USB 3.0

Mobile IPv4 and Mobile IPv6 protocols share similar ideas, but their implementations are somewhat different. Figure 2 shows the basic elements of Mobile IPv6. Mobility signaling and security features (IPsec) are integrated in the IPv6 protocol as header extensions, whereas Mobile IPv4 uses a separate UDP (User Datagram Protocol) based protocol for registrations. These registrations apply special mobility security associations. In IPv6 stateless address auto configuration, addresses can be generated easily by combining the network prefix of a visited network and an interface identifier of the MN. In addition, address exhaustion is not a problem. Therefore, an IPv6 Care-of Address (CoA) is always co-located at the MN, and the concept of the foreign agent has been eliminated. Also, route optimization is built into Mobile IPv6. If route optimization is used, user privacy may be violated, because it will reveal the true location of the mobile node. If the MN needs to discover it’s HA dynamically, it can make the enquiry using IPv6 anycast. This is more efficient and reliable than IPv4 directed multicast, which may return several replies. Several ICMPv6 (Internet Control Message Protocol for IPv6) mechanisms provide support for mobility management. These include:

 Router Advertisement
 Router Solicitation
 Address Auto-configuration
(Stateful and stateless)
 Neighbor Discovery

Some of these have been extended in Mobile IPv6 to better support its needs. These changes include a new home agent bit to the router advertisement, a new bit to the prefix information option format, allowing the router to efficiently advertise its global IPv6 address instead of the link local address. Also, the timing rules for router advertisements and solicitations have been refined and a new Advertisement Interval Option has been defined for Router Advertisements.