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SA
Source Address
SABM
Set Asynchronous Balanced Mode
SABME
Set Asynchronous Balanced Mode Extended
A logical link control command protocol data unit used to establish a link. The SABME command PDU establishes an LLC2 - numbered and acknowledged - connection to the destination LLC that operates in asynchronous balanced mode.
SAN
Storage Area Network
SAR
Segmentation and Reassembly
In ATM, a sub-layer of AAL; a process performed on ATM information cells.
SARM
Set Asynchronous Response Mode
SAS
Single Attachment Station
A station that has a single attachment to the FDDI network, usually to the primary ring
SASE
Specific Application Service Element - OSI
SDCD
Secondary Data Carrier Detect
SDDI
Shielded Distributed Data Interface
FDDI Early, proprietary schemes for running 100 Mb/s FDDI over twisted pair wiring. SDDI was replaced by the FDDI TP-PMD standard.
SDH
Synchronous Digital Hierarchy
· Called Sonet in the US : Synchronous Optical Network
· For data stream of E1, PDH end ATM.
. A standard technology for optical fiber-based synchronous data transmission, running on copper cable. The international equivalent of SONET
SDLC
Synchronous Data Link Control
A link level communications protocol used in an IBM / SNA network that manages synchronous, code-transparent, serial information transfer over a link connection.
SDLLC
A feature where translation between SDLC and IEEE 802.2 type 2 is performed.
SDSL
Symmetric Asymmetrical Digital Subscriber Line
See Adsl
SDSU
SMDS Data Service Unit
A DSU for access to SMDS via high-speed serial interfaces - HSSI - and other serial interfaces.
SDV
Segment Delay Value
A value used in calculating the path delay variance in Ethernet networks.
SEQ
Sequence
SGMP
Simple Gateway Monitoring Protocol
RFC 1028. Evolved into SNMP
SI
Secondary In
In an FDDI network, a port that connects dual attached devices, typically to trunk rings
SID
Signaling Identifier / Service ID
A number that defines at the MAC layer, a particular mapping between a cable access router and the CMTS. The SID is used for the purpose of upstream bandwidth allocation and class-of-service management.
SIP
Session Initiation Protocol
SIP
Switched Multi-megabit data service - SMDS - Interface Protocol
The protocol used to support SMDS service, consisting of the level 3 protocol data unit containing source and destination addresses and an information field up to 9188 bytes long.
SL
Section Layer - Sonet
SLA
Service Level Agreement
SLARP
Cisco Serial Line Address Resolution Protocol
SLIP
Serial Line Internet Protocol - RFC 1055
A TCP/IP protocol that allows IP packets to be transmitted over a serial link, such as a dial-up or private telephone line.
SLU
Secondary Logical Unit
SMDI
Simple Message Desk Interface - Cisco ®
SMDS
Switched Multi-megabit Data Service
- High Speed, packet switched, datagram-based WAN networking technology offered by telephone companies.
- A connectionless, high-speed data service offered by most telephone companies that allows LANs to connect across a wide area network. Other common WAN services include frame relay, PPP, and X.25.
SMF
Single-Mode Fiber - FDDI networks
SMF-PMD
Single Mode Fiber-Physical Medium Dependent
A standard for the physical medium dependent - PMD -sub-layer that sets the specifications for operating FDDI protocols in a single-mode fiber environment and extends the basic FDDI link distance to 60 kilometers.
SMI
Structure of Management Information
RFC 1155 spec. rules to define managed object in the MIB
SML
Service Management Layer
Used by the SLA for the optical layer protocol for clients.
SMT
Station Management
Defines how ring stations are managed. FDDI X2T9.5
SMTP
Simple Mail Transfer Protocol
RFC 821. An Internet TCP protocol providing electronic mail services., working on Port 25.
SNA
System Network Architecture
A proprietary network architecture used in IBM® systems to connect terminals to a mainframe.
SNADS
SNA Distribution Services
SNAP
Sub Network Access Protocol
A version of the IEEE local area network logical link control frame similar to the data link level transmission frame that allows the use of nonstandard higher-level protocols
SNDCP
Subnet Dependent Convergence Protocol - ISO
SNICP
Subnet Independent Convergence Protocol - ISO
SNMP
Simple Network Management Protocol
- Administration protocol used to gather information from a network device to an administrator console/program.
- A standard for network management that uses a common software agent to manage local and wide area network equipment from different vendors; part of the Transmission Control Protocol / Internet Protocol suite and defined in RFC 1157.
