Network Layer Mobile IP Slides adapted from Prof. Dr.-Ing. Jochen - - PowerPoint PPT Presentation

Network Layer Mobile IP

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Slides adapted from Prof. Dr.-Ing. Jochen H. Schiller and W. Stallings

Mobile IP - Definition

 “Mobile IP (MIP) is a modification to IP that

allows nodes to continue to receive datagrams no matter where they happen to be attached to the Internet”

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Mobile IP Concept

 Mobile IP adds mobility support to the Internet network

layer protocol IP.

• The Internet started at a time when no-one had a concept of

mobile computers.

• The Internet of today lacks mechanisms for the support of

users traveling through the world. – IP is the common base for thousands of applications and runs

• ver dozens of different networks; this is the reason for

supporting mobility at the IP layer.

 Motivation for Mobile IP:

• Routing
• based on IP destination address, network prefix determines

physical subnet

• Change of physical subnet implies change of IP address to

have a topological correct address (standard IP) or needs special entries in the routing tables

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• Create specific routes to end-systems – mobile nodes?
• change of all routing table entries to forward packets

to the right destination

• does not scale with the number of mobile hosts and

frequent changes in the location

• Changing the IP address?
• adjust the host IP address depending on the current

location

• almost impossible to find a mobile host, DNS has not

been built for frequent updates

• TCP connection break

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Mobile IP Requirements

• Transparency
• mobile end-systems keep their IP address
• continuation of communication after interruption of link possible
• point of connection to the fixed network can be changed
• Compatibility
• support of the same layer 2 protocols as IP does
• no changes to current end-systems and routers required
• Mobile end-systems can communicate with fixed systems
• Security
• authentication of all registration messages
• Efficiency and scalability
• only little additional messages to the mobile system required

(connection typically via a low bandwidth radio link)

• world-wide support of a large number of mobile systems in the

whole Internet

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Real-life Solution

 Take up the analogy of you moving from one

apartment to another. What do you do?

• Leave a forwarding address with your old post-office
• The old post-office forwards mail to your new post-
• ffice, which then delivers it to you

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MIPv4: Overview

 MIPv4 Nodes

• MN (Mobile Node): Host
• CN (Correspondent Node): Host
• HA (Home Agent): Router
• FA (Foreign Agent): Router

 MIPv4 Address

• HoA (Home Address): MN
• CoA (Care-of-Address): FA

MIPv4 Agents

 Home Agent (HA) & Foreign Agent (FA)

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Home Address (HoA) and Care-of Address (CoA)

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Protocols Operation

 Agent Discovery  Registration  Data Transfer

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MIPv4: Control Operations

 Agent Discovery

• MN  FA (CoA)
• ICMP Agent Solicitation & Advertisement

 Registration to HA (via FA)

• MN  FA  HA
• Over UDP (destination port 434)

 Data Tunneling

• CN => HA (HoA) => FA (CoA) => MN
• IP-in-IP Tunneling, ..

Mobile IP in detail

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CN

• 2. HA Discovery Request
• 3. HA Discovery Reply
• 4. HA Registration through FA
• 5. HA Registration Ack.
• 1. CoA Discovery

MN HA 1 2 3

• - MN is Registered with HA --

4 5

• - CoA and HA Discovery --
• - Registration Procedure --
• - CN starts communication with MN --
• 6. Data Packet
• 7. IP-in-IP Encapsulation
• 8. Tunneled Data
• - Signals 6-10a as above --

8 7

• 6a. Data Packet
• - MN starts communication with CN --

8a Detunnelled Data

• 9. Binding Update

6a 6a

• - Discovery and Registration as above --

FA 8a 6 10

• 10. IP-in-IP tunneling

9 9 10a

• 10a. Detunnelled Data

CN

• 2. HA Discovery Request
• 3. HA Discovery Reply
• 4. HA Registration BU
• 5. HA Registration BU Ack.
• 1. CoA Discovery

MN HA 1 2 3

• - MN is Registered with HA --

4 5

• - CoA and HA Discovery --
• - Registration Procedure --
• - CN starts communication with MN --
• 6. Data Packet
• 7. IP-in-IP Encapsulation
• 8. Tunneled Data
• - Signals 6-10 as above --

