I347-AT4 Datasheet, PDF (32/148 Pages) Intel Corporation – Intel® Ethernet Network Connection I347-AT4 Datasheet

I347-AT4—Device Functionality
MAC
PCS
PMA
System
Interface (SGMII)
0_0.14 = 1b
PMD
Copper
Interface
Figure 8. MAC Interface Loopback Diagram - Copper Media Interface
3.3.2
Line Loopback
Line loopback allows a link partner to send frames into the I347-AT4 to test the
transmit and receive data path. Frames from a link partner into the PHY, before
reaching the MAC interface pins, are looped back and sent out on the line. They are
also sent to the MAC. The packets received from the MAC are ignored during line
loopback. Refer to Figure 9. This allows the link partner to receive its own frames.
Before enabling the line loopback feature, the PHY must first establish link to another
PHY link partner. If auto-negotiation is enabled, both link partners should advertise the
same speed and full-duplex. If auto-negotiation is disabled, both link partners need to
be forced to the same speed and full-duplex. Once link is established, the line loopback
mode can be enabled.
Register 21_2.14 = 1b enables the line loopback on the copper interface.
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