MAC protocols (such as 802.5 Token-Ring or 802.3 Ethernet) provide bit-level error checking through cyclic redundancy checking (CRC). MAC protocols are sometimes also called frame types.
The CRC count which is added to every transmitted packet, assures that 99.9999 percent of the packets received are corruption free. MAC protocols define the addressing for each node on a NetWare network. This addressing is configured with each network interface card.
Both NetWare and UnixWare systems must bind a frame type to a network card in order to communicate over the network. If your network supports multiple MACs/frame types, multiple frame types may be bound to the same network interface card.