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： m /05/03

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

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

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

Overview IP Mobility in IETF Mobile IPMobile IP HAWAIIHAWAII Cellular IPCellular IP

Mobile IP Overview IP Mobility in IETF Mobile 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

Tunneling Home Network Mobile IP Overview IP Mobility in IETF Mobile IP Tunneling Core Network Tunneling Foreign Network HAFA Orig Tunneling MT (CoAddr) Original Packet Src=Orig, dst= HAddr Tunneled Packet Src=Orig, dst= CoAddr Original Packet Src=Orig, dst= HAddr

Mobile IP Overview IP Mobility in IETF Mobile 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.

HAWAII Overview IP Mobility in IETF HAWAII 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.

HAWAII Tunneling Core Network Router at hierachical level 1 Intra domain hand over Inter domain hand over(MIP) Foregin domain root router Access point MT Home domain root router

Cellular IP Overview IP Mobility in IETF Cellular 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.

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

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)

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

TIMIP- Architecture Access point (level 1) Access router (level 2) Access router (level n-x) Access network gateway (level n). Tunneling Core network... MT

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 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.

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

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

TIMIP- Power UP Access point (level 1) Access router (level 2) Access router (level n-x) Access network gateway (level n). Tunneling Core network... MT 1 2 RoutingUpdate updates routing table RoutingUpdateACK 3 RoutingUpdate RoutingUpdateACK updates routing table RoutingUpdate RoutingUpdateACK 45

TIMIP- Power UP Routing Update/ACK message includes 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 SignatureRequest message SignatureReply message SignatureReply message

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.

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 and the ANG as the default router. (APs performing proxy ARP of the ANG with there own MAC address)

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 MT itself 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

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 HA Foreign ANG MT (MIP proxy) Key database Registration AuthenticationRequest ANG IP,HA IP K1, k2 AuthenticationReply MIP RegistrationRequest MIP RegistrationReply MD5(k2,MIP registration reply) (mobile-home authentication extension) MD5(k1,AuthenticationReply) AuthenticationRequest MD5(k1,AuthenticationRequest) AuthenticationReply Match? MD5(k1,AuthenticationReply)

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.

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

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 Old APNew APMT SHACK SHIN SHREQ SHREP Old AP address Old APNew APLegacy MT SHREP-Ack U-SHREP  To MT SHIN : Seamless Handover Initiate SHACK : Seamless Handover Acknowledgement SHREQ : Seamless Handover Request SHREP : Seamless Handover Reply U-SHREP : Unsolicited Seamless Handover Reply

Conclusion In TIMIP, power-on and handoff are inferred from layer 2 notification at the wireless access points. 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. It can be implemented as an independent application with no impact on the IP protocol stack. Combined Ideas from CIP & HAWAII Combined Ideas from CIP & HAWAII Ideas from CIPIdeas from CIP Refreshing of routing paths is performed by data packets sent by MT. Ideas from HAWAIIIdeas 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