In a medium-sized bowl, cream together ? pound butter or margarine and 2 cups sugar. Set aside. In a large mixing bowl, beat 2 eggs, and add 1 teaspoon vanilla and 8 oz. sour cream. Stir well. Add in the butter and sugar mixture, and stir until well-combined. Now, mix in 2 cups self-rising flour. Set aside, while you make your filling/topping. In a small bowl, stir together ? cup brown sugar, ? cup chopped pecans, and 1 teaspoon cinnamon. Spoon half of the cake batter into a well-greased and floured tube pan. Spread out evenly, and sprinkle ? of the brown sugar-pecan filling over the top. Spoon the other half of the cake batter over the first half of batter and filling, smooth out, and top with the remainder of the brown sugar-pecan filling/topping. Bake at 350 degrees for 1 hour. Let cool in the oven with the oven door open for 1 hour. Remove pan from the oven, and transfer the coffee cake from the pan to a nice cake plate (top-side-up). This is not only a beautiful coffee cake, but its taste is splendid!