Introducing HP-UX Mobile IPv6

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2.1.1 Protocol Comparison: Mobile IPv4 and Mobile IPv6
Mobile IPv6 benefits from the opportunities provided by IPv6 and from the lessons learned from Mobile
IPv4. Additionally, mobility was a core factor in the design of IPv6, where as it was an afterthought in
the design of IPv4. For these reasons, Mobile IPv6 has several core operational advantages over
Mobile IPv4. The following is a list of the major differences between Mobile IPv4 and Mobile IPv6:
• IPv4 addresses are 32 bits long—IPv6 addresses are 128 bits long, which almost eliminates the
possibility of using-up all the addresses in IPv6.
• IPv4 uses Network Address Translation (NAT) to conserve the number of public IP addresses an
organization can use on networks like the Internet—IPv6 eliminates the need for NAT.
• Mobile IPv4 uses tunnel routing to deliver packets to Mobile Nodes—Mobile IPv6 uses tunnel routing
and source routing with IPv6 headers.
• Mobile IPv4 deploys Foreign Agents for Mobile Node movement detection and to decapsulate packets
addressed to the Mobile Node’s Care-of Address—IPv6 Mobile Nodes decapsulate messages sent to
the Care-of Address itself, and uses IPv6 Router Advertisements for movement detection, thereby
eliminating the need for Foreign Agents.
• Mobile IPv4 uses Agent Discovery for Movement Detection—Mobile IPv6 uses IPv6 Router Discovery.
• Mobile IPv4 Route Optimization is an extension to the protocol, not part of the base RFC; requires pre-
configured and static security associations; and, is difficult to operate with ingress-filtering routers—
Mobile IPv6 Route Optimization is a fundamental part included in the protocol; integrated Return
Routability to dynamically secure Route Optimization; and, operates effectively with ingress-filtering
routers.
• Mobile IPv4 reverse tunneling is an extension to the protocol—Mobile IPv6 bi-directional tunneling is
part of the core protocol.
• Mobile IPv4 uses one Home Address—Mobile IPv6 uses a globally routable Home Address and a link-
local Home Address.
• Mobile IPv4 uses ARP to determine the link-layer address of neighbors—Mobile IPv6 uses IPv6
Neighbor Discovery and is de-coupled from any given link-layer.
• Mobile IPv4 Dynamic Home Agent Address Discovery uses broadcast approach and returns separate
replies from each Home Agent to the Mobile Node—Mobile IPv6 Dynamic Home Agent Address
Discovery uses anycast addressing and returns a single reply to the Mobile Node.
• Mobile IPv4 Mobile Nodes can obtain Care-of Addresses via Agent Discovery, DHCP, and manual
configuration—Mobile IPv6 Mobile Nodes can obtain Care-of Addresses via Stateless Address
Autoconfiguration, DHCP, and manual configuration
• Mobile IPv4 uses Foreign Agent Care-of Address and a co-located Care-of Address—Mobile IPv6
Care-of Addresses are all co-located.