Mobile IP, and Micro Mobility

1. Mobile IP, and Micro Mobility Gihwan Choghcho@cs.chonbuk.ac.kr

2. Presentation Outline • Our talk includes • Mobile IP, and Mobile IP in IPv6 • micro mobility variants • HAWAII • Cellular IP • fast handoff • proactive, anchor handoff • hierarchical handoff • paging extension • as a conclusion

3. Mobile IP • Now, let’s talk about • Mobile IP,and Mobile IP in IPv6 • micro mobility variants • HAWAII • Cellular IP • fast handoff • proactive, anchor handoff • hierarchical handoff • paging extension • as a conclusion

4. Why Mobile IP ? (I) • Background • Internet explosion • increasing the mobile workforce, and mobile users • increased reliance on networked computing • prevailing the portable devices, technologies • IPv4 routing considerations • two level hierarchical address structure (network id, host id) • longest prefix (network id) matching based static routing • host id based routing may produce the scalability problem • if a host moves around, the network id should be changed! • then, the routing scheme to the MH may not applied!! • clearly, a corresponding host does not know (need not – by network layering concept) the moving host’s current network id

5. Why Mobile IP ? (II) • So, which layer should take charge of host mobility? • applications, transport? IP? NI? • sure, IP could give to higher level protocols the abstraction that the network address remains unchanged, therefore Mobile IP • Mobile IP allows users of portable computers to move form one place to another and yet maintain transparent network access through the wireless link • Initially, it does not assumed in design phase, for the host mobility nature, so much appropriated to macro mobility • however, in the practical point of view, most moving entities have some degree of moving pattern, that is micro mobility family

6. Protocol Overview (I) [1][2] • Three steps with the protocol • agent discovery: MAs may advertise their availability for they provide service, or a newly arrived MH may send a solicitation to learn if any prospective agents are present • ICMP router discovery [3] • registration: when an MH is away from home, it registers its care-of address with its HA • UDP control messages [1] [2] • tunneling: datagrams sent to an MH is away from home must be tunneled to hide its home address from intervening routers • encapsulation protocol [4][5]

7. Protocol Overview (II) Mobile Node FA (FA) HA (HA) Correspondent Node Agent Solicitation agent discovery Agent Advertisement Registration Request Registration Request Registration Reply registration Registration Reply Data sent Data received tunneling

8. Correspondent Node HA location registration Mobile Node data paths (before registration) packet tunneling Internet data paths (after registration) data paths (sent from MN) FA host moving Mobile Node tunnel FA Protocol Overview (III) agent discovery

9. FA Triangle Routing on Mobile IP • Triangle routing is undesirable : • Increased network utilization (sensitivity to network partition) • Irregularity of performance variance Internet Host Home-based Location Reply Path Tunneling Home Agent MH k Host Moving

10. Mobile IPv4 – revised (I) • Specification that the SPI of the MN-HA authentication extension is to be used as part of the data over which the authentication algorithm must be computed • Specification that FA may send advertisements at a rate faster than once per second, but must be chosen so that the advertisements do not burden the capacity of the local link • Specification that FAs should support reverse tunneling, and HAs must support decapsulation of reverse tunnels

11. Mobile IPv4 – revised (II) • Changed the pre-configuration requirements for the MHs to reflect its capability • An FA is not required to discard Registration Replies that have a home address field that does not match any pending Registration Request • Allowed registration to be authenticated by use of a security association between the MH and a suitable authentication entity acceptable to the HA • noted that HMAC-MD5 should be considered for use in place of the “prefix+suffix” mode of MD5 as originally mandated in RFC 2002

12. Mobile IPv4 – revised (III) • Clarification that an MA should only put its own addresses into the initial list of routers in the mobility advertisement • RFC 2002 suggests that an MA might advertise other default routers • Specification that an MH must ignore reserved bits in Agent Advertisement, as opposed to discarding such advertisements • in this way, new bits can be defined later, without affecting the ability for MHs to use the advertisements even when the newly defined bits are not understood

13. Mobile IPv4 – revised (IV) • Specification that the FA checks to make sure that the indicated HA does not belong to any of its network interface before relaying a Registration Request • if the check fails, and the FA is not the MH’s HA, then the FA rejects the request with code 136 • Specification that, while they are away from the home network, MHs must not broadcast ARP packets to find the MAC address of another internet node • Specification that an FA must not use broadcast ARP for an MHs MAC address on a foreign network • it may obtain the MAC address by copying the information from an Agent Solicitation or a Reg. Request transmitted from an MH

14. Mobile IPv4 – revised (V) • Specification that an FA’s ARP cache for the MH’s IP address must not be allowed to expire before the MH’s visitor list entry expires • Clarified that an HA must not make any changes to the way it performs proxy ARP after it rejects an invalid deregistration request • Specification that multi-homed HA must use the registered care-of address as the source address in the outer IP header of the encapsulated datagram • Inserted “T” bit into its proper place in the Registration Request message format

15. Micro Mobility – HAWAII [6] • Now, let’s talk about • Mobile IP, and Mobile IP in IPv6 • micro mobility variants • HAWAII • Cellular IP • fast handoff • proactive, anchor handoff • hierarchical handoff • paging extension • as a conclusion

16. IP Micro Mobility – HAWAII (I) • Overview • Handoff Aware Wireless Access Internet Infrastructure (by Lucent) • domain-based approach for supporting mobility • approach : most user mobility is local to a domain • specialized path setup schemes • host-based routing entry • Characteristics • reduce mobility related disruption to user application • reduce the number of mobility related updated • simplify QoS support • improved reliability with soft-state transition • provide macro mobility in conjunction with Mobile IP • include the paging concept

