In Wireshark I see about 3000 lines related to TFTP
1679 207.007190 192.168.3.3 192.168.3.69 TFTP Read Request, File: mba.pxe\000, Transfer type: octet\000, tsize\000=0\000
followed by 10 lines, ending in this one
1703 207.269571 192.168.3.3 192.168.3.69 TFTP Acknowledgement, Block: 10...