C H A P T E R

C H A P T E R 1

The dmfe Device Driver

The dmfe (Davicom Fast Ethernet) device driver handles the Davicom(R) DM9102A devices on the Netra X1 and Sun Fire V100 servers.

This chapter has the following sections:

Hardware Overview

The DM9102A device provides a 100BASE-TX or 10BASE-T Ethernet network interface, including the PCI interface and Media Access Control (MAC) functions. The internal transceiver, which connects to an RJ-45 connector, provides the physical layer functions. The device can automatically set the link speed to 10 or 100 Mbps and it conforms to the 100BASE-T IEEE 802.3u Ethernet Standard .

Operating Speeds and Duplex Modes

You can operate the link in any of the following combinations of speed and duplex mode:

100 Mbps, full-duplex
100 Mbps, half-duplex
10 Mbps, full-duplex
10 Mbps, half-duplex

These speeds and duplex settings are described in the Ethernet Standard .

Auto-Negotiation

A key feature of the Davicom DM9102A Fast Ethernet device is auto-negotiation. The auto-negotiation protocol, as specified by the Ethernet Standard allows the device to determine automatically the appropriate speed and duplex settings. When the system is powered on, the device uses the auto-negotiation protocol to:

Advertise its own speed and duplex capabilities to the hub or switch it is connected to (the "link partner"),

Accept notification of the link partner's capabilities,
And to select the mode of operation that permits the highest possible data-throughput given the link partner's capabilities:
- 100 Mbps, full-duplex
- 100 Mbps, half-duplex
- 10 Mbps, full-duplex
- 10 Mbps, half-duplex

If the DM9102A device is connected to a remote system or interface that supports auto-negotiation, your system automatically selects the correct link speed and duplex mode.

If you connect the DM9102A device to a hub or switch with which the auto-negotiation protocol fails to operate successfully, you can configure the DM9102A device not to use auto-negotiation. If you do this you need to specify the speed and duplex setting for it to use (see Chapter 2 and Chapter 3 ).