Nokia Research Center Using Mobile IP, a mobile node registers with its home agent each time it changes care-of address. If the distance between the visited network and the home network of the mobile node is large, the signaling delay for these registrations may be long. This document describes a new kind of `regional' registrations, i.e. registrations local to the visited domain. The regional signaling is performed via a new network entity called a Gateway Foreign Agent and introduces a layer of hierarchy in the visited domain. Regional registrations reduce the number of signaling messages to the home network, and reduce the signaling delay when a mobile node moves from one foreign agent to another within the same visited domain. This document is an optional extension to the Mobile IPv4 protocol.