Glossary - 32
FORE Systems ES-2810 Ethernet Switch User's Manual
Glossary
Structured Connectors (SC) - see Stick and Click.
Sublayer - a logical subdivision of a layer.
SubNetwork Access Protocol (SNAP) - a specially reserved variant of IEEE 802.2 encoding
SNAP indicates to look further into the packet where it will fine a Type field.
Subscriber Network Interface (SNI) - the interface between an SMDS end user’s CPE and the
network directly serving the end user, supported by either a DS1 or DS3 access arrangement.
Super Frame (SF) - a term used to describe the repeating 12 D4 frame format that composes a
standard (non-ESF) T1 service.
Super User - a login ID that allows unlimited access to the full range of a device's functionality,
including especially the ability to reconfigure the device and set passwords.
Sustainable Cell Rate (SCR) - ATM Forum parameter defined for traffic management. For VBR
connections, SCR determines the long-term average cell rate that can be transmitted.
Sustained Information Rate (SIR) - In ATM this refers to the long-term average data transmis-
sion rate across the User-to-Network Interface. In SMDS this refers to the committed informa-
tion rate (similar to CIR for Frame Relay Service).
Switch - Equipment used to interconnect lines and trunks.
Switched Connection - A connection established via signaling.
Switched Multimegabit Data Service (SMDS) - a high-speed, datagram-based, public data net-
work service expected to be widely used by telephone companies in their data networks.
Switched Virtual Channel Connection (SVCC) - A Switched VCC is one which is established and
taken down dynamically through control signaling. A Virtual Channel Connection (VCC) is
an ATM connection where switching is performed on the VPI/VCI fields of each cell.
Switched Virtual Circuit (or Channel) (SVC) - a channel established on demand by network sig-
nalling, used for information transport between two locations and lasting only for the dura-
tion of the transfer; the datacom equivalent of a dialed telephone call.
Switched Virtual Path Connection (SVPC) - a connection which is established and taken down
dynamically through control signaling. A Virtual Path Connection (VPC) is an ATM connec-
tion where switching is performed on the VPI field only of each cell.
Switching System - A set of one or more systems that act together and appear as a single
switch for the purposes of PNNI routing.
Symmetric Connection - a connection with the same bandwidth specified for both directions.
Synchronous - signals that are sourced from the same timing reference and hence are identical
in frequency.
Synchronous Data Link Control (SDLC) - IBM's data link protocol used in SNA networks.
Synchronous Optical Network (SONET) - a body of standards that defines all aspects of trans-
porting and managing digital traffic over optical facilities in the public network.
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