Intel PCI User Manual

159

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 

Configuration of the link can be accomplished by several methods ranging from software forcing 

the link settings to Auto-Negotiation by the internal PHY. 

 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.

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.