C H A P T E R

C H A P T E R 1

The hme Device Driver

This chapter gives a hardware overview of the SUNW,hme device, provides information on the operating speeds and modes for the SUNW,hme device, and discusses auto-negotiation. Note that the external transceiver is not present on the SunSwiftTM SBus Adapter or the SunSwiftTM PCI Adapter. The following sections describe features of the SUNW,hme device.

Supported Hardware

The hme device driver handles the SUNW,hme device on these hardware devices:

SunSwift SBus Adapter
SunSwift PCI Adapter
SunFastEthernet Adapter 2.0
SunFastEthernet PCI Adapter
Sun Ultra systems and Sun Enterprise servers

TABLE 1-1 Transceivers Available In Sun Adapters
Adapters	Transceivers
SunSwiftTM SBus Adapter	Internal only
SunSwiftTM PCI Adapter	Internal only
SunTM FastEthernet Adapter 2.0	Both External and Internal
SunTM FastEthernet PCI Adapter	Both External and Internal

Hardware Overview

The SUNW,hme device provides 10BASE-TX or 100BASE-T networking interfaces using the Fast Ethernet Parallel Port SCSI (FEPS) ASIC and an internal transceiver. The driver automatically sets the link speed to 10 or 100 Mbps and conforms to the 100BASE-T IEEE 802.3u Ethernet standard . The FEPS (SBus based) or PFEX (PCI-bus based) ASIC provides the SBus or PCI interface and Media Access Control (MAC) functions. The internal transceiver, which connects to an RJ-45 connector on all of the above hardware devices, provides the physical layer functions.

In addition to the RJ-45 connector, a Media Independent Interface (MII) connector, which is an Ultra DB 40 connector, is also provided on some adapters. The MII connects to an external transceiver that may use any physical media, such as copper or fiber, as specified in the 100BASE-TX standard. When an external transceiver is connected to the MII, the driver selects the external transceiver and disables the internal transceiver. The external transceiver may also support the 100BASE-T4 standard, which allows the link to operate in 100 Mbps speed using four pairs of category 3 or better cable.

Operating Speeds and Modes

You can operate the link in any of the following speeds and modes with the SUNW , hme device:

100 Mbps, full-duplex
100 BASE-T4 (with external transceiver only)
100 Mbps, half-duplex
10 Mbps, full-duplex
10 Mbps, half-duplex

The 100BASE-T I EEE 802.3u Ethernet Standard describes these speeds and modes.

Auto-Negotiation

The auto-negotiation protocol , as specified by the 100BASE-T IEEE 802.3u Ethernet Standard , selects the operation mode (half-duplex or full-duplex) at boot time or when the link state changes (the link fails or tries to connect). The auto-negotiation protocol also selects the speed and the full-duplex or half-duplex mode.

Details of the way the SUNW,hme device uses auto-negotiation are provided in Appendix A .

The auto-negotiation protocol does the following:

Identifies all link partner-supported modes of operation
Advertises its capabilities to the link partner
Selects the highest common denominator mode of operation based on the following priorities (in decreasing order):
- 100 BASE-T4
- 100 Mbps, full-duplex
- 100 Mbps, half-duplex
- 10 Mbps, full-duplex
- 10 Mbps, half-duplex

The link partner is the networking device (system, Ethernet hub, or Ethernet switch) at the other end of the link or cable.

If the SUNW,hme device is connected to a remote system or interface that is not capable of auto-negotiation, the system automatically selects the correct speed and half-duplex mode.

If adapters or systems are connected to a link partner and the auto-negotiation protocol fails to operate successfully, you can configure the device so it does not use this protocol. This forces the driver to set up the link in the mode and speed of your choice.