HI,
Are you running Full load?
18 hours is too long. Please check the extraction job log in SM37 in ECC.
Do you have sufficient BGDs available in ECC?
How many records have come to BW in infopackage monitor?
I suggest you to cancel the job in ECC and make the "Total technical Status" to red. Please execute the infopackage again after checking the ECC system status with your BASIS.
Regards,
Suman