FORE Systems ES-2810 Ethernet Switch User's Manual
Glossary - 15
Glossary
Glossary
Frame - a variable length group of data bits with a specific format containing flags at the
beginning and end to provide demarcation.
Frame Check Sequence (FCS) - In bit-oriented protocols, a 16-bit field that contains transmis-
sion error checking information, usually appended to the end of the frame.
Frame Relay - a fast packet switching protocol based on the LAPD protocol of ISDN that per-
forms routing and transfer with less overhead processing than X.25.
Frame Synchronization Error - an error in which one or more time slot framing bits are in error.
Frame-Based UNI (FUNI) - An ATM switch-based interface which accepts frame-based ATM
traffic and converts it into cells.
Frame-Relay Service (FRS) - A connection oriented service that is capable of carrying up to
4096 bytes per frame.
Framing - a protocol that separates incoming bits into identifiable groups so that the receiving
multiplexer recognizes the grouping.
Frequency Division Multiplexing (FDM) - a method of dividing an available frequency range
into parts with each having enough bandwidth to carry one channel.
Gbps - gigabits per second (billion)
Generic Cell Rate Algorithm (GCRA) - an algorithm which is employed in traffic policing and is
part of the user/network service contract. The GCRA is a scheduling algorithm which ensures
that cells are marked as conforming when they arrive when expected or later than expected
and non-conforming when they arrive sooner than expected.
Generic Connection Admission Control (GCAC) - This is a process to determine if a link has
potentially enough resources to support a connection.
Generic Flow Control (GFC) - the first four bits of the first byte in an ATM cell header. Used to
control the flow of traffic across the User-to-Network Interface (UNI), and thus into the net-
work. Exact mechanisms for flow control are still under investigation and no explicit defini-
tion for this field exists at this time. (This field is used only at the UNI; for NNI-NNI use
(between network nodes), these four bits provide additional network address capacity, and
are appended to the VPI field.)
GIO - a proprietary bus architecture used in certain Silicon Graphics, Inc. workstations.
Header - protocol control information located at the beginning of a protocol data unit.
Header Error Control (HEC) - a CRC code located in the last byte of an ATM cell header that is
used for checking cell header integrity only.
High Density Bipolar (HDB3) - A bipolar coding method that does not allow more than 3 con-
secutive zeroes.
High Level Data Link Control (HDLC) - An ITU-TSS link layer protocol standard for point-to-
point and multi-point communications.
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