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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

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


Contents
Contents Latency for End-to-End TCP

  • Introduction

  • Related Works

  • Experimental Methodology

  • Experimental Results

  • Conclusion


Mobility related terminology

INTRODUCTION Latency for End-to-End TCP

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


Mobile ip mip

reconfiguration Latency for End-to-End TCP

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)


Motivation

INTRODUCTION Latency for End-to-End TCP

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


Overview

INTRODUCTION Latency for End-to-End TCP

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


Hierarchical mobile ipv6 hmipv6

MAP Latency for End-to-End TCP

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


Local handoff latency reduction

RELATED WORKS Latency for End-to-End TCP

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


Mipv6 with fast handover

HI(Handover initiation) Latency for End-to-End TCP

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


Hmipv6 with fast handover

Forwarding Latency for End-to-End TCP

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


Simultaneous bindings

Simultaneous Latency for End-to-End TCP

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


Seamless handoff for mip s mip

DE Latency for End-to-End TCP

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


Decision engine

Handoff mechanism Latency for End-to-End TCP

RELATED WORKS

Decision Engine

MN location

Tracking

<- Signal strength

Handoff

Decision

Linear

Stochastic

Stationary near the center


Handoff mechanism

RELATED WORKS Latency for End-to-End TCP

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 >


Optimized s mip

RELATED WORKS Latency for End-to-End TCP

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


Implementation

EXPERIMENTAL METHODOLOGY Latency for End-to-End TCP

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


Simulation network topology

EXPERIMENTAL METHODOLOGY Latency for End-to-End TCP

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


Mipv6 hmipv6

TCP sequence number Latency for End-to-End TCP

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


Fast handover

TCP sequence number Latency for End-to-End TCP

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


Hmipv6 with fast handover1

< CN’s cwnd > Latency for End-to-End TCP

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)


S mip

Sender (CN)’s view Latency for End-to-End TCP

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 ->


Handoff delay

< Linear case > Latency for End-to-End TCP

< 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


Tcp goodput

EXPERIMENTAL RESULT Latency for End-to-End TCP

TCP Goodput

Linear : 1.447s

PP: 14.23s

MN is stationary near the PAR


Congestion window

EXPERIMENTAL RESULT Latency for End-to-End TCP

Congestion Window

Linear movement

Ping-ping movement

S-MIP

Simultaneous

Binding


Conclusion
Conclusion Latency for End-to-End TCP

  • 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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