Presentation on theme: "Terminal Independent Mobility for IP (TIMIP) KNU 12 JUL 2002 Terminal Independent Mobillity for IP."— Presentation transcript:
Terminal Independent Mobility for IP (TIMIP) KNU 12 JUL 2002 Terminal Independent Mobillity for IP
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
Terminal Independent Mobillity for IP 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
Terminal Independent Mobillity for IP IP Mobility in IETF Overview IP mobility in IETF –Mobile IP –Cellular IP –Handoff Aware Wireless Access Internet Architecture
Terminal Independent Mobillity for IP Mobile IP RFC 2002 Terminal has two address –HAaddr 홈망에서 사용, 불변 –CoAddr 외부 망에 있는 동안 임시적으로 사용, 망에 따라 변화 FA 의 router advertisement message 를 통해 획득 HA & FA –HA 는 MT 로 오는 모든 패킷을 받아 HAaddr 로 또는 CoAddr 로 터 널링 –FA 는 터널을 통해 받은 패킷을 decapsulation 하여 MT 로 전달 Triangular Routing & IP tunneling are difficult to integrate with RSVP
Terminal Independent Mobillity for IP Tunneling Home Network Mobile IP Tunneling Core Network Tunneling Foreign Network HAFA MT Orig Dst=Haddr(MT) Dst=CoAddr Tunneling
Terminal Independent Mobillity for IP 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 MT 로 보내어지는 패킷은 일반적인 라우팅 프로토콜을 사용하여 먼저 DRR 에 도착, 그 다음 HAWAII 프로토콜 사용 Domain 내에서 이동할 시에는 IP 주소를 유지, 터널링 되지 않음 Path 는 모바일 터미널의 일반적인 MIP registration message 에 의해 trigger 된다. Domain 간의 이동시 Foreign Domain 의 DRR 이 FA 역할을 하여 CoAddr 할당 및 터널링 되는 패킷을 수신
Terminal Independent Mobillity for IP HAWAII Tunneling Core Network Router at hierachical level 1 Home domain root router Intra domain hand over Inter domain hand over Foreign domain root router Access point
Terminal Independent Mobillity for IP CIP CIP 는 handover 를 predict 하기 위해 layer-2 정보를 이용 MIP 와 HAWAII layer-3 handover 과정은 MIP signaling 에 의해 trigger -> latency high, significant packet loss 마크로이동성은 MIP 를 이용하여 지원하고 마이크로 이동성은 CIP 프로토콜 을 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
Terminal Independent Mobillity for IP CIP – soft hand off Time out 시 엔트리 삭제 Data packet 에의한 갱신
Terminal Independent Mobillity for IP 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) AP 에서 layer-2 hand off 기법을 사용하면 Terminal 과 AP 사이에 special IP layer signaling 이 필요치 않게된다. (TIMIP)
Terminal Independent Mobillity for IP 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
Terminal Independent Mobillity for IP TIMIP architecture Tunneling Access point (level 1) Access router (level 2) Access router (level n-x) Access network gateway (level n) Core network
Terminal Independent Mobillity for IP TIMIP details Registration of MT on ANG PowerUP process 를 통한 path 설정 Path/Routing table 의 관리 Authentication 관리 Macromobility for Legacy Terminals Macromobility for MIP Terminals Context Transfer Conclusion
Terminal Independent Mobillity for IP 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
Terminal Independent Mobillity for IP Power-UP MT first appears in a TIMIP domain, routing path is created along the hierarchy of ARs Tunneling Core Network Access point (level 1) Access router (level 2) Access router (level n-x) Access network gateway (level n)
Terminal Independent Mobillity for IP Power Up process 1. The MT performs a layer-2 association 2. At the AP, layer-2 에서 IP layer 로 MT 의 존재를 notify. –MT 가 MAC addr 을 보내면 AP 는 ANG 가 보낸 terminal registration information broadcast 를 참조하여 IP 를 매치시킨다 –AP 는 자신의 routing entry 에 MT 를 등록 3. AP 는 상위 레벨로 Routing 정보를 Update 4. RoutingUpdate/RoutingUpdateAck 를 사용하여 상위 레벨로 계속 갱신되 면서 routing path 가 생성된다 5. ANG 까지 도달하면 routing path creation 을 중지 (path 가 만들어짐 ) MT 와 ANG 가 만든 path 상에 있지 않은 AR 들은 MT 에 대한 routing table 을 갖 지 않으며, 이런 AR 들이 MT 로 향하는 패킷을 받게 되면 상위로 전달한다.
