1 Mobilité IP

2 Plan Introduction – Qu’est-ce que la mobilité IP ? Architecture Mobile IP Mécanismes de mobilité IP – Découverte d’agent – Enregistrement – Tunnelage Fonctionnalités avancées Micro-mobilité Support de mobilité fourni par IPv6 Mobile IP & 3G Conclusion

3 Différents types de mobilité

4 Nomadisme (DHCP) Ordinateurs mobiles (Mobile IP, IEEE ) Réseaux mobiles (réseaux Ad-hoc) Besoin de protocoles fournissant un service de localisation

5 Mobilité IP ≠ LANs sans fil (WLAN) LANs sans fil aujourd’hui : – IEEE , Bluetooth … – AP IEEE AP = pont entre le réseau fixe et le réseau sans fil handoffs de niveau 2 supportés mais PAS la mobilité IP (les handoffs sont supportés au sein d’un même sous-réseau IP) Mobilité IP ≠ Interface sans fil

6 Mobilité IP ≠ LANs sans fil (WLAN)

7 Différents types de mobilité Terminal Mobility - Wireless connection between a terminal and access point (base station) or between several terminals(ad hoc network) - Keeps registration/call between customer and network while in motion - Enabling fonctions: handover, paging Personal Mobility - Enables a customer to be identifiable regardless of the terminal, the terminal type, the operator/provider domain, and the type of network he is currently registered with - User profiles are available across terminal/network/operator boundaries - Number portability Service Mobility - Enables usage of tailored and personalized services even if the customer is roaming to foreign networks - Includes service portability Session Mobility - Allows to interrupt sessions and to resume them later, possibility from another terminal or another network

8 Différents types de mobilité

9 Mobilité

10 Introduction Mobile IP (1) Sillage des réseaux GSM – Mobilité = nécessité pour les utilisateurs d’un système de communication – Tous les réseaux existants se donnent pour mission de proposer ce service Standard TCP/IP : réseau le + étendu au monde – Principe Anywhere, Any Time, Network Access – Réseau IP : l’une des principales sources d’information

11 Introduction Mobile IP (2) Échelle planétaire : – Quasi-totalité des réseaux fournissent une entrée au réseau Internet – Avec mobilité : garantie d’un accès universel, simple d’emploi et pratique Groupe de travail de l’IETF : proposition IP Mobile – Proposer une localisation planétaire par l’adresse IP (à l’instar du roaming du GSM) IP préexiste au concept nomade – GSM doté dès l’origine de telles fonctions – IP : « bricolage » de solutions pour ajouter la mobilité

12 Cahier des charges pour l’architecture de mobilité IP Two major requirements arise when considering IP mobility: – Application transparency : Dealing with a mobile configuration should not necessitate a mobile-aware application. This is needed in order to avoid application replacement on all Internet hosts! – Seamless roaming : When a user goes out of his corporate network and roams around in the Internet, the requirement is to assure a seamless Internet communication between this user and his correspondents whatever the access network used by the mobile roaming user Dealing with mobility at the IP layer provides a way to answer the above requirements

13 Problématique de la mobilité dans IP Difficultés pour intégrer à IP de nouvelles fonctions devant offrir la mobilité

14 Why isn’t IP mobility simple? (1) The complexity comes from the current use of IP addresses. An IP address is used to – identify a particular end-system. In this respect, IP addresses are equivalent to FQDNs (Fully Qualified Domain Names) and the equivalence is maintained in a DNS, Domain Name Server – identify a particular TCP session in an IP host since a TCP socket consists of a (destination IP address, destination port number) couple – determine a route to a destination IP host. The first two uses come into contradiction with the third use when mobility is considered

15 IP mobility: routing

16 Why isn’t IP mobility simple? (2) The first use supposes that a host’s IP address should never change since the DNS should always point to the same IP address The second use supposes that a host’s IP address should never change during a TCP session otherwise the session would be lost The third use supposes that when the host is roaming outside its home network (the network which has the prefix of the host’s IP address), it should change its address (and take an address with a prefix given by the visited network) in order to receive the datagrams destined to it

17 Why isn’t IP mobility simple? (3) A possible answer to the third constraint would be to use a DHCP (Dynamic Host Configuration Protocol) server in order to obtain an address on the visited network This however poses a problem with the first two constraints – First, the IP address of a host having changed, the DNS in the home network should be updated by the mobile host on the visited network. This may be very dangerous on a security standpoint! – Second, this solution can not provide a seamless continuous mobility capability since when the mobile host’s IP address is changed, all TCP sessions involving this host should be dropped and reinitialized with the new IP address

