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Software Developer’s Manual 155
Ethernet Interface
Ethernet Interface 8
8.1 Introduction
The PCI/PCI-X Family of Gigabit Ethernet Controllers provide a complete CSMA/CD function
supporting IEEE 802.3 (10Mb/s), 802.3u (100Mb/s), 802.3z and 802.3ab (1000Mb/s)
implementations. They perform all of the functions required for transmission, reception and
collision handling called out in the standards.
The internal Gigabit Media Independent Interface/Media Independent Interface (GMII/MII)
supports the onboard 10/100/1000 BASE-T transceivers full duplex operation and supports the
onboard 10/100 BASE-T transceivers in full or half duplex operation.
Note: The 82541xx, 82547GI/EI, and 82540EP/EM do support SerDes functionality.
8.2 Link Interfaces Overview
82546GB/EB and 82545GM/EM Ethernet controllers contain an internal 10-bit Fibre Channel
Interface (TBI), as specified in IEEE 802.3z, for full-duplex operation with a SerDes transceiver.
This configuration is applicable to 1000BASE-SX, -LX, or –CX links. When in internal SerDes
mode, they provide the full Physical Coding Sub-layer implementation including Auto-Negotiation
as called out in IEEE 802.3z.
82544GC/EI Ethernet controllers support a 10-bit TBI, as specified in IEEE 802.3z, for full-
duplex operation with a SerDes transceiver. This configuration is applicable to 1000BASE-SX, -
LX, or –CX links. When in TBI mode, they provide the full Physical Coding Sub-layer
implementation including Auto-Negotiation as called out in IEEE 802.3z.
Selection between the various configurations is programmable via each MAC’s Extended Device
Control Register (CTRL_EXT.LINK_MODE bits) and defaulted via EEPROM settings. Note that
the external TBI interface is a single resource that can only be associated with a single MAC.
The GMII/MII mode used to communicate between the MAC and the internal PHY supports 10/
100/1000 Mbps operation, with both half- and full-duplex operation at 10/100 Mbps, and full-
duplex operation at 1000 Mbps.
Note: The Ethernet controllers are optimized for full-duplex operation in 1000 Mbps mode. Half-duplex
1000 Mbps operation is NOT supported and is not recommended.
The internal copper PHY features 10/100/1000-BaseT signalling and is capable of performing
intelligent power-management based on both the system power-state and LAN energy-detection
(detection of unplugged cables). Power management includes ability to shut-down to extremely
low (powered-down) state when not needed, as well as ability to auto-negotiate to lower-speed
(and less power-hungry) 10/100 Mbps operation when the system is in low power-states.