3Com CoreBuilder 2500 Getting Started Manual page 102

6 G
LOSSARY
multimode fiber
A fiber optic cable that transmits signals by using
light-emitting diodes (LEDs). Multimode fiber is
used widely to transmit data.
operating system
A program that manages and provides access to
system resources.
PHY (Physical Layer) standard
A portion of the ANSI FDDI standard (X3T9.5) that
specifies the data encoding mechanism and the
clock recovery and data framing parameters for
FDDI.
PMD (Physical Layer Medium Dependent) standard
A portion of the ANSI FDDI standard (X3T9.5) that
specifies the lower sublayer of the physical layer for
FDDI, including the power levels and characteristics
of the optical transmitter and receiver, interface
optical signal requirements including jitter, the
connector receptacle footprint, the requirements of
conforming FDDI optical fiber cable plants, and the
permissible bit error rates.
primary ring
One of two counter-rotating, fiber optic rings that
serve as the root of an FDDI network. The primary
ring normally enters each station on the trunk ring
through the A port and exits through the B port.
See secondary ring.
protective grounding
Connection to the ground, or to a conductor that
is grounded, to ensure safety from electric shock
and prevent equipment damage.
punch-down block
A central wiring connection device typically located
in the wiring center of a voice or data network.
3Com recommends Type 110 or Type 66
punch-down blocks.
remote management
Usually refers to the management of workstations at
distant locations linked to the main LAN by a
network modem. Remote management can be done
in the CoreBuilder system through a serial port
connected to an external modem. See modem.
repeater
An FDDI node that serves as a two-way relay of the
optical signals in an FDDI network. A repeater does
not have any MAC or concentrator functionality.
ring
A series of stations across which information is
passed sequentially, each station in turn examining
or copying the information, finally returning it to the
originating station. The ring has a predictable
response time determined by the number of
stations. See primary ring, secondary ring, FDDI
dual ring.