Terminal Independent Mobility for IP (TIMIP)

1. Terminal IndependentMobility for IP(TIMIP) 12 JUL 2002 Juitem@TeNET, KNU Terminal Independent Mobillity for IP

2. Abstract • 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 macro-mobility • TIMIP uses context-transfer mechanisms compatible with those of SeaMoby WG’s to support seamless hand-off

3. 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 • Several IP micromobility models • MIP • HAWAII • CIP • These three proposals require change of legacy IP protocol stacks to support mobility aware capability

4. IP Mobility in IETF • Overview IP mobility in IETF • Mobile IP • Cellular IP • Handoff Aware Wireless Access Internet Architecture

5. Mobile IP • RFC 2002 • Terminal has two address • HAaddr • 홈망에서 사용, 불변 • CoAddr • 외부 망에 있는 동안 임시적으로 사용, 망에 따라 변화 • FA의 router advertisement message를 통해 획득 • HA & FA • HA는 MT로 오는 모든 패킷을 받아 HAaddr로 또는 CoAddr로 터널링 • FA는 터널을 통해 받은 패킷을 decapsulation하여 MT로 전달 • Triangular Routing & IP tunneling are difficult to integrate with RSVP

6. ForeignNetwork HomeNetwork Tunneling Tunneling Tunneling Tunneling Tunneling Tunneling FA HA Mobile IP Dst=CoAddr Dst=Haddr(MT) Tunneling CoreNetwork MT Dst=Haddr(MT) Orig

7. HAWAII • 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 • Each domain owns a root gateway(Domain Root Router) => HA 역할 • MT로 보내어지는 패킷은 일반적인 라우팅 프로토콜을 사용하여 먼저 DRR에 도착, 그 다음 HAWAII 프로토콜 사용 • Domain 내에서 이동할 시에는 IP 주소를 유지, 터널링 되지 않음 • Path는 모바일 터미널의 일반적인 MIP registration message에 의해 trigger된다. • Domain 간의 이동시 Foreign Domain의 DRR이 FA역할을 하여 CoAddr할당 및 터널링 되는 패킷을 수신

8. Tunneling Tunneling Homedomainrootrouter Foreigndomainrootrouter HAWAII Core Network Router athierachicallevel 1 Accesspoint Intra domainhand over Inter domainhand over

9. CIP • CIP는 handover를 predict하기 위해 layer-2 정보를 이용 MIP와 HAWAII layer-3 handover 과정은 MIP signaling에 의해 trigger -> latency high, significant packet loss • 마크로이동성은 MIP를 이용하여 지원하고 마이크로 이동성은 CIP프로토콜을 이용하는 방식 • 이동 노드의 위치를 관리하기 위해 페이징 캐쉬와 라우팅 캐쉬를 사용 • 페이징 캐쉬 • 서비스 지역내의 idle 상태의 호스트들의 대강의 위치정보저장 • 라우팅 캐쉬 • 서비스 지역내의 액티브 이동 호스트의 위치를 짧은 시간단위로 추적하고 관리 • Soft hand off 사용 => 패킷이 전달 될 때에는 두 개의 캐쉬의 정보를 이용하여 이동 노드까지의 경로를 설정한 후 전달. 시스템의 과부화 방지

10. CIP – soft hand off • Time out시 엔트리 삭제 • Data packet에의한 갱신

11. 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 special IP layer signaling • Replace the protocol stack of all legacy terminals can be a hard task (considering various OS & version) • AP에서 layer-2 hand off 기법을 사용하면 Terminal과 AP사이에 special IP layer signaling 이 필요치 않게된다.(TIMIP)

12. TIMIP • TIMIP • TIMIP can be implemented in the network nodes and work transparently to the IP layer of the terminals • Different Elements • Access router (AR) • A number of access routers organize access network • Each router incorporates mobility management functions • Access point (AP) • An AR that directly communicates with the mobile terminals at the radio interface • Access Network Gateway (ANG) • The root AR, interfacing with the core IP network • Perform mobility management functions to support MIP-based macromobility • Mobile terminal (MT) • Runs the user applications • Roaming between different APs performed by layer-2

