Internet, Networking, & Security > Home Networking Overview of Autosensing Ethernet Devices Learn about this network optimization technique By Bradley Mitchell Bradley Mitchell Writer Massachusetts Institute of Technology University of Illinois An MIT graduate who brings years of technical experience to articles on SEO, computers, and wireless networking. lifewire's editorial guidelines Updated on June 30, 2021 Home Networking Ethernet The Wireless Connection Routers & Firewalls Network Hubs ISP Broadband Installing & Upgrading Wi-Fi & Wireless Trending Videos Close this video player Network adapters that support traditional and Fast Ethernet choose the speed at which they run through a procedure called autosensing. Autosensing is a feature of 10/100 Ethernet hubs, switches, and NICs. It involves probing the capability of the network using low-level signaling techniques to select compatible Ethernet speeds. Autosensing was developed to make the migration from traditional Ethernet to Fast Ethernet products easier. What Happens When They Connect? When first connected, 10/100 devices automatically exchange information with each other to agree on a common speed setting. The devices run at 100 Mbps if the network supports it, otherwise, they drop down to 10 Mbps to ensure a "lowest common denominator" of performance. Many hubs and switches are capable of autosensing on a port-by-port basis. In this case, some computers on the network may be communicating at 10 Mbps and others at 100 Mbps. 10/100 products often incorporate two LEDs of different colors to indicate the speed setting that is currently active. Was this page helpful? Thanks for letting us know! Get the Latest Tech News Delivered Every Day Subscribe Tell us why! Other Not enough details Hard to understand Submit