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報告者：林靖祐 學 號： m9356022

Terminal Independent Mobility for IP (TIMIP) António Grilo, Pedro Estrela, Mário Nunes, INESCIST, PORTUGAL IEEE Communication Magazine - December 2001. 報告者：林靖祐 學 號： m9356022. 2005/05/03. Outline. Introduction Overview IP Mobility in IETF Mobile IP HAWAII Cellular IP

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報告者：林靖祐 學 號： m9356022

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  1. Terminal Independent Mobility for IP (TIMIP)António Grilo, Pedro Estrela, Mário Nunes, INESCIST, PORTUGALIEEE Communication Magazine - December 2001 報告者：林靖祐 學 號：m9356022 2005/05/03

  2. Outline • Introduction • Overview IP Mobility in IETF • Mobile IP • HAWAII • Cellular IP • Terminal Independent Mobility for IP (TIMIP) • Power up • Micromobility • Macromobility • Context transfer • Conclusion

  3. Introduction • New Architecture for IP mobility in wireless access networks • Based on principles similar to those in the CIP and HAWAII architectures • Suited for micro-mobility scenarios • Still using MIP for macromobility • TIMIP uses context-transfer mechanismsto support seamless hand-off

  4. Introduction • Layer-2 Mobility • Easy to accomplish & already supported (eg. Wireless LAN) • Does not allow terminal to roam between different LANs and to cross between router domains • Layer-3 Mobility • Internet-wide mobility at the cost of more complex management • Macromobility scenarios • MIP • micromobility scenarios • HAWAII • CIP • These three proposals require change of legacy IP protocol stacks to support mobility aware capability

  5. Overview IP Mobility in IETF • Mobile IP • HAWAII • Cellular IP

  6. Overview IP Mobility in IETFMobile IP • Mobile IP • Could be used in both micromobility and macromobility scenarios. • Terminal has two address • home address (HAddr) • care-of address (CoAddr) • HA & FA • Home agent (HA) • Foreign agent (FA) • Tunnel

  7. HomeNetwork Tunneling Tunneling Tunneling Tunneling Tunneling Tunneling MT ForeignNetwork Tunneling HA FA (CoAddr) Overview IP Mobility in IETFMobile IP Tunneled Packet Src=Orig, dst= CoAddr CoreNetwork Original Packet Src=Orig, dst= HAddr Original Packet Src=Orig, dst= HAddr Orig

  8. Overview IP Mobility in IETFMobile IP • Mobile IP problems • Triangulation and IP tunneling are difficult to integrate with RSVP. • Triangulation may cause a significant increase in end-to-end transmission delay.

  9. Overview IP Mobility in IETFHAWAII • HAWAII • (Handoff-Aware Wireless Access Internet Infrastructure) • HAWAII was proposed in order to solve the QoS and efficiency issues of MIP • Special forwarding entries are installed on specific routers aware of the location of specific terminal • Each domain is structured according to a hierarchy of nodes, forming a logical tree • Each domain owns a root gateway • (Domain Root Router) => HA • Retain same address when moving within domain. • MIP procedure is used when the terminal moves to a foreign domain.

  10. Tunneling Tunneling Foregindomainrootrouter Homedomainrootrouter MT MT MT HAWAII CoreNetwork Router athierachicallevel 1 Accesspoint Intra domainhand over Inter domainhand over(MIP)

  11. Overview IP Mobility in IETFCellular IP • Each domain is composed of a number of CIP nodes structured in a tree. • The CIP nodes maintain routing cache and paging cache. • MIP procedure is used when the terminal moves to a foreign domain.

  12. MT X: from G X: from F X: from F,G X: from F,G Overview IP Mobility in IETFCellular IP • Paging caches • Routing caches E E G times out X: from C X: from C Gateway Gateway C C router router G G R R Global Internet with Mobile IP Global Internet with Mobile IP D D A A F F B B Paging-update FA FA

  13. TIMIP • Terminal Independent Mobility for IP (TIMIP) • Can be totally implemented in the network nodes and work transparently to the IP layer of the terminals. • TIMIP domain is an IP subnet organized as a logical tree of access routers whose root is the access network gateway (ANG)

  14. TIMIP- Different Elements • Access network gateway (ANG) • The root AR, interfacing with the core IP network • Perform mobility management functions to support MIP-based macromobility • Access router (AR) • Each AR incorporates mobility management functions • Access point (AP) • Is an AR that directly communicates to MT • Mobile terminal (MT) • Runs the user applications • Roaming between different APs performed by layer-2

  15. Corenetwork Tunneling Tunneling MT MT MT MT Accessnetworkgateway (level n). Accessrouter(level 2) Accessrouter(level n-x) Accessrouter(level 2) TIMIP- Architecture ... ... Accesspoint(level 1) Accesspoint(level 1) ...

  16. TIMIP • All IETF proposals for IP mobility require the mobile terminals to use a mobility-aware protocol stack • Mobile terminals notify handoff by means of specialIP layer signaling • Replace the protocol stack of all legacy terminals can be a hard task (considering OS & version) • TIMIP • Coupling the IP layer with layer-2 handoff mechanisms at the APs, avoids the need for special IP layer signaling between the terminal and the AP.

