A Literature Survey on Handoff for Mobile IPv6 <s> III. FAST HANDOVER SCHEME <s> We introduce enhanced forwarding from the previous care-of address (EFWD) for fast handovers in mobile IPv6. EFWD enables a mobile node to directly control a bi-directional tunnel that is used to redirect data from the previous subnet's access router to new subnet's access router. As a result, data loss during a handover can be prevented. EFWD also reduces handover latency by expediting the mobile node's movement detection and new subnet's access router discovery, and by eliminating time to acquire a new care-of address. Main benefit of EFWD is the removal of link layer pre-triggers that are required by fast mobile IPv6 and generally infeasible for wireless technologies other than cellular systems. Empirical results indicate that performance of EFWD is nearly optimal as fast mobile IPv6, which incurs 30-40 msec handover latency with 3-4 lost UDP packets. <s> BIB001 </s> A Literature Survey on Handoff for Mobile IPv6 <s> III. FAST HANDOVER SCHEME <s> This paper specifies access router based movement detection and care-of address configuration for fast handover in Mobile IPv6. An access router which will serve a mobile node performs movement detection, formulates a new CoA of the mobile node and does duplicate address detection behalf of the mobile node. After confirming the uniqueness of the new CoA, the access router sends it through a RA message. Since an access router can quickly determine the L3 movement by the comparison between neighbor caches and L2 information of a mobile node, a mobile node does not have to wait to receive RA messages from access routers. Thus, the movement detection delay is reduced. Since DAD is performed by an access router in advance, a mobile node does not have to do normal DAD and it can use the new CoA for its interface directly. <s> BIB002
The main idea of Fast handover scheme improves the switch performance by introducing link layer mobility prediction or link layer trigger mechanisms, through altering the basic Mobile IPv6 protocol in motion detection, new care-of address configuration, and duplicate address detection process. The benefit of such programs is that it effectively reduces handoff latency and data loss rate, while increasing a new signal load. At present, representative scheme in fleetness eager exchange is Mobile IPv6 fleetness eager exchange for scheme (FMIPv6)  . To further enhance the cutting performance, Enhanced Forwarding from the previous care-of address (EFWD) program BIB001 , and Router-based switching program BIB002 has been proposed, the former design is which through introducing link layer trigger mechanism and establishing the tunnel between the old and new networks to reduce switching delay and data loss. The latter is designed to access the router instead of the use of the MN to do motion detection, care-of address configuration and duplicate address detection work. FMIPV6 is mainly disscussed, EFWD and Routerbased switching program are presented simply at the follows. FMIPv6 basic operation as shown in Figure 2 :(1) When the MN as the second level trigger being aware of the need to enter a new subnet, the router will send a request broker news RtSolPr to the old router. (2)The old router receives and later returns a cut initiate news HI to the new access router. (3)The new access router receives a message, and then it sends a confirmation message HACK. (4)As an agent on a router solicitation message response, old access router will send a Proxy Router Advertisement (PrRtAdv) message to MN and MN will get the care-of address. (5)MN receives PrRtAdv message sent by the old router and gives a fast binding acknowledgment message F-BACK to MN and to the network in which the old router is located and also to the new access router network through the tunnel. (6)When the MN get to a new subnet and has worked with a new subnet established after the second layer connection, MN issued a fast neighbor advertisement messages F-NA, then new access router can forward data to MN. Through analysis of the switching process, we can find: In aspect of switching delay, FMIPv6 protocol eliminates the basic mobile IPv6 handover procedure in the mobile monitoring, the new care-of address configuration and duplicate address detection delay, FMIPv6's handover delay much smaller than the basic mobile IPv6 handover latency. In terms of data loss, the mobile node to switch to the new network, the completion of binding up to the home agent before using the original network and bi-directional tunnel between the new network to send and receive data, eliminating the basic mobile IPv6 protocol binding caused by the registration process loss of data. In the signaling load, Compared with the basic Mobile IPv6 protocol, FMIPv6 increases signaling interaction load. In the implementation complexity, FMIPv6 introduces a link-layer mobility prediction mechanism, Compared with the basic Mobile IPv6, FMIPv6 increases protocol design and implementation complexity. In a word, FMIPv6's handover delay is smaller than the basic Mobile IPv6, data loss is low, but it increase the load of signaling interaction and also the complexity of protocol design and implementation. This plan of designing program is to introduce trigger mechanism, to reduce the delay that is between old net and new net and prevent losing data. The basic operation of EFWD is telling the old access router the current location and requiring to build a new links to old router and new ,when the mobile node moved in new net and passed checking.Node can hold the communication by two-way links until finish login and bound. In aspect of switching delay, EFWD use mechanism of trigger link to remove the moving checking delay. In terms of data loss, EFWD remove checking movie and losing data in login. In the signaling load, EFWD is more than IPV6. In the implementation complexity, EFWD only need mechanism of trigger link,so it is a Little more complex than IPV6. All in word, the predict mechanism is not necessary for EFWD, moreover,the implement of EFWD is easier than IPV6. the delay and losing data is better than MIPV6 but worse than FMIPV6. The design of Router-based switching program is to replace mobile node with access router to do motion detection, care-of address configuration and duplicate address detection work. After the mobile node completed the link layer switching, the access router of its neighbours can find mobile nodes' network-layer handoff by comparing the cache table and link identification information of mobile nodes. Access router will configure a new care-of address for the mobile node immediately and do duplicate address detection, then deliver the effective address to the mobile node. The mobile node can immediately use the address to begin the binding registration process, thereby reduce the switching delay time. In aspect of switching delay, the access router's replacing the mobile node to do motion detection, care-of address configuration and duplicate address detection can effectively reduce the delay. In terms of data loss, a slight decrease is in the router than MIPv6, but not as good as FMIPv6 and EFWD. In the signaling load, the program is similar to MIPv6. In the implementation complexity, the program's harder than MIPv6 because it increases the complexity of the design of access router and the burden on the router. All in all router-based switching solutions in terms of handover delay and data loss is better than MIPv6, and it increases the complexity of router design and the burden of the router.