1. 行動多媒體通訊標準參考模式 (Reference Models) 報告者：童曉儒

2. Outline Introduction Network-Layer Mobility Transport-Layer Mobility Application-Layer Mobility Conclusion

3. Introduction Mobility means the ability of a mobile host (MH) to overcome the location-dependent nature of IP address by a suitable translation mechanism, and to send and receive datagrams efficiently from any location.

4. Introduction

5. Network-Layer Mobility Protocol Macromobility –Macromobility refers to user mobility that is infrequent and also spans considerable space, often between several administrative domain. Micromobility –Micromobility protocols operate in a restricted administrative domain and provide the MHs within that domain with connections to the core network, while keeping signaling cost, packet loss, and handover latency as low as possible.

6. Network-Layer Mobility Protocol Macromobility Protocols –Mobile IP Micromobility Protocols –Cellular IP (CIP) –Intra Domain Mobility Management Protocol (IDMP)

7. Mobile IP Mobile Node (MN) –the node under consideration Home Agent (HA) –a stationary network node (e.g., a router) at the home network Foreign Agent (FA) –A network node (e.g. a router) in the foreign network Care-of Address (COA) –The address in the foreign network Correspondent Node (CN) –communication partner

8. Internet router FA HA home network foreign network (physical home network for the MN) (current physical network for the MN) routerend-system CN mobile node MN Illustration

9. Mobile IP Operations Basic idea of Mobile IP: a MN acquires a COA in a foreign network from a foreign agent and registers to the home agent; all messages sent to its home address is forwarded by its home agent to its COA Three steps –discovering home/foreign agents and the care-of address (COA) –registering the care-of address –data transfer using the care-of address

10. Discovering the Agents and Care-of Address Mobile IP discovery process –(home or foreign) agent broadcasts advertisements at regular intervals announce the network list one or more available care-of addresses –mobile node takes a care-of address –mobile node can also send solicitation to start the process

11. Registering the Care-of Address Once a mobile node has a care-of address, its home agent must find out about it Registration process –mobile node sends a registration request to its home agent with the care-of address information –home agent approves/disapproves the request –home agent adds the necessary information to its routing table –home agent sends a registration reply back to the mobile node

12. Registration Operations in Mobile IP MH = Mobile HostHA = Home Agent FA = Foreign Agent Discussion: what is the major challenge of the registration process?

13. Internet receiver FA HA MN home network foreign network sender 1 1. Sender sends to the IP address of the receiver as usual, FA works as default router CN Data Transfer from the Mobile Node

14. Internet sender FA HA MN home network foreign network receiver 1 2 3 1. Sender sends to the IP address of MN, HA intercepts packet 2. HA tunnels packet to COA, here FA, by encapsulation 3. FA forwards the packet to the MN CN Data Transfer from the Mobile Node

15. Tunneling Operations in Mobile IP Correspondent Node X

16. Micromobility Solutions To reduce signaling load and delay to the home network during movements within one domain  Tunnel-based micro-mobility schemes  Mobile IP regional registration (MIP-RR)  Hierarchical Mobile IP (HMIP)  Intradomain mobility management protocol (IDMP)  Routing-based micro-mobility schemes  Cellular IP (CIP)  Handoff Aware Wireless Access Internet Infrastructure (HAWAII)

17. Simple Comparison CIP/HAWAIIIDMP Handoff/ Path setup Routing Table update Tunnel Update Paging Paging cache /Multicast Multicast Function Deployment All nodesSome nodes

18. Cellular IP Cellular IP represents a new mobile host protocol simple, and flexible protocol for highly mobile hosts CIP supports local mobility & efficiently internet works with Mobile IP

19. Cellular IP architecture

20. Packets will be first routed to the host's home agent and then tunneled to the gateway The gateway "detunnels'' packets and forwards them toward base stations Packets transmitted by mobile hosts are first routed to the gateway and from there on to the Internet MOBILE IP CELLULAR IP

21. X : from D X : from D, E X : from E X : from C E B D R A C F G Internet with Mobile IP GW X X : from F Cellular IP Handoff

22. Handoff Cellular IP handoff –Hard handoff –Semi handoff Hard handoff –During the Handoff Latency the downlink packets are lost. Semi handoff –Improvement over Hard Handoff

