Franck Le This document describes Mobile IPv6 regional registration as an optional extension to Mobile IPv6. Regional registration introduces visited-domain mobility agent functionality for proxying a public care-of-address which remains the same while the mobile node moves in the visited domain. This reduces the binding update signaling latency for the mobile node and signaling load outside the visited domain. The protocol defines regional mobility capability negotiation, regional binding update signaling, and regional-aware data routing through a hierarchy of visited-domain mobility agents. The protocol allows for an arbitrary point in the visited-domain hierarchy to distribute the connection-state maintenance between several mobility agents. IPSec AH is used for securing the protocol as in basic Mobile IPv6.