8 7

• 6a. Data Packet
• - MN starts communication with CN --
• 9. Binding Update

6a 6a

• - Discovery and Registration as above --

FA 6 10

• 10. Binding Ack

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MIPv4 MIPv6

Discovering the care-of address

 Discovery process built on top of an existing standard

protocol: router advertisements

 Router advertisements extended to carry available care-of

addresses called: agent advertisements

 Foreign agents (and home agents) send agent

advertisements periodically

 A mobile host can choose not to wait for an

advertisement, and issue a solicitation message

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Agent advertisements

 Foreign agents send advertisements to advertise available

care-of addresses

 Home agents send advertisements to make themselves

known

 Mobile hosts can issue agent solicitations to actively seek

information

 If mobile host has not heard from a foreign agent its

current care-of address belongs to, it seeks for another care-of address

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Agent advertisement

 MIP does not use a new packet type for agent

advertisement;

• it uses the router advertisement packet of ICMP, and
• appends an agent advertisement message.

Registering the Care-of Address

 Once mobile host receives care-of address, it registers it

with the home agent

 A registration request is first sent to the home agent

(through the foreign agent)

 Home agent then approves the request and sends a

registration reply back to the mobile host

 Security?

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Registration Illustration

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Home agent discovery

 If the mobile host is unable to communicate with

the home agent, a home agent discovery message is used

 The message is sent as a broadcast to the home

agents in the home network

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Tunneling to the Care-of address

 When home agent receives packets addressed to mobile

host, it forwards packets to the care-of address

 How does it forward it? - encapsulation  The default encapsulation mechanism that must be

supported by all mobility agents using mobile IP is IP- within-IP

 Using IP-within-IP, home agent inserts a new IP header in

front of the IP header of any datagram

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Tunneling (contd.)

 Destination address set to the care-of address  Source address set to the home agent’s address  After stripping out the first header, IP processes

the packet again

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Tunneling Illustration

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Encapsulation

• riginal IP header
• riginal data

new data new IP header

• uter header

inner header

• riginal data

Encapsulation I

 Encapsulation of one packet into another as payload

• e.g. IPv6 in IPv4 (6Bone), Multicast in Unicast (Mbone)
• here: e.g. IP-in-IP-encapsulation, minimal encapsulation or GRE (Generic Record

Encapsulation)

 IP-in-IP-encapsulation (mandatory, RFC 2003)

• tunnel between HA and COA

Care-of address COA IP address of HA TTL IP identification IP-in-IP IP checksum flags fragment offset length DS (TOS) ver. IHL IP address of MN IP address of CN TTL IP identification

• lay. 4 prot.

IP checksum flags fragment offset length DS (TOS) ver. IHL TCP/UDP/ ... payload

Encapsulation II

 Minimal encapsulation (optional)

• avoids repetition of identical fields
• e.g. TTL, IHL, version, DS (RFC 2474, old: TOS)
• only applicable for non fragmented packets, no space left for fragment identification

care-of address COA IP address of HA TTL IP identification

• min. encap.

IP checksum flags fragment offset length DS (TOS) ver. IHL IP address of MN

• riginal sender IP address (if S=1)

S

• lay. 4 protoc.

IP checksum TCP/UDP/ ... payload reserved

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Mobile IPv6 (MIPv6)

 MIPv6 = MIPv4 + IPv6  Major Differences from MIPv4

• FA in MN
• No FA for MIPv6
• CoA: IP address of MN
• By DHCPv6 or IPv6 Stateless Auto-Configuration
• Route Optimization
• To solve the “Triangular Routing” Problem
• Provided by default
• MN  CN

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MIP: Triangular Routing Problem

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MIPv6: Route Optimization

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MIPv6: Binding Update

 Binding Update to HA

• Using IPSEC: MN and HA have a security association
• AH (Authentication Header)
• ESP (Encapsulating Security Payload)

 Binding Update to CN

• Return Routability (RR) procedure
• For Security
• Binding Update (BU) procedure
• Route Optimization

