Tài liệu Mobile & wireless networking – lecture 9 mobile ip - geert heijenk

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262001 Mobile & Wireless Networking Lecture 9: Mobile IP [Schiller, Section 8.1] Geert Heijenk Mobile and Wireless Networking 2009 / 2010 Outline of Lecture 9     Mobile IP Basics 3 parts of Mobile IP:           Advertising Care-of Addresses Registration Tunneling Mobile IPv6 Mobile IPv6 extensions       Hierarchical Mobile IPv6 Fast Handover for Mobile IPv6 Proxy Mobile IPv6 2 Mobile and Wireless Networking 2009 / 2010 Motivation for Mobile IP RFC 3344   Routing       Specific routes to end-systems?       based on IP destination address, network prefix (e.g. 129.13.42) determines physical subnet change of physical subnet implies change of IP address to have a topological correct address (standard IP) or needs special entries in the routing tables change of all routing table entries to forward packets to the right destination does not scale with the number of mobile hosts and frequent changes in the location, security problems Changing the IP-address?       adjust the host IP address depending on the current location almost impossible to find a mobile system, DNS updates take too long time TCP connections break, security problems 3 Mobile and Wireless Networking 2009 / 2010 Example network HA MN (Home Agent) (Mobile Node) router home network Internet (physical home network for the MN) FA foreign network (Foreign Agent) router (current physical network for the MN) CN (Correspondent Node) router 4 Mobile and Wireless Networking 2009 / 2010 Data transfer to the mobile system HA 2 MN home network receiver 3 Internet FA 1 CN sender foreign network 1. Sender sends to the IP address of MN, HA intercepts packet (proxy ARP) 2. HA tunnels packet to Care-of Address (COA), here FA, by encapsulation 3. FA forwards the packet to the MN 5 Mobile and Wireless Networking 2009 / 2010 Data transfer from the mobile system HA 1 home network MN sender Internet FA foreign network 1. Sender sends to the IP address of the receiver as usual, FA works as default router CN receiver 6 Mobile and Wireless Networking 2009 / 2010 Types of Home Networks Home agent as a separate system on the home network Internet Home agent integrated with a router on the home network Internet A virtual home network Internet 7 Mobile and Wireless Networking 2009 / 2010 Co-located Care-of Address HA MN home network receiver Internet Tunneling foreign network Standard Router CN sender 8 Mobile and Wireless Networking 2009 / 2010 Outline of Lecture 9     Mobile IP Basics 3 parts of Mobile IP:           Advertising Care-of Addresses Registration Tunneling Mobile IPv6 Mobile IPv6 extensions       Hierarchical Mobile IPv6 Fast Handover for Mobile IPv6 Proxy Mobile IPv6 9 Mobile and Wireless Networking 2009 / 2010 Agent advertisement 0 7 8 type #addresses 15 16 23 24 checksum lifetime 31 code addr. size router address 1 preference level 1 router address 2 preference level 2 ... type = 16 type = 16 length sequence number length = 6 + 4 * #COAs R B H F M G r T reserved registration lifetime R: registration required COA 1 B: busy, no more registrations COA 2 H: home agent F: foreign agent ... M: minimal encapsulation G: GRE encapsulation r: =0, ignored (former Van Jacobson compression) T: FA supports reverse tunneling reserved: =0, ignored 10 Mobile and Wireless Networking 2009 / 2010 Home Network & Move Detection   Home Network is detected if:     Network Prefix IP Source Address advertisement = Network Prefix Home Address Move is detected if:         No advertisement has been received within Lifetime Network Prefixes have changed no advertisements --> use promiscuous mode assistance from higher / lower layers 11 Mobile and Wireless Networking 2009 / 2010 Registration Registration Request Mobile Node Foreign Agent Home Agent Registration Reply Registration Request Mobile Node Home Agent Registration Reply Registration Request Home Agent Mobile Node Registration Reply 12 Mobile and Wireless Networking 2009 / 2010 Mobile IP registration request 0 7 8 type = 1 15 16 S B DM G r T x home address home agent COA 23 24 lifetime 31 identification extensions . . . S: simultaneous bindings B: broadcast datagrams D: decapsulation by MN M mininal encapsulation G: GRE encapsulation r: =0, ignored T: reverse tunneling requested x: =0, ignored 13 Mobile and Wireless Networking 2009 / 2010 Mobile IP registration reply 0 7 8 type = 3 15 16 code home address home agent 31 lifetime identification Example codes: extensions . . . registration successful 0 registration accepted 1 registration accepted, but simultaneous mobility bindings unsupported registration denied by FA 65 administratively prohibited 66 insufficient resources 67 mobile node failed authentication 68 home agent failed authentication 69 requested Lifetime too long registration denied by HA 129 administratively prohibited 131 mobile node failed authentication 133 registration Identification mismatch 135 too many simultaneous mobility bindings 14 Mobile and Wireless Networking 2009 / 2010 Simultaneous Bindings       A Mobile Node may register multiple bindings simultaneously The Home Agent makes multiple copies of packets destined for the mobile node, and tunnels a copy to each care-of address Simultaneous bindings may be used to     facilitate seamless hand-off avoid too frequent registrations 15 Mobile and Wireless Networking 2009 / 2010 Tunneling         Packet destined to the mobile node are routed to the home network (normal IP operation) Home Agent intercepts packets on the home network Home Agent encapsulates packets, and tunnels them to the care-of address At the care-of address (either Foreign Agent or co-located), the packet is decapsulated, and delivered to the mobile node 16 Mobile and Wireless Networking 2009 / 2010 Packet Interception by Home Agent     Advertise reachability of Mobile Node Home Address Proxy and Gratuitous ARP:     Home Agent Replies to ARP requests for the Mobile Node (Proxy ARP) The Home Agent (or Mobile node) broadcasts a not requested ARP after a change has occurred (Mobile Node has roamed out (or in)) (Gratuitous ARP) 17 Mobile and Wireless Networking 2009 / 2010 Encapsulation original IP header new IP header outer header original data new data inner header original data 18 Mobile and Wireless Networking 2009 / 2010 Encapsulation I Encapsulation of one packet into another as payload     e.g. IPv6 in IPv4 (6Bone), Multicast in Unicast (Mbone) here: e.g. IP-in-IP-encapsulation, minimal encapsulation or GRE (Generic Record Encapsulation) IP-in-IP-encapsulation (mandatory, RFC 2003)   tunnel between HA and COA ver. IHL DS (TOS) length IP identification flags fragment offset TTL IP-in-IP IP checksum IP address of HA Care-of address COA ver. IHL DS (TOS) length IP identification flags fragment offset TTL lay. 4 prot. IP checksum IP address of CN IP address of MN TCP/UDP/ ... payload 19 Mobile and Wireless Networking 2009 / 2010 Encapsulation II Minimal encapsulation (optional) (RFC 2004)       avoids repetition of identical fields e.g. TTL, IHL, version, DS (RFC 2474, old: TOS) only applicable for unfragmented packets, no space left for fragment identification ver. IHL DS (TOS) length IP identification flags fragment offset TTL min. encap. IP checksum IP address of HA care-of address COA lay. 4 protoc. S reserved IP checksum IP address of MN original sender IP address (if S=1) TCP/UDP/ ... payload 20 Mobile and Wireless Networking 2009 / 2010
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