Abstract: A system and method for dynamically switching between different physical layer devices (PHYs) in a network interface. The system comprises a network interface in a network device, e.g., a network card in a computer system which includes a first PHY device and a second PHY device. The first PHY device is coupled to a first transmission medium (such as fiber-optic cable) which requires a continuous connection to the computer system when active. For a SERDES device, this continuous connection is required because the PHY needs constant access to its physical coding sublayer (PCS), which is located external to the PHY. The second PHY device is coupled to a second transmission medium (such as copper cable) which does not require this continuous connection. This second PHY may be, for example, a G/MII device, which includes the PCS internally. The network interface card further includes a link switching unit, a physical layer interface unit, and a control unit.

Abstract: The present invention provides a method and an apparatus for transferring data between a computer system and a network interface card that avoids virtual-to-physical address translations. The computer system allocates blocks of memory during system initialization for storing data in transit between the computer system and the NIC, and the physical addresses of these blocks of memory are stored in a table on the NIC. Consequently, address conversion is performed only once, when the memory is allocated. When a request to transfer data to the NIC is received from the upper layers, the device driver copies the data from the upper layers into the next available memory block. The device driver then formats a command and passes it to the NIC for processing. Data transfer commands are communicated to the NIC through a packet descriptor command (PDC), which is a 32-bit value subdivided into fields that completely describe the data transfer operation.