What Does Autosense Mean?

Autosense refers to a feature found in network adapters that allows them to automatically recognize the current local network’s speed and adjust its own setting accordingly. It is often used with Ethernet, fast Ethernet, switches, hubs and network interface cards.


Most autosensing is used with network adapters that support network interfaces. Some systems have specialized autosensing that automatically configures and prioritizes the communication needed to transmit signals.

Techopedia Explains Autosense

Autosense is a feature most often used with network adapters that adjusts settings according to network conditions and supports autoconfiguration.

Autosense for network adapters was first developed by National Semiconductor in 1994 using NWay telecommunications protocol. It was used with Ethernet devices such as a switch and router, which allowed devices to operate at different network speeds. The NWay automatically configured the best, highest speed and what mode the device should use by briefly controlling the cable to adjust the settings. NWay supports 10Base-T, 10Base-T duplex, 100Base-T, 100Base-TX duplex and 100Base-T4.

When an Ethernet 10/100 card is first connected to a network, the speed is automatically adjusted. The card will default to the highest speed (100) unless the network connection does not support it. A hub or switch can also autoadjust its speed by autosensing the speed that is required. Various hubs and switches use autosense on a port-to-port basis.

Autosense can automatically detect a current condition in several ways:

  • Automatic MDI/MDI-X: Detects whether a crossover cable is needed in gigabit Ethernet
  • Media Sensing: A feature found in a printer that detects paper size and type of paper and determines whether there is a connection to the network
  • Auto Negotiate or NWay: Recognizes settings such as line speed in Ethernet 10/100 cards and adjusts them appropriately
  • Medium Dependent Interface (MDI) port: Used to connect to other switches or hubs without requiring a crossover cable

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Margaret Rouse is an award-winning technical writer and teacher known for her ability to explain complex technical subjects to a non-technical, business audience. Over the past twenty years her explanations have appeared on TechTarget websites and she's been cited as an authority in articles by the New York Times, Time Magazine, USA Today, ZDNet, PC Magazine and Discovery Magazine.Margaret's idea of a fun day is helping IT and business professionals learn to speak each other’s highly specialized languages. If you have a suggestion for a new definition or how to improve a technical explanation, please email Margaret or contact her…