A Novel Distributed Dynamic Location Management Scheme for Minimizing Signaling Costs in Mobile IP

A Novel Distributed Dynamic Location

Management Scheme for Minimizing

Signaling Costs in Mobile IP

Authors: Jiang Xie, Ian F. AkyildizCS 6204CS 6204

Oct 11, 2005Oct 11, 2005

Presented by Hui ZhangPresented by Hui Zhang

AgendaAgenda► IntroductionIntroduction►Distributed & Dynamic Regional Distributed & Dynamic Regional

Location ManagementLocation Management►Signaling Cost FunctionSignaling Cost Function►Optimal Regional Network SizeOptimal Regional Network Size►Analysis ResultsAnalysis Results►ConclusionConclusion

IntroductionIntroduction► Mobile IP:Mobile IP:

Increasing Demands for mobile wireless access Increasing Demands for mobile wireless access to Internet applications.to Internet applications.

enables terminals to maintain all ongoing enables terminals to maintain all ongoing communications while moving from one subnet communications while moving from one subnet to another.to another.

► Some challenges:Some challenges: The signaling cost may become very expensiveThe signaling cost may become very expensive

► Location updates may become very significant as the Location updates may become very significant as the number of MNs increases.number of MNs increases.

The signaling delay may be very longThe signaling delay may be very long► If the distance between the visited network and the If the distance between the visited network and the

home network of the MN is large, the signaling delay for home network of the MN is large, the signaling delay for the location registration is long.the location registration is long.

Introduction (cont’d)Introduction (cont’d)►Mobile IP Regional Registration aimsMobile IP Regional Registration aims

To reduce the number of signaling To reduce the number of signaling messages to the home networkmessages to the home network

To reduce the signaling delay when an MN To reduce the signaling delay when an MN moves from one subnet to anothermoves from one subnet to another

IETF:IETF: Internet Engineering Task Force

Care-of address

GFA: Gateway Foreign Agent MN: Mobile NodeGFA: Gateway Foreign Agent MN: Mobile NodeFA: Foreign AgentFA: Foreign Agent HA: Home AgentHA: Home Agent

Care-of address

Care-of address

GFA: GFA: Gateway Foreign Agent MN: MN: Mobile Node FA: FA: Foreign Agent HA: HA: Home Agent CNCN : :correspondent node

packets1

Packets2(Tunnel)

DisadvantagesDisadvantages► Centralized System ArchitectureCentralized System Architecture

A centralized GFA manages all the traffic within a regional network.

► Mobile IP regional registration is more sensitive to the failure of GFAs.

The number of FAs under a GFA is very critical for the system performance.

Distributed Dynamic Regional Distributed Dynamic Regional Location ManagementLocation Management

► Distributed GFA management schemeDistributed GFA management scheme Each FA can function either as an FA or a GFAEach FA can function either as an FA or a GFA The first FA should act as GFAThe first FA should act as GFA GFA maintains a visitor listGFA maintains a visitor list GFA relays all the home registration requests to the GFA relays all the home registration requests to the

HAHA► Dynamic schemeDynamic scheme

There is no fixed regional network boundary for There is no fixed regional network boundary for each MN.each MN.

The number of FAs under a GFA is not fixed, but The number of FAs under a GFA is not fixed, but adjusted for each MN according to the user-variant adjusted for each MN according to the user-variant and time-variant user parametersand time-variant user parameters.

An MN decides when to perform a home location An MN decides when to perform a home location update according to its changing mobility and update according to its changing mobility and packet arrival pattern.packet arrival pattern.

ArchitectureArchitecture

AdvantagesAdvantages► The traffic load is The traffic load is

distributed to each distributed to each mobility agentmobility agent

► The system robust is The system robust is enhancedenhanced

► Each MN has its own Each MN has its own optimized system optimized system configuration FROM configuration FROM TIME TO TIMETIME TO TIME

Protocol for MNsProtocol for MNs► Each MN keeps a buffer for Each MN keeps a buffer for

storing IP addresses of storing IP addresses of mobility agents. mobility agents.

