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A Comparison of Mechanisms for Improving Mobile IP Handoff Latency for End-to-End TCP

A Comparison of Mechanisms for Improving Mobile IP Handoff Latency for End-to-End TCP. MobiCom 2003 Robert Hsieh and Aruna Seneviratne School of Electrical Engineering and Telecommunications The University of New South Wales. 26 th February, 2004 Presented by Sookhyun, Yang. Contents.

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A Comparison of Mechanisms for Improving Mobile IP Handoff Latency for End-to-End TCP

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  1. A Comparison of Mechanisms for Improving Mobile IP Handoff Latency for End-to-End TCP MobiCom 2003 Robert Hsieh and Aruna Seneviratne School of Electrical Engineering and Telecommunications The University of New South Wales 26th February, 2004 Presented by Sookhyun, Yang

  2. Contents • Introduction • Related Works • Experimental Methodology • Experimental Results • Conclusion

  3. INTRODUCTION Mobility Related Terminology • Mobile node (MN) • Handoff (Handover) • Layer 2 handoff • Beacon message • Access router (AR) • Access network (AN) • Mobile IP (MIP) • Handoff latency • Home network (HN) • Foreign (Visited) network • Home Agent (HA) • Foreign agent (FA) • Correspondent node (CN) Internet draft: http://www.ietf.org/internet-drafts/draft-ietf-seamoby-mobility-terminology-06.txt

  4. reconfiguration tunneling binding intercept INTRODUCTION Mobile IP (MIP) • When a MN moves and attach itself to another network • Need to obtain a new IP address • All existing IP connections to the MN need to be terminated and then reestablished • Solution to this problem at MIP • Indirection provided with a set of network agents • Handoff latency • Address reconfiguration procedure • HA registration process • No modification to existing routers or end correspondent nodes Foreign network (FN) IP’ COS (Care-of-address) CN FA IP HA IP IP Home network (HN) Mobile node (MN) Access point (AP)

  5. INTRODUCTION Motivation • Effects of Mobile IP (MIP) handoff latency • Packet losses • Severe End-to-End TCP performance degradation • Mitigation of these effects with MIPv6 extensions • Hierarchical registration management • Address pre-fetching • Local retransmission mechanism • No comparative studies regarding the relative performance amongst MIPv6 extensions

  6. INTRODUCTION Overview • Evaluate the impact of layer-3 handoff latency on End-to-End TCP for various MIPv6 extensions • Hierarchical MIPv6 • MIPv6 with Fast-handover • Hierarchical MIPv6 with Fast-handover • Simultaneous Bindings • Seamless handoff architecture for MIP (S-MIP) • Propose an evaluation model examining the effect of linear and ping-pong movement on handoff latency and TCP goodput • Optimize S-MIP by further eliminating the possibility of packets out of order

  7. MAP MAP binding binding Micro mobility Macro mobility Mobility Anchor Point (MAP) RELATED WORKS Hierarchical Mobile IPv6 (HMIPv6) Minimize HA registration delay!! Internet CN HA RCOA_2 AR RCOA_1 AR AR AR AR AR AR AR AR AR AP RCOA_1 LCOA’ AP AP RCOA_2 LCOA’’ Access network Access network RCOA_1 LCOA Internet draft - http://www.ietf.org/internet-drafts/draft-ietf-mipshop-hmipv6-01.txt

  8. RELATED WORKS Local Handoff Latency Reduction • Low latency address configuration • Reduce address reconfiguration time • Configure an address for MN in an network likely to move to before it moves • UseL2 trigger • Method • Pre-registration • Perform L3 handoff before completion of L2 handoff • Post-registration • Setup a temporary bi-directional tunnel between oFA and nFA • Allow MN to continue using oFA while registration at the time or later • MIPv6 with Fast-Handover • Combined method of pre-registration and post-registration • Three phases • Handover initiation • Tunnel establishment • Packet forwarding

  9. HI(Handover initiation) 1 Handover initiation Hack(Handover ack) 2 Tunnel Establishment btw oFA & nFA F-BAck 3 Forward packets Packet forwarding phase F-NA(Fast neighbor advertisement) Deliver packets RELATED WORKS MIPv6 with Fast-Handover nFA MN oFA Beacon L2 trigger RtSolPr(Router solicitation proxy) PrRtAdv(Proxy router advertisement) F-BU(Fast-binding update) with COA F-Back(Fast-binding ack) Disconnect Connect Internet draft - http://www.ietf.org/internet-drafts/draft-ietf-mipshop-fast-mipv6-01.txt

  10. Forwarding Forwarding RELATED WORKS HMIPv6 with Fast-handover • Combine HMIPv6 with Fast-handover • Reduce latency due to address configuration and HA registration • Relocate the forwarding anchor point from oAR to the MAP Internet CN HA MAP MAP AR AR AR AR nAR AR nAR oAR Access network Access network

  11. Simultaneous binding RELATED WORKS Simultaneous Bindings • Reduce packet losses • N-casting packets with multiple bindings • Forward packets for a short period to the MN’s current location and to n-other locations where the MN is expected move to • Forwarding carried by oAR, MAP or HA nAR1 MAP nAR2 oAR AP (Access point) Internet draft- http://www.ietf.org/internet-drafts/draft-elmalki-mobileip-bicasting-v6-05.txt