13. Tunneling Tunneling TIMIP architecture Accessrouter(level 2) Corenetwork Accesspoint(level 1) Accessrouter(level n-x) Accessnetworkgateway (level n) Accessrouter(level 2) Accesspoint(level 1)

14. TIMIP details • Registration of MT on ANG • PowerUP process를 통한 path 설정 • Path/Routing table의 관리 • Authentication 관리 • Macromobility for Legacy Terminals • Macromobility for MIP Terminals • Context Transfer • Conclusion

15. Registration Info on ANG for MT • In order for a terminal to be recognized by the TIMIP network, it has to be registered.(can be accomplished by offline) • The ANG keeps information on all mobile terminals recognized by the mobile network • 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

16. CoreNetwork Tunneling Tunneling Power-UP • MT first appears in a TIMIP domain, routing path is created along the hierarchy of ARs 4 2 1 3 5 Accessnetworkgateway (level n) Accessrouter(level 2) Accessrouter(level n-x) Accesspoint(level 1)

17. Power Up process • 1. The MT performs a layer-2 association • 2. At the AP, layer-2에서 IP layer로 MT의 존재를 notify. • MT가 MAC addr을 보내면 AP는 ANG가 보낸 terminal registration information broadcast를 참조하여 IP를 매치시킨다 • AP는 자신의 routing entry에 MT를 등록 • 3. AP는 상위 레벨로 Routing 정보를 Update • 4. RoutingUpdate/RoutingUpdateAck 를 사용하여 상위 레벨로 계속 갱신되면서 routing path가 생성된다 • 5. ANG까지 도달하면 routing path creation을 중지(path가 만들어짐) MT와 ANG가 만든 path 상에 있지 않은 AR들은 MT에 대한 routing table을 갖지 않으며, 이런 AR들이 MT로 향하는 패킷을 받게 되면 상위로 전달한다.

18. Routing Path • Using RoutingUpdate/ACK message • Message includes timestamp • 모든 AP는 NTP로 동기화되어 있으므로 MT가 router reconfiguration 보다 빠르게 이동할 경우에도 consistency 를 보장. • Routing path is soft-state, refreshed by the data packet sent by MT • Soft-state에 의한 timeout 발생시, 해당 AR에서 • ICMP Echo Request를 source를 ANG로 set해서 MT로 보낸다 • 유효한 path라면 MT의 reply에 의해서 라우팅 테이블 유지 • 사라진 path라면 Routing Table에서 제거(시간내에 reply를 받지 못할경우)

19. Authentication • Unprotected IP networks, it allows MTs to power on with false MAC & IP addTo avoid this, using authentication option field • Authen.Opt field가 on이면, ANG의 DB와 MT의 키 값으로 인증 • Authentication Process • Authentication takes place after powerup • AP sends SignatureRequest to wellknown UDP port in the MT, to ANG respectively • Receive Reply both from MT& ANG • 두 메시지가 match 되면, routing table update • SignatureRequest message • <IP of MT, IP of ANG, rand, timestamp> • SignatureReply message • <SigReq fields, 128-bit MD5 message digest calculated with authentication key>

20. CoreNetwork Tunneling Tunneling Micromobility Handoff between two AP s in same domain Accessrouter(level 2) 6 5 Accessrouter(level n-x) Accessnetworkgateway (level n) 1 Accessrouter(level 2) 3 2 4

21. Micromobility(Con’t) • 1~4 same as those of the power-up procedure • 5. Exchange of RoutingUpdate / ACK messages climb up the hierarchy levels, until the crossover AR • Crossover AR(AR which belongs simultaneously to the old path and to the new path) • Crossover AR starts the deletion of old routing path • AR send a RoutingUpdate message to MT through the old route path, and detects not accessible • 6. Exchange of RoutingUpdate/ACK messages goes down the AR tree following the old path, until the OLD AP is reached.

