1 / 60

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

行動多媒體通訊標準參考模式 (Reference Models) 報告者：童曉儒. Outline. Introduction Network-Layer Mobility Transport-Layer Mobility Application-Layer Mobility Conclusion. Introduction.

issacy
Télécharger la présentation

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

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

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

  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 Host HA = Home Agent • FA = Foreign Agent Discussion: what is the major challenge of the registration process?

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

  14. Data Transfer from the Mobile Node HA 2 MN Internet home network 3 receiver foreign network FA 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 packetto the MN 1 CN sender

  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

  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 Packets transmitted by mobile hosts are first routed to the gateway and from there on to the Internet MOBILE IP The gateway "detunnels'' packets and forwards them toward base stations CELLULAR IP

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

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

  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 • < source address, source port, dest address, dest port > • < source address, source port, token >

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

  44. Application-Layer Mobility • Session Initiation Protocol (SIP)

  45. Session Initiation Protocol (SIP) • 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.

  46. 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.

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

  48. 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 SIP Addressing

  49. SIP Request

More Related