18 Mobile IP standardization process The standardization of Mobile IP is being mainly carried out at the IETF (Internet Engineering Task Force) The IP Routing for Wireless/Mobile Hosts (MobileIP) Working Group is in charge of defining and specifying the Mobile IP architecture and protocols The major architecture components are already in the standards track (Request For Comments, RFCs ) Some very interesting enhanced functionalities are still considered as work in progress and specified in Internet Drafts These documents and other related information may be found at the mobileip WG home page on the Web :

19 PLAN Introduction – Qu’est-ce que la mobilité IP ? Architecture Mobile IP Mécanismes de mobilité IP – Découverte d’agent – Enregistrement – Tunnelage Fonctionnalités avancées Micro-mobilité Support de mobilité fourni par IPv6 Mobile IP & 3G Conclusion

20 Overview of the IP mobility architecture

21 Functional entities Mobile node : A host or a router that roams from one network or subnetwork to another outside its home network without changing its long term IP address (the home address) Home agent : This is typically a router on a mobile node’s home network which delivers datagrams to departed mobile nodes, and maintains current location information for each Foreign agent : This is typically a router on a mobile node’s visited network that collaborates with the Home agent to complete the delivery of datagrams to the mobile node while it is away from home

22 The Mobile IP basic concept The Mobile IP architecture resolves the above contradiction by using 2 IP addresses for a mobile host : – The Home address is a permanent address used to identify uniquely the IP host on the Internet (answers the two first IP addresses constraints) – The Care-of address is a temporary address used to route the datagrams destined to the mobile host to the current attachment point of this host (answers the last IP addresses constraint)

23 Plan Introduction – Qu’est-ce que la mobilité IP ? Architecture Mobile IP Mécanismes de mobilité IP – Découverte d’agent – Enregistrement – Tunnelage Fonctionnalités avancées Micro-mobilité Support de mobilité fourni par IPv6 Mobile IP & 3G Conclusion

24 Main Functions Agent Discovery : – Home Agents & Foreign Agents send advertisements on the link. A mobile can ask for advertisements to be sent. Registration : – When a mobile is away, it registers its temporary address with its home agent Tunneling : – The packets for the mobile are intercepted by the HA and tunnelled to the mobile

25 Mobile IP

26 Protocol overview 1. Home Agent & Foreign Agent broadcast or multicast agent advertisements on their respective links. 2. Mobile nodes listen to Agent Advertisements. They examine the contents of these advertisements to determine whether they are on the home or on a visited network 3. A mobile node on a visited network acquires a temporary address (care of address)

27 Protocol overview 4. The mobile registers its COA with its home agent 5. The Home Agent sends ARP on the Home Network The packets for the mobile are intercepted and sent to the current position of the mobile 6. The packets arrive to the COA and are decapsulated in order to extract the original packet 7. The packets from the mobile are sent directly to the correspondents

28 IP mobility mechanisms Agent discovery Registration Tunneling

29 Agent Discovery Process by which the mobile detects where it is attached (home or visited network) Allows the mobile to determine a COA when the mobile is on a visited network Based on 2 types of messages: – Agent Advertisement : broadcast or multicast by the agents – Agent Solicitation : sent by a mobile which does not want to wait for an AA Message authentication

30 Agent Solicitation Message

31 Mobile Agent Discovery An extension, called the Mobility Agent extension, is appended to ICMP Router Advertisement to constitute the Agent Advertisement message A Foreign Agent uses the Agent Advertisement message in order to indicate the Care-of Address to a Mobile Node A Home Agent uses the Agent Advertisement message so that a Mobile Node knows when it has returned to its Home Network A Mobile Node is allowed to send ICMP Router Solicitation messages in order to elicit a Mobility Agent Advertisement

32 Mobile Agent Discovery Getting a COA A Care-of Address may be obtained from the Foreign Agent by an Agent Advertisement. – It may also be obtained from a RAS (Remote Access Server) implementing PPP or from a DHCP server on a foreign LAN. – In this case the Care-of Address is said to be collocated since it is directly assigned to the Mobile Node interface and not to a Mobile Node through a Foreign Agent. For a collocated Care-of Address, the tunnel terminates at the Mobile Node interface

33 Agent Advertisement Message

34 Mobile Agent Discovery It is based upon an extension of the ICMP (Internet Control Message Protocol) Router Discovery protocol A router periodically broadcasts ICMP Router Advertisement messages on the different directly attached subnetworks This allows the hosts on these subnets to discover the router

