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Packet vs. circuit switching data networks: An expert explains the differences

Network administration expert, Lindi Horton answers a query regarding packet vs. circuit switching in regards to data networks by using an analogy to help explain the concept of both.

What is the difference between packet and circuit switched data networks?

A group of children are playing in a playground. It’s a beautiful day, and they’re all laughing and running around. A boy yells across the field, “Hey Tommy! You wanna play catch?” Tommy replies, “Absolutely, let’s go.” Across the way, Suzie is playing telephone with Sara. Two cans attached to a string are used to relay their important messages back and forth.

You might be wondering where I’m going with this quick story. This scene is an analogy for the primary difference between packet switched and circuit switched networks. Fundamentally, a packet switched network establishes a path from host to host over a shared medium, i.e. the boys in this story. Packet switching relies on shared resources to transfer data across the network, similar to yelling across a field where multiple conversations are going on at the same time. They have to share the resources.

A circuit switched network is greedier with its resources but ensures the availability of those resources. Similar to the girls in the s tory, circuit switching establishes a path by reserving circuits along the way. From point A to point B you have allocated specific resources for the duration of the conversation. Host A and Client B have sole rights to leverage those resources until terminating the call. In the past circuit switching technologies existed mostly for voice communications. In today’s day and age, voice traffic is also sharing the road with data networks in a converged packet switched environment.

This was last published in May 2011

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