SNPP
Simple Network Paging Protocol - RFC 1861
SNTP
Simple Network Time Protocol - RFC 2030
SO
Secondary Out
In an FDDI network, a port that connects dual attached devices, typically to trunk rings.
SOH
Section Overhead
SONET
Synchronous Optical Networks
- High-Speed - up to 2.5 Gbps - synchronous network designed to run an optical fiber. Approved as an international standard in 1988. The RBOCs are likely to make SONET popular as a transmission system un-relying SMDS.
- A family of fiber optic transmission rates ranging from 51.84 Mb/s to 13.22 Gb/s that provides the flexibility to transport many digital signals with different capacities and to provide a design standard for manufacturers.
Source Route
Source Route Transparent Bridging
SPAN
Full duplex digital transmission line between two digital facilities.
SPANNING TREE
A loop-free subset of a network's topology.
SPE
Synchronous Payload Envelope
A Sonet frame containing overhead information -POH- and actual user data
SPID
Service Protocol Identifier - ISDN
SR
Source Routing
A token ring standard that supports routing frames through a multiple ring. Each source route frame carries information about the route the frame must follow to reach its destination
SRB
Source Route Bridge or Source Route Bridging
A systems-level concept used in many token ring environments where the end stations take on the responsibility of learning the exact ring-to-ring path a packet must take to reach its destination and provide all that information in a special routing field of the LAN packet.
SRF
Status Report Frame
A type of station management frame in FDDI that periodically announces conditions of interest to the FDDI manager, such as configuration changes, undesirable conditions, and MAC neighbor changes.
Specifically routed frame. Frame generated by an end station that receives an ARE or STE frame. The SRF contains a list of routing designators and maps a specific path back to the source end station.
SRPI
Server Requester Programming Interface - IBM ®
SRT
Source Routing Transparent
A token ring standard that supports both source route and transparent bridging frames between bridges and end stations on multiple-ring token ring networks.
SRTB
Source Routing Transparent Bridge
Device that can support both source route and non-source route end stations.
SS7
Signaling System Number 7
- Norm which defines the process to exchange data signals between data bases, operators, and used to build intelligent networks.
Separate the voice and the transport on the network.
- A standard signaling protocol used in PSTN, supporting advanced calling services
SSAP
Session Service Access Point
ISO / Source Service Access Point - IEEE 802
An address field used be logical link control - LLC -protocols to identify the specific service access point that initiated a protocol data unit - PDU -
SSP
Storage Service Providers
SSRT
Sub-second Response Time
ST
Spanning Tree
ST Connector
Straight-Tip Connector
An AT&T® bayonet connector for fiber optic cable that uses a precision ceramic plug and a flexible sleeve.
STE
Spanning Tree Explorer / or Signaling Terminal
Equipment - CCITT
STM
Synchronous Transport Module
A definition of the electrical level signal rate and frame structure for SDH networks. STM-1 is equivalent to STS-3 for SONET.
STM -1 : 155 M-bits/s
STM - 64 = 64 times STM-1Using WDM. Fiber Optic multiplex.
STP
Shielded Twisted Pair
A cable consisting of two insulated wires, twisted together and surrounded by a braided metal shield or foil under the outer insulation. Shielding provides more protection against EMI - electromagnetic interference.
STP
Spanning Tree Protocol
Technique based on the IEEE 802.1 standard that detects and eliminates logical loops in a bridged or switched network. When multiple paths exist, the STP algorithm configures the network to use only the most efficient path.
STS
Synchronous Transport Signal - Sonet
STSPP
Synchronous Transport Signal Payload Pointer - Sonet
SU
Subscriber Unit
An alternate term for cable access router.
SVC
Switched Virtual Circuit
See also Circuit Switching
A virtual circuit connection established across a network on an as-needed basis and lasting only for the duration of the transfer.
Circuit-switched is a type of network in which a physical path is obtained for and dedicated to a single connection between two end-points in the network for the duration of the connection. Ordinary voice phone service is circuit-switched. The telephone company reserves a specific physical path to the number you are calling for the duration of your call. During that time, no one else can use the physical lines involved.
SYNCHRONOUS
Transmission mode wit a fixed bit data rate between the transmit device and the receiver.
The bit Start and Stop are not used as there are for an asynchronous communication.
SWITCH
A network device that completes or selects a path for data circuits, packets, frames, or cells.
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