GMII and 1G or 2.5G SGMII - 16.2 English

1G/2.5G Ethernet PCS/PMA or SGMII LogiCORE IP Product Guide (PG047)

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16.2 English

The Gigabit Media Independent Interface (GMII), a parallel interface connecting a MAC to the physical sublayers (PCS, PMA, and PMD), is defined in IEEE 802.3-2008, clause 35. For a MAC operating at a speed of 1 or 2.5 Gbps, the full GMII is used; for a MAC operating at a speed of 10 Mbps or 100 Mbps, the GMII is replaced with a Media Independent Interface (MII) that uses a subset of the GMII signals.

The Serial-GMII (SGMII) is an alternative interface to the GMII/MII that converts the parallel interface of the GMII/MII into a serial format capable of carrying traffic at speeds of 10 Mbps, 100 Mbps, and 1 Gbps or 2.5Gbps. This radically reduces the I/O count and for this reason is often preferred by Printed Circuit Board (PCB) designers. The SGMII specification is closely related to the 1000BASE-X or 2500BASE-X PCS and PMA sublayers, which enables it to be offered in this core.