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AR# 20741

LogiCORE Gigabit Ethernet MAC v5.0 Core - Excessive delay between tx_data_valid and tx_ack when transmitting jumbo frames when jumbo frame support is disabled

Description

General Description: 

A problem exists in the LogiCORE Gigabit Ethernet MAC v5.0 Core when trying to transmit jumbo frames when the "Transmitter Jumbo Frame Enable" option is disabled. Specifically, the frame is truncated and GMII_TX_ER is asserted as expected, but the latency between tx_data_valid and tx_ack for the next frame becomes excessive (sometimes hundreds of cycles). This unnecessary delay consequently reduces data throughput rates.

Solution

This will be fixed in the Gigabit Ethernet MAC v6.0 Core which will be released in 7.1i IP Update #1. 

 

To work around the issue until then, ensure that the Jumbo Frame option is enabled in the transmitter if jumbo frames will be involved.

AR# 20741
Date Created 09/03/2007
Last Updated 05/19/2014
Status Archive
Type General Article