In Section 6.5, one proposed solution that allowed mobile users to maintain their IP addresses as they moved among foreign networks was to have a foreign network advertise a highly specific route to the mobile user and use the existing routing infrastructure to propagate this information throughout the network. We identified scalability as one concern. Suppose that when a mobile user moves from one network to another, the new foreign network advertises a specific route to the mobile user, and the old foreign network withdraws its route. Consider how routing information propagates in a distance-vector algorithm (particularly for the case of interdomain routing among networks that span the globe).
a. Will other routers be able to route datagrams immediately to the new foreign network as soon as the foreign network begins advertising its route')
b. Is it possible for different routers to believe that different foreign networks contain the mobile user?
c. Discuss the timescale over which other routers in the network will eventually learn the path to the mobile users.