35 Mobile Agent Discovery Mobility Agent Advertisement Extension Flags: – R=Registration required at the Foreign Agent – B=Busy – H=Home Agent – F=Foreign Agent – M,G,V indicate the encapsulation type Type identifies the Mobility Agent Advertisement extension Length is the total length of this extension which depends on the number of Care-of Addresses Lifetime specifies the duration of the Care-of Address support on the Foreign Agent For a Home Agent, Zero Care-of Address is advertised For a Foreign Agent, typically one Care-of Address is advertised Sequence Number is incremented at each Advertisement

36 Registration Functionnalities – Ask for routing functionnalities of the FA – Tell the HA the new location of the mobile – Update a binding which is about to expire – De-register the mobile when it is back on its home network Triggered as soon as the mobile detects it changed its point of attachement Use of the information obtained by agent discovery to determine the type of registration to be done Two registration procedures – With the«ForeignAgent» – With the temporary address of the mobile

37 Registration Once the Mobile Node receives a Care- of Address, it should register its (Home Address, Care-of Address) binding at his Home Agent This is done using 2 messages : – Registration Request – Registration Reply They both use a UDP/IP service

38 Registration

39 Registration request

40 Registration

41 Registration Registration Request Flags : – S=Simultaneous Registrations (multiple Care-of Adresses) – B=Broadcast – D=Care-of Address collocated with the Mobile Node – M,G,V indicate the encapsulation type Type identifies the Registration message Lifetime specifies the duration of the mobility addresses binding Home Address is bound to the Care-of Address Home Agent identifies the Home Agent that should register the binding Identification is used to protect against replay attacks and allows to correlate a Registration Request with a Registration Reply message The Mobile-Home authentication extension is used to authenticate the Mobile Node at the Home Agent

42 Registration Reply Registering with the FA – The FA receives the message and may reject it: Invalid authentication The lifetime value exceeds what may be accepted by the FA The mobile wishes to use a tunneling type not supported by the FA The FA has not enough resources – Otherwise, it forwards the request to the HA Registering with the HA – The HA also checks the registration should be accepted (same conditions) – If it is accepted, the HA Updates its binding table Sends a proxy ARP message on the local link

43 Registration Registration Reply Type identifies the Registration message Lifetime specifies the duration of the mobility addresses binding Home Address identifies the Mobile Node to which this message is related Home Agent identifies the Home Agent having registered the binding Identification is used to protect against replay attacks and allows to correlate a Registration Request with a Registration Reply message The Mobile-Home authentication extension is used to authenticate the Home Agent at the Mobile Node Code gives the result of the registration – 0 : registration accepted – 66, 69, : registration denied by the Foreign Agent – 130, 131, : registration denied by the Home Agent

44 Registration Reply The FA receives a registration reply – If the RR is invalid, the agent sends a Registration Reply describing the reason why the registration was rejected – Otherwise, theagent Updates its binding table Forwards the message to the mobile Starts to handle the messages for the mobile Reception of the RR by the mobile – If the registration was rejected, the mobile tries to change its registration procedure – Otherwise the mobile updates its routing table

45 Registration Reply

46 Registration Reply

47 Registration Via le Foreign Agent :

48 Exemple Adresse home du mobile node = HA du mobile node = FA address = FA care of address = Home node source port = 434 Mobile node source port = 1094 FA source port = 1105 Care-of-address registration lifetime = s HA granted lifetime = s

49 Exemple

50 Exemple

51 Exemple Annuler l’enregistrement (au retour au réseau home) :

52 Exemple

53 De-registration

54 Discovering the HA's address Manual configuration on the mobile Automatically – By broadcasting a registration request

55 Learning the HA address

56 Learning the HA address

57 Learning the HA address

58 Movement detection Using the lifetime field – If the lifetimeexpires, the mobile supposes it has attached to a new link or the agent has failed. It waits for an Agent Advertisement or sends an Agent Sollicitation Detection using the network prefix

59 Routing To the home network – The packets for a mobile are always sent to its home network – No specific routing –conventional routing – If the mobile sends data, it behaves as any other node on the Internet To a visitednetwork – A router on the local link broadcasts an ARP request to inform the packets for the mobile should be sent to it. – The packets are intercepted by the HA and tunnelled to the mobile's COA(s) – At the end of the tunnel, they are decapsulated and delivered to the mobile

