That include both as based on Government report of India only
28667 based on legal migration but over staying. And based on census report of 2001 the figure of illegal Bangladeshi is put 3 million this is quite understandable if we take into account the number of people those who did not come back after 1971 and some hindus those who migrated during 1970s and 1980s. But still seems to me quite high number. But these are no where near to the 20 million.
As they are living in India for decades and morn and brought up in India ... so India should treat them as national and Bangladesh has no liability on them.
This is the government press release. Now stop barking.
Press Information Bureau English Releases
A number of Bangladeshi nationals who have entered into the country on valid travel documents have been found to be overstaying. As per information available, 28,667 Bangladeshi nationals were found to be overstaying as on 31st December, 2010.