17. IP Micro Mobility – HAWAII (II) • Mobility support for inter-HAWAII domain : Mobile IP • so, macro mobility • HAWAII protocol defines the mobility support for intra-HAWAII domain, so, micro mobility • each router maintains a routing entry per moving host • then, change only the corresponding entry on host moving • as a result, in a domain, the overhead of top most router can be distributed into the lower-level routers • host handoff may support by • a forwarding scheme • a non forwarding scheme

18. IP Micro Mobility – HAWAII (III) • Use path setup message to establish and update host-based routing entries in selective routers in the domain -> where, how, and which routers are updates? • Forwarding scheme : optimized for TDMA network • update the forwarding entry from old BS to new BS • Non forwarding scheme : optimized for CDMA network • update the forwarding entry from new BS to old BS • Other routers has no MH’s current location • Forwarding entry must be updated in periodical, so soft state update, to prevent its out-of-state situation • refresh message

19. IP Micro Mobility – HAWAII (IV)

20. IP Micro Mobility – HAWAII (V)

21. Forwarding Path Setup

22. Non-Forwarding Path Setup

23. Paging • Network determines the exact location by paging to deliver packets • “idle” MHs update the network less frequently than “active”MHs • network has only approximate location information for idle MHs

24. Hierarchy using Domain

25. Paging Design Goals • Efficiency • limit updates from the MH when idle to conserve battery power • Scalability • push paging initiation closer to the base station • Reliability • allow paging initiation to occur at any router/base station (no single points of failure) • Flexibility • allow for fixed, hierarchical, or user-defined paging areas

26. Paging Support … HAWAII (I)

27. Paging Support … HAWAII (II)

28. Router Operation

29. Paging with Mobile-IP • When using FAs • group set of FAs into multicast group • previous FA initiates paging • impact of previous FA failure • When operating without FAs • paging initiated from HA • globally visible multicast address or separate unicasts necessary • scalability is an issue

30. Micro Mobility – Cellular IP [7] • Now, let’s talk about • Mobile IP, and Mobile IP in IPv6 • micro mobility variants • HAWAII • Cellular IP • fast handoff • proactive, anchor handoff • hierarchical handoff • paging extension • as a conclusion

31. Cellular IP (CIP) • Cellular IP is intended to: • specify a protocol that allows routing IP datagrams to an MH • provide local mobility and handoff support • minimize packet losses with the location update delay • interwork with Mobile IP to provide wide area mobility support • Design principles • location information is stored in distributed data bases • location information referring to an MH is created and updated by regular IP datagrams • location information is stored as soft state • location management strategy is separated between the idle MH and the active MH

32. Protocol Requirement • Protocol requirement • a host connected to a cellular IP network must be able to send IP datagram to hosts outside the cellular IP network • datagrams arriving to a cellular IP network should be delivered with high probability to the destination host • datagram delivery in a cellular IP network should be take placed without leaving the cellular IP network • an MH migrating between cellular IP network must be to use Mobile IP for wide area mobility, that is, a host in a cellular IP network has a home address with a care-of-address • hosts inside a cellular IP network are identified by IP addresses, but these have no location significance • hosts outside the cellular IP network must not need any updating or enhancement, i.e. they must remain unware of the host’s current location inside the cellular IP network

33. Hierarchical Mobility Management (I) • Global mobility with Mobile IP

34. Hierarchical Mobility Management (II) • Local mobility with cellular IP • fast handoff within a mobile access network • less load in the global Internet

35. Wireless Overlay Networks

36. Mobile Access Network

37. Protocol Overview (I) • Base stations periodically emit beacon signals to be locate the nearest base station by MHs • All IP packets transmitted by an MH are routed from the BS to the GW by hop-by-hop shortest path routing regardless of the destination address • Cellular IP nodes maintain routing cache • packets transmitted by the MH create and update entries in each node's cache, thus an cache entry maps the MH’s IP address to the interface through which the packet entered the node • The chain of cached mappings referring to a single MH constitutes a reverse path for downlink packets addressed to the same MH

38. Protocol Overview (II) • as the MH migrates, the chain always points to its current location because its uplink packets create new mappings and old mappings are automatically cleared after a soft state timeout • To prevent its mappings from timing out, an MH can periodically transmit control packets • control packets are regular IP packets with empty payloads • MHs that are not actively transmitting or receiving data but want to be reachable for incoming packets, let their routing cache mappings time out but maintain paging cache mappings • IP packets addressed to these MHs will be routed by paging caches • paging caches have a longer timeout value than routing caches and are not necessarily maintained in every Node

39. Mobile IP vs. Cellular IP • Global mobility support vs. local fast smooth handoff

40. Uplink Path : Shortest Path

41. Uplink Packets Create Location Information

42. Downlink Packets (I) • Mobile IP’s centralized location management

43. Downlink Packets (II) • Cellular IP’s distributed location database

44. Control Packet in Uplink if no Data or a Move Detected

45. Handoff is Automatic

46. Idle Host Location Management Tradeoff

47. Location Management of Idle Hosts • Paging setup • paging cache maintains in just some selected nodes • broadcast if a node has not paging (and routing) cache • paging cache is updated with a control packet, with longer timeout and less frequently

48. Paging Cache Update with a move

49. Paging Route with Paging Cache

50. Cellular IP MH • Each MH has two states in legal, active and idle • when the state changed from idle to active, it sends a route update packet to the gateway • if an MH is in the active state • the MH has to send a route update packet whenever it changes its current base station • if an MH is in the idle state • the MH has to send a paging update packet whenever it enters a new paging area or it meets a predefined period