Title of Invention

A METHOD FOR FAST HANDOFF METHOD IN DUAL TO IPv4 TRANSITION SCENARIO

Abstract

This invention is related to mobility management in particular fast handoff in transition scenarios. This is applicable for mobile nodes moving from one link to other link. This method decreases the latency and packet loss during handoff in transition scenarios. This invention explains a fast handoff method in transition scenario implemented in a communication system comprising two or more cells with PAR and MN dual stack capable and NAR is IPv4 only node, a method comprising the steps of: MN sending "v6 in v4 Tunnel Create" to PAR with NAR's IPv4 address and its L2 address; PAR sending "IPv4 Address Request" with MN's L2 address to NAR after receiving "v6 in v4 Tunnel Create"; NAR assigning new IPv4 address to MN and replying to PAR with "IPv4 Address Response" containing MN's new IPv4 address; PAR sending "v6 in v4 Tunnel Acknowledgement" with MN's new IPv4 address; and MN sending "start forward" after attaching to new link, if it receives "v6 in v4 Tunnel Acknowledgement".

Full Text

FIELD OF THE INVENTION This invention is related to mobility management in particular fast handoff in transition scenarios. This is applicable for mobile nodes moving from one link to other. This method decreases the latency and packet loss during handoff in transition scenarios. More particularly, the present invention relates to a method for fast handoff in dual to IPv4 transition scenario. DESCRIPTION OF RELATED ART The [FMIPv6] specifies a protocol to improve handover latency due to mobile IPv6 procedures, namely movement detection, new care of address configuration and binding update. This protocol enables MN to quickly detect that it has moved to a new subnet by providing the new access point and the associated subnet prefix information when the MN is still connected to its current subnet. By using this information MN formulates a prospective New Care of Address (NCoA) when it is still present on the PAR's link. In order to reduce the binding update latency, the protocol specifies a tunnel between Previous Care of Address (PCoA) and NCoA. The [LMIPv4] specifies a protocol to achieve low latency mobile IPv4 handoffs. This protocol proposes two methods namely PRE-REGISTRATION and POST-REGISTRATION and a combination of these two methods to achieve low latency handoffs in IPv4 networks. The PRE-REGISTRATION method allows the MN to be involved in anticipated IPv4-layer handoff. The POST-REGISTRATION handoff method proposes extensions to the Mobile IPv4 protocol to allow the oFA (old FA) and nFA (new FA) to utilize L2 triggers to set up a bi-directional tunnel between oFA and nFA that allows the MN to continue using its oFA while on nFA's subnet. The combined method involves running a PRE-REGISTRATION and a POST-REGISTRATION handoff in parallel. Fast handoff methods are defined either between IPv6 networks or IPv4 networks but not in transition scenarios. SUMMARY OF THE INVENTION An IP address is used to identify both node and its location inside an IP network. It is obvious that whenever a mobile node moves inside the network, its IP address must also change. Many approaches have been proposed to support mobility in IP networks, sometimes designed to solve only specific problems. Handover latency, signaling and packet loss are the major issues need to be addressed. These methods work when a mobile node is moving between IPv6 networks or IPv4 networks but not when a mobile node is moving between IPv6 and IPv4 networks. This invention is related to mobility management in particular fast handoff in transition scenarios where the mobile IP node moves from dual stack subnet (subnet with at least one dual stack router) to IPv4 only link. This method proposes a way to decrease the latency and minimize the data loss during handoff. The invention proposes a way to continue IPv6 communication when a dual stack capable MN is moving to IPv4 only network without packet loss and latency. The invention involves the tunneling mechanism. After the initial handoff handshake between MN and PAR, MN sends "v6 in v4 Tunnel Create" to PAR with NAR's IPv4 address and MN's L2 address. After receiving that signal PAR sends "IPv4 Address Request" with MN's L2 address to NAR. NAR responds to this signal of PAR by assigning new IPv4 address to MN by issuing "IPv4 Address Response". After receiving this signal PAR sends "v6 in v4 Tunnel Acknowledgement" to MN with MN's new IPv4 address. After attaching to the new link, MN sends "start forward" to NAR to receive the packets. Accordingly, this invention explains a method for fast handoff in dual to IPv4 transition scenario implemented in a communication system comprising two or more cells with PAR and MN dual stack capable and NAR is IPv4 only node, a method comprising the steps of: (a) MN sending "v6 in v4 Tunnel Create" to PAR with NAR's IPv4 address and its L2 address; (b) PAR sending "IPv4 Address Request" with MN's L2 address to NAR after receiving "v6 in v4 Tunnel Create"; (c) NAR assigning new IPv4 address to MN and replying to PAR with "IPv4 Address Response" containing MN's new IPv4 address; (d) PAR sending "v6 in v4 Tunnel Acknowledgement" with MN's new IPv4 address; and (e) MN sending "start forward" after attaching to new link, if it receives "v6 in v4 Tunnel Acknowledgement". The said method further comprising of, NAR assigning new IPv4 address to MN by itself or getting using DHCP. Also it further comprises, PAR forming the tunnel end point between PAR's IPv4 address and MN's NCoA (IPv4 address) after receiving "IPv4 Address Response" for the packets addressed to MN's PCoA (IPv6 address). Further it has, MN forming the tunnel end point between it's new IPv4 address and PAR's address for the packets originated from PCoA address (IPv6 address) after sending "start forward". In the method, MN sends RtSolPrto its access router (PAR) to resolve one or more access point identifiers for subnet specific