Type: Answers

Type: Errata

Area: Intellectual Property



Late Collision in Half-Duplex 10/100-Mbps Ethernet MAC

Description

MAC function with 1000BASE-X/SGMII PCS may detect late collision when it is operating in 10/100-Mbps half-duplex mode. The external third party PYH and cables introduce latency in addition to the latency of the 1000BASE-X/SGMII PCS with embedded PMA. This issue arises when the total latency exceeds the 512-bit slotTime as defined in IEEE 802.3 Clause 4.4.

This issue affects MAC function designs that contain 10/100/1000 Mbps Ethernet MAC with 1000BASE X/SGMII PCS operating in 10/100 Mbps half duplex mode.

Workaround/Fix

Use 10/100/1000 Mbps Ethernet MAC only with GMII/MII or RGMII for 10/100 Mbps half duplex mode operation.This issue is fixed in version 11.0 of the Triple Speed Ethernet MegaCore function.