The versatility of Ethernet means that users have many choices of media, speed, and features. This could have turned Ethernet into a configuration nightmare.
Fortunately, automatic negotiation mechanisms were introduced in the mid-to late 1990s. Auto-Negotiation enables a pair of link partners to communicate whenever either end is initialized, reset, or reconfigured. The negotiation enables them to discover an optimal set of mutually supported capabilities.
Currently, two separate Auto-Negotiation technology families exist:
10Mbps, 100Mbps, and 1000Mbps twisted-pair interfacesVendors have built single-speed and multispeed twisted-pair interfaces that support Auto-Negotiation. Twisted-pair link partners can negotiate ...