IBM ATM OC-3c - Manual (Page 132)

4 G LOSSARY
multiplex
In this user guide, multiplexing means to take packets
from several sources and interleave them into one
connection. For example, packets from data, voice,
and video sources can be fed down one connection.
NNI
Network Node Interface — Sometimes known as
Network-to-Network Interface.
OAM
Operations and Maintenance — A set of
administration and supervisory actions regarding
network performance monitoring, failure detection
and system protection. Special type cells are used to
carry OAM-related information.
Octet
8 bits or 1 byte.
OC-n
Optical Carrier-n — The physical interface for
transmission over optical fiber at n times 51.84Mbps
(for example, OC-3 is at 155.52Mbps, OC-12 at
622.08Mbps, OC-48 at 2.488Gbps).
Payload
Part of the ATM cell, it contains the actual
information to be carried, and occupies 48 bytes. Also
see PTI.
PTI
Payload Type Identifier — A 3-bit cell header field for
encoding information regarding AAL and EFCI.
PVC
Permanent Virtual Circuit — A virtual connection
established by network management between two
points that is permanently available.
routing
A network management function responsible for
forwarding packets from their source to their
destination. A number of routing algorithms exist to
suit different network topologies and requirements.
SAR
Segmentation and Reassembly — Partitions
(segments) information frames into cells at the source
and reassembles these cells back into information
frames at the destination. These activities occur at the
lower half of the AAL. It inserts the data from the
information frames into the cell. It adds any necessary
header or trailer bits to the data and passes the
48-octet to the ATM Layer. Each AAL type has its own
SAR format. At the destination, the cell payload is
extracted and converted to the appropriate
information frame.
SDH
Synchronous Digital Hierarchy — A hierarchy that
determines signal interfaces for very high speed
digital transmission over optical fiber links.
SNMP
Simple Network Management Protocol — A standard
defined for handling management information.