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MIPv6: Binding Update

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MIPv6: RR (Return Routability)

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MIPv6: Changes to IPv6

 New IPv6 Protocol (Header)

• Mobility Header: a new IPv6 extension header
• To carry MIPv6 Binding Update messages
• How is in the MIPv4 ?
• New Option in Destination Option Header
• Home Address Option
• New Type in Routing Header
• Type 2 Routing Header

 New ICMP Messages

• ICMP HA Address Discovery Request/Reply
• ICMP Mobile Prefix Solicitation/ Advertisement

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MIPv6: IPv6 Header

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MIPv6: Mobility Header

 A New Extension Header of IPv6

• Messages for Return Routability
• Home Test Init Message
• Care-of Test Init Message
• Home Test Message
• Care-of Test Message
• Messages for Binding Update
• Binding Update Message
• Binding Acknowledgement Message
• Binding Error Message
• Binding Refresh Request Message

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MIP Extensions

 Mobile IPv4 (MIPv4)

• Low-Latency Handover for MIPv4 (FMIPv4)
• Regional Registration for MIPv4 (HMIPv4)

 Mobile IPv6 (MIPv6)

• Fast Handover for MIPv6 (FMIPv6)
• Hierarchical MIPv6 (HMIPv6)

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FMIPv6: Fast Handover for MIPv6

MN PAR NAR CN signaling signaling

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FMIPv6: Operations

 Handover Initiation

• L2 Triggers, RtSolPr, PrRtAdv
• Between MN and AR

 Tunnel Establishment

• HI (Handover Initiate) and HACK
• Between PAR and NAR

 Packet Forwarding

• PAR => NAR (data buffering at NAR)
• FBU, FBack
• NAR => MN:
• FNA (Fast NA)

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FMIPv6: Operational Flows

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HMIPv6: Overview

 Motivations

• Localized (Regional) Mobility Management
• Hierarchical
• MIP: MN  HA
• HMIP: MN  MAP  HA

– MAP: Mobility Anchor Point

 IP Address (CoA)

• RCoA (Regional CoA): in the MAP region
• LCoA (On-Link CoA): in the AR region

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HMIPv6: Architecture

HA CN MAP AR1 AR2 MN

RCoA Movement

LCoA_1 LCoA_2

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HMIPv6: Operations

 MN

• When entering an AR region in the MAP domain,
• it gets LCoA (AR region) and RCoA (MAP region)
• RCoA does not change in the MAP domain
• Local Binding Update (LBU) to MAP
• Bind LCoA & RCoA to MAP

 MAP (Acting as a local HA)

• Only the RCoA need to be registered with CN/HA
• Relay all packets between MN and HA/CN

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HMIPv6: MAP Tunnel (MAP  MN)

HA CN MAP AR1 AR2 MN

LCoA MAP RCoA CN Home Addr Outer header Inner header

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HMIPv6 HMIPv4

HA/CN

• 2. HA Discovery Request
• 3. HA Discovery Reply
• 4. MA Registration BU
• 5. MA Reg. BU Acknowledgement
• 1. CoA Discovery

MN MA 1 2 3

• - MN is Registered with MA --

4 5

• - CoA and HA Discovery --
• - Registration Procedure --
• 4. MA/HA Registration BU
• 5. HA Registration BU

5 4 7

• - Encapsulated Method --

6

• - Sequential Method --

6 7

• 6. HA Registration BU
• 7. HA Reg. BU Acknowledgement
• - MN is Registered with HA --
• 6. HA Reg. BU Acknowledgement
• 7. HA Reg. BU Acknowledgement
• - MN is Registered with HA and MA--
• - MN moves from FA1 to FA2 --

HA/CN

• 2. HA Discovery Request
• 3. HA Discovery Reply
• 4a. Registration Request
• 1. CoA Discovery

MN RFA1 1 2 3

• - MN is Registered with HA --

FA1 GFA

• - CoA and HA Discovery --
• - Registration Procedure --

4a 4b 4c 4d 5a 5b 5c 5d

• 4b. Registration Request w/extension
• 4c. Registration Request w/extension
• 4d. Registration Request
• 5a. Registration Reply
• 5b. Registration Reply w/extension
• 5c. Registration Reply w/extension
• 5d. Registration Reply

