MOBILE IP

Mobile networking should not be confused with portable networking Portable networking requires connection to same

ISP Portable Networking Technology

Cellular systems Cellular Digital Packet Data (CDPD) 3G

Bluetooth Low cost, short range radio links between mobile

devices Wireless Ethernet (802.11)

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Mobile networking3/50

IP assumes end hosts are in fixed physical locations IP addresses enable IP routing algorithms to get

packets to the correct network Each IP address has network part and host part

This keeps host specific information out of routers DHCP is used to get packets to end hosts in

networks This still assumes a fixed end host

What happens if we move a host between networks?

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Without Mobile IP, devices must tear down and set up connections as they move from location (network) to location (network) They change network so they must change IP

address Mobile users don’t want to know that they are

moving between networks

Internet

IP address A

IP address B

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Mobile IP was developed as a means for transparently dealing with problems of mobile users Enables hosts to stay connected to the Internet regardless of

their location Enables hosts to be tracked without needing to change their IP

address Requires no changes to software of non-mobile hosts/routers Requires addition of some infrastructure Has no geographical limitations Requires no modifications to IP addresses or IP address format Supports security Could be even more important than physically connected

routing

Mobile IP and its Variants Mobile IPv4 (MIPv4)

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

Mobile IPv6 (MIPv6) MIPv6 Fast Handover for MIPv6 (FMIPv6) Hierarchical MIPv6 (HMIPv6)

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IETF RFCs MIP

MIPv4: RFC 3344 (2002) MIPv6: RFC 3775 (2004)

FMIP (Fast Handover for MIP FMIPv6: RFC 4068 (2005)

Fast Handovers for Mobile IPv6 FMIPv4: RFC 4881 (2007)

Low-Latency Handoffs in Mobile IPv4 HMIP (Hierarchical MIP)

HMIPv6: RFC 4140 (2005) Hierarchical Mobile IPv6

HMIPv4: RFC 4857 (2007) Mobile IPv4 Regional Registration

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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

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

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• The home address is permanent• The care-of address changes as the mobile host

moves from one network to another.

14.13.16.9 Care-of ad-dress131.5.24.8 Home ad-dress

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Home Agent (HA) A router with additional functionality Located on home network of MN Does mobility binding of MN’s IP with

its CoA Forwards packets to appropriate

network when MN is away Does this through encapsulation

Foreign Agent (FA) Another router with enhanced

functionality If MN is away from HA the it uses an FA to

send/receive data to/from HA Advertises itself periodically Forward’s MN’s registration request Decapsulates messages for delivery to MN

Protocols Operation Agent Discovery (MN FA (CoA))

HA’s and FA’s broadcast their presence on each network to which they are attached It is possible for a mobile node to solicit agent advertisement to avoid waiting

for an agent to advertise. Beacon messages via ICMP Router Discovery Protocol (IRDP) MN’s listen for advertisement and then initiate registration

Registration to HA (via FA) (MN FA HA) When MN is away, it registers its CoA with its HA Typically through the FA with strongest signal Registration control messages are sent via UDP to destination port 434

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

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MIPv4: Control & Data Flows

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Mobile IP does not use a new packet type for agent solicitation; it uses the router solicitation packet of ICMP.

(Maintain “Visitor list”)

(Maintain Mobility Binding Table)

Tables maintained on routers13/

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Mobility Binding Table Maintained on HA of MN Maps MN’s home address

with its current CoA Visitor List

Maintained on FA serving an MN

Maps MN’s home address to its MAC address and HA address

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.

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Registration request and reply

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Registration request format

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Registration reply format

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The Tunneling18/50

HA encapsulates all packets addressed to MN and forwards them to FA IP tunneling

FA decapsulates all packets addressed to MN and forwards them via hardware address (learned as part of registration process)

NOTE that the MN can perform FA functions if it acquires an IP address eg. via DHCP

Bidirectional communications require tunneling in each direction

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The Mobile Node sends packets using its home IP address effectively maintaining the appearance that it is always on its home network.

Data packets addressed to the Mobile Node are routed to its home network, where the Home Agent now intercepts and tunnels them to the care-of address toward the Mobile Node.

Tunneling has two primary functions: encapsulation of the data packet to reach the tunnel endpoint, and decapsulation when the packet is delivered at that endpoint.

The default tunnel mode is IP Encapsulation within IP Encapsulation Typically, the Mobile Node sends packets to the Foreign Agent, which routes them to their final

destination, the Correspondent Node The above data path is topologically incorrect because it does not reflect the true IP network

source for the data—rather, it reflects the home network of the Mobile Node. Because the packets show the home network as their source inside a foreign network, an

access control list on routers in the network called ingress filtering drops the packets instead of forwarding them.

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A feature called reverse tunneling solves the problem by having the Foreign Agent tunnel packets back to the Home Agent when it receives them from the Mobile Node

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Home Agent (HA)

Remote Agent (RA)

Correspondent node (CN)

Mobile node (MN)

Mobile IP in Ac-tion

Mobile Node moves to remote network

1. MN sends Registration request with its new CoA

3. MN sends Registration response, after validating request and updating binding table4. Packets sent to MN from CN are tunneled to RA using binding table

Home Address Care-of-AddressA B

Mobility Binding table

2. Mobile binding created for MN with new CoA

CN is successfully communicating with MN via HA

HA Looks binding table

Home Address = A

CoA = B

The movement of the mobile host

is transparent to

the rest of the Internet.

Key Objective of MIP

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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 Flows36/50

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

MovementLCoA_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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MIP in Real World: 3GPP2 (CDMA)

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MIP in 3GPP2

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PROXY MIPV6 (PMIPV6)“Network-based” Localized Mobility Management

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 NetworkMN’s Home Network (Topological Anchor Point)

Proxy Care of Address (Proxy-CoA)The address of MAG. That will be the tunnel end-point.

IP TunnelA IPinIP tunnel LMA and MAG.

MAG2

LMA: Localized Mobility AgentMAG: 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 ..etc4. MAG sends the Proxy Binding Update to LMA on behalf of

MN5. MAG receives the Proxy Binding Ack. from LMA6. 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

DHCPRelayAgent

DHCP Server

MN-IdentifierAccess 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 TunnelingMN LMAMAG CN

MN sends a packet to CNMAG forwards to LMA

LMA sends to CN

CN sends packet to MNLMA 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

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