The NIC provides a physical connection between the networking cable and the computer's internal bus. The larger the number of bits that can be transferred to the NIC, the faster the NIC can transfer data to the network cable. Cards are available to support almost all networking standards, including the latest Fast Ethernet environment. Full duplex networking is another option, where a dedicated connection to a switch allows a NIC to operate at twice the speed. In larger designs, signal quality begins to deteriorate as segments exceed their maximum length.
Hubs provide the signal amplification required to allow a segment to be extended a greater distance.
A hub takes any incoming signal and repeats it out all ports. If the hub is attached to a backbone, then all computers at the end of the twisted pair segments can communicate with all the hosts on the backbone. The number and type of hubs in any one-collision domain is limited by the Ethernet rules. These repeater rules are discussed in more detail later. A very important fact to note about hubs is that they only allow users to share Ethernet.