5. (30 points) Consider the following network example. Suppose that the distance vector (DV) routing algorithm is used to compute the distance between nodes. W W 8 8 8 1 1 X Y (a) Original network x 20 Y (b) New network with new link cost (a) (15 points) Show the procedure of nodes X, Y and W computes their Distance Vector for network illustrated by Figure (a), i.e., link costs are C(xw)=1, C(xy)=4, and C(yw)=8. Answer: In the following, each column shows the node X, Y and Z's table update respectively: (a) Node X's Table (b) Node Y's Table (C) Node W's Table Node XY W Node XY W Node XY W X X X Y Y W W W Node XY W X Y W Nodex YW X Y Node XY W X Y W W Node XY X Y W Node | X X Y W Node XYW X Y W (b) (15 points) After completing previous step (a) calculations, the link cost of xy is suddenly changed from 4 to 20. Show the procedure of nodes X, Y and W updates their Distance Vector for network illustrated by Figure (b), i.e., link costs are C(xw)=1, C(xy)=20, and Cyw)=8. (Hint: bad news travel slow or county to infinity problem) Answer: In the following, each column shows the node X, Y and Z's table update respectively: (a) Node X's Table Node XYW X Y W (b) Node Y's Table Node |XY|W X Y W (C) Node W's Table Node XYW X Y W Node XYW X Y Node XY W X Y W Node XYW Y W W Node XYW X Y W Node |XY|W X Y W Node XY X Y W