Computer Networks: A Systems Approach - Chapter 1 Foundation

Vocabulary flashcards covering the fundamental concepts, architectures, and performance metrics of computer networking based on Chapter 1 of 'A Systems Approach'.

Computer Network

A collection of general-purpose programmable hardware and software that is not optimized for a particular application but is instead able to carry many different types of data and support a wide range of applications.

Scalability

The property of a system that is designed to support growth to an arbitrarily large size.

Link

A physical medium, such as a coaxial cable or an optical fiber, that connects two or more computers.

Nodes

The computers or specialized pieces of hardware connected by a network link.

Point-to-point link

A physical link that is limited to a single pair of nodes.

Multiple-access link

A physical link where more than two nodes share a single physical medium, such as those used in cellular or Wi-Fi networks.

Switched Network

A set of nodes organized so that certain nodes, which are attached to at least two links, run software to forward data received on one link out on another.

Packet switching

A method of networking where nodes send discrete blocks of data (packets or messages) using a strategy called store-and-forward.

Store-and-forward

A strategy where each node in a network receives a complete packet, stores it in internal memory, and then forwards the complete packet to the next node.

Circuit switching

A networking strategy that first establishes a dedicated circuit across a sequence of links and then allowed bitstreams to travel from a source to a destination.

Hosts

Nodes located on the outside of a network cloud that support users and run application programs.

Switches

Nodes inside a network cloud whose primary function is to store and forward packets.

Internetwork (internet)

An interconnection of independent networks, formed by connecting clouds through routers or gateways.

Router (gateway)

A node connected to two or more networks that forwards messages from one network to another.

Address

A byte string used to identify a specific node and distinguish it from other nodes connected to a network.

Routing

The process of determining systematically how to forward messages toward a destination node based on its address.

Unicast

A communication scenario where a source node sends a message to a single destination node.

Multicast

A communication scenario where a source node sends a message to a subset of other nodes on the network.

Broadcast

A communication scenario where a source node sends a message to all nodes on the network.

Multiplexing

The process of sharing a single system resource among multiple users.

Synchronous Time-Division Multiplexing (STDM)

A multiplexing method that divides time into equal-sized quanta and gives each flow a chance to send data in a round-robin fashion.

Frequency-Division Multiplexing (FDM)

A multiplexing method that transmits each flow over the physical link at a different frequency.

Statistical Multiplexing

A form of multiplexing where the physical link is shared over time and data is transmitted from flows on demand rather than during predetermined time slots.

Congestion

A state in which a switch receives packets faster than it can send them on an outgoing link, forcing it to buffer packets or eventually drop them.

Quality of Service (QoS)

A network's ability to allocate bandwidth to particular flows and fairly manage the transmission of packets.

Logical Channel

An abstraction provided by a network to connect application processes, providing specific services like reliable delivery or privacy.

Layering

A tool for managing complexity where a system is designed as a sequence of layers, each providing a more abstract level of service to the layer above.

Protocol

An abstract object that provides a communication service that higher-level objects use to exchange messages.

Service Interface

The set of operations that local objects on the same computer can perform on a protocol to use its communication services.

Peer Interface

The set of rules governing the form and meaning of messages exchanged between counterpart molecules on different machines.

Protocol Specification

A combination of prose, pseudocode, and diagrams that defines the abstract interfaces and message meanings for a protocol.

Encapsulation

The process where a high-level protocol's message is placed in the payload of a low-level protocol's message, which then adds its own control information.

Header

A small data structure attached to the front of a message used by protocol peers to communicate control information.

Demultiplexing key

An identifier in a protocol header used to record which high-level protocol or application a message belongs to.

OSI Architecture Layers

The seven layers are: Physical, Data Link, Network, Transport, Session, Presentation, and Application.

Internet Protocol (IP)

The protocol at the 'narrow waist' of the Internet architecture that supports the interconnection of multiple networking technologies.

Transmission Control Protocol (TCP)

An end-to-end transport protocol that provides a reliable byte-stream channel to application programs.

User Datagram Protocol (UDP)

An end-to-end transport protocol that provides an unreliable datagram delivery channel.

Socket API

The interface that the operating system provides to its networking subsystem, allowing applications to attach to the network.

Bandwidth

A measure of network performance defined by the number of bits that can be transmitted over the network in a certain period of time, often expressed in $Mbps$.

Latency (Delay)

The time it takes a message to travel from one end of a network to the other, calculated as $Latency = \text{Propagation} + \text{Transmit} + \text{Queue}$.

Round-trip time (RTT)

The specific latency measurement of how long it takes to send a message from one end of the network to the other and back.

Delay imes Bandwidth Product

The product of latency and bandwidth which corresponds to the 'volume' of the network pipe, or the maximum number of bits in flight at once.

Jitter

The variation in latency from packet to packet within a packet stream.

Feature Velocity

The rate at which new capabilities and services are introduced into a network.

Software Defined Networks (SDNs)

A networking approach that uses commodity hardware and moves intelligence into software to accelerate innovation and simplify management.