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MOBILE IP
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
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)
Mobile networking
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
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
 DHCP
 This

keeps host specific information out of routers
is used to get packets to end hosts in networks
still assumes a fixed end host
What happens if we move a host between
networks?
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IP address A
Internet
IP address B


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
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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
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
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)
IETF RFCs
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
MIP



MIPv4: RFC 3344 (2002)
MIPv6: RFC 3775 (2004)
FMIP (Fast Handover for MIP

FMIPv6: RFC 4068 (2005)


FMIPv4: RFC 4881 (2007)


Fast Handovers for Mobile IPv6
Low-Latency Handoffs in Mobile IPv4
HMIP (Hierarchical MIP)

HMIPv6: RFC 4140 (2005)


Hierarchical Mobile IPv6
HMIPv4: RFC 4857 (2007)

Mobile IPv4 Regional Registration
MIPv4: Overview
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
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
Home Address (HoA) and Care-of Address (CoA)
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14.13.16.9 Care-of address
131.5.24.8 Home address
• The home address is permanent
• The care-of address changes as the mobile host moves from one
network to another.
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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
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
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, ..
MIPv4: Control & Data Flows
(Maintain “Visitor list”)
(Maintain Mobility Binding Table)
Mobile IP does not use a new packet type for agent solicitation;
it uses the router solicitation packet of ICMP.
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Tables maintained on routers
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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
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
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.
Registration request and reply
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Registration request format
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Registration reply format
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The Tunneling
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
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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Mobile IP in Action
CN
is successfully
communicating
with MN via HA
Mobility
Binding
table
Home Address
A
Mobile node (MN)
Correspondent node (CN)
Care-of-Address
B
HA Looks binding table
Home Address = A
Home Agent (HA)
1. MN sends Registration request with its new CoA
2. Mobile binding created for MN with new CoA
3. MN sends Registration response, after validating request and
updating binding table
Remote Agent (RA)
4. Packets sent to MN from CN are tunneled to RA using binding table
CoA = B
Mobile Node moves to remote network
Key Objective of MIP
The movement of the mobile host
is transparent to
the rest of the Internet.
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Mobile IPv6 (MIPv6)
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

MIPv6 = MIPv4 + IPv6
Major Differences from MIPv4
 FA
in MN
 No
FA for MIPv6
 CoA:
 By
IP address of MN
DHCPv6 or IPv6 Stateless Auto-Configuration
 Route
 To
Optimization
solve the “Triangular Routing” Problem
 Provided by default
 MN  CN
MIP: Triangular Routing Problem
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MIPv6: Route Optimization
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MIPv6: Binding Update
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
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
 For
Routability (RR) procedure
Security
 Binding
 Route
Update (BU) procedure
Optimization
MIPv6: Binding Update
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MIPv6: RR (Return Routability)
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MIPv6: Changes to IPv6
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
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


New Type in Routing Header


Home Address Option
Type 2 Routing Header
New ICMP Messages
ICMP HA Address Discovery Request/Reply
 ICMP Mobile Prefix Solicitation/ Advertisement

MIPv6: IPv6 Header
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MIPv6: Mobility Header
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
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

MIP Extensions
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
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)
FMIPv6: Fast Handover for MIPv6
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CN
PAR
NAR
signaling
signaling
MN
FMIPv6: Operations
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
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)
FMIPv6: Operational Flows
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HMIPv6: Overview
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
Motivations
 Localized
(Regional) Mobility Management
 Hierarchical
MN  HA
 HMIP: MN  MAP  HA
 MIP:


MAP: Mobility Anchor Point
IP Address (CoA)
 RCoA
(Regional CoA): in the MAP region
 LCoA (On-Link CoA): in the AR region
HMIPv6: Architecture
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HA
CN
MAP
AR2
AR1
LCoA_1
MN
RCoA
LCoA_2
Movement
HMIPv6: Operations
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
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
HMIPv6: MAP Tunnel (MAP  MN)
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HA
CN
MAP
AR2
AR1
MN
Outer header
LCoA
MAP
Inner header
RCoA
CN
Home Addr
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?
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
Host-based MIPv4/v6 has not been yet deployed
that much.
 Why
 Too


host-based MIP is not deployed yet?
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
PMIPv6
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

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.
Technical Background

Host-based vs. Network-based Mobility
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HA
HA
Route Update
Route Update
AR
AR
Movement
Host-based Mobility
Movement
Network-based Mobility
Proxy MIPv6 Overview
LMA: Localized Mobility Agent
MAG: Mobile Access Gateway
IP Tunnel
A IPinIP tunnel LMA and MAG.
Home Network
LMA
MN’s Home Network Prefix (MN-HNP)
CAFE:1:/64
MN’s Home Network (Topological
Anchor Point)
MAG1
Host A
LMA Address (LMAA)
MAG2
LMM
(Localized Mobility
Management)
Domain
That will be the tunnel entrypoint.
MN’s Home Network Prefix (MN-HNP)
CAFE:2:/64
Proxy Binding Update (PBU)
Host B
MN Home Address (MN-HoA)
MN continues to use it as long as it
roams within a same domain
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Control message sent out by MAG to LMA to
register its correct location
Proxy Care of Address (Proxy-CoA)
The address of MAG.
That will be the tunnel end-point.
Proxy MIPv6 Overview
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


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.
Proxy MIPv6 Overview
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
Overall Procedures
1.
2.
3.
4.
5.
6.
MN moves and attaches to an access router
After authentication, MAG (access router) identifies MN
MAG obtains MN’s profile containing the Home Address ..etc
MAG sends the Proxy Binding Update to LMA on behalf of MN
MAG receives the Proxy Binding Ack. from LMA
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.
Proxy MIPv6 Overview
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DHCP
Relay
Agent
MN
MAG
Access to a new IP link
MN-Identifier
In case that profile
store does not have
MN Home Prefix
AAA Server
(Policy Store)
MN-Identifier
AAA Request
AAA Reply + Policy Profile
Proxy Binding Update
MAG emulates the
MN’s home link
Router Advertisement
Proxy Binding Ack. (MN Home Prefix)
Tunnel Setup
DHCP Request
DHCP Request
DHCP Response
DHCP Response
This can be omitted
when stateless
configuration is used.
DHCP
Server
LMA
Proxy MIPv6
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
Proxy Registration
 LMA
needs to understand the Proxy Registration.
Proxy Binding Update
Proxy Binding Acknowledgement
Proxy MIPv6
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
Tunnel Management
 LMA-MAG
tunnel is a shared tunnel among many MNs.
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.
 1:1

LMA’s Prefix-based Routing
 LMA
will add prefix routes to MN’s home network
prefix over the tunnel.
Proxy MIPv6
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
MAG Operation


It emulates the home link for each MN.
After the access authentication, MAG will obtain MN’s profile
which contains:




It establishes a IPv6/IPv6 tunnel with the LMA.



MN’s home address
MN’s home network prefix
LMA address ..etc.
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)
Proxy MIPv6
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
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.
Proxy MIPv6
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
Data Transport
 LMA-MAG
Tunneling/Reverse Tunneling
MAG
MN
MN sends a packet to CN
MAG sends to MN
CN
LMA
MAG forwards to LMA
LMA forwards to MAG
LMA sends to CN
CN sends packet to MN
IPv6 header (src=MAG_ADDR, dst=LMA_ADDR)
IPv6 header (src=LMA_ADDR, dst=MAG_ADDR)
IPv6 header (src=MN_ADDR, dst=CN_ADDR)
IPv6 header (src=CN_ADDR, dst=MN_ADDR)
Payload
Paylaod

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