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Ethernet Interface — Intel
®
82575EB Gigabit Ethernet Controller
324632-003 Intel
®
82575EB Gigabit Ethernet Controller
Revision: 2.1 Software Developer’s Manual and EEPROM Guide
January 2011 241
9.0 Ethernet Interface
The 82575 provides a complete CSMA/CD function supporting IEEE 802.3 (10 Mb/s), 802.3u (100 Mb/
s), 802.3z and 802.3ab (1000 Mb/s) implementations. It performs all of the functions required for
transmission, reception and collision handling called out in the standards.
• Each 82575 MAC can be configured to be used a different media interface. While the most likely
application is expected to be based on use of the internal copper PHY, the 82575 supports the
following configurations:
• Internal Copper PHY.
• External SerDes device such as an optical SerDes (SFP or onboard) or backplane connections.
• External SGMII device. This mode is used for SFP connections or external SGMII PHYs.
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. lists the encoding on the
LINK_MODE field for each of the modes.
Table 78. Link Mode Encoding
The GMII/MII mode used to communicate between the MAC and the internal PHY and SGMII mode
supports 10/100/1000 Mb/s operation, with both half- and full-duplex operation at 10/100 Mb/s, and
full-duplex operation at 1000 Mb/s.
The SerDes function can be used to implement a Fiber/optics-based solution or backplane connection
without requiring an external transceiver/SerDes.
Note: There are two SerDes modes supported by the 82575, a legacy mode
(EXT_CTRL.LINK_MODE = 01b) and a recommended one (EXT_CTRL.LINK_MODE = 11b).
The following description refers to both modes. Both modes implement the same protocol.
However the control and status registers used in the two modes are different.
The SGMII interface can be used to connect to SFP modules; however, the following limitations apply:
• No Tx clock
• AC coupling only
Link Mode 82575 Mode
00b Internal PHY
01b Reserved
10b SGMII
11b New SerDes