23. Hard-Handoff 2.MN send Route Update Packet to GW 3.BSs are refresh RS 4.GW send data packets to MN 1.MN From Old BS to New BS

24. Semi soft-Handoff Improvement over Hard Handoff ; NO packet loss & smooth handoff. Need for buffering at the cross over point :For smooth handoff

25. IDMP IDMP is a two-level generalization of the Mobile IP architecture, with a special node called the mobility agent (MA) providing an MN a domain-wide stable point of packet redirection It will be independent of any specific solution for global (interdomain) mobility management IDMP offers intradomain mobility by using multi-CoA The mobility agent (MA) is similar to a MIP-RR GFA and acts as a domain-wide point for packet redirection A subnet agent (SA) provides subnet-specific mobility services

26. IDMP (cont ’ d) Local care-of address (LCoA) –This identifies the MN’s attachment to the subnet –Unlike MIP’s CoA, the LCoA in IDMP only has local scope –By updating its MA of any changes in the LCoA, the MN ensures that packets are correctly forwarded within the domain Global care-of address (GCoA) –This address resolves the MN’s current location only up to a domain- level granularity and hence remains unchanged as long as the MN stays within a single domain –By issuing global binding updates that contain this GCoA, the MN ensures that packet are routed correctly to its present domain

27. The architecture of IDMP

28. Path setup At power-up, MN obtains a LCoA from SA In IDMP’s SA mode, MN must obtain LCoA from Agent Advertisement of its SA In collocated mode, MN obtains its LCoA from DHCP server MN receives MA’s CoA, GCoA, from SA or DHCP server MN informs the MA of its new LCoA using intradomain location update msg and updates its HA with GCOA Now, packers from remote CN are forwarded to MN’s GCoA and intercepted by MA, tunnels them to MN’s current LCoA

29. IDMP message flow during the initial intradomain location update

30. IDMP call flow during subsequent intradomain movement

31. Handoff MN moves from SA2 to SA3 subnet, MN or SA2 generated movementImminent msg to MA On reception of this msg, MA multicasts all inbound packets to the entire set of neighboring SA(SA1,SA3) which buffer them in per-MN buffers When MN performs a subnet-level registration with SA3, SA3 can immediately forward all buffered packets to the MN –Buffered packets at other SAs are discarded after specified time MN updates the MA with its intra- domain location

32. Paging Paging Area –A set of subnets –An idle MN updates its location only if it detects moved out of its current PA When MA receives packets for a MN which is currently registered but in idle mode, it multicasts Page Solicitation packet to all subnets in current PA When the dormant MN is paged, it obtains LCoA from the SA to which it is currently attached and sends a location update to the MA When the MN reregisters with the MA, the buffered packets in the MA are forwarded to the MN

33. Transport-Layer Mobility The transport layer maintains the true end- to-end connection, whereas the lower layer is completely ignorant of this end-to-end semantic. Transport-Layer Mobility Protocol –TCP-Migrate

34. TCP Segment Encapsulation

35. TCP Segment Format

36. TCP breaks data stream into segments

37. Sliding windows are used to transmit data stream efficiently and for flow control

38. TCP-Migrate Migrate TCBs from established connections –Special SYN packets include a Migrate option Migrate SYNs do not establish new connections, but migrate previously-established ones Established connections are referenced by a token –Maintain all old state (sequence space, options, etc.) –Tokens negotiated during initial connection establishment through the use of a Migrate-Permitted option.

39. TCP-Migrate After a successful token negotiation, TCP connections may be uniquely identified –

40. -TCP Migrate Permitted option -TCP Migrate option TCP Migrate Permitted option TCP Migrate option

41. TCP Migrate Permitted option Hosts wishing to initiate a migrateable TCP connection send a Migrate-Permitted option in the initial SYN segment. the Migrate-Permitted option comes in two variants—the insecure version, of length 3, and the secure version, with length 20. Computing value of token in the Migrate- Permitted option exchange.

