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Xilinx UG194 Virtex-5 FPGA Embedded Tri-Mode Ethernet MAC ...

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Chapter 6: Physical Interface<br />

Introduction to the Physical Interfaces<br />

OSI<br />

Reference<br />

<strong>Mode</strong>l<br />

Layers<br />

Application<br />

Presentation<br />

Session<br />

Transport<br />

Network<br />

Data Link<br />

PHY - Physical<br />

PCS - Physical Coding Sublayer<br />

PMA - Physical Medium Attachment<br />

PMD - Physical Medium Dependent<br />

Figure 6-1 illustrates the position of the <strong>Ethernet</strong> <strong>MAC</strong> sublayers and physical interface<br />

options within the OSI model.<br />

PCS<br />

PMA<br />

PMD<br />

MEDIUM<br />

1000BASE-X<br />

(eg optical fiber medium)<br />

LAN<br />

CSMA/CD<br />

Layers<br />

Higher Layers<br />

LLC - Logical Link Control<br />

<strong>MAC</strong> Control (Optional)<br />

<strong>MAC</strong> - Media Access Control<br />

Reconciliation<br />

MII - Media Independent Interface<br />

Figure 6-1: <strong>MAC</strong> Sublayer Partitioning, Relationship to the ISO/IEC OSI Reference <strong>Mode</strong>l<br />

The <strong>Ethernet</strong> <strong>MAC</strong> sublayer itself is independent of, and can connect to, any type of<br />

physical layer device. In Figure 6-1, two alternative physical sublayer standards are<br />

shown:<br />

BASE-T PHYs provide a link between the <strong>MAC</strong> and copper mediums. This<br />

functionality is not offered within the <strong>Ethernet</strong> <strong>MAC</strong>. However, external BASE-T PHY<br />

devices are readily available on the market. These can connect to the <strong>Ethernet</strong> <strong>MAC</strong><br />

using GMII/MII, RGMII, or SGMII interfaces.<br />

BASE-X PHYs provide a link between the <strong>MAC</strong> and (usually) fiber optic mediums.<br />

The <strong>Ethernet</strong> <strong>MAC</strong> itself can support the 1 Gb/s BASE-X standard. 1000BASE-X can<br />

be offered by connecting the <strong>Ethernet</strong> <strong>MAC</strong> to a RocketIO serial transceiver.<br />

The interface type and 1000BASE-X sublayer functionalities are summarized in the<br />

following subsections.<br />

138 www.xilinx.com TE<strong>MAC</strong> User Guide<br />

<strong>UG194</strong> (v1.10) February 14, 2011<br />

PCS<br />

PMA<br />

PMD<br />

MEDIUM<br />

1000BASE-T<br />

100BASE-T<br />

10BASE-T<br />

(eg copper medium)<br />

GMII - Gigabit Media Independent Interface<br />

RGMII - Reduced Gigabit Media Independent Interface<br />

SGMII - Serial Gigabit Media Independent Interface<br />

Note:<br />

The functions shown<br />

in gray are performed<br />

by the <strong>Ethernet</strong> <strong>MAC</strong> block<br />

GMII/MII<br />

RGMII<br />

SGMII<br />

<strong>UG194</strong>_6_01_072606<br />

R

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