The NIC on an Ethernet system can be of several types depending on the needs of where the NIC is connected. On a Workstation the deciding factors my be a combination of, low cost, ease of installation and a full suite of drivers. On a server the main consideration is performance. On a workstation a transfer speed of 10Mbps and a ISA bus may be all that is required whereas on a Server the NIC requirements may include a higher data transfer speed of up to 200Mbps with a PCI bus. It is important to realize that a server on a network system will be handling many requests from a variety of hosts. Without a decent transfer rate or a bus that has a low CPU utilization, the system could become congested and unusable to the nodes connected to the network.

All 10Base-T and 10/100Base-T NICs contain a Chipset that controls many different functions of a NIC. This Chipset is contained on a single chip on the NIC. These functions are as following

• MAC (Media Access Controller) The MAC (OSI level 2, data link) determines when a node can transmit a packet over a Network. It sends frames to PHY for conversion into packets and transmission on the media, and receives frames from the PHY and sends them to the software that processes the frames. It is important to note that a MAC is media independent. The MII (Media independent interface) connects the MAC and the PHY. The PHY determines the type of media that the data will be transmitted on and the MAC does not have any features that are tied to the type of media.
• Buffer memory controllers, Some NICs have interface pins to support external buffer memory. This may be an important when dealing with Client systems that may be using older processors and have limited memory. Some NICs have on board memory to allow the storage of incoming and outgoing packets. Still other types of NICs allow the MAC to access the local machines memory to store packets.
• Device and vendor ID's, Some NIC's contain an ID address that is integrated into the MAC chip. This address identifies the node to the rest of the network. It is also important to know that a network administrator can assign this address on some NICs.
• Integrated PHY, The PHY is the interface between the MAC and the external network media (OSI level 1, Physical). The PHY changes the MAC data into a format that can be transmitted over the network media. It can also be external to the NIC usually utilized with 100Mbps transfer speeds. Some units being shipped today include a modular PHY that can be changed to accommodate the type of media being employed.
• LED controls, The LED can be either located on the NIC (usually next to the media interface) or can be external. The LED indicates the operational status of the NIC.

Boot ROM, An optional component on some classes of NICs is a boot ROM. This component contains the software code that permits a diskless workstation to boot up and log onto a network. This feature is usually found on Unix workstations.