  17. TIMIP-Registration Info on ANG for MT • In order for a terminal to be recognized by the TIMIP network, it has to be registered. • Information ANG keep on each MT • MAC address • IP address • MIP capability • IP address of the MIP home agent • Authentication key • Authentication option • Once these data is configured at the ANG, it is forwarded to the APs so that they are able to know the IP address of newly associated terminals based on MAC add

  18. TIMIP- Power UP • MT first appears in a TIMIP domain, routing path is created along the hierarchy of ARs 1. MT perform a layer2 association with an AP. 2. Layer2 notifies the IP layer, triggering the routing reconfiguration procedure. • Layer2 sends the MAC address of the MT to the IP layer. • The MAC is matched against the information broadcast by the ANG to find the respective IP address. • If AP has no routing table entry for the MT Update routing Table. 3~5. Creat Routing Path • RoutingUpdate/RoutingUpdateAck messages reaches the ANG, completes the routing path

  19. updates routing table updates routing table 2 Corenetwork Tunneling Tunneling MT Accessnetworkgateway (level n). Accessrouter(level 2) Accessrouter(level n-x) Accessrouter(level 2) TIMIP- Power UP ... ... 1 RoutingUpdateACK 3 RoutingUpdateACK RoutingUpdate 4 5 RoutingUpdate Accesspoint(level 1) RoutingUpdateACK RoutingUpdate Accesspoint(level 1) ...

  20. TIMIP- Power UP • RoutingUpdate/ACK messageincludes timestamp • All APs are synchronized by means of the Network Time Protocol (NTP) • Routing path is “soft-state”, refreshed by the data packet sent by MT • ICMP EchoRequest/EchoReply messages to refresh the routing path when no package send by MT after a predefined timeout. • SignatureRequest/SignatureReply messages for the security issue • SignatureRequest message • <IP of MT, IP of ANG, rand, timestamp> • SignatureReply message • <SigReq fields,128-bit MD5 message digest calculated with authentication key>

  21. TIMIP- Micromobility • 1~4. Same as the power up procedure. • 5. Crossover AR sends MT the RoutingUpdate message through old routing path. • 6. APs Exchange of RoutingUpdate/RoutingUpdateAck messages down to the old AP, deleting the old entry relative to the MT.

  22. TIMIP- Micromobility • Address Resolution Protocol (ARP) in TIMIP • If the source and destination is in the same domain but associated to the different AP, the ARP request (obtain MAC address) will not reach its destination. • Configure the MTs with a special subnet mask of 255.255.255.255 and the ANG as the default router. (APs performing proxy ARP of the ANG with there own MAC address)

  23. TIMIP- Macromobility • Macro-mobility for MIP terminals • When the MT support MIP but belongs to a different domain, the ANG plays the role of FA. • Handoffs between APs within the foreign domain are handled by TIMIP micromobility procedure. • The MTitself authenticate the MIP messages when communicating with the HA. • ANG broadcasts Router Advertisement message periodically • MT receive RouterAd Msg, notify HA about the CoAddr through the ANG

  24. AuthenticationRequest <ANG IP,HA IP,MIP Registration Request,timestamp> AuthenticationReply <ANG IP,HA IP,MD5(k2,MIP Registration Request),timestamp> MIP RegistrationReply AuthenticationRequest MD5(k2,MIP registration reply) (mobile-home authentication extension) <ANG IP,HA IP,MIP Registration Reply(except the mobile-home authentication extension),timestamp> AuthenticationReply <ANG IP,HA IP,MD5(k2,MIP Registration Reply),timestamp> TIMIP- Macromobility • Macro-mobility for legacy terminals • K1：The Authentication key between the MT and ANG for TIMIP domain • K2：The Authentication key of MT’s home network MD5(k1,AuthenticationRequest) MD5(k1,AuthenticationReply) MD5(k1,AuthenticationReply) Key database HA Foreign ANG MT Registration (MIP proxy) ANG IP,HA IP K1, k2 MIP RegistrationRequest Match?

  25. TIMIP- Macromobility • Macro-mobility for legacy terminals • ANG de-encapsulates the tunneled IP packets that come from the HA to the MT and forwards them to the MH. • MT must change IP gateway configuration when moves to different domain. • This inconvenience is avoided by configuring the MTs with a well known ANG IP address recognized by all APs of all TIMIP domain.

  26. TIMIP- Context Transfer • To assure seamless mobility, context information is pertaining to active IP flows after routing path is updated due to hand off • Context transfer Framework for Seamless Mobility

  27. Old AP New AP MT Old AP New AP Legacy MT SHIN  Old AP address U-SHREP To MT SHACK SHREP-Ack SHREQ SHREP TIMIP- Context Transfer • MT moves to New AP using SHIN • Required Changes Old AP can send context info without receiving request. (using USHREP), legacy terminal cannot provide the add of old AP to new AP in SHIN/SHACK message SHIN : Seamless Handover Initiate SHACK : Seamless Handover Acknowledgement SHREQ : Seamless Handover Request SHREP : Seamless Handover Reply U-SHREP : Unsolicited Seamless Handover Reply

  28. Conclusion • In TIMIP, power-on and handoff are inferred from layer 2 notification at the wireless access points. • It can be implemented as an independent application with no impact on the IP protocol stack. • Combined Ideas from CIP & HAWAII • Ideas from CIP • Refreshing of routing paths is performed by data packets sent by MT. • Ideas from HAWAII • Routing reconfiguration during handoff within a TIMIP domain only needs to change the routing tables of the access routers located in the shortest path between the new AP and the old AP. • Inter domain packet delivery does not require notification to ANG

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