information. In response the access router sends PrRtAdv with subnet information. If the access point belongs to IPv6 network, access router sends new AR-information and if the access point belongs to IPv4 only network, access router gives new access router's (NAR) IPv4 address and prefix. MN sends the "v6 in v4 Tunnel Create" to PAR which contains MN's L2 address and NAR's IPv4 address when MN anticipates handoff where the source address of the message is MN's IPv6 address (PCoA). After receiving "v6 in v4 tunnel create", PAR optionally starts buffering the packets address to MN and the PAR sends "IPv4 Address Request" message to NAR which contains MN's L2 address. The "start forward" message contains MN's L2 address. MN reverse tunnels all the data packets if any to PAR and PAR decapsulates and forward the data packets. BRIEF DESCRIPTION OF ACCOMPANYING DRAWINGS Figure 1 shows a possible scenario where the present invention is applicable. Figure 2 shows the operation of the method disclosed in this invention when NAR is the router in the link to where MN is moving. DETAILED DESCRIPTION OF THE INVENTION The preferred embodiments of the present invention will now be explained with reference to the accompanying drawings. It should be understood however that the disclosed embodiments are merely exemplary of the invention, which may be embodied in various forms. The following description and drawings are not to be construed as limiting the invention and numerous specific details are described to provide a thorough understanding of the present invention, as the basis for the claims and as a basis for teaching one skilled in the art how to make and/or use the invention. However in certain instances, well-known or conventional details are not described in order not to unnecessarily obscure the present invention in detail. Future broadband wireless networks will rely on packet switching technologies and will be entirely based on the IP protocol suite, both in the wireless and wired parts of the network. Since IP was not designed with mobility in mind, there are several problems that need to be solved before all-IP wireless networks are deployed. A first problem to be addressed is that, inside an IP network, an IP address is used to identify both a node and its location. Thus when a mobile node moves inside the network, its IP address must change. Many approaches have been proposed to support mobility in IP networks, sometimes designed to solve only specific problems. Handover latency, signaling and packet loss are the major issues need to be addressed These methods works when a mobile node is moving between IPv6 networks or IPv4 networks but not when an mobile node is moving between IPv6 and IPv4 networks. IPv4 to IPv6 Transition is currently in the infant stage. Hence, many IPv6 networks are coming up and there is need for supporting fast handoffs in these transition scenarios. The primary object of this invention is to invent a fast handoff method which handles IPv6 connectivity, latency and packet loss effectively, when a dual stack capable mobile node is moving from dual stack capable link (link with at least one dual stack capable router) to IPv4 only link. Figure 1 shows a possible scenario where this invented method is applicable. PAP is the access point with which MN is currently associated with. PAR is the previous access router. MN and PAR are dual stack capable. NAP and NAR are new access point and new access router respectively. NAR is IPv4 only router. When MN anticipates the handoff, MN starts the handoff method as disclosed in this specification. Figure 2 shows the operation of the method disclosed in this invention when NAR is the router in the link to where MN is moving. In this figure, MN and PAR are dual stack capable and NAR is IPv4 only node. MN exchanges RtSolPr, PrRtAdv messages at any convenient time, to get the neighboring subnet information. When MN anticipates handoff, it will send "v6 in v4 tunnel create" message to PAR to form tunnel and get new IPv4 address. PAR and NAR will exchange "IPv4 address request" and "IPv4 address response" to assign new IPv4 address for MN. PAR will send "v6 in v4 tunnel Acknowledgement" to MN with new IPv4 address A mobile IPv4 only node can use Mobile IPv4 [MIPv4] to maintain connectivity while moving between IPv4 subnets. Similarly, a mobile IPv6 only node can use Mobile IPv6 [MIPv6] to maintain connectivity while moving between IPv6 subnets. One of the ways of migrating to IPv6 is to deploy dual stack node running both IPv4 and IPv6. Such a node will be able to get both IPv4 and IPv6 addresses and thus can communicate with the current IPv4 Internet as well as any IPv6 nodes and networks as they become available. A dual stack node can use Mobile IPv4 for its IPv4 stack and Mobile IPv6 for its IPv6 stack so that it can move between IPv4 and IPv6 subnets. The invention deals with mobility management in particular fast handoff in transition scenarios where the mobile node moves from dual stack link to IPv4 only link. This method has got its advantage that it decreases the latency and packet loss during handoff. Fast handoff methods are proposed either between IPv6 networks or IPv4 networks. FMIPv6 works when MN moves between IPv6 networks and "Low Latency Handoffs in Mobile IPv4" works when MN moves between IPv4 networks. In this invention a fast handoff method is proposed which works when a dual stack capable MN is moving to IPv4 only network. For this method, we assume that previous access router and MN is dual stack capable. The proposed method will be implemented in previous access router, new access router and MN. The operation of the proposed invention is described herein: 1. MN sends RtSolPr to its access router (PAR) to resolve one or more access point identifiers for subnet specific information 2. In response access router sends PrRtAdv with subnet information 3. If the access point belongs to IPv6 network, access router will send new AR-info as in the case of FMIPv6 method 4. If the access point belongs to IPv4 only network, access router will give new access router's (NAR) IPv4 address and prefix 5. If the MN is going to associate with an access point which belongs to IPv4 only network, the following method is applicable, otherwise FMIPv6 method is applicable 6. To continue IPv4 communication, if any, "Low Latency Handoffs in Mobile IPv4" or any other IPv4 fast handoff method can be used 7. MN sends "v6 in v4 Tunnel Create" to PAR which contains MN's L2 address and NAR's IPv4 address when MN anticipates handoff. Source address of the message will be MN's IPv6 address (PCoA). 