In Section 7.5, 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 inter domain routing among networks that span the globe).

a. Will other routers be able to route data-grams immediately to the new for eign 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.