Terminal Independent Mobillity for IP Routing Path Using RoutingUpdate/ACK message –Message includes timestamp – 모든 AP 는 NTP 로 동기화되어 있으므로 MT 가 router reconfiguration 보다 빠르게 이동할 경우에도 consistency 를 보 장. Routing path is soft-state, refreshed by the data packet sent by MT Soft-state 에 의한 timeout 발생시, 해당 AR 에서 –ICMP Echo Request 를 source 를 ANG 로 set 해서 MT 로 보낸다 유효한 path 라면 MT 의 reply 에 의해서 라우팅 테이블 유지 사라진 path 라면 Routing Table 에서 제거 ( 시간내에 reply 를 받지 못할경우 )
Terminal Independent Mobillity for IP Authentication Unprotected IP networks, it allows MTs to power on with false MAC & IP add To avoid this, using authentication option field –Authen.Opt field 가 on 이면, ANG 의 DB 와 MT 의 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 – SignatureReply message –
Terminal Independent Mobillity for IP Micromobility Handoff between two AP s in same domain Access router (level 2) Access router (level n-x) Access network gateway (level n) Tunneling Core Networ k
Terminal Independent Mobillity for IP 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.
Terminal Independent Mobillity for IP 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 »MT 와 ANG 인증 후, ANG 와 HA 인증 ANG de-encapsulates the tunneled IP packet comes from HA ANG 는 core network 로 통하는 IP gateway 역할
Terminal Independent Mobillity for IP Macromobility for legacy terminal MT 와 ANG 인증 –ANG send MT authenticationReq msg 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 which is authenticated by the terminal with MD5 –MD5(k1, Autientication Reply) –ANG send authenticated MIP Registration Request msg to HA. ANG 와 HA 인증 –ANG send AuthenticationReq to MT authenticated with MD5 –MD5( K1, MIP Registration Repky) –MT answer with AuthenticationReply
Terminal Independent Mobillity for IP 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.
Terminal Independent Mobillity for IP 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
Terminal Independent Mobillity for IP Problems & Solution In Micro mobility –Single subnet 에서 (ex LAN) destination 이 동일한 subnet 내에 있지만 다른 AP 를 이용할 경우 ARP request 는 destination 의 MAC 을 얻을 수 없다. – 방안 1. AP 를 MT 의 proxy ARP 역할을 하도록 설정 » 설정 복잡, radio frequency 에서 broadcast traffic 증가 – 방안 2. AP 를 ANG 의 proxy 로 설정 »( for special subnet mask) »(ANG as the default router) »MT 가 속한 local 의 모든 AP 로 ARP 가 보내진다
Terminal Independent Mobillity for IP Problems & Solution In Macromobility –MT 가 다른 TIMIP domain 으로 이동할 경우 IP Gateway 역할을 하는 ANG 의 IP addr 이 변경 된다 모든 TIMIP 의 모든 AP 가 인지할 수 있는 well- known ANG IP 로 MT 를 config 함으로써 해결 (well known ANG IP 로 gratuitous ARP 를 broadcast)
Terminal Independent Mobillity for IP 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
Terminal Independent Mobillity for IP Reference Terminal Independent Mobility for IP IEEE Communications Magazine Dec 2001 Terminal Independent Mobile IP draft-estrela-timip-00.txt Expires: September 2002 March 2002.