Hierarchical Mobile IPv6 (HMIPv6) is the proposed enhancement of Mobile Internet Protocol versions 6 (
) that is designed to reduce the amount of signaling required and to improve
speed for mobile connections. HMIPv6 is a proposed standard from the Internet Engineering Task Force (
). MIPv6 defines a means of managing global (between-site) mobility, but doesn't address the issue of local (within-site) mobility separately. Instead, it uses the same mechanisms in both cases, which is an inefficient use of resources in the case of local mobility. HMIPv6 adds another level, built on MIPv6, that separates local from global mobility. In HMIPv6, global mobility is managed by the MIPv6 protocols, while local handoffs are managed locally.
A new node in HMIPv6 called the Mobility Anchor Point (MAP) serves as a local entity to aid in mobile handoffs. The MAP, which replaces MIPv4's
, can be located anywhere within a hierarchy of routers. In contrast to the foreign agent, there is no requirement for a MAP to reside on each subnet. The MAP helps to decrease handoff-related
because a local MAP can be updated more quickly than a remote
Using MIPv6, a
sends location updates to any node it corresponds with each time it changes its location, and at intermittent intervals otherwise. This involves a lot of signaling and processing, and requires a lot of resources. Furthermore, although it is not necessary for external hosts to be updated when a mobile node moves locally, these updates occur for both local and global moves. By separating global and local mobility, HMIPv6 makes it possible to deal with either situation appropriately.