description
RADring
Installation & Operation Manual
2-36 RI/RO Modules Functional Description 3/11/98 12:33
TFC Fiber-optic
Converter
Module
The TFC is a Token Ring Fiber-optic Converter module for connecting
trunks to adjacent hubs or access units over fiber-optic cable. The TFC
converts the electrical signal to an optical one and vice versa. It can be
configured to work as Ring In or Ring Out in the fiber-optic trunk. The TFC
also supports the satellite configuration. The TFC occupies one slot in
RADring enclosure
Special circuitry provides fault protection by detecting a drop in optical
signal and initiating automatic ring partitioning. Detection is also provided
for remote fault condition, where the remote side does not receive the
optical signal; automatic partitioning is also activated at the remote side. The
TFC has a redundant channel option (TFC/2) whereby a fault on the active
link will automatically activate the redundant link. By switching to the
redundant link instead of using the backup, added fault tolerance is
provided, so that even if there is a security failure somewhere else in the
ring, the ring will continue to operate. This feature is also suited to high
reliability satellite applications.
Since the TFC is only a converter and not a repeater, certain limitations are
introduced when using the TFC. Lobe lengths are limited on the RADring
hub to 50 m at 16 Mbps on Type 1 and 100 m at 4 Mbps on Type 1. In
addition it is recommended that only 3 TFC links be cascaded one after the
other in order to prevent jitter problems. These jitter limitations can be
overcome by using the TJA module in conjunction with the RADring. See
Chapter 6 for more details on planning with the TFC. The TFC module is
also compatible with the TFC/SA and TFC card integrated in TAUs.
CH1 CH2
TFC
TX
RX
TX
RX
CH1
CH2
CH1 CH2
TFC
TX
RX
TX
RX
CH1
CH2
CH1 CH2
TFC
TX
RX
TX
RX
CH1
CH2
CH1 CH2
TFC
TX
RX
TX
RX
CH1
CH2
CH1 CH2
TFC
TX
RX
TX
RX
CH1
CH2
CH1 CH2
TFC
TX
RX
TX
RX
CH1
CH2
CH1 CH2
CML/NM
RESET
CH1 CH2
CML/NM
RESET
CH1 CH2
CML/NM
RESET
TFC 2 TFC 2
TFC 2
TFC 2/F TFC1 TFC1
MAIN
MAIN
REDUNDANT
REDUNDANT
RADring
(SATELLITE)
Figure 2-28 Redundant fiber Optic Link With TFC’s