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Transport of Media Independent Handover Messages Over IP

Transport of Media Independent Handover Messages Over IP. I-D: draft-rahman-mipshop-mih-transport-01.txt. 67 th IETF Annual Meeting MIPSHOP Working Group. Key Concepts. Re-use existing well proven Internet protocols for Discovery of MIH nodes Transport of MIH messages Security Etc.

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Transport of Media Independent Handover Messages Over IP

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  1. Transport of Media Independent Handover Messages Over IP I-D: draft-rahman-mipshop-mih-transport-01.txt 67th IETF Annual Meeting MIPSHOP Working Group

  2. Key Concepts • Re-use existing well proven Internet protocols for • Discovery of MIH nodes • Transport of MIH messages • Security • Etc. • Use functionalities already provided by MIH (IEEE 802.21) & focus on transport mechanism • Define new functionality at MIH application layer where needed

  3. Network Model An MIH application enabled node that supports and/or manages MNs for seamless HO Mobility Manager #1 Mobility Manager #N Internet Signaling over IP Signaling over IP WiMAX Network WLAN Network Cellular Network Contains MIH Proxy Function WLANAP WiMAX BS MIH Proxy Cellular BS L2 Signaling MN contains MIH application & multiple access technologies Mobile Node Mobility

  4. Summary of Proposal • Hard coding or DHCP to discover Mobility Manager (MM) • Mobile Node (MN) discovers MM at initialization • Depends on number of MMs • DHCP as per draft-daniel-dhc-mihis-opt-02.txt (Park, et al.) • UDP as MIH transport mechanism between MM and MN • Easy to implement, simple & fast, used by many other control protocols e.g. SIP • IPSec for security mechanism • Existing MIH functionalities in order to • Setup and keep track of MIH node identifiers, session and transaction identifiers • Discover capabilities of MIH peers • Provide reliability with optional ACK bit fields • Retransmission timers at MIH application layer to complement UDP for reliability • And associated congestion control mechanism

  5. An MIH Enabled Mobile Node • The MIH application shall have a newly defined port number (from IANA) New Port Number MIH App. Other App. UDP IP WLAN Cellular Cellular Interface WLAN Interface

  6. Transport Mechanism for Reliable MIH Message Delivery • Sender of MIH message may request an acknowledgement • Done by setting ACK Request bit in MIH message • Sender sets retransmission timer based on type of MIH message (i.e. Information, Event, Command) • If ACK does not arrive within timeout period then retransmit • If ACK arrives within timeout then assume message delivered correctly • If ACK Request bit was set, the receiver shall send an ACK message • Done by setting ACK Respond bit in MIH message • ACK can be piggy backed with data

  7. MIH Application Retransmission Timers • Three retransmission timers defined for Information Service (IS), Event Service (ES), and Command Service (ES)

  8. MIH Signaling Example 1: Directly Over UDP/IP Mobile Node Cellular WLAN Mobility Manager Power up: connect to WLAN 1 Obtain Neighbor List 2 Send a request for IS (e.g. NL) and set application timer T1 ACK not received timeout after T1 Retransmit request for IS and re-set application timer T1 3 4 Send IS response (with piggy backed ACK) and set application timer T1 5 Send ACK MN then decides to move to cellular (based on radio conditions) 6 Send ‘Link Up’ ES to inform about HO completion (no ACK required) Session continues over cellular 7

  9. MIH Signaling Example 1: Via WLAN MIH Proxy WLAN (Proxy) Mobile Node Cellular Mobility Manager 1 Power up: connect to WLAN Obtain Neighbor List 2 Send a request for IS (e.g. NL) Inter-work L2 message to UDP/IP message 3 Forward IS request ACK not received timeout after T1 4 Retransmit IS request 5 Send ACK 6 Send IS response 7 Send ACK Inter-work UDP/IP message to L2 message 8 Forward IS response

  10. NAT Traversal, Fragmentation, & Security • MNs can be behind NATs • If MNs behind NATs initiate sessions with MM then there will be no NAT traversal problems • Trend in IEEE 802.21 is to use small MIH messages • ES and CS: small and will not require fragmentation • IS can be large: use IP fragmentation when needed together with retransmission timers for reliability • Use relevant IPSec features i.e. Encapsulated Security Payload and/or Authentication Header for secure messaging

  11. Conclusions • Re-use existing protocols as much as possible and define new functionalities only where needed • Use UDP: existing, fast, & simple to use transport protocol • Used by other protocols e.g. SIP commonly uses UDP, CAPWAP also uses UDP, & the IETF NETLMM Working Group also considers UDP for transport • Use existing MIH (IEEE 802.21) functionalities: • Provides options for ACKs, sessions & transactions management • Use MIH Application Retransmission timers for reliability

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