Carleton University struck a deal with its contract instructors and teaching staff but failed to settle with security workers ahead of the 12:01 a.m. strike deadline.
So members of the OPSEU Local 404 are on the picket lines this morning, stopping some cars at the entrances of campus.
President Devon Reeves said there were elements the school administration wouldn't budge on.
"Carleton really still wanted to bargain concessions, which we told them we weren't doing. Our group has been behind the rest of the province for over a decade now. It's just, this was a chance to kind of right some wrongs and make this place a real career place for people," he said.
OC Tranpspo won't cross the pickup lines so bus service is limited to outside the campus borders.
The Ottawa District Labour Council said it has also thrown its support behind the striking security staff.
While they're on strike Carleton has hired security officers but they don't have the same powers as the special constables now on the picket lines.