S - Definitions

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  • S

    SD-WAN security

    SD-WAN security refers to the practices, protocols and technologies protecting data and resources transmitted across software-defined wide area network infrastructure.

  • secure access service edge (SASE)

    Secure access service edge (SASE), pronounced sassy, is a cloud architecture model that bundles together network and cloud-native security technologies and delivers them as a single cloud service.

  • Seebeck effect

    The Seebeck effect is a phenomenon in which a temperature difference between two dissimilar electrical conductors or semiconductors produces a voltage difference between the two substances.

  • serial digital interface (SDI)

    Serial digital interface (SDI) is a standard for digital video and audio transmission over coaxial or fiber optic cabling.

  • Service Profile Identifier (SPID)

    In telecommunications, a Service Profile Identifier (SPID) is a number assigned by a phone company to a terminal on an Integrated Services Digital Network (ISDN) B-channel.

  • session border controller (SBC)

    A session border controller (SBC) is a dedicated hardware device or software application that governs the manner in which phone calls are initiated, conducted and terminated on a voice over Internet Protocol (VoIP) network.

  • session layer

    The session layer is Layer 5 of the OSI communications model. It is the long-lived logical connection that persists between endpoints over time.

  • Signaling System 7 (SS7)

    Signaling System 7 (SS7) is an international telecommunication protocol standard that defines how the network elements in a public switched telephone network (PSTN) exchange information and control signals.

  • single-user multiple input, multiple output (SU-MIMO)

    Single-user multiple input, multiple output (SU-MIMO) is a multitransmitter and receiver technology that lets a wireless access point send multiple, simultaneous data streams to one compatible endpoint at a time.

  • sliding window (windowing)

    The sliding window (windowing) technique is used by Transmission Control Protocol (TCP) to manage the flow of packets between two computers or network hosts.

  • small cell

    A small cell is an umbrella term used to describe a miniature radio access point or wireless network base station with a low radio frequency power output, footprint and range.

  • Snort

    Snort is an open source network intrusion detection system (NIDS) created by Sourcefire founder and former CTO Martin Roesch.

  • Spanning Tree Protocol (STP)

    Spanning Tree Protocol (STP) is a Layer 2 network protocol used to prevent looping within a network topology.

  • spectrum analyzer

    A spectrum analyzer is a device that measures and displays signal amplitude (strength) as it varies by frequency within its frequency range (spectrum).

  • split horizon

    Split horizon is a method used by distance vector protocols to prevent network routing loops.

  • star network

    A star network is a local area network (LAN) topology in which all nodes -- personal computers (PCs), workstations or other devices -- are directly connected to a common central computer that is often referred to as a hub.

  • stateful inspection

    Stateful inspection, also known as dynamic packet filtering, is a firewall technology that monitors the state of active connections and uses this information to determine which network packets to allow through the firewall.

  • Stream Control Transmission Protocol (SCTP)

    Stream Control Transmission Protocol (SCTP) is a connection-oriented network protocol for transmitting multiple streams of data simultaneously between two endpoints that have established a connection in a network.

  • subcarrier

    A subcarrier is a secondary modulated signal frequency modulated into the main frequency (the carrier) to provide an additional channel of transmission.

  • subnet (subnetwork)

    A subnet, or subnetwork, is a segmented piece of a larger network. More specifically, subnets are a logical partition of an IP network broken into multiple, smaller network segments.

  • Switched Multimegabit Data Service (SMDS)

    Switched Multimegabit Data Service (SMDS) is a public, packet-switched service aimed at enterprises that need to exchange large amounts of data with other enterprises over the wide area network on a nonconstant or bursty basis.

  • SYN scanning

    SYN scanning is a tactic that a malicious hacker can use to determine the state of a communications port without establishing a full connection.

  • Synchronous Data Link Control (SDLC)

    Synchronous Data Link Control (SDLC) is a transmission protocol used to synchronously transfer code-transparent, serial-by-bit data over a communications channel.

  • Synchronous Digital Hierarchy (SDH)

    Synchronous Digital Hierarchy (SDH) is a group of fiber optic transmission rates that transport digital signals with different capacities.

  • system administrator (sysadmin)

    A system administrator (sysadmin) is an information technolog professional who supports a multiuser computing environment and ensures continuous, optimal performance of IT services and support systems.

  • What is a self-organizing network (SON) and do you need one?

    A self-organizing network (SON) is an intelligent infrastructure designed to simplify and accelerate the planning, configuration, management, optimization and healing of mobile radio access networks (RANs).

  • What is an SD-branch?

    An SD-branch is a single, automated, centrally managed, software-centric platform that replaces or supplements an existing branch network architecture.

  • What is an SDN controller (software-defined networking controller)?

    A software-defined networking controller is an application in SDN architecture that manages Flow control for improved network management and application performance.

  • What is SD-WAN (software-defined WAN)? Ultimate guide

    Software-defined WAN is a technology that uses software-defined networking concepts to distribute network traffic across a wide area network, or WAN.

  • What is shielded twisted pair (STP) and how does it work?

    Shielded twisted pair (STP) is a kind of cable made up of smaller wires where each small pair of wires is twisted together and has an outer coating to electrically shield it.

  • What is signal-to-noise ratio and how is it measured?

    A signal-to-noise ratio compares the strength of a desired signal with any undesired signals created by background noise.

  • What is Simple Network Management Protocol (SNMP)?

    Simple Network Management Protocol (SNMP) is an application-layer protocol for monitoring and managing network devices on a local area network or wide area network.

  • What is software-defined networking (SDN)?

    Software-defined networking (SDN) is a networking approach in which software is used to easily configure and centrally manage IT networks.

  • What is streaming network telemetry?

    Streaming network telemetry is a real-time data collection service in which network devices, such as routers, switches and firewalls, continuously push data related to the network's health to a centralized location.

  • What is Synchronous Optical Network (SONET)?

    Synchronous Optical Network (SONET) is a North American standardized digital communication protocol for synchronous data transmission over optical fibers.

  • What is the Server Message Block (SMB) protocol? How does it work?

    The Server Message Block (SMB) protocol is a client-server communication protocol used for sharing access to files, printers, serial ports and other resources on a network.