Chennai is 2.5 hours ahead of Addis Ababa
Best overlap: 8:30 AM to 3:30 PM in Addis Ababa is 11:00 AM to 6:00 PM in Chennai.
Shoot for 8:30 AM to 3:30 PM in Addis Ababa; your Chennai colleagues will see that as 11:00 AM to 6:00 PM. That's a roomy 7 hours of common time each day, so finding a slot that suits everyone is rarely a problem.