usb snoopy log

hi
I am reading a log file produced by snoopypro. But I am confused by the urb
pairs: vendor_device and control transfer.Below is a part of the log file:

00000133 0.35331659 >>>>>>> URB 5 going down…
00000134 0.35333168 – URB_FUNCTION_VENDOR_DEVICE:
00000135 0.35337694 TransferFlags = 00000000
(USBD_TRANSFER_DIRECTION_OUT, ~USBD_SHORT_TRANSFER_OK)
00000136 0.35339370 TransferBufferLength = 00000001
00000137 0.35342052 TransferBuffer = 8120cbe8
00000138 0.35343309 TransferBufferMDL = 00000000
00000139 0.35344231
00000140 0.35345404 0000: 01
00000141 0.35346494 UrbLink = 00000000
00000142 0.35347751 RequestTypeReservedBits = 00
00000143 0.35348924 Request = 02
00000144 0.35350097 Value = 0000
00000145 0.35351355 Index = 0053
00000146 0.35691202
00000147 0.35691621 <<<<<<< URB 5 coming back…
00000148 0.35694471 – URB_FUNCTION_CONTROL_TRANSFER:
00000149 0.35696231 PipeHandle = 81290194
00000150 0.35698242 TransferFlags = 00000002
(USBD_TRANSFER_DIRECTION_OUT, USBD_SHORT_TRANSFER_OK)
00000151 0.35699751 TransferBufferLength = 00000001
00000152 0.35701259 TransferBuffer = 8120cbe8
00000153 0.35702684 TransferBufferMDL = 811c3528
00000154 0.35704025 UrbLink = 00000000
00000155 0.35709221 SetupPacket : 40 02 00 00 53 00 01 00
00000156 0.56357035 UsbSnoop - IRP_MJ_INTERNAL_DEVICE_CONTROL,
IOCTL_INTERNAL_USB_SUBMIT_URB

Both the urbs’ direction are host_to_device.Could someone tell me what they
exactly do and the function difference. Any help will be appreciated.