8. After receiving "v6 in v4 tunnel create", PAR can optionally start buffering the packets address to MN. 9. PAR sends "IPv4 Address Request" message to NAR which contains MN's L2 address. 10. NAR will assign an IPv4 address (NCoA) to MN, and it will send in "IPv4 Address Response" message which contains MN's L2 address and new IPv4 address assigned to MN i.e. NCoA. 11. NAR can assign address itself, or can contact DHCP server and return the address. 12. After receiving "IPv4 address response", PAR forms tunnel between its IPv4 address and NCoA. PAR will tunnel all the buffered IPv6 packets (if any) and arriving data packets (addressed to PCoA) to NCoA and NAR will buffer the packets. 13. PAR sends the "v6 in v4 Tunnel Acknowledgement" message to MN which contains MN's new IPv4 address (NCoA). 14. As soon as MN associates in the new network, MN will send a "start forward" message to NAR, so that it can forward the buffered packets 15. "start forward" message will contain MN's L2 address 16. MN will reverse tunnel all the data packets (if any) to PAR and PAR will decapsulate and forward the data packets. The above-presented description is of the best mode contemplated for carrying out the present invention. The manner and process of making and using it is in such a full, clear, concise and exact terms as to enable to any person skilled in the art to which it pertains to make and use this invention. New embodiments in particular, which also lie within the scope of the invention can be created, in which different details of the different examples can in a purposeful way be combined with one another. This invention is however, susceptible to modifications and alternate constructions from that disclosed above which are fully equivalent. Consequently, it is not the intention to limit this invention to the particular embodiment disclosed. On the contrary, the intention is to cover all modifications and alternate constructions coming within the spirit and scope of the invention as generally expressed by the following claims which particularly point out and distinctly claim the subject matter of the invention. GLOSSARY OF TERMS AND DEFINITIONS THEREOF AP :- Access Point - A layer 3 device CoA :- Care of Address FMIPv6 :- Fast handovers for Mobile IPv6 L2 :- Layer 2 - Data Link Layer L3 :- Layer 3 - Network Layer (IP layer) MN :- Mobile Node NAP :- Next Access Point NAR :- Next Access Router NCoA :- New Care of Address. PAP :- Previous Access Point. PAR :- Previous Access Router. PCoA :- Previous Care of Address. PrRtAdv > Proxy Router Advertisement. RtSolPr :- Router Solicitation for Proxy router Advertisement. WE CLAIM 1. A method for fast handoff in dual to IPv4 transition scenario implemented in a communication system comprising two or more cells with PAR and MN dual stack capable and NAR is IPv4 only node, a method comprising the steps of: (a) MN sending "v6 in v4 Tunnel Create" to PAR with NAR's IPv4 address and its L2 address; (b) PAR sending "IPv4 Address Request" with MN's L2 address to NAR after receiving "v6 in v4 Tunnel Create"; (c) NAR assigning new IPv4 address to MN and replying to PAR with "IPv4 Address Response" containing MN's new IPv4 address; (d) PAR sending "v6 in v4 Tunnel Acknowledgement" with MN's new IPv4 address; and (e) MN sending "start forward" after attaching to new link, if it receives "v6 in v4 Tunnel Acknowledgement". 2. A method as claimed in claim 1, further comprising of, NAR assigning new IPv4 address to MN by itself or getting using DHCP. 3. A method as claimed in claim 1, further comprising of, PAR forming the tunnel end point between PAR'S IPv4 address and MN's NCoA (IPv4 address) after receiving "IPv4 Address Response" for the packets addressed to MN's PCoA (IPv6 address). 4. The method in claim 1, further comprising of, MN forming the tunnel end point between it's new IPv4 address and PAR'S address for the packets originated from PCoA address (IPv6 address) after sending "start forward". 5. A method as claimed in claim 1 wherein MN sends RtSolPr to its access router (PAR) to resolve one or more access point identifiers for subnet specific information. 6. A method as claimed in claim 5 wherein in response the access router sends PrRtAdv with subnet information. 7. A method as claimed in claim 5 wherein if the access point belongs to IPv6 network, access router sends new AR-information and if the access point belongs to IPv4 only network, access router gives new access router's (NAR) IPv4 address and prefix. 8. A method as claimed in claim 1 wherein MN sends the "v6 in v4 Tunnel Create" to PAR which contains MN's L2 address and NAR's IPv4 address when MN anticipates handoff where the source address of the message is MN's IPv6 address (PCoA). 9. A method as claimed in claim 1 wherein after receiving "v6 in v4 tunnel create", PAR optionally starts buffering the packets address to MN and the PAR sends "IPv4 Address Request" message to NAR which contains MN's L2 address. 10. A method as claimed in claim 1 wherein the "start forward" message contains MN's L2 address. 11. A method as claimed in claim 10 wherein MN reverse tunnels all the data packets if any to PAR and PAR decapsulates and forward the data packets. 12. A fast handoff method in transition scenario substantially described particularly with reference to the accompanying drawings. Dated this 18th day of November 2005

