6GLOSSARY
PVC Permanent Virtual Circuit. An ATM mode in which the
communication circuit between two nodes on a
network is manually set up and torn down.
SAR Segmentation and Reassembly. A procedure that
breaks down and reassembles variable-length
packets from legacy LAN (Ethernet and token ring)
applications. The SAR chip set receives protocol
data units (PDUs) from the convergence sublayer
and divides them into small segments, typically 44
bytes long. Two header bytes and two trailer bytes
are added to these segments. The resulting
segment is a 48-byte PDU that fits into the payload
of an ATM cell.
SDH Synchronous Digital Hierarchy. A European body of
standards that defines all aspects of transmitting
and managing digital traffic over optical fiber.
Service bit rate
The bit rate available to a user for the transfer of
data over the network.
Signaling An ATM connection procedure that implements
explicit routes through switches to establish a
communication link with another station on the
network.
SONET Synchronous Optical Network. A growing body of
standards that defines all aspects of transmitting
and managing digital traffic over optical (fiber)
facilities.