Routing Glossary - Yenra

Advanced Gateway Server, an early Cisco router product. Historical specifications describe the particular hardware generation and should be kept separate from present-day networking requirements.

Application-specific integrated circuit: a chip designed for a particular set of functions. Networking devices may use ASICs for packet processing and other tasks with defined performance requirements.

Asynchronous Transfer Mode: a connection-oriented networking technology using fixed 53-byte cells. Virtual connections organize traffic through the network; the acronym here refers to telecommunications rather than a cash machine.

The proportion of a defined period during which a service meets its agreed usable state. A percentage is meaningful only with a measurement period, service boundary and treatment of excluded downtime.

The central network links and systems that carry traffic between other parts of a network. What counts as the backbone depends on the network's topology and organizational boundaries.

The data-carrying capacity of a network link or service, commonly expressed in bits per second. Delivered throughput also depends on overhead, contention and the endpoints. In radio engineering, bandwidth can instead mean a range of frequencies.

Read the guide: Technology Terms That Help You Read Product Specifications

Compare: Throughput, Latency

A general term for high-capacity communications access. Regulatory speed thresholds vary by jurisdiction and date; use a service's stated download and upload rates for a specific comparison.

A description applied to equipment intended for telecommunications-provider operation. Establish the actual requirements for availability, redundancy, maintenance and support instead of treating the phrase as a universal certification.

Communication that establishes a dedicated connection or reserved circuit resources for a session. Traditional telephone networks used this approach; the particular system determines how resources are allocated.

The network functions that establish and maintain information used to direct traffic, such as routing decisions. Packet forwarding applies that information in the data plane.

Combining services such as voice, video and data on a shared communications infrastructure. Capacity, service quality and operational responsibilities still need to be defined for each service.

The ability to continue a specified service when a component or operation fails. Its extent depends on the failure types covered and on whether redundant parts share a common vulnerability.

A wide-area networking technology that carries frames over virtual circuits. Records for inherited services may describe local circuit identifiers, access rates and committed information rates.

Gigabits per second: one billion bits per second. It is a rate, while gigabytes describe an amount of data; eight bits make one byte before accounting for transfer overhead.

Internet Protocol: the network-layer protocol family used to address and carry packets between networks. IPv4 and IPv6 provide different address formats; delivery behavior also depends on other protocols and the path.

Variation in packet delay over time. Real-time voice and video systems may buffer arriving data to absorb some variation, trading additional delay for steadier playback.

The core of an operating system that manages resources and provides essential services to software. Its responsibilities commonly include memory, scheduling and interaction with device drivers.

The delay for a specified operation or communication. Network measurements may describe one-way delay or round-trip time, so keep that distinction and the units with the result. Low latency helps interactions respond promptly.

Read the guide: Technology Terms That Help You Read Product Specifications

Compare: Bandwidth (network capacity), Throughput

A module providing network interfaces and related functions within equipment such as a modular router. Port types, supported modules and software compatibility determine its role in a particular chassis.

Multiprotocol Label Switching: forwarding network traffic using labels assigned to a path or forwarding class. Labels help organize traffic through an MPLS network; service behavior also depends on its configuration.

Related coverage: MPLS

A boundary where users, devices or other networks connect to the network being described. Its location depends on the scope of the diagram or service under discussion.

Network service provider: an organization supplying network connectivity or related services. A service description should identify its coverage, handoff and responsibilities.

Related coverage: Gigabit Ethernet Test Equipment

A thin strand of transparent material that guides light carrying information. Fiber type, optical wavelength, transceivers and the link's losses determine the connection it can support.

A unit of data carried through a packet network, with control information and a payload. The protocol determines its fields; not every packet contains all the information needed to order a complete application message.

Sharing network links by transmitting data in separate packets. Different flows can use the same link; delivery, ordering and recovery from loss depend on the protocols used.

Point of presence: a location where a provider makes network connectivity or related services available. The equipment and interconnections at that location determine its role.

A physical connection point for a network interface, such as an Ethernet socket or optical-module slot. Its connector, signaling standard and supported equipment must be considered together.

An agreed set of rules for exchanging information between systems. A protocol specifies behavior or message structure; a connector specifies a physical connection.

Quality of service: mechanisms and policies that classify and treat network traffic differently. Prioritization, queueing and resource controls can support service goals, but do not create unlimited link capacity.

A router component that performs control functions such as maintaining routing information. How control and forwarding are divided depends on the router's architecture.

A device or software function that forwards packets between networks using forwarding information. Its interface support and configuration determine which networks it connects.

The ability of a system to accommodate a larger workload or deployment. A useful claim identifies what grows, which resources must be added and how performance changes.

Synchronous Optical Network, a standardized optical transport system associated with North American telecommunications. Interpreting an inherited circuit requires its line rate, payload, timing and handoff details.

The internal interconnection that carries traffic between a device's input and output interfaces. Its architecture and capacity contribute to how the device handles simultaneous traffic.

Terabits per second: one trillion bits per second. It describes a data rate, not an amount of storage or a guaranteed application-transfer speed.

The rate of data successfully transferred across a defined boundary during a measured interval. Application payload throughput can be lower than the link's capacity because of overhead, congestion and endpoint limits; state what was counted.

Read the guide: Technology Terms That Help You Read Product Specifications

Compare: Bandwidth (network capacity), Latency

Voice over Internet Protocol: carrying voice communication as data over IP networks. Call quality depends on the endpoints, network path, delay and packet delivery as well as the service.

Related coverage: VoIP Guides: Calls, Equipment, SIP, and Operations