60 Interception by the HA 2 possibilities – Accessibility advertisement : only on HA routers with several interfaces – Using the proxy ARP Mobile's HA's Updated by the HA and by the mobile node when it returns on its home network

61 Packet interception by the HA

62 Home Network configurations

63 Proxy and Gratuitous ARP Proxy In the cases A and B above, the Home Agent should intercept the datagrams intended to Mobile Nodes using a Proxy ARP mechanism In the case C, all datagrams intended to Mobile nodes will be naturally intercepted by the Home Agent. Here, all the hosts are outside their Home Network which become a Virtual Network Gratuitous ARP should be used by the Home Agent in order to change the ARP cache entry for a roaming Mobile node’s Home Address on the Home Network When the Mobile Node gets back to its Home Network, Gratuitous ARP should again be used by the Mobile Node itself to restore the ARP cache entry

64 Security aspects (1) The security issue is fundamental for registration messages otherwise impersonation and session hijacking attacks would be trivial Authentication should be applied to these messages The Mobile IP architecture specifies its own security mechanisms for use with IPv4 since IPsec, the new standardized security architecture, is not mandatory with IPv4 An authentication extension is thus appended to each of the above messages The default authentication algorithm is a keyed-MD5 in prefix + suffix mode The result of the authentication is thus a 128 bit message digest transmitted in the authentication extension

65 Security aspects (2) Type identifies the authentication extension (Mobile-Home, Home Agent- Foreign Agent,...) SPI specifies the authentication context (algorithm, mode, key...) The Authenticator is calculated over the entire message + this authentication extension

66 Firewalls and packet filtering problems (1)

67 Firewalls and packet filtering problems (2) Ingress filtering is often applied in the border gateway of a corporate network playing the role of a firewall This prevents Mobile Node generated datagrams to reach the Internet coming from the Visited Network Solutions – Send datagrams with Source Address=Care-of Address this is a loosing proposition because it runs counter to the architecture – Send datagrams encapsulated in an outer IP header with Source Address=Care-of Address this is a better proposition but the Correspondent Nodes are not required to be able to do the decapsulation Encapsulated datagrams may be sent to the Home Agent which sends them back to the Correspondent Node this is a suboptimal solution on the routing standpoint

68 Firewalls and packet filtering problems (3) Correlated problem : the firewall on the Home Network side should also filter all datagrams coming from the Internet with a Source Address corresponding to an inner address (with the same prefix as the Home Network) Solutions : – If the Home Agent is collocated with the Gateway/Firewall, the firewall will know when such datagrams should be accepted – Otherwise, a protocol between the Home Agent and the Firewall may be necessary – Finally, a solution may consist in tunneling all such datagrams to the Home Agent which should play the role of a bastion host and be attached to a DMZ for safety

69 Datagram Tunneling A Correspondent Node sends datagrams to a Mobile Node with the Destination Address field containing the Mobile Node’s Home Address Based on the destination address, these datagrams reach the Home Network There, the Home Agent intercepts the datagrams and encapsulates them into an outer IP header that tunnels the initial datagrams to the Foreign Agent or directly to the Mobile Node (in the case of a collocated Care-of Address) Multiple encapsulation schemes may be used including : – IP-within-IP encapsulation – Minimal encapsulation The datagrams sent by the Mobile Node reach directly the Correspondent Node

70 Reminder : IPv4 header format

71 IP-within-IP encapsulation The original IP header remains unchanged when transmitted in the tunnel (the TTL field is decremented) – Source Address : Correspondent Node Address – Destination Address : Mobile Node’s Home Address The new IP header has : – Source Address : Home Agent Address – Destination Address : Care-of Address When fragmentation is needed, it should be done at the inner IP datagram level otherwise the fragments won’t transport the Mobile Node’s Home Address used at the Foreign Agent to send the decapsulated datagram on the right data link

72 Minimal encapsulation S indicates the presence of the Original Source Address field Minimal encapsulation limits the number of supplementary bytes necessary for tunneling It prevents however from performing fragmentation

73 Soft Tunnel State It is interesting to maintain at the Home Agent level (the entry point of the tunnel) a number of parameters on the state of each established tunnel. These parameters constitute the Soft Tunnel State and include : – The Path MTU on this tunnel for fragmentation purposes – The state of the tunnel (broken or not) – The Correspondent Node using the tunnel The Home Agent may then relay ICMP error messages to the Correspondent Node source of the tunneled datagrams Typically, ICMP host unreachable messages are sent back to the Correspondent Node when the datagrams are not delivered through the tunnel

