Why does the Low Latency 40-100Gbps Ethernet IP core indicate payload length error for RX frames with payload size less than 46 bytes?

Description

The Low Latency 40-100Gbps Ethernet IP core incorrectly interprets any value in the length field of a packet with payload size less than 46 bytes as an error. This issue occurs because the IP core does not adequately allow for the case in which the Ethernet link partner padded a short payload with padding bytes as required by the Ethernet protocol.

Example:

Actual payload = 17 bytes

Minimum payload size = 17 bytes 29 bytes padded zeros = 46 bytes

Length field = 17 bytes

17 bytes < 46 bytes, which causes the IP core to report incorrect payload length error

Resolution

The problem will be addressed in a future version of the Low Latency 40-100 Gbps Ethernet IP core.