Vector clock List of (node, counter) pairs Eg.[x,2]y,3]vs.[x,3y:4][z,1] [x,1y,3]vs.[z,1ly,3 Use timestamp p E.g. D(x, 1: tl, y,1]: t2) Remove the oldest version when reach a thresholdVector clock • List of (node, counter) pairs E.g. [x,2][y,3] vs. [x,3][y,4][z,1] [x,1][y,3] vs. [z,1][y,3] • Use timestamp E.g. D([x,1]:t1,[y,1]:t2) • Remove the oldest version when reach a thresthold