Type: Answers

Type: Errata

Area: Intellectual Property

Some Low Latency 40-100GbE IP Core 100GbE Variations Have Lower Than Expected Bandwidth Because of Wrong Value in IPG_COL_REM Register


The Low Latency 40-100GbE IP core IPG_COL_REM register at offset 0x406 should have the value of 20 decimal in 100GbE variations and the value of 4 decimal in 40GbE variations. However, the LL 40-100GbE IP core v14.1 sets this register to the value of 4 in 100GbE variations.

This issue applies to all LL 100GbE IP cores for which you specify an inter-packet gap in the LL 40-100GbE parameter editor.

This issue reduces the bandwidth of the LL 100GbE IP core.


To work around this issue and correct the interpacket gap , write the value of 20 decimal to the IPG_COL_REM register in your LL 100GbE IP core variation.

This issue is fixed in version 15.0 of the Low Latency 40- and 100-Gbps Ethernet MAC and PHY IP core.