Layer 1 Devices
Dedicated Layer 1 devices are mostly extinct in today's environments. As technology advanced, the functionality became obsolete or was rolled into layer 2 devices.
Repeater - Has 2 ports. Takes received data from one side and retransmits it on the other. It allows the physical transmission medium to be extended.
Hub - A multi-port repeater. Data is received on one port, and retransmitted out ALL other ports (except port it was received on)
- Single Collision Domain
- Single Broadcast Domain