Documents:

1701-CHE-2005 CORRESPONDENCE OTHERS 03-12-2012.pdf

1701-CHE-2005 AMENDED PAGES OF SPECIFICATION 27-11-2012.pdf

1701-CHE-2005 AMENDED CLAIMS 27-11-2012.pdf

1701-CHE-2005 CORRESPONDENCE OTHERS 02-01-2013.pdf

1701-CHE-2005 EXAMINATION REPORT REPLY RECEIVED 27-11-2012.pdf

1701-CHE-2005 FORM-1 27-11-2012.pdf

1701-CHE-2005 FORM-13 27-11-2012.pdf

1701-CHE-2005 FORM-13 19-06-2006.pdf

1701-CHE-2005 FORM-5 27-11-2012.pdf

1701-CHE-2005 OTHER PATENT DOCUMENT 27-11-2012.pdf

1701-CHE-2005 POWER OF ATTORNEY 27-11-2012.pdf

1701-CHE-2005 AMENDED PAGES OF SPECIFICATION 02-01-2013.pdf

1701-CHE-2005 AMENDED CLAIMS 02-01-2013.pdf

1701-CHE-2005 FORM-1 02-01-2013.pdf

1701-CHE-2005 POWER OF ATTORNEY 02-01-2013.pdf

1701-che-2005-abstract.pdf

1701-che-2005-claims.pdf

1701-che-2005-correspondnece-others.pdf

1701-che-2005-description(complete).pdf

1701-che-2005-drawings.pdf

1701-che-2005-form 1.pdf

1701-che-2005-form 26.pdf

1701-che-2005-form13.pdf