74 Plan Introduction – Qu’est-ce que la mobilité IP ? Architecture Mobile IP Mécanismes de mobilité IP – Découverte d’agent – Enregistrement – Tunnelage Fonctionnalités avancées Micro-mobilité Support de mobilité fourni par IPv6 Mobile IP & 3G Conclusion

75 Enhanced functionnalities Optimisation du routage Smooth handoff

76 Routing optimisation Goal : Avoid triangle routing Idea: – Tell the correspondents the current position of the mobile node Problem: – Change the correspondent's IP stack

77 Triangle Routing

78 Route optimization (1) The basic Mobile IP mechanisms create a Triangle Routing between the Correspondent Node, the Home Agent and the Mobile Node. This Triangle Routing is far from being optimal especially in the case of a Correspondent Node very close to the Mobile Node Route optimization consists of eliminating this problem This is done by updating the Correspondent Node giving it the mobility binding (Home Address, Care-of Address) of the Mobile Node For security purposes, it is the responsibility of the Home Agent to send the mobility binding to the Correspondent Nodes that need them

79 Route optimization (2) Correspondent Node

80 Route optimization (3) Binding updates are authenticated by a route optimization authentication extension (same as for the Mobile- Home authentication extension) Route optimization offers an efficient routing technique but supposes that the Correspondent Nodes are able to implement the route optimization protocol This may be the main reason why this mechanism has not yet been definitively adopted as an RFC

81 Foreign Agent - Smooth Handoff When a mobile moves, it registers with a new FA Goal: Tell the old FA the current position so that the packets in transit are redirected to the mobile (avoid losses and retransmissions) Protocol: – The mobile registers with the new FA and tells the address of its old FA – The new FA sends a BU to the old FA so that it forwards the packets to the new location of the mobile

82 Smooth Handoff (1) Correspondent Node

83 Smooth Handoff (2) During the handoff, it is important that the datagrams intended to the Mobile Node and received by the previous Foreign Agent not be lost A smooth handoff may be obtained if the previous Foreign Agent receives a binding update with the new Care-of Address of the Mobile Node allowing it to relay the datagrams to the new Foreign Agent This is best achieved if it remains a local mechanism between the Mobile Node and both the current and previous Foreign Agents (the Home Agent is too far to perform this binding update) This poses however a security problem since it is highly improbable, in the current state of Internet security, that an authentication security association be established between the Mobile Node and the Foreign Agents

84 Smooth Handoff (3) Correspondent Node

85 Smooth Handoff (4) If the previous Foreign Agent does not hold the new mobility binding for the Mobile Node, it may send back the decapsulated datagram to the Home Agent. This may create routing loops if the Foreign Agent has lost the trace of the Mobile Node and the Mobile Node is not connected elsewhere The Foreign Agent should re-encapsulate the decapsulated datagram into a Special Tunnel getting it back to the Home Agent with the Care-of Address as the source address of the outer header This allows the Home Agent to compare the current registration with the returned Care-of Address and decide whether it should tunnel the datagram or not thus avoiding routing loops

86 Plan Introduction – Qu’est-ce que la mobilité IP ? Architecture Mobile IP Mécanismes de mobilité IP – Découverte d’agent – Enregistrement – Tunnelage Fonctionnalités avancées Micro-mobilité Support de mobilité fourni par IPv6 Mobile IP & 3G Conclusion

87 Micro mobility: Différents types de mobilité

88 Micro mobility A mobile has to register with its HA every time it moves – Macro mobility (Mobile IP) – Micro Mobility (Hawaii, Cellular IP …) Smaller cells + more mobiles => need to ditinguish micro/macro mobility The mobile registers with the HA when it moves to a new mciro mobility domain

89 Micro mobility IP Fonctionnement en mode paquet – Différence par rapport aux autres réseaux cellulaires publics – GSM, UMTS, CDMA 2000 : interfaces radio majoritairement en mode circuit Universalité du protocole IP – Infrastructures répandues dans le monde entier Micromobilité : va devenir une donnée primordiale des réseaux Protocole de micro mobilité = complémentaire d'IP mobile – Macromobilité : possibilité pour un utilisateur de quitter son réseau d'abonnement pour se rendre dans un autre domaine du réseau IP Adresse temporaire dans le nouveau domaine Enregistrement auprès de l'agent local de sa zone d'abonnement Génération d'un temps de latence – Échange de nombreux messages de signalisation – Micro mobilité : mobilité locale Transparente pour le réseau d'abonnement de l'utilisateur mobile