FA2 RFA2

• 7. Reg. Reg w/ Hierarchical FA ext.
• 8. Reg. Reg w/ Hierarchical FA ext.
• 6. Reg Reg w/ Previous FA Notification

6 7 8 9 10 11 10a 11a 12

• 10. BU to Crossover Router
• 10a. BU Ack
• 9. BU to previous FA
• 11a. BU ack
• 12. Reply
• 11. BU to Crossover Router

COS

Hierarchical MIP

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MIP in Real World: 3GPP2 (CDMA)

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MIP in 3GPP2

Proxy MIPv6 (PMIPv6)

“Network-based” Localized Mobility Management

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Why Network-based?

 Host-based MIPv4/v6 has not been yet deployed

that much.

• Why host-based MIP is not deployed yet?
• Too heavy specification for a small terminal

– RFC 3344 (MIPv4): 99 pages – RFC 3775 (MIPv6): 165 pages

• Battery problem
• Waste of air resource
• No Stable MIPv4/v6 stack executed in Microsoft

Windows OS

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PMIPv6

 IETF NETLMM WG  Internet Draft

• “Proxy Mobile IPv6,”
• draft-ietf-netlmm-proxymip6-00.txt (2007)

 GOAL

• This protocol is for providing mobility support to any

IPv6 host within a restricted and topologically localized portion of the network and without requiring the host to participate in any mobility related signaling.

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Technical Background



Host-based vs. Network-based Mobility

Host-based Mobility Network-based Mobility

AR HA Route Update

Movement Movement

HA Route Update AR

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Proxy MIPv6 Overview

LMM (Localized Mobility Management) Domain

MAG1

Host B Host A

LMA

Proxy Binding Update (PBU)

Control message sent out by MAG to LMA to register its correct location

Home Network

MN’s Home Network (Topological Anchor Point)

Proxy Care of Address (Proxy-CoA)

The address of MAG. That will be the tunnel end-point.

IP Tunnel

A IPinIP tunnel LMA and MAG.

MAG2

LMA: Localized Mobility Agent MAG: Mobile Access Gateway LMA Address (LMAA)

That will be the tunnel entry- point.

MN’s Home Network Prefix (MN-HNP) CAFE:2:/64 MN’s Home Network Prefix (MN-HNP) CAFE:1:/64

MN Home Address (MN-HoA)

MN continues to use it as long as it roams within a same domain

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Proxy MIPv6 Overview

 No host stack change for IP mobility  Avoiding tunneling overhead over the air  Re-use of Mobile IPv6

• PMIPv6 is based on Mobile IPv6 [RFC3775]

 Only supports Per-MN-Prefix model

• Unique home network prefix assigned for each MN.
• The prefix follows the MN.

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Proxy MIPv6 Overview



Overall Procedures

1. MN moves and attaches to an access router 2. After authentication, MAG (access router) identifies MN 3. MAG obtains MN’s profile containing the Home Address ..etc 4. MAG sends the Proxy Binding Update to LMA on behalf of MN 5. MAG receives the Proxy Binding Ack. from LMA 6. MAG sends Router Advertisements containing MN’s home network prefix

• Stateless Case: MN will still configure (or maintain) the

same as its home address.

• Stateful Case: the network will ensure that it always gets

its home address.

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Proxy MIPv6 Overview

MN MAG

MN-Identifier

AAA Server (Policy Store)

AAA Request AAA Reply + Policy Profile

DHCP Relay Agent DHCP Server

MN-Identifier Access to a new IP link

LMA

Router Advertisement Proxy Binding Update Proxy Binding Ack. (MN Home Prefix) DHCP Request DHCP Response DHCP Request DHCP Response

Tunnel Setup

This can be omitted when stateless configuration is used. MAG emulates the MN’s home link In case that profile store does not have MN Home Prefix

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Proxy MIPv6

 Proxy Registration

• LMA needs to understand the Proxy Registration.

