Node (networking)
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Node (networking)
In networking and telecommunications, a node is a fundamental unit. This term is broad and refers to any device connected to a network. The exact meaning of "node" can change based on the network's specific context and the part of the network architecture being discussed.
Generally, a node is a specific point within a communication network. It can either be where data transmission begins or ends (an endpoint), or it can be a redistribution point that forwards data to other nodes.
General Role
Most broadly, a node acts in one of two ways:
As an Endpoint: This is a device where communication starts or finishes. Examples include computers, phones, printers, or servers that are the original source or final destination of a message. As a Redistribution or Junction Point: This type of device routes, switches, or forwards data along the network path between different endpoints. Examples include routers, switches, and hubs. Nodes are connected by communication channels, often referred to as links or lines. The way these nodes and links are arranged defines the network's topology.
Node Types and Examples
The term "node" is used differently across various networking fields:
Computer Networks: In typical computer networks, nodes are devices that connect to the network and can send, receive, or forward information. Devices like computers (laptops, desktops, servers), printers, and network attached storage (NAS) devices are often considered endpoints. Network infrastructure devices such as routers, switches, and hubs are also nodes, serving as redistribution points or junctions for data. Data Communications: While more specific terms like Data Terminal Equipment (DTE) and Data Communication Equipment (DCE) are sometimes used, both DTEs (e.g., computers) and DCEs (e.g., modems) function as nodes in a data communication link.
Telecommunications: In telecommunications networks, a node can be a public or private connection point. Examples include telephone switching centers, cell towers in mobile networks, or individual telephones and fax machines acting as user endpoints. Peer-to-Peer (P2P) Networks: In P2P networks, which are common for file sharing or cryptocurrencies, a node is typically any client or server program that participates in the network by running the specific P2P software. Each instance of the software participating is considered a node. Distributed Systems and Blockchain: In distributed systems, including blockchain networks, a node is an instance of the software participating in the system's operation. In a blockchain, a node might store a full or partial copy of the ledger, validate transactions, and help maintain the network's consensus. Examples include full nodes, light nodes, and mining nodes in cryptocurrency networks like Bitcoin or Ethereum.
Node Identification
Nodes on a network are typically identified using unique addresses to enable communication. The type of address used depends on the network layer and technology:
MAC Addresses: These are used to uniquely identify nodes at the data link layer of a network. IP Addresses: These identify nodes at the network layer in IP networks (both IPv4 and IPv6). Other network-specific identifiers may be used in different protocols or systems.