  12. DE RELATED WORKS Seamless Handoff for MIP (S-MIP) • Provide a different approach to solve the timing ambiguity problem • Build on HMIPv6 with Fast-Handover • Use MN location and movement pattern to instruct MN when and how handoff is initiated • Decision engine (DE) • Store the history of MN locations • Determine movement pattern • Make “handoff decision” for MN MAP nAR2 oAR nAR1 MN

  13. Handoff mechanism RELATED WORKS Decision Engine MN location Tracking <- Signal strength Handoff Decision Linear Stochastic Stationary near the center

  14. RELATED WORKS Handoff Mechanism • Linear movement • Synchronized packet simulcasting (SPS) • Optimized S-MIP • Stochastical manner • oAR and nAR are anticipation-mode • Maintain MN’s binding with oAR, nAR before F-NA • Reduce unnecessary re-setup • Stationary state near the center • Establish multiple bindings with ARs • MN uses more than one COAs MAP optimization DE S-packet F-packet oAR nAR S-buffer F-buffer MN < SPS mechanism >

  15. RELATED WORKS Optimized S-MIP • Elimination of the possibility of packets out of order • Upon sending the F-BU to the oAR, MN must immediately switch to the nAR • After receiving F-BU, oAR must immediately forward packets to the nAR • oAR only needs to send the FBAck to the nAR • IP packet filtering mechanism at nAR • oAR incorrectly forwards IP packets with the S-bit set as f-packets • Compare IP packets within the s-buffer and f-buffer at nAR • Discard identical packets in s-buffer • [optimized] Examine 16 bit identification, fragment offset, and flag fields in IP header

  16. EXPERIMENTAL METHODOLOGY Implementation • Simulator • Network Simulator version 2 (ns-allinone2.1b6a) • Patch with the ns wireless extension module allowing basic MIPv4 • Extension to the ns-2 • Mobile IPv6 protocol • Hierarchical Mobile IPv6 protocol • Fast-handover protocol • Simultaneous bindings protocol • Optimized S-MIP protocol • Modification • Infrastructure mode: WaveLan with connection monitor (CMon) • Additional handoff algorithm: Midway handoff

  17. EXPERIMENTAL METHODOLOGY Simulation Network Topology • Max num of packets received • by the receiver in sequence • < Performance focus > • Handoff delay • TCP goodput • CN’s Congestion window Overall handoff delay (D) = time(first-transmitted~retransmitted) +time(CN->MN) Micro mobility Linear / ping-ping

  18. TCP sequence number Time (seconds) EXPERIMENTAL RESULT – Handoff delay MIPv6 & HMIPv6 Sender (CN)’s view • a: MIPv6 (resolution time 100ms) • b~e: HMIPv6 (resolution time 100ms) • f~I: HMIPv6 (resolution time 200ms) address resolution L2 handoff BU at MAP Out-of-sequence packet • MIP’s D = 814ms • HMIPv6’s D = 326ms

  19. TCP sequence number Proportional to distance (FA~HA) Time (seconds) EXPERIMENTAL RESULT – Handoff delay Fast-Handover Sender (CN)’s view • f ~ i : fast-handover • (resolution time 100ms) RtSolPr~PrRtAdv BU L2 handoff • D = 358ms • Even though forwarding mechanism, • MN is unable to receive packets until • the binding update is completed

  20. < CN’s cwnd > Packet forwarding Out-of-sequence packet Packet loss due to L2 handoff receive (data) send (ack) EXPERIMENTAL RESULT – Handoff delay HMIPv6 with Fast-Handover Receiver (MN)’s view TCP sequence number D = 270ms Time (seconds)

  21. Sender (CN)’s view TCP sequence number Hand off = 100ms No packet loss No out-of-sequence packet Time (seconds) TCP sequence number No packet loss Out-of-sequence packet Time (seconds) EXPERIMENTAL RESULT – Handoff delay S-MIP <- Optimized S-MIP Non optimized S-MIP ->

  22. < Linear case > < Ping-pong case > • Completely • break down MIP 814ms HMIPv6 326ms MIPv6 with Fast-handover 358ms • Affected • to a lesser extent • Severe throttling HMIPv6 with Fast-handover 270ms Simultaneous Bindings 268ms • Excellent resilience S-MIP (nonop) 0ms S-MIP 0ms EXPERIMENTAL RESULT Handoff Delay

  23. EXPERIMENTAL RESULT TCP Goodput Linear : 1.447s PP: 14.23s MN is stationary near the PAR

  24. EXPERIMENTAL RESULT Congestion Window Linear movement Ping-ping movement S-MIP Simultaneous Binding

  25. Conclusion • Analyze various handoff latency reduction framework • Show the possibility of significantly reducing the latency by S-MIP • Optimize the S-MIP scheme • Future works • S-MIP under multiple connection scenarios • Scalability of the Decision Engine (DE) • Design more sophisticated positioning schemes for S-MIP Correspondent node (CN)

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