192620010 Mobile & Wireless Networking Lecture 9: Mobile IP - PowerPoint PPT Presentation

192620010 Mobile & Wireless Networking Lecture 9: Mobile IP [Schiller, Section 8.1] Geert Heijenk Mobile and Wireless Networking 2013 / 2014

Outline of Lecture 11 q Mobile IP Basics q 3 parts of Mobile IP: q Advertising Care-of Addresses q Registration q Tunneling q Mobile IPv6 q Mobile IPv6 extensions q Hierarchical Mobile IPv6 q Fast Handover for Mobile IPv6 q Proxy Mobile IPv6 2 Mobile and Wireless Networking 2013 / 2014

Motivation for Mobile IP RFC 5944 q Routing q based on IP destination address, network prefix (e.g. 129.13.42) determines physical subnet q 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 q Specific routes to end-systems? q change of all routing table entries to forward packets to the right destination q does not scale with the number of mobile hosts and frequent changes in the location, security problems q Changing the IP-address? q adjust the host IP address depending on the current location q almost impossible to find a mobile system, DNS updates take too long time q TCP connections break, security problems 3 Mobile and Wireless Networking 2013 / 2014

Example network HA MN (Home Agent) (Mobile Node) router home network Internet foreign (physical home network network FA for the MN) (Foreign Agent) router (current physical network for the MN) CN (Correspondent router Node) 4 Mobile and Wireless Networking 2013 / 2014

Data transfer to the mobile system HA 2 MN home network 3 receiver Internet foreign FA network 1. Sender sends to the IP address of MN, HA intercepts packet (proxy ARP) 1 2. HA tunnels packet to Care-of Address CN (COA), here FA, by encapsulation 3. FA forwards the packet to the MN sender 5 Mobile and Wireless Networking 2013 / 2014

Data transfer from the mobile system HA 1 MN home network sender Internet FA foreign network 1. Sender sends to the IP address of the receiver as usual, CN FA works as default router receiver 6 Mobile and Wireless Networking 2013 / 2014

Types of Home Networks Home agent as a separate system on Internet the home network Home agent integrated with a router Internet on the home network Internet A virtual home network 7 Mobile and Wireless Networking 2013 / 2014

Co-located Care-of Address HA MN home network receiver Internet foreign Tunneling network Standard Router CN sender 8 Mobile and Wireless Networking 2013 / 2014

Outline of Lecture 11 q Mobile IP Basics q 3 parts of Mobile IP: q Advertising Care-of Addresses q Registration q Tunneling q Mobile IPv6 q Mobile IPv6 extensions q Hierarchical Mobile IPv6 q Fast Handover for Mobile IPv6 q Proxy Mobile IPv6 9 Mobile and Wireless Networking 2013 / 2014

Agent advertisement 0 7 8 15 16 23 24 31 type code checksum #addresses addr. size lifetime router address 1 preference level 1 router address 2 preference level 2 type = 16 length = 6 + 4 * #COAs . . . R: registration required B: busy, no more registrations type = 16 length sequence number H: home agent registration lifetime rsv R B H F M G r T U X I F: foreign agent COA 1 M: minimal encapsulation COA 2 G: GRE encapsulation . . . r: =0, ignored T: FA supports reverse tunneling U: UDP tunneling (firewall traversal) X: support for registration revocation I: support for regional registration by foreign agent rsv: =0, ignored 10 Mobile and Wireless Networking 2013 / 2014

Home Network & Move Detection q Home Network is detected if: q Network Prefix IP Source Address advertisement = Network Prefix Home Address q Move is detected if: q No advertisement has been received within Lifetime q Network Prefixes have changed q no advertisements --> use promiscuous mode q assistance from higher / lower layers 11 Mobile and Wireless Networking 2013 / 2014

Registration Registration Request Mobile Foreign Home Node Agent Agent Registration Reply Registration Request Mobile Home Node Agent Registration Reply Registration Request Home Mobile Agent Node Registration Reply 12 Mobile and Wireless Networking 2013 / 2014

Mobile IP registration request 0 7 8 15 16 23 24 31 type = 1 T x lifetime S B D M G r home address home agent COA 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 2013 / 2014

Mobile IP registration reply 0 7 8 15 16 31 type = 3 code lifetime home address home agent 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 2013 / 2014

Simultaneous Bindings q A Mobile Node may register multiple bindings simultaneously q The Home Agent makes multiple copies of packets destined for the mobile node, and tunnels a copy to each care-of address q Simultaneous bindings may be used to q facilitate seamless hand-off q avoid too frequent registrations 15 Mobile and Wireless Networking 2013 / 2014

Tunneling q Packet destined to the mobile node are routed to the home network (normal IP operation) q Home Agent intercepts packets on the home network q Home Agent encapsulates packets, and tunnels them to the care-of address q 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 2013 / 2014

Packet Interception by Home Agent q Advertise reachability of Mobile Node Home Address q Proxy and Gratuitous ARP: l Home Agent Replies to ARP requests for the Mobile Node (Proxy ARP) l 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 2013 / 2014

Encapsulation original IP header original data new IP header new data outer header inner header original data 18 Mobile and Wireless Networking 2013 / 2014

Encapsulation I Encapsulation of one packet into another as payload q e.g. IPv6 in IPv4 (6Bone), Multicast in Unicast (Mbone) q here: e.g. IP-in-IP-encapsulation, minimal encapsulation or GRE (Generic Record Encapsulation) IP-in-IP-encapsulation (mandatory, RFC 2003) q 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 2013 / 2014

Encapsulation II Minimal encapsulation (optional) (RFC 2004) q avoids repetition of identical fields q e.g. TTL, IHL, version, DS (RFC 2474, old: TOS) q 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 2013 / 2014

Generic Routing Encapsulation original original data header GRE original outer header original data header header RFC 2890 new header new data ver. IHL DS (TOS) length IP identification flags fragment offset TTL GRE IP checksum IP address of HA Care-of address COA C K S reserved0 ver. protocol checksum (optional) reserved1 (optional) key (optional) sequence number (optional) 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 21 Mobile and Wireless Networking 2013 / 2014

Mobile IP with reverse tunneling q Router accept often only “topological correct“ addresses (firewall!) q a packet from the MN encapsulated by the FA is now topological correct q furthermore multicast and TTL problems solved (TTL in the home network correct, but MN is too far away from the receiver) q Reverse tunneling does not solve q problems with firewalls , the reverse tunnel can be abused to circumvent security mechanisms (tunnel hijacking) q optimization of data paths, i.e. packets will be forwarded through the tunnel via the HA to a sender (double triangular routing) q The standard is backwards compatible q the extensions can be implemented easily and cooperate with current implementations without these extensions q Agent Advertisements can carry requests for reverse tunneling 22 Mobile and Wireless Networking 2013 / 2014