We are using packet capture file to generate stream block.But at receiver end it is missing 4 bytes.
When we generate traffic using packet capture ,By default the below option is checked.
If we don't exclude the FCS, it will become part of the payload after the pcap is converted to a stream block.So now you will have 4 extra bytes in the payload because Spirent will add its own FCS to the frame.If we uncheck the option, STC will keep last 4 byte of the packet from pcap file when generating stream Block.
Unchecked the option to resolve the issue.