90 Micro mobility

91 Macro / Micro mobility

92 Solutions de micro mobilité Enregistrements régionaux HMIP Cellular IP Hawaii

93 Regionalized registration (1)

94 Regionalized registration (2) Regionalized registration is a solution to the reduction of the registration traffic between a Home and a Visited Network over the Internet in order to update the mobility binding of the Mobile Nodes The idea is to construct a hierarchy of Foreign Agents, each FA registering a Care-of Address for the Mobile Node at its father FA level Multiple successive tunnels are thus constructed to reach the Mobile Node from the Home Agent When a Mobile Node moves from the region of FA7 to FA8, a registration should only be sent to FA4 and the tunnel FA4FA7 would be replaced by a tunnel FA4FA8 When a Mobile Node moves from the region of FA7 to FA9, a registration should be sent to FA1 (and not to the Home Agent) and the tunnels would be replaced accordingly

95 Solutions de micro mobilité Enregistrements régionaux HMIP Cellular IP Hawaii

96 HMIP: Hierarchical Mobile IP Problem: a mobile registers with its HA every time it moves Goal: reduce registration time by using regional registrations

97 HMIP: Registration(1)

98 HMIP: Registration(2)

99 HMIP: Routing

100 HMIP: Ericsson(1) Several levels in the hierarchy FA sends advertisements A (pour FA7) A (pour FA6) The MN registers the with its HA IP tunnels are set up between the FAs

101 HMIP: Ericsson(2) When it moves, the mobile checks the routes to determine if it is in the same hierarchy (for FA7) (for FA6) Fast handoffs : a mobile may register with several FAs The packets are bicasted by the GFA

102 Solutions de micro mobilité Enregistrements régionaux HMIP Cellular IP Hawaii

103 IP cellulaire:Couplage IP Mobile / IP cellulaire IP cellulaire n'intervient que sur le réseau d'accès – Aucun routeur du réseau de cœur n'a conscience de l'existence d'IP cellulaire – Système peu coûteux à l'installation car pas de modification pour les routeurs Fonctionnement simple – Définition d'une passerelle ou GW (Gateway) Accès au réseau Internet Située à la racine du domaine : joue le rôle d'agent étranger Possède une adresse IP qui sert de COA (Care-Of Address) à tous les visiteurs du domaine À la réception de paquets encapsulées, la GW ôte l'en-tête additionnel IP cellulaire met en œuvre des techniques qui lui sont propres pour transférer le paquet vers le mobile adéquat – Grâce aux adresses IP permanentes

104 Cellular IP:principes Caches distribués – Position des mobiles – Information de routage

105 IP cellulaire Base Stations – Wireless Access Points – IP routing replaced by Cellular IP routing Gateways – Mobile IP support – Mobile Nodes use the as COA Mobile Node – Inside the Cellular IP network, mobile nodes are identified with their home address

106 Architecture IP cellulaire

107 Architecture IP cellulaire Réseau d'accès contient des stations de base – Couverture de microcellules (id GSM) – Couverture de picocellules, desservies par de petites antennes dans des espaces privatifs Souplesse de fonctionnement grâce à IP – Méthode de transmission sur l'interface radio indépendante des opérations liées au routage et à la gestion de la mobilité Détection du passage d'une cellule à une autre – Diffusion périodique d'une signature de chaque station de base : voie balise – Signal pilote servant à mesurer la puissance du signal radio émis par chaque station de base Stations de base câblées de manière hiérarchique – Sommet = racine du domaine = passerelle

108 Architecture IP cellulaire

109 Opérations dans le réseau 3 opérations principales – Paging Localisation d'un utilisateur lors de l'arrivée de paquets à destination – Routage Acheminement des paquets vers l'utilisateurs à travers les principaux éléments du réseau d'accès – Handoff Gestion des déplacements de l'utilisateur via le réseau d'accès IP cellulaire se comporte comme un système sans fil – Les terminaux choisissent toujours la station de base qui diffuse le signal pilote le plus puissant – Handoff : changement de station de base – Mise à jour de tous les RC lorsque la route est nouvelle

110 Objectifs de Cellular IP Migration facile Bonne connectivité Support du soft handoff Passage à l’échelle avec une complexité minimale

111 Cellular IP Réseau distribué Les noeuds ne connaissent pas la topologie Pas de base de données centralisée Bon passage à l’échelle

