A water-absorbent composition which absorbs water in the presence of multiple valent ions. A relationship, between a sender of a call signal and a receiver of a call signal, that exists in at least one network service server, is confirmed. In one embodiment, in the process of handing over the mobile node, the first access router provides the PRT to the second access router, thereby reducing data latency, and a disruption for an application executing on the mobile node.