A node can mean different things in different contexts. A node can be defined in the context of a tree data structure or in the context of an open-source, cross-platform, JavaScript runtime environment (node.js) used for executing server-side JavaScript code. However, in this article, we will talk about a node in the context of a communication network.

Node definition

In any communication network, a node is a point where all the information exchange takes place. It can be any physical entity that is capable of receiving, storing, transmitting and redistributing data. Some examples of nodes that you use everyday in your home, school or office include your phone, personal computer, modem, network printer, network scanner, etc.

A computer node or a phone can be used to store information, send emails, stream videos, etc. A network printer receives print requests from other devices (nodes) on the network while a scanner sends scanned files to these nodes.

Bridges, switches and hubs and routers are some other nodes found commonly in a communication network. A router is used to redistribute information it receives.

A node can be seen as the basic building unit of a network. Each node has some form of identification, which could be an IP (Internet Protocol) address or a MAC (Media access control) address. This identification is must for the node to communicate with the rest of the network.

Types of nodes

Nodes have different nomenclature on the basis of the network they belong to and the function they perform. Some of the commonly used terminologies are:

  1. Internet Nodes: Found in both internet and intranet, host computers fall into this category. The characteristic of these nodes is that they are identified using an IP address.
  2. Physical network nodes: These types of nodes are found in both LAN (Local area networks) and WAN (wide area networks). The difference between physical network nodes and internet nodes is that LAN nodes are identified using a MAC address and not an IP address.
    An example of these types of nodes would be switches, hubs, router, etc.
  3. Telephone network nodes: This covers two types of telecommunication service – fixed telephone lines and cellular networks. In the case of fixed telephone lines, telephone exchanges act as a node as they are responsible for the transfer of data.
    These exchanges can be public or private in nature. For the cellular networks, an example of a node would be a base station controller (BSC) or Gateway GPRS Support Node (GGSN).
  4. Cable TV network nodes: Fibre optic cables are now widely used for cable TV networks. The key nodes in these networks include homes and (or) businesses connected by a typical fibre optic receiver. These networks are geographically constricted.
  5. Supernode: This node is defined in a peer-to-peer network. A peer-to-peer network is a type of network where there is no central server. A partial or full copy of the data is stored on every node that joins the network.
    In a peer-to-peer network, a supernode acts as a relay to transfer information between two nodes.  Depending on the network, users may or may not have control over whether they become a supernode.

Network connections

When two nodes in a network communicate with each other, they form what is called a network connection. Physical network connections are of two types:

  1. Point-to-point: These connections are formed when one node is allowed to communicate with exactly one other node directly.
  2. Multipoint: A node is said to have a multipoint connection when it can send messages directly to multiple devices in parallel.

Fun facts about network nodes

In the 1960s, Paul Baran and Donald Davies independently developed the concept of packet switching. With the introduction of distributed networks and packet switching, the concept of network nodes came into practice.

On October 29, 1969, the first four nodes of ARPANET were connected between four universities – University of California at Los Angeles (UCLA), Stanford Research Institute,  University of California at Santa Barbara (UCSB) and University of Utah.

ARPANET (Advanced Research Projects Agency Network) was a precursor to the Internet and laid the foundation of our current network communications.