In a large bowl, cream butter and 2 cups sugar until fluffy. Add vanilla. Add eggs, one at a time, beating well after each addition. Combine flour, baking powder, baking soda and salt. Add alternately with sour cream, beating enough after each addition to keep batter smooth. Spoon one third of the batter into a greased 25 cm tube pan. Combine remaining sugar, cinnamon, and nuts. Sprinkle over batter. Repeat layers two more times. Bake at 350 deg f for 70 minutes or until cake tests done. Cool for 10 minutes, remove cake to wire rack to cool completely. Makes 16 servings.