Triple Mac Ethernet in SGMII mode for custom board

Good Evening All

I am using the triple mac ethernet in SGMII mode. Auto negotiation works fine but after 19 bytes excluding pre-amble and SFD , the ip core enters in invalid frame length error . As soon as the next ethernet packet is received, same thing repeats . What can be the issue . I am using UDP for sending data .I tried with different lengths as well. I am attaching the signal tap snapshot file as well . Bottom signal is ff_rx_data(8 bit fifo is used)once it receives the 08 00,4500 , it enters invalid frame length error. signal tap attached as wellSignal tap image

Regards

Vikas Kumar

Deputy Manager

RFMW,PDIC

Bharat Electronics Limited

Bangalore