Node (networking)

Node (networking)

In networking and telecommunications, a node is a basic unit. The term has a broad meaning and is used to refer to any device connected to a network. The specific meaning of "node" varies depending on the context of the network and the layer of the network architecture being discussed.

Generally, a node is a point within a communication network. It can be an Endpoint for data transmission or a Redistribution point that forwards data to other nodes.

General Role

In the most general sense, a node serves as either:

• An **Endpoint**: A device where communication originates or terminates. Examples include computers, phones, printers, or servers that are the final destination or initial source of a message.
• A **Redistribution or Junction Point**: A device that routes, switches, or forwards data along the network path between endpoints. Examples include routers, switches, and hubs.

Nodes are connected by communication channels (often called links or lines), and the arrangement of nodes and links forms the network's topology.

Node Types and Examples

The term "node" is used in different ways across various networking domains:

• **Computer Networks:** In typical computer networks, nodes are devices that are connected and capable of sending, receiving, or forwarding information.

   * Examples include computers (laptops, desktops, servers), printers, network attached storage (NAS) devices – often considered endpoints.
   * Network infrastructure devices like routers, switches, hubs, and modems are also considered nodes, acting as redistribution points or junctions.

• **Data Communications:** While sometimes more granular terms are used (like Data Terminal Equipment - DTE, and Data Communication Equipment - DCE), both DTEs (e.g., computers) and DCEs (e.g., modems) can be considered nodes in a data communication link.
• **Telecommunications:** In telecommunications networks, a node can be a public or private connection point.

   * Examples include switching centers or central offices, cell towers in mobile networks, or individual telephones or fax machines as user endpoints.

• **Peer-to-Peer (P2P) Networks:** In P2P networks like those used for file sharing or cryptocurrencies, a node is typically any client or server program participating in the network by running the specific P2P software. Each participating instance is a node.
• **Distributed Systems and Blockchain:** In distributed systems, including blockchain networks, a node is an instance of the software participating in the system.

   * In a blockchain, a node might store a full or partial copy of the ledger, validate transactions, and contribute to maintaining 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 facilitate communication. The type of address used depends on the network layer and technology:

• MAC Addresses: Used to uniquely identify nodes at the Data link layer.
• IP Addresses: Used to identify nodes at the Network layer in IP networks (IPv4 and IPv6).
• Other network-specific identifiers in different protocols or systems.

See Also

• Network topology
• Computer network
• Telecommunications
• Peer-to-peer
• Distributed system
• Blockchain
• Endpoint
• Router (computing)
• Network switch
• Hub (computing)
• IP address
• MAC address
• Topology (networking)

References

• Template:Cite book - A standard textbook covering network fundamentals, including nodes.
• Template:Cite book - Another textbook covering data communication concepts and network components.
• Cloudflare - What is a Node? - An online resource explaining network nodes.