S

Scheduling

Determining the order in which traffic is processed for transmission onto a network.

Secondary storage

Storage sites that aggregate management data from multiple primary storage sites.

Secure sockets library

A security mechanism that uses RSA-based authentication to recognize a party's digital identity and RC4 to encrypt and decrypt the accompanying transaction or communication.

Security

A requirement to guarantee the integrity (accuracy and authenticity) of a user's information and physical resources, as well as access to the user's and system's resources.

Security awareness

Getting users educated and involved with the day-to-day aspects of security in their network and helping them understand the potential risks of violating security policies and procedures.

Security cell

In the network architecture, when security constrains performance to operate within a security perimeter, or cell.

Security policies and procedures

Formal statements on rules for system, network, and information access and use designed to minimize exposure to security threats.

Server

Computing device that provides a service to one or more users (i.e., clients).

Service

See Network services.

Service characteristics

Individual network performance and functional parameters that are used to describe services.

Service levels

A group or set of characteristics that forms a higher-level representation of services.

Service metrics

Measurements of service characteristics in the network to monitor, verify, and manage services.

Service-level agreement

Also known as an SLA, an informal or formal contract between a provider and user that defines the terms of the provider's responsibility to the user and the type and extent of accountability if those responsibilities are not met.

Service offering

Services offered by the network to the rest of the system.

Service plan

A written description of the network performance (capacity, delay, and reliability) required for the flows that are described in the flowspec.

Service request

Network services that are requested by users, applications, or devices.

Service-provider architectural model

Architectural model based on service-provider functions, focusing on privacy and security, service delivery to customers (users), and billing.

Service switching

Switching based on flow or end-to-end information, dependent on the type of service required.

Session

An instance of one or more concurrent applications, resulting in one or more traffic flows.

Shaping

In traffic conditioning, delaying traffic to change a performance characteristic.

Shared-medium mechanism

When all devices on the network (or subnetwork) share the same physical medium.

Soft boundary

A routing boundary in which IGPs are predominantly used to pass routing information.

Soft state

Determining and maintaining state until the connection is established or for a short period after the connection is established.

Specialized devices

Devices that provide specific functions to their users.

Specific

As used with security, refers to well-defined rules about who, what, and where security is applied.

State

Information (typically local or end-to-end addresses) associated with connections in a technology.

Stateful

Determining and maintaining state information for connections between source and destination.

Stateless

Not determining or maintaining any state information between source and destination for connections.

Static routes

Routes that are configured manually, by network personnel or scripts, in network elements and that do not change until manually deleted or modified.

Stochastic service

Service that requires some degree of predictability (probability), more than best effort, yet does not require the accountability of a guaranteed service.

Storage archives

Secondary and tertiary storage sites for network management data.

Stub network

A network with only one path into or out of it.

Subnet

A segment of a network, created as an additional level of hierarchy imposed on a network, through changing its address mask.

Subnet mask

An address mask that has been changed from its natural (classful) mask to add an additional level of hierarchy.

Subnetting

Using part of the device (host) address space to create another layer of hierarchy. This is done by changing the address mask.

Supernet mask

The address mask created when supernetting—that is, reducing the mask size to aggregate network addresses.

Supernetting

Aggregating network addresses by changing the address mask to decrease the number of bits allocated to the network.

Supportability

A measure of how well the customer can keep the system performing, as designed, over the entire life of the system.

Switching

Forwarding information (e.g., cells, frames, packets) between segments of a network or subnetwork. This is usually done at the link or network layers but may occur at any layer.

System

A set of components that work together to support or provide connectivity, communications, and services to users of the system.

Systems architecture

Developing a high-level end-to-end structure for the system, which consists of users, applications, devices, and networks. This includes the relationships between each of these components.

Systems methodology

Viewing the network that you are architecting and designing, along with a subset of its environment (everything that the network interacts with or impacts), as a system.