► An MN records the address An MN records the address of the GFA into its buffer of the GFA into its buffer when it enters a new when it enters a new regional network and then regional network and then performs a home performs a home registrationregistration

► After the home registration, After the home registration, the optimal number of FAs the optimal number of FAs for a regional network is for a regional network is computed based on the up-computed based on the up-to-date parameters of the to-date parameters of the MN MN

ComparisonComparison► ‘‘Distributed system architecture’Distributed system architecture’ and

‘‘dynamic regional network’dynamic regional network’ are independent. So, there are four possible combinations: Centralized Centralized system architecture and fixedfixed regional

network, DistributedDistributed system architecture and fixedfixed regional

network, DistributedDistributed system architecture and dynamicdynamic

regional network, and CentralizedCentralized system architecture and dynamicdynamic

regional network

Comparison (cont’d)Comparison (cont’d)

Signaling CostSignaling Cost►Location Update Cost - Location Update Cost - CCLULU

Home registration costHome registration cost Regional registration costRegional registration cost

►Packet Delivery Cost – Packet Delivery Cost – CCPUPU The transmission costThe transmission cost Processing cost to route a tunneled packet Processing cost to route a tunneled packet

from the HA to the serving FA of an MNfrom the HA to the serving FA of an MN►Total Signaling Cost - Total Signaling Cost - CCTOTTOT

CCTOTTOT = = CCLU LU + + CCPUPU

Home registration costHome registration cost

Regional registration costRegional registration cost

Location Update CostLocation Update Cost► The cost model of Centralized SchemeThe cost model of Centralized Scheme

► The cost model of distributed fixed The cost model of distributed fixed scheme and distributed dynamic scheme and distributed dynamic schemescheme

•M: m-th movement (the action an MN moves out of a subnet)•Tf: the average time an MN stays in each subnet•E[M]: the expectation of M, which is a function of k •k: the number of FAs beneath a GFA, the size of a subnet

Packet Delivery CostPacket Delivery Cost

Packet Delivery Cost (cont’d)Packet Delivery Cost (cont’d)► The total packet delivery cost per unit The total packet delivery cost per unit

timetime Centralized SchemeCentralized Scheme

distributed fixed scheme & distributed distributed fixed scheme & distributed dynamic schemedynamic scheme

Optimal Regional Network Optimal Regional Network SizeSize

► The optimal number of FAs beneath a GFA The optimal number of FAs beneath a GFA ((kopt) is defined as the value of k that ) is defined as the value of k that minimizes the cost functionminimizes the cost function

► The iterative algorithm is used to calculate The iterative algorithm is used to calculate the the kopt Because k can only be an Because k can only be an

integer, the cost function is integer, the cost function is not a continuous function of not a continuous function of k. Therefore, it is not k. Therefore, it is not appropriate to take appropriate to take derivative with respect to k derivative with respect to k of the cost function to get of the cost function to get the minimum.the minimum.

Analysis ResultsAnalysis Results► Centralized Fixed Scheme Centralized Fixed Scheme

vsvs Distributed Fixed SchemeDistributed Fixed Scheme even under non-optimal

regional network size, the distributed scheme always performs better than the centralized IETF Mobile IP regional registration scheme

the distributed scheme with optimal regional network size can further improve the performance.

Distributed Fixed Scheme vs Distributed Dynamic Scheme

► the signaling cost of the distributed dynamic scheme is less than that of both the distributed fixed scheme using fixed optimal regional network size and using user-variant optimal size.

Distributed Fixed Scheme vs Distributed Dynamic Scheme

► the distributed fixed system always pays higher cost than the distributed dynamic system

► The Distributed The Distributed Dynamic regional Dynamic regional location location management is the management is the better choicebetter choice

ConclusionConclusion► Introduced a Distributed Dynamic regional

location management for Mobile IP A distributed GFA system architecture where

each FA can function either as an FA or a GFA.►may allocate signaling burden more evenly.

A dynamic scheme to dynamically optimize the regional network size of each MN according to its current traffic load and mobility

► Analytical results demonstrated that the signaling bandwidth is significantly reduced through the distributed system architecture compared with the IETF Mobile IP regional registration scheme.

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