Transgressions, not intrusions, occur along Sino-India border:

Transgressions along the India-China border occured when troops of both the countries undertook patrolling "upto their respective perception of the Line of Actual Control (LAC)," Defence Minister Manohar Parrikar said today.
In September, Chinese troops had "transgressed temporarily across our perception of the LAC in Chumar area," he said in reply to a written question in Rajya Sabha, adding they pulled back after a flag meeting.
"There have been no instances of intrusion along the India-China border. There is no commonly delineated LAC between India and China. There are areas along the border where India and China have differing perception of LAC," Parrikar said.

"Transgressions occur, on occasions, on account of both sides undertaking patrolling upto their respective perception of LAC," the Minister said.
Replying to another related question, he said "due to such difference of perceptions, transgressions have also occured in the general area of Pangong Tso Lake."
Parrikar said the government regularly takes up any violation along the LAC through the established mechanisms, including border personnel meeting, flag meetings and Working Mechanism on Consultation and Coordination on India-China Border Affairs.