Proxy Binding Update Proxy Binding Acknowledgement

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Proxy MIPv6

 Tunnel Management

• LMA-MAG tunnel is a shared tunnel among many MNs.
• 1:1 relation  m:1 relation
• One tunnel is associated to multiple MNs’ Binding

Caches.

• Life-time of a tunnel should not be dependent on the

life time of any single BCE.

 LMA’s Prefix-based Routing

• LMA will add prefix routes to MN’s home network

prefix over the tunnel.

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Proxy MIPv6

 MAG Operation

• It emulates the home link for each MN.
• After the access authentication, MAG will obtain MN’s

profile which contains:

• MN’s home address
• MN’s home network prefix
• LMA address ..etc.
• It establishes a IPv6/IPv6 tunnel with the LMA.
• All the packets from MN are reverse tunneled to its

LMA

• All the packets from the tunnel are routed to MN.

 Router Advertisement should be UNICASTed to

an MN

• It will contain MN’s Home Network Prefix (MN-HNP)

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Proxy MIPv6

 MN Operation

• Any MN is just a IPv6 host with its protocol operation

consistent with the base IPv6 specification.

• All aspects of Neighbor Discovery Protocol will not

change.

• When MN attaches to a new AR, it receives a Router

Advertisement message from the AR with its home prefix.

• Throughout the PMIP domain, MN using DHCP

procedure or in stateless address configuration mode, will obtain the same home address.

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Proxy MIPv6

 Data Transport

• LMA-MAG Tunneling/Reverse Tunneling

MN LMA MAG CN

MN sends a packet to CN MAG forwards to LMA LMA sends to CN CN sends packet to MN LMA forwards to MAG MAG sends to MN

IPv6 header (src=MAG_ADDR, dst=LMA_ADDR) IPv6 header (src=MN_ADDR, dst=CN_ADDR) Payload IPv6 header (src=LMA_ADDR, dst=MAG_ADDR) IPv6 header (src=CN_ADDR, dst=MN_ADDR) Paylaod

MIPV6 EXPERIMENTAL EVALUATION

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Protocol Handover Signaling

Binding update Binding Acknowledgement Home Test Init Home Test Care-of Test Init Care-of Test Binding update Binding Acknowledgement Mobile Node Foreign Agent Home Agent Corespondent Node L2 Latency Router Advertisement DAD Neighbor Solicitation L3 Movement Detection Registration Delay Router Solicitation Neighbor Advertisement

Handover Latency Analysis

Signaling

 Link Layer Establishment Delay (DL2): The time required by the

physical interface to establish a new association. This is the L2 handover between access routers.

 Movement Detection (DRD): The time required for the mobile node

to receive beacons from the new access router, after disconnecting from the old AR.

 Duplicate Address Detection (DDAD): The time required to

recognize the uniqueness of an IPv6 address.

 BU/Registration Delay (DREG): The time elapsed between the

sending of the BU from the MN to the HA and the arrival/transmission of the first packet through the new access router.

Handover Latency Analysis

• The handover delay for MIPv6 can analytically be

computed as: DMIPv6 =DL2 + DRD + DDAD + DREG

• The delays can be further broken down to:

DMIPv6 = (TPRB + TAUTH + TRASS) + (TRSOL + TRADV) + DDAD + (THBU + THBA + 2THOTI + 2THOT + TCBU + TCBA)

Techniques to reduce overall handoff latency

 L2 Trigger  Optimistic Duplicate Address Detection  Fast Beacons  Fast Solicited Router Advertisements

MIPv6 Testbed

IPv6 Network Home subnet Visited subnet

MN HA MN

Correspondent subnet

CN FA 2001:1a18:1:9:: 2001:1a18:1:10:: 2001:1a18:1:2::

• The

experimental testbed consists

• f three wireless

LANs connected through an IPv6 cloud.

• Twenty

experiments were run for each configuration and the average times are computed and analyzed.

