Intel Intel Gigabit Ethernet Controllers, PCI-X manual Auto-Negotiation and Link Setup1

Ethernet Interface

The normal rules for IPG are followed during packet bursting after the first packet has met the minimum slot time requirements, with the exception that the Inter Frame Content (IFC) is extension symbols rather than IDLEs. Under some circumstances, it might be desirable to extend this IPG time during a burst. This can be done via the AIFS field in the AIT register. See Section 13.4.35.

8.5Auto-Negotiation and Link Setup1

Configuration of the link can be accomplished by several methods ranging from software forcing the link settings to Auto-Negotiation by the internal PHY. Section 8.6.1 describes the process of bringing the link up including configuration of the MAC and PHY, as well as the various methods of determining duplex and speed configuration.

The PHY performs Auto-Negotiation per 802.3ab clause 40 and extensions to clause 28. Link resolution is obtained from the PHY after the link has been established via the MDIO interface, by the controller via specific input signals from the PHY or by the controller’s specific auto detection functions.

Upon power up, or device reset via the RST# input, the controller initiates Auto-Negotiation based on the default settings in the Device Control and Transmit Configuration Word registers, as well as settings read from the EEPROM. If enabled in the EEPROM, the Ethernet controller will immedi- ately perform Auto-Negotiation.

8.6Auto-Negotiation and Link Setup2

Configuration of the link can be accomplished by several methods ranging from software forcing the link settings to Auto-Negotiation by either the MAC (Internal Serdes mode) or the internal PHY (GMII/MII mode). The following sections describe the process of bringing the link up including configuration of the MAC and PHY, as well as the various methods of determining duplex and speed configuration.

The process of determining link configuration differs slightly depending on the Ethernet controller type and version. In Internal Serdes mode, the MAC performs Auto-Negotiation per clause 37 of the 802.3z standard. The transceiver used in this mode (the SerDes) does not participate in the Auto-Negotiation process as all aspects of Auto-Negotiation are controlled by the MAC.

For internal PHY mode, the PHY performs Auto-Negotiation per 802.3ab clause 40 and extensions to clause 28. Link resolution is obtained from the PHY after the link has been established via the MDI/O interface, by the Ethernet controller via specific input signals from the PHY, or by the Ethernet controller’s specific auto detection functions.

The method for configuring the link between two link partners is highly dependent on the mode of operation as well as the functionality provided by the specific physical layer device (PHY or SerDes). For Internal Serdes mode, the Ethernet controller provides the complete 802.3z PCS function on-chip. For GMII/MII mode, the PCS and Auto-Negotiation functions are maintained within the PHY.

1.82541xx, 82547GI/EI, and 82540EP/EM only.

2.Applicable to the 82546GB/EB, 82545GM/EM, and 82544GC/EI only.

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