The Differentiated Services architecture does not have any provision to support the mobile host. This paper analyzes the performance of a scheme to support the mobility service in the Diff-Serv using the Mobile IP. As results, it is shown that the cost varies around 2 times of that of the Mobile IP. Premium service shows higher costs than Assured service does. It is also shown that packet drop probability for mobile hosts may be managed negligible if the proposed scheme is used.