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 1/3 of the batter into a greased 10" 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.