a certain quantity of oil consumption is considered NORMAL. Although that permissible quantity might differ from car to car, however, usually upto 1 liter consumption per 1000 km is considered OK....all it needs is a simple refill of the consumed volume.
in your case you said your car consumes 1 liter per 2000 km....it means half liter per 1000 km. which i think should not be a cause of concern....simply regularly check oil gauge and dont let oil level go below the lower dot on the dipstick/gauge...add up the consumed oil quantity, and keep the oil level between the two gauges... (and avoid over-filling, as it may also seriously cause damage)..
lets see what Xulfiqar bhai got to say on this.