At that time, Ethernet only supported connections to coaxial cables.

The first Ethernet bridges were two-port devices that could link two of the original Ethernet systemвЂ™s coaxial cable segments together. ThatвЂ™s the result of lots of hard work on the part of the standards engineers to define a set of standards that vendors could agree upon and implement in their switch designs. The standardization of bridging operations in switches makes it possible to buy switches from different vendors that will work together when combined in a network design. Ethernet bridging was initially defined in the 802.1D IEEE Standard for Local and Metropolitan Area Networks: Media Access Control (MAC) Bridges. To do this, they copy Ethernet frames from one switch port to another, based on the Media Access Control (MAC) addresses in the Ethernet frames. By moving Ethernet frames between the switch ports, a switch links the traffic carried by the individual network connections into a larger Ethernet network.Д®thernet switches perform their linking function by bridging Ethernet frames between Ethernet segments. Ethernet switches link Ethernet devices together by relaying Ethernet frames between the devices connected to the switches.

Mac ethernet connection several tries