It begins from suklapaksha Ekadasi and celebrated for 23 days wherein Namperumal listens to the vedas and Nammazhvar's Thiruvaimozhi as rend.ered by the Araiyars. The festival is divided into two parts, ten days before and after the ekadasi day of the bright waxing period of the month, which is Vaikunta Ekadasi. The first period of ten days is called Thirumozhi Thirunal or pagal patthu and the second period of ten days is called Thiruvaimozhi Thirunal or rapatthu.
Gateway to Heaven(ParamaBatha Vaasal.) During the Vaikunta Ekadasi day and the subsequent nine days, Lord Namperumal enters the Thirumamani mandapam (Paramapatham) through this door known as Paramapatha Vaasal.(sorga vaasal) It is one of the most auspicious days in all the Vishnu Temples. The Vaikunta Dwaram or the Gate to the heaven is opened on this day. In srirangam this is the passage leading to the thirumamani mandapam a replica of sri vaikuntham, the permanent abode of Lord Maha Vishnu. Scores of devotees queue up to pass through the Gate of Vaikunta in the temples in the belief that they would escape from the cycle of re-birth, if they step on the Parmapada vaasal on the sacred day of Vaikunta Ekadasi. This helps us reach our ultimate destination, Vaikuntha, which is the place of no return and thus the human soul is free from the ills of this world.
The Vaikunta Ekadasi festival is an occasion when the Paramapada vaasal is opened for devotees