To get through tissnet you need to meet following requirements:
Must complete 10+2
Must be graduate
So, by the above information provided by you, you meet the requirements for the exam.
Work hardest and All the BEST.
the basic eligibility criteria for tissnet is
a candidate should complete his/ her graduation of 3 years from any recognised university or institute.
candidate need to complete 10+2 and 3 years of bachelor degree course.
so it will be no problem for you as you are from ignou.
The minimum eligibility criteria is to be a graduate to apply for TISS NET which you fullfil. So in my opinion you can apply, but I would recommend you either check their official website and go through the eligibility criteria. If nothing is mentioned there, contact the college itself and speak to the concerned person or if possible visit the campus to get the right information because rules keep changing.