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MOBILITY (MOBILE IP) PowerPoint Presentation
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  2. application transport network link physical Στοίβα Πρωτόκολλων Διαδικτύου • application: supporting network applications • FTP, SMTP, STTP • transport: host-host data transfer • TCP, UDP • network: routing of datagrams from source to destination • IP, routing protocols • link: data transfer between neighboring network elements • PPP, Ethernet • physical: bits “on the wire”

  3. Κινητικότητα – Τι Είναι; • Από την πλευρά του network layer: no mobility high mobility Ο κινητός χρήστης χρησιμοποιεί ένα σημείο πρόσβασης Ο κινητός χρήστης περνά μέσω πολλών σημείων πρόσβασης, διατηρώντας τις ενεργές συνδέσεις (όπως με το κινητό τηλέφωνο) Ο κινητός χρήστης συνδέεται και αποσυνδέεται από το δίκτυο με DHCP

  4. Κινητικότητα – Λεξιλόγιο (1) Permanent Address(PA): address in home network, can always be used to reach mobile e.g., Home Agent(ΗΑ): entity that will perform mobility functions on behalf of mobile, when mobile is remote wide area network Home Network: permanent “home” of mobile (e.g., 128.119.40/24) Correspondent

  5. Κινητικότητα – Λεξιλόγιο (2) visited network: network in which mobile currently resides (e.g., 79.129.13/24) Permanent address: remains constant (e.g., Care-of-address (CoA): address in visited network. (e.g., 79,129.13.2) wide area network wide area network Foreign Agent (FA): entity in visited network that performs mobility functions on behalf of mobile. Correspondent node (CN): wants to communicate with mobile

  6. Mobile IP • IETF standard (RFC 3220) • C. Perkins • Τρεις βασικές λειτουργίες: • agent discovery • registration with agents • indirect routing of datagrams • Λειτουργεί σε επίπεδο δικτύου

  7. Agent Discovery • Agent advertisement: foreign/home agents advertise service by broadcasting ICMP messages H,F bits: home and/or foreign agent R bit: registration required

  8. Λειτουργίες Agent Advertisement • Ανίχνευση των mobility agents • Το MN καταλαβαίνει αν είναι home/foreign agent • Συγκρίνει το τμήμα δικτύου της IP address του agent με το αντίστοιχο τμήμα της δικής του Permanent address. Αν δεν είναι ίδια είναι σε foreign network. • Απαριθμεί διαθέσιμες care-of addresses • Πληροφορεί MN σχετικά με χαρακτηριστικά στοιχεία που προσφέρει το FA • Π.χ.Εναλλακτικές τεχνικές ενθυλάκωσης • IP packet within IP packet • minimal encapsulation

  9. 1 2 Mobility: Registration visited network • End result: • Foreign agent knows about mobile • Home agent knows location of mobile home network wide area network mobile contacts foreign agent on entering visited network foreign agent contacts home agent home: “this mobile is resident in my network”

  10. visited network: 79.129.13/24 home agent foreign agent ICMP agent adv. HA: COA: Mobile agent MA: COA: 79.129.1 3.2 …. registration req. registration req. COA: HA: COA: MA: HA: Lifetime: 9999 MA: identification:714 Lifetime: 9999 …. identification: 714 encapsulation format …. registration reply registration reply time HA: MA: HA: Lifetime: 4999 MA: 6 Identification: 714 Lifetime: 4999 encapsulation format Identification: 714 …. …. Mobile IP: Registration

  11. Mobile IP: Securing Registration 2 τύποι επιθέσεων: • Ψεύδο-FA, Λύση: Authentication Extension • Type: type of authentication extension (mobile-home, mobile-foreign, foreign-home) • Authenticator: A variable length string calculated by computing a MD5 message over the shared secret key, the fixed length portion, and all extensions without the Authenticator field • Length: 4 + the number of bytes in the authenticator • Security parameter index (SPI): An index that identifies a security context between a pair of nodes. The security context is configured so that the two nodes share a secret key and parameters (e.g. algorithm for computing the Authenticator field) relevant to this association. • Στέλνει αντίγραφα παλαιών registration messages, Λύση: Identification πεδίο

  12. foreign agent receives packets, forwards to mobile home agent intercepts packets, forwards to foreign agent correspondent addresses packets using home address of mobile mobile replies directly to correspondent 3 2 4 1 Mobility via Indirect Routing visited network home network wide area network

  13. packet sent by home agent to foreign agent: a packet within a packet dest: dest: dest: packet sent by correspondent dest: Encapsulation (Tunneling) foreign-agent-to-mobile packet Permanent address: Care-of address:

  14. foreign agent receives packets, forwards to mobile mobile replies directly to correspondent 4 2 4 1 3 Λύση στο Triangle Routing correspondent forwards to foreign agent visited network home network wide area network correspondent requests, receives foreign address of mobile

  15. Επίπεδα Κινητικότητας • Macro-Mobility • Κινητικότητα μεταξύ διαφορετικών διαχειριστικών τομέων ή τεχνολογιών • Mobile IP • Micro-Mobility • Κινητικότητα μεταξύ διαφορετικών σημείων πρόσβασης ενός διαχειριστικού τομέα • Cellular IP • HAWAI • (Nano-mobility)

  16. Macro-Mobility Same route Home CN Internet Encapsulated, alternative routes Domain 1 FA Domain 2 FA Mobile node Mobile node

  17. Micro-mobility Same route Home CN Internet Domain 1 FA Domain 2 FA Mobile node Encapsulated, alternative routes Mobile node

  18. Ιεραρχία Κινητικότητας Same route Home CN Internet Encapsulated, alternative routes macro Domain 1 FA Domain 2 FA Mobile node FA FA micro Mobile node Mobile node

  19. Hierarchical mobility • Enhanced, hierarchical Mobile IP • Updates only up to the level needed HA 1 7 Internet FA 1 4 FA FA FA 1 6 7 8 3 4 2 5 FA FA FA FA FA FA FA FA 7 8 1 2 3 4 5 6 MN