Basic or Net pay for notice period?

Hi I have been working with an MNC in Gurgaon since January 2014. There is a notice period of two months or TWO MONTHS salary, if I don't serve the notice period. I believe it should be the basic pay of two months salary, as it Is not mentioned in the appointment letter. Now company is asking me to pay two months NET SALARY. My appointment letter says...... After the expiry of the probation period either party is entitled to terminate the contract by giving 60 days notice. Where as the company reserv the right to request service of notice or PAY SALARY in lieu of, your notice period waiver or payment in lieu will be at the sole discretion of the company, but in no event will be less then the minimum period required by applicable law. Do I need to pay the Basic or Net pay of my salary. I am not in the situation to pay net amount instead of basic pay of two months salary. Please suggest me the available options or is there any way to get this waived. Thank you.