22. Macromobility for legacy terminal • When MT(Legacy) enters a TIMIP domain • terminal is locally authenticated and a routing path is created between the MT and the ANG • Conferring registration information, the ANG realizes it is a foreign MT and it does not implement MIP • Constantly, ANG must act as a MIP proxy on behalf of the MT • Notify the HA about MT’s CoAddr • CoAddr is obtained by RegistrationRequest Msg • Registration Mgs needs Authentication, ANG does not know MT’s Authentication key • MT와 ANG인증 후, ANG와 HA인증 • ANG de-encapsulates the tunneled IP packet comes from HA • ANG는 core network로 통하는 IP gateway 역할

23. Macromobility for legacy terminal • MT와 ANG인증 • ANG send MT authenticationReq msg • <IP of ANG, IP add of HA, MIP Registraion Request, timestamp> which is authenticated by ANG with MD5 • MD5(K1, AuthenticationRequ) • K1 : Autientication key between MT & ANG in TIMIP domain • MT finds K1 in key DB, obtain K2(authentication key of HA) • MT answer AuthenticationReply • <IP of ANG, IP of HA, MD5(K2, MIP Reg Req), timestamp> which is authenticated by the terminal with MD5 • MD5(k1, Autientication Reply) • ANG send authenticated MIP Registration Request msg to HA. • ANG와 HA인증 • ANG send AuthenticationReq to MT • <IP of ANG, IP of HA, MIP REG reply, timestamp> authenticated with MD5 • MD5( K1, MIP Registration Repky) • MT answer with AuthenticationReply • <IP of ANG, IP of HA, MD5, timestamp • MD5( K2, MIP Registration Repky)

24. Macromobility for MIP Terminals • When MT supports MIP, belongs to different domain ANG acts as FA • MT powers-on in the same way as legacy MTs • ANG broadcasts Router Advertisement message periodically • MT receive RouterAd Msg, notify HA about the CoA through the ANG .

25. Context Transfer • Context Transfer • To assure seamless mobility, context information is pertaining to active IP flows after routing path is updated due to hand off • Context information can be related to security, header compression, QoS, ans so on • Compatible with Seamoby WG’s context transfer • MT moves to New AP using SHIN(seamless Handover Initiate) • New AP answer ACK • New AP send SHREQ(seamless Handover Request) to old AP usin ICMP message option. • New AP receive reply from old AP • 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 => old AP is configured to send a U-SHREP msg addressed to the terminal new AP send SHREP-ack msg to old AP

26. Problems & Solution • In Micro mobility • Single subnet에서 (ex LAN) destination이 동일한 subnet내에 있지만 다른 AP를 이용할 경우 • ARP request는 destination의 MAC을 얻을 수 없다. • 방안1. AP를 MT의 proxy ARP역할을 하도록 설정 • 설정 복잡, radio frequency에서 broadcast traffic 증가 • 방안2. AP를 ANG의 proxy로 설정 • ( 255.255.255.255for special subnet mask) • (ANG as the default router) • MT가 속한 local의 모든 AP로 ARP가 보내진다

27. Problems & Solution • In Macromobility • MT가 다른 TIMIP domain으로 이동할 경우 IP Gateway 역할을 하는 ANG의 IP addr이 변경된다 • 모든 TIMIP의 모든 AP가 인지할 수 있는 well-known ANG IP로 MT를 config함으로써 해결 (well known ANG IP로 gratuitous ARP를 broadcast)

28. Conclusion • In TIMIP, power-on and handover are inferred from layer-2 notification at the wireless access points. • IP mobility signaling is completely implemented in the network nodes and thus transparent to the IP layer of the terminals • MT’s authentication function can be implemented as an independent application • 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

29. Reference • Terminal Independent Mobility for IPIEEE Communications Magazine Dec 2001 • Terminal Independent Mobile IPdraft-estrela-timip-00.txtExpires: September 2002 March 2002 .