10BASE-T Ethernet became popular due its ease of use, its usage of unshielded twisted pair (UTP) cabling and its low cost. 10 is for 10 Megabits per second (Mbps) operation, BASE is for baseband operation, and T is for the twisted pair cable used for the network. The Network Interface Card (NIC) performs the functions of a transceiver so that no external transceiver is needed for stations. 10BaseT requires the use of a hub or concentrator because it uses a star topology. The hub serves as a central switching station thus controlling the incoming and outgoing signals. When using star topology if a station goes down it does not affect the rest of the network. Typically a RJ45 connector is connected to UTP cabling and is run straight from the hub to the NIC (10BaseT NIC's have a built-in RJ45 transceiver). Pins 1 and 3 transmit data and pins 3 and 6 receive data (the other pins are not used).

10 BASE-T WIRING RULES

• Maximum length per segment is 100 meters or 330 feet.
• Maximum of 2 devices per segment; one is the station and the other is the hub.
• Maximum of 2 Inter-Repeater Links between devices without using bridge or switch (A hub is a repeater ).
• Star topology.
• Certain hubs come with a standard BNC and/or AUI connection.
• Hubs can connect to fiber optic or coax networks.
• Unsheilded twisted pair no less than Category 2 is required for 10BaseT operation, however, Category 3 or higher is preferred.
• UTP cabling is not recommended for areas with electromagnetic
• or radio frequency interference (EMI/RFI).
• NIC's come with built-in transceivers so connections are made
• directly to the NIC.
• NIC's with standard AUI ports must use a twisted pair transceiver.

Ethernet Hub

An Ethernet hub, active hub, network hub, repeater hub, multiport repeater or hub is a device for connecting multiple Ethernet devices together and making them act as a single network segment. It has multiple input/output (I/O) ports, in which a signal introduced at the input of any port appears at the output of every port except the original incoming. A hub works at the physical layer (layer 1) of the OSI model. The device is a form of multiport repeater. Repeater hubs also participate in collision detection, forwarding a jam signal to all ports if it detects a collision.

Some hubs may also come with a BNC and/or Attachment Unit Interface (AUI) connector to allow connection to legacy 10BASE2 or 10BASE5 network segments. The availability of low-priced network switches has largely rendered hubs obsolete but they are still seen in 20th century installations and more specialized applications.

An image of ethernet hub -