Packet Switching and Circuit Switching are two key ways for data to travel in networks.
Definitions
Circuit Switching was used for phone calls back in the days. It creates a dedicated line between you and the person you’re calling. The line stays open during the call for instant, clear voice but is reserved for that call only. It is a communication method where a dedicated connection path is establised and reserved for the entire duration between two endpoints.
Example: Old landline phones
Today, Packet Switching dominates, while Circuit Switching is almost phased out. It works over the internet, breaking voice/video into packets that travel shared routes. Your data splits into smaller packets that find their own way, like puzzle pieces.
Example: WhatsApp calls, Netflix streaming, browsing. It is a data transmission method where messages are divided into packets that are sent independently across a network and reassembled at the destination.
Both have played important roles in digital communication.
Timeline
to briefly visualize the history of packet switching and circuit switching
1870s – 1890s
Circuit Switching
The first manual switchboard lights up in New Haven, Connecticut. Operators connecting callers physically with path cords. Circuits for voice; no sharing and a private path until the call ends.
Photo: Alexander Graham Bell, who patented the telephone in 1876, inaugurating the 1,520-km (944-mile) telephone link between New York City and Chicago on October 18, 1892.
1920s – 1950s
Crossbar Switches
Fully automatic crossbar switches are introduced to make circuit-switched telephony faster and more suitable for big cities and more people.
Photo: Telephone crossbar switch made by Swedish Ericsson, 1921. This switch could support up to 100 callers.
1962 – 1964
Packet Switching part 1
1962 – 1964, Paul Baran suggests breaking messages into small packages and routing them over a distributed network for less failures. This is the start of Packet Switching
Photo: Paul Baran presenting his work at RAND Alumni Association event in 2009. You can see the network of unmanned nodes on the photo. The nodes would use a scheme called “Hot-Potato-Routing”.
1965
Packet Switching part 2
Donald Davies at UK Nation Physical Laboratory develops a packet-switched data network. The word “packet” described the 128-byte datablocks flowing through the system. Way more efficient than circuits.
Photo: Donald Watts Davies
1969 – 1973
ARPANET
ARPANET (Advanced Research Projects Agency Network, the first computer network was built at UCLA (Santa Monica, close to where Baran worked). It sends it first packet between UCLA and Stanford, making it one of the first networks demonstrating that packets can link to many different sites.
Photo: Visual representation of the spread of ARPANET in the states, september 1974
1974
Modern Internet
Vinton Cerf and Robert Khan publish the TCP/IP design. This standardized a packet-based protocol suite that allowed different networks to interconnect and efficiently launching the modern Internet architecture.
Photo: Vinton Cerf and Robert Khan together
1900 – today
Modern World
Photo: Nico El Nino/Shutterstock – slashgear.com – “Evolution of the internet…”
The public internet, web, streaming, cloud services, VPN… It all rely on Packet Switching, with routers and switches forwarding IP packets across shared links.
Circuit Switching is still relevant mainly in legacy telephone networks and some fixed voice systems, but even telephones is gradually migrated to packet-based technologies like VoIP and mobile data.
Photo: Illustration of international connection
