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MOBILITY (MOBILE IP). 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
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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”
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
Κινητικότητα – Λεξιλόγιο (1) Permanent Address(PA): address in home network, can always be used to reach mobile e.g., 128.119.40.186 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
Κινητικότητα – Λεξιλόγιο (2) visited network: network in which mobile currently resides (e.g., 79.129.13/24) Permanent address: remains constant (e.g., 128.119.40.186) 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
Mobile IP • IETF standard (RFC 3220) • C. Perkins • Τρεις βασικές λειτουργίες: • agent discovery • registration with agents • indirect routing of datagrams • Λειτουργεί σε επίπεδο δικτύου
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
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
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”
visited network: 79.129.13/24 home agent foreign agent ICMP agent adv. HA: 128.119.40.7 COA: 79.129.13.2 Mobile agent MA: 128.119.40.186 COA: 79.129.1 3.2 …. registration req. registration req. COA: 79.129.13.2 HA: 128.119.40.7 COA: 79.129.13.2 MA: 128.119.40.186 HA: 128.119.40.7 Lifetime: 9999 MA: 128.119.40.186 identification:714 Lifetime: 9999 …. identification: 714 encapsulation format …. registration reply registration reply time HA: 128.119.40.7 MA: 128.119.40.186 HA: 128.119.40.7 Lifetime: 4999 MA: 128.119.40.18 6 Identification: 714 Lifetime: 4999 encapsulation format Identification: 714 …. …. Mobile IP: Registration
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
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
packet sent by home agent to foreign agent: a packet within a packet dest: 128.119.40.186 dest: 128.119.40.186 dest: 128.119.40.186 packet sent by correspondent dest: 79.129.13.2 Encapsulation (Tunneling) foreign-agent-to-mobile packet Permanent address: 128.119.40.186 Care-of address: 79.129.13.2
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
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)
Macro-Mobility Same route Home CN Internet Encapsulated, alternative routes Domain 1 FA Domain 2 FA Mobile node Mobile node
Micro-mobility Same route Home CN Internet Domain 1 FA Domain 2 FA Mobile node Encapsulated, alternative routes Mobile node
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
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