112 Cellular IP Cellular IP nodes do not know the exact location of a mobile Hop by hop routing IP addresses are mapped to ports on Cellular IP nodes Soft state mappings

113 Mappings Paging cache/Routing Cache

114 État de l'utilisateur État actif – Utilisateur en train d'envoyer ou de recevoir des paquets – Initialisé à la suite d'un paging ou d'une demande d'émission – Position du terminal déterminée à la cellule près État oisif (ou idle) – Permet de réduire la signalisation sur le lien radio – L'utilisateur peut rester attaché au réseau d'accès tout en étant inactif – Localisé dans un groupement de cellules Permet d'accueillir un grand nombre de visiteurs dans un même domaine Pas d'enregistrement à chaque passage dans chaque cellule – Si un utilisateur oisif reçoit des paquets, on s'appuie sur un paging À l'initiative du nœud cherchant à localiser l'utilisateur

115 Localisation d’un utilisateur 2 exigences pour la réussite d'une localisation – Laisser toute la liberté à un terminal oisif Ne pas le contraindre à se signaler – Mettre en œuvre un mécanisme optimal pour atteindre le terminal oisif à un coût moindre lorsqu'il devient actif 2 procédures employées pour répondre à ces besoins – Enregistrement de la localisation de temps à autre en cas d'activité Cache de routage ou RC (Routing Cache) – Emploi de paging en cas d'oisiveté Cache de paging ou PC (Paging Cache)

116 Caches de paging Liberté de mouvement pour les utilisateurs – Ne facilite pas leur localisation – Il faut retrouver un mobile oisif pour lui transmettre un paquet Surplus de signalisation Caches installés dans certains nœuds ou stations de base – Connaissance partielle de la localisation des mobiles – Complétée par le paging Mise à jour des Paging Caches – Par l'envoi vers la racine d'un paquet vide : paging-update – Paging-update transmis de manière périodique

117 Identification d'un terminal oisif

118 Caches de paging

119 Cache de routage Permet d'acheminer le flux de paquets vers l'utilisateur – Routage saut par saut (hop by hop) – Enregistrement du chemin à l'initiative de l'utilisateur Lorsqu'il envoie un paquet vers la racine, tous les nœuds intermédiaires retiennent le chemin pour l'utiliser en sens inverse Si l'utilisateur cesse son activité réseau – Possibilité de se maintenir dans les RC Transmission de paquets vides : route-update, vers la racine Sinon, effacement sur temporisation

120 Routage

121 Route discovery – When the mobile receives PP, it sends a Route-Update Packet to the base station F which forwards it towards GW – All the RCs on the route are updated

122 Downlink routing If there is no PC on the GW: – GW buffers the packet – GW sends a Paging Packet with the mobile's id – If the nodes have paging caches, hop by hop routing, otherwise, the packet is broadcast

123

124 Handoff Initiated by the mobile When a mobile gets close to a new BS, it redirects its packets to the new BS The first packet redirected configures a new route The packets are send to the old and new BS during a certain time

125 Summary Use of the home address No temporary address No encapsulation The mobile sends the gateway address to the HA is learnt by the BS

126 Solutions de micro mobilité Enregistrements régionaux HMIP Cellular IP Hawaii

127 Hawaii

128 Hawaii

129 Routing Update ( 1)

130 Routing Update ( 2)

131 Hawaii

132 Plan Introduction – Qu’est-ce que la mobilité IP ? Architecture Mobile IP Mécanismes de mobilité IP – Découverte d’agent – Enregistrement – Tunnelage Fonctionnalités avancées Micro-mobilité Support de mobilité fourni par IPv6 Mobile IP & 3G Conclusion

133 IPv4 vs IPv6

134 Mobile IPv6 IPv6 mobility relies on: – New functionnalities in IPv6 – A native support of mobility A global and unique IPv6 address is assigned to each mobile node: the Home Address – This address identifies the mobile A mobile is able to communicate directly with mobile nodes (no triangle routing)

135 Main functionnalities in IPv6 The correspondents must – Have a binding in their binding cache – Learn the location of the mobile by handling Binding Updates – Route the packets directly to the mobile (Routing Header) TheHA must – Be a router on the mobile's home network – Intercept the packets on the home network – Tunnel (IPv6 encapsulation) these packets directly to the mobile

136 Reaching the mobile A mobile can always be reached via its HA A mobile on a visited network always has a COA (selfconfiguration) The Router Advertisement indicates the subnetwork’s prefix Combination of this prefix with the MAC address Movement detection is also accomplished with Neighbor Discovery procedures Multi-homing