42. TCP Migrate option The Migrate option is used to request the migration of a currently open TCP connection to a new address. It is sent in a SYN segment to a host with which a previously-established connection already exists. A token –is computed in the Migrate-Permitted option exchange. –is negotiated between both ends during the initial connection establishment. –The previously broken TCP connection can be resumed

43. After the initiating host’s reception of the SYN/ACK with the Migrate-Permitted, both hosts can then compute a shared secret key. Sequence number of host iSequence number of host j

45. Application-Layer Mobility Session Initiation Protocol (SIP)

46. The Session Initiation Protocol (SIP) is gaining aceptance as an application-layer signaling protocol for Internet multimedia and telephony services, as well as for wireless Internet application. These session include Internet multimedia conference, distance learning, Internet telephone calls, multimedia distribution and similar applications.

47. Session Initiation Protocol (SIP) Session can be advertised using multicast protocols such as SAP, electronic mail, news groups, web pages or directories ( LDAP), among others. SIP transparently supports name mapping and redirection services, allowing the implementation of ISDN and Intelligent Network telephony subscriber services.

48. Incorporating protocols Session Initiation Protocol (SIP) Resource Reservation Protocol (RSVP) Real-time protocol (RTP) Real-time Streaming protocol (RSTP) Session Announcement protocol (SAP) Session Description protocol (SDP)

49. SIP Addressing User @ host The user part is a user name or a telephone number The host part is either a domain name or a numeric network address

50. SIP Request Message NameFunction INVITEInvite user(s) to a session. ACKAcknowledgment of an INVITE request BYESent when a call is to be released OPTIONSQuery server about capability CANCELCancel a pending request REGISTERRegister with a SIP server

52. Figure 1 : Example of SIP proxy server

53. Figure 2 : Example of SIP redirect server

54. SIP mobility: setting up a call

55. SIP mobility : mobility host moves

56. SIP INVATE request

57. Mobile host registration

58. Conclusion

59. References [1] C. Perkins, “IP Mobility Support for IPv4,” IETF RFC 3344, Aug 2002. [2] T. La. Porta et al., “IP-Based Access Network Infrastructure for Next- Generation Wireless Data Networks,” IEEE Pers. Commun., vol. 7, no. 4, Aug 2000. [3] C-Y. Wan, A. T. Campbell, and A. G. Valko, “Design, Implementation, and Evaluation of Cellular IP,” IEEE Pers. Commun., vol. 7, no. 4, Aug. 2000, pp. 42–49. [4] A. Grilo, P. Estrela, and M. Nunes, “Terminal Independent Mobility for IP (TIMIP),” IEEE Commun. Mag., Dec. 2001, pp. 34–41. [5] S. Das et al., “IDMP: An Intra-Domain Mobility Management Protocol for Next-Generation Wireless Networks,” IEEE Wireless Commun., vol. 9, no. 3, June 2002, pp. 38–45. [6] A. C. Snoeren and H. Balakrishnan, “An End-to-End Approach to Host Mobility,” Proc. 6th Int’l. Conf.Mobile Comp. and Net., Boston, MA, Aug. 2000. [7] M. Handley et al., “SIP: Session Initiation Protocol,” IETF RFC 2543, Mar. 1999.

60. References [8] J. Manner et al., “Evaluation of Mobility and Quality of Service Interaction,” Comp. Networks, vol. 38, 2002, pp. 137–63. [9] C. Perkins and D. Johnson, “Route Optimization in Mobile IP,” draft- ietf-mobileip-optim-11.txt, Sept. 2001, work in progress. [10] 3GPP TS 23.060, “General Packet Radio Service (GPRS), Service Description, Stage 2,” Dec 2001. [11] E. Gustafsson, A. Jonsson, and C. Perkins, “Mobile IPv4 Regional Registration,” draft-ietf-mobileip-reg-tunnel- 06.txt, Mar. 2002, work in progress. [12] D. A. Maltz and P. Bhagwat, “MSOCKS: An Architecture for Transport Layer Mobility,” INFOCOM, vol. 3, pp. 1037–45, 1998. [13] D. E. Eastlake, “ Secure Domain Name System Dynamic Update,” IETF RFC 2137, Apr. 1997. [14] E. Wedlund and H. Schulzrinne, “Mobility Support Using SIP,” 2nd ACM/IEEE Int’l. Wksp. Wireless and Mobile Multimedia, Aug. 1999, pp. 76–82. [15] F. Vakil et al., “Supporting Mobility for TCP with SIP,” draft-itsumo- sipping-mobility-tcp-00.txt, Dec. 2001, work in progress.