Preheat oven to 350 degrees F (175 degrees C). Place ham in a large baking dish.
Bake in the preheated oven for 45 minutes. Whisk brown sugar, ginger ale, mustard, and cinnamon together in a bowl; brush over ham. Continue baking ham until the meat pulls away easily from the bone, about 45 more minutes. An instant-read thermometer inserted into the center should read 145 degrees F (63 degrees C).
