3Com CoreBuilder 2500 Getting Started Manual page 99

DAS
Dual Attachment Station. A station directly
attached to FDDI's dual token rings. A DAS has four
fiber attachments, one receive and one transmit
fiber for each ring. Rather than an individual user
workstation, a DAS is most likely to be the device
controlling LAN operation, such as an FDDI
concentrator, bridge, router, server, minicomputer, or
mainframe. A DAS can be either single-MAC or
dual-MAC and contains one A-B port pair.
dual-MAC
A DAS that has one MAC inserted in each of the
dual rings. See DAS and MAC.
duplex fiber cable
A cable composed of two insulated optical fibers.
Ethernet
A CSMA/CD, 10 Mbps, local area data network
technology, developed by Digital Equipment
Corporation, Intel, and Xerox Corporation. It is one
of the most popular baseband LAN technologies in
use.
Fast Ethernet
A 100 Mbps, local area data network technology.
FDDI
Fiber Distributed Data Interface. A
high-performance, fiber-optic, token ring LAN
technology that operates at 100 Mbps over
distances up to 100 kilometers with up to 500
connected stations. FDDI can go up to 200
kilometers with up to 1000 connected stations
when wrapped.
FDDI dual ring
The pair of counter-rotating, logical rings (primary
and secondary) common to the FDDI network. This
architecture provides a high degree of reliability. In
normal operation, only the primary ring carries
data. The second or backup ring is used for
automatic recovery in case of failure. If a network
fault occurs, only the stations on either side of the
fault are affected. They detect the fault and
automatically bypass the fault to maintain
continuous transmission of data.
FDDI paths
The segments of an FDDI ring that pass through a
station. Every FDDI station must contain a primary
path. The primary path represents, to the best of
the station's knowledge, the segment(s) of the
primary ring that pass through the station.
In addition, a station may optionally contain a
secondary path representing the segment(s) of the
secondary ring that pass through the station. A
station may contain additional paths representing
segments of rings other than the primary and
secondary. Such paths are called local paths.
G 3
LOSSARY