MOBILITY (MOBILE IP)

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” application transport network link physical

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) Τρεις βασικές λειτουργίες: 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

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

Mobile IP: Registration visited network: 79.129.13/24 home agent HA: 128.119.40.7 foreign agent COA: 79.129.13.2 COA: 79.129.1 3.2 …. ICMP agent adv. Mobile agent MA: 128.119.40.186 registration req. 79.129.13.2 Lifetime: 9999 identification:714 identification: 714 encapsulation format registration reply Lifetime: 4999 Identification: 714 MA: 128.119.40.18 6 time

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

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

Encapsulation (Tunneling) foreign-agent-to-mobile packet dest: 79.129.13.2 dest: 128.119.40.186 packet sent by home agent to foreign agent: a packet within a packet dest: 128.119.40.186 Permanent address: 128.119.40.186 Care-of address: 79.129.13.2 dest: 128.119.40.186 packet sent by correspondent

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

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 Home CN Internet Domain 1 Domain 2 Mobile node Mobile Same route Home CN Internet Encapsulated, alternative routes Domain 1 FA Domain 2 FA Mobile node Mobile node

Micro-mobility Home CN Internet Domain 1 Domain 2 Mobile node Mobile 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