Just call me NIC

Just call me NIC

The network interface card (NIC), also known as a network adapter, is central to the concepts of networking covered on the A+ exams.

The NIC is a physical and logical link for a PC to a network. It is installed inside the computer in an open expansion slot. NICs are available for most of the expansion bus architectures, so getting a card for an available slot is easy. However, the most common bus used for NICs is the PCI (Peripheral Component Interconnect), but many legacy ISA (industry standard architecture) cards are still in use.

Tip When choosing a NIC for a system, try to get one that is Plug and Play (PnP) compatible to make setup easier. Even with PnP, a network card can be a pain to set up. Some NICs use DIP switches or jumpers, and some use software to configure its identity and compatibility to the network.

The setup needed for the NIC is controlled by two factors: the PC itself and the NOS (network operating system, such as Windows NT/2000 or Novell NetWare). If you have the choice, do yourself a big favor and use the same brand and model NIC in every PC on the network. Mixing NICs on a network can be a pain, and you know where.

The NIC is a translator that works between the network and the PC. Networks transmit data in a serial data format (one bit at a time), and the data bus of the PC moves data in a parallel format (eight bits at a time). The NIC acts as a go-between to convert the signal from serial-to-parallel or parallel-to-serial, depending on its direction. The NIC also formats the data as required by the network architecture.

The NIC attaches a PC or other networked device to the network cabling and the network system. The primary purposes of the NIC are to serve as a transceiver, a device that transmits and receives data to and from other NICs (installed in the other networked nodes and devices), and to connect to the network cabling.

Here are a few NIC characteristics you should know:

l MAC (Media Access Control) address: Each NIC is physically encoded with a unique identifying address that is used to locate it on the network. This address is 48 bits (6 bytes) long.

l System resources: A NIC is configured to the computer with an IRQ, an I/O address, and a DMA channel. A NIC commonly uses IRQ3, IRQ5, or IRQ10, and an I/O address of 300h.

l Data bus compatibility: NICs are designed with compatibility to a particular data bus architecture. ISA (Industry Standard Architecture) and PCI (Peripheral Components Interconnect) cards are the most common.

l Data speed: The NIC card must be compatible to the data speed of the network. The data transfer speeds of a network are determined by several factors, including the cable media, the topology, and the network connectivity devices in use. For example, a token ring network uses STP cable-- the workstations attach to the network through MAUs (Multi-station Access Units)--and typically runs at either 4Mbps or 16Mbps. An Ethernet network uses UTP cable (or coax), attaches its workstations through hubs or switches, and most commonly runs at either 10Mbps or 100Mbps.

Many NICs have the ability to sense the data speed in use. A NIC designated as a 10/100 NIC has the ability to autosense between a 10Mbps and a 100Mbps network.

l Connectors: Several different connectors are used to connect NICs to network cabling. The type of connector depends mostly on the type of cable in use. Coax cabling primarily uses a BNC (for which they are several alleged meanings, none of which you need to know for the A+ exams) connector. Fiber-optic cabling is rarely used for cabling to workstations because of its cost. The most commonly used connector for networking is the RJ-45 connector, which is very much like the connector on your telephone, only a little bigger.