137 IPv6 Destination options Binding Update : – To inform the HA or the correspondents of the new COA Binding request – Ask for a BU. Used when a correspondent thinks its binding will soon expire Binding Acknowledgement – Sent by the HA. Acknowledges a BU containing the COA Home Address – Included in every IPv6 packet from the mobile to its correspondent The packet is supposed to be originated from the home network and not the visited network Uses 144 bits in the header of every packet

138 Cache association management Every time a mobile moves it sends a Binding Update (BU): The BU includes a lifetime The mobile keeps a list of the correspondents to which it sent a BU The temporary address sent to the HA is called the principal COA

139 The IETF model

140 BU format

141 Binding Acknowledge message ACK message based on a destination header extension Sent if the A bit is set in the BU sent by the mobile Also includes an authentication header

142 Binding Request & Home address Allows the correspondents to update their bindings Store the principal address of the mobile

143 IPv6 Nodes Handling IPv6 mobility forces the nodes to implement some functionnalities: Be able to receive and handle BUs SendBAs Use RoutingHeader Maintain a Binding Cache An IPv6 node must be able to Do IPv6 decapsulation Send BUs and receive BAs Maintain a list of BUs sent

144 IPv6 routers At least one router on the mobile's home network may act as a HA A HA must: – Maintain a Binding table – Intercept packets in the mobile's home network – Encapsulate these packets and send them to the mobile's COA

145 HA discovery Modification of the Routing Advertisement (RA) message of Neighbor Discovery Add an option to the RA message Modify the minimal time (3 seconds) between two RAs (1 message/sec) Send a BU (with the H bit set) to the anycast address of the HAs

146 IPv6 and mobility (1) IPv6 represents an almost perfect protocol basis for mobile networking – First, the attendant address configuration protocols allow each Mobile Node to obtain a Care-of Address without the need for Foreign Agents which disappear from the architecture – Second, IPsec implementation is mandatory to IPv6 compliant systems. This resolves security pitfalls by providing a widely available and standardized security architecture Particularly, mobility bindings are now done by the Mobile Nodes themselves – Third, the destination options IPv6 header extension provides means to sending mobility bindings updates from the Mobile Nodes directly to Correspondent Nodes very efficiently This simplifies the smooth handoff procedure

147 IPv6 and mobility (2) Correspondent Node

148 Data mobility perspectives The Mobile IP architecture is being finalized at the IETF with its basic mechanisms already terminated and some enhanced functionalities being added progressively The market opportunities for this architecture are huge and should follow the explosive growth of both computer/Internet industries on the one hand and mobile telephony on the other hand Some work still has to be done however to integrate both approaches by having a single network infrastructure for both Mobile IP and other mobility approaches such as the third generation of Mobile Cellular Networks (UMTS) This conforms to the global “service integration over a consolidated network infrastructure” trend for public networks

149 HMIPv6 MAP (Mobility Anchor Point) – Minimizes interruptions due to handoffs The mobiles use the MAP's as COA MAP receives the packets and delivers them to the mobile The access routers send the

150 HMIPv6 The access routers send the MAP's in RAs The mobile may roam and keep the same MAP If the mobile changes its MAP, it sends a new BU to its HA and correspondents

151 HMIPv6 IPv6MobHA IPv6MobCOA

152 Plan Introduction – Qu’est-ce que la mobilité IP ? Architecture Mobile IP Mécanismes de mobilité IP – Découverte d’agent – Enregistrement – Tunnelage Fonctionnalités avancées Micro-mobilité Support de mobilité fourni par IPv6 Mobile IP & 3G Conclusion

153 MIP-UMTS standardized architecture

154 MIP-UMTS other solutions (1/2)

155 MIP-UMTS other solutions (2/2)

156 3GPP Network Reference Architecture – R5

157 Mobile IP in UMTS

158 Data mobility perspectives The Mobile IP architecture is being finalized at the IETF with its basic mechanisms already terminated and some enhanced functionalities being added progressively The market opportunities for this architecture are huge and should follow the explosive growth of both computer/Internet industries on the one hand and mobile telephony on the other hand Some work still has to be done however to integrate both approaches by having a single network infrastructure for both Mobile IP and other mobility approaches such as the third generation of Mobile Cellular Networks (UMTS) This conforms to the global “service integration over a consolidated network infrastructure” trend for public networks