Specifications

Glossary–11
partition
A repeater port is said to be partitioned when it is management disabled or autoparti-
tioned.
PC
Personal computer.
PHY
A Fiber Distributed Data Interface (FDDI) standard that defines symbols, line states,
clocking requirements, and the encoding of data for transmission.
physical layer medium dependent
FDDI standards that define the media and protocols to transfer symbols between
adjacent PHYs.
physical topology
The arrangement of cables and hardware that make up the network.
PMD
Physical layer medium dependent.
primary port
A redundant master repeater port that is placed in the active state when redundant
ports are configured.
protocol
A formal set of rules governing the format, timing, sequencing, and error control of
exchanged messages on a data network. A protocol may also include facilities for
managing a communications link or contention resolution.
A protocol may relate to data transfer over an interface, between two logical units
directly connected, or on an end-to-end basis between two end users over a large and
complex network. There are hardware protocols and software protocols.
Protocol Data Unit (PDU)
A data object exchanged by protocol layers that contains both protocol control infor-
mation and user data.