List of Equipment and Software

Mobile Node Home Agent Foreign Agent Corresponded Node

IBM ThinkPad T42p Acer Veriton 9100 Dell Optiplex GX1 Dell Optiplex GX1 Intel Pentium M 1.86GHz Intel Pentium 4 1500MHZ Intel Pentium III 50OMHz Intel Pentium III 500MHz 2048 cache 256 cache 512 cache 512 cache Atheros AR5212 802.11abg NIC D-Link, PCI IEEE802.11b card, GWL-520, Atheros chipset Auto channel Channel 1 Channel 6 LINUX, Fedora Core 5, kernel 2.6.16 MIPL v2.02

MIPv6 Testbed Parameters

Parameter Value Parameter Value

mtu 1500 MinRouterAdv 0.03 - 1s (0.5) autoconf 1 MaxRouterAdv 0.07 - 1.5s (1.5) forwarding 1 (MN=0) DAD On / Off (On) Home / Co Test Init 1 Beacon Interval 50-100 ms (100)

• Rt. Solicitation

1 BU 1.5

Handoff Latency time

 We forced the MN to perform hard handoff with

the command iwconfig

 We measured the handoff time as follows:

• DL2+RD= TRECEPTIONOFRA- TIWCONFIG
• DDAD=TBUHA-TRECEPTIONOFRA
• DREG=DHAREG+DCNREG
• DHAREG=TBACKHA-TBUHA
• DCNREG=TBACKCN-TBUCN

Results

 With default values of RA=0.5-1.5, DAD on, Beacon

Interval 100 ms the Total Handoff Time is DMIPv6 = 3.68 sec.

 DL2+RD=0.612s, DDAD = 1.414s and DREG= 1.651s  The major share in the handover latency goes to DREG.

The BU and registration functions account for 45% of the total delay. The DAD function takes another 38% and the movement detection (including the L2 delay) accounts for the rest 17%.

Results

DAD component contribution to the MIPv6 Handover Latency

• When the DAD function is switched off the respective delay is

reduced by almost 1sec which is the default timer value for this

• peration.
• If we operate in a controlled environment where the probability of

duplicate addresses is negligible, then we can discard the DAD function and achieve a decrease in the total MIPv6 delay of at most

• ne second.

Handoff Latency RA=0.5-1.5 1=DAD on+Beacon Interval=100ms 2=DAD on+Beacon Interval=60ms 3=DAD off+Beacon Interval=100ms 4=DAD off+Beacon Interval=60ms

0.5 1 1.5 2 2.5 3 3.5 4

1 2 3 4

Total Handoff Latency(sec) REG-CN REG-HA DAD L2+RD

Results

Handoff Latency RA Interval 1=0.03-0.07, 2=0.04-0.08, 3=0.07=0.11, 4=0.1-0.5, 5=0.5-1.5

0.648477 0.30285 0.162878 0.16558 0.1512074 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8

1 2 3 4 5 Latency(sec)

REG-CN REG-HA DAD L2+RD

Router Advertisement Interval effect

• n handover component latencies
• The change in the RA interval only affects the combined

DL2 + DRD.

• We observe a 200-400% reduction in the corresponding

delay between the default and lower values.

Results

Router Advertisement Interval effect on overall handover latency.

• The effect on the overall handover delay is not as

dramatic since the contribution of the DRD delay to the total is only 17%.

Results

Router Advertisement and Beacon Interval

• Adjust the ranges using MinRouterAdvintervals between 0.1 and

0.5 sec.

• 300% reduction in an almost linear manner.
• The figure is appended with plots of different Beacon Intervals,

which do not provide any insight to their importance.

L2 and RD Delays 1=0.1-0.3RA, 2=0.2-0.6RA, 3=0.3-0.9RA, 4=0.4-1.2RA, 5=0.5-1.5RA 0,1 0,2 0,3 0,4 0,5 0,6 0,7 1 2 3 4 5 L2 and RD Delays Beacon Interval=100 Beacon Interval=80 Beacon Interval=60

Results

0.3 0.6 0.9 1.2 1.5 1.5 60 80 100 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 Max Router Advertisement L2 Handoff (Beacon Interval-Router Adv) Beacon Interval L2 Handoff 0.2 0.25 0.3 0.35 0.4 0.45 0.5 0.55 0.6

Handover delay vs Router Advertisement and Beacon interval Combined contribution of RA interval and Beacon interval on lower layer delays.