192620010 Mobile & Wireless Networking Lecture 9: Mobile IP - - PowerPoint PPT Presentation

Mobile and Wireless Networking 2013 / 2014

192620010 Mobile & Wireless Networking Lecture 9: Mobile IP [Schiller, Section 8.1]

Geert Heijenk

Mobile and Wireless Networking 2013 / 2014

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Outline of Lecture 11

q Mobile IP Basics q 3 parts of Mobile IP:

q Advertising Care-of Addresses q Registration q Tunneling

q Mobile IPv6 q Mobile IPv6 extensions

q Hierarchical Mobile IPv6 q Fast Handover for Mobile IPv6 q Proxy Mobile IPv6

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Motivation for Mobile IP RFC 5944

q Routing

q based on IP destination address, network prefix (e.g. 129.13.42)

determines physical subnet

q 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

q Specific routes to end-systems?

q change of all routing table entries to forward packets to the right

destination

q does not scale with the number of mobile hosts and frequent

changes in the location, security problems

q Changing the IP-address?

q adjust the host IP address depending on the current location q almost impossible to find a mobile system, DNS updates take too

long time

q TCP connections break, security problems

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Example network

Internet router router router

FA

(Foreign Agent)

HA

(Home Agent)

MN

(Mobile Node) home network foreign network (physical home network for the MN) (current physical network for the MN)

CN

(Correspondent Node)

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Data transfer to the mobile system

Internet sender

FA HA MN

home network foreign network receiver

1 2 3

• 1. Sender sends to the IP address of MN,

HA intercepts packet (proxy ARP)

• 2. HA tunnels packet to Care-of Address

(COA), here FA, by encapsulation

• 3. FA forwards the packet

to the MN

CN

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Data transfer from the mobile system

Internet receiver

FA HA MN

home network foreign network sender

1

• 1. Sender sends to the IP address
• f the receiver as usual,

FA works as default router

CN

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Types of Home Networks

Home agent as a separate system on the home network Home agent integrated with a router

• n the home network

A virtual home network

Internet Internet Internet

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Co-located Care-of Address

Internet sender

Standard Router HA MN

home network foreign network receiver

CN Tunneling

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Outline of Lecture 11

q Mobile IP Basics q 3 parts of Mobile IP:

q Advertising Care-of Addresses q Registration q Tunneling

q Mobile IPv6 q Mobile IPv6 extensions

q Hierarchical Mobile IPv6 q Fast Handover for Mobile IPv6 q Proxy Mobile IPv6

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type = 16 length = 6 + 4 * #COAs R: registration required B: busy, no more registrations H: home agent F: foreign agent M: minimal encapsulation G: GRE encapsulation r: =0, ignored T: FA supports reverse tunneling U: UDP tunneling (firewall traversal) X: support for registration revocation I: support for regional registration by foreign agent rsv: =0, ignored

Agent advertisement

preference level 1 router address 1 #addresses type

• addr. size

lifetime checksum COA 1 COA 2 type = 16 sequence number length 7 8 15 16 31 24 23 code preference level 2 router address 2 . . . registration lifetime . . .

R B H F M G r

rsv

T U X I

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Home Network & Move Detection

q Home Network is detected if:

q Network Prefix IP Source Address advertisement = Network Prefix

Home Address

q Move is detected if:

q No advertisement has been received within Lifetime q Network Prefixes have changed q no advertisements --> use promiscuous mode q assistance from higher / lower layers

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Mobile Node Foreign Agent Home Agent Registration Request Registration Reply Mobile Node Home Agent Registration Request Registration Reply Mobile Node Home Agent Registration Request Registration Reply

Registration

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Mobile IP registration request

home agent home address type = 1 lifetime 7 8 15 16 31 24 23 T x identification COA extensions . . .

S B D M G r

S: simultaneous bindings B: broadcast datagrams D: decapsulation by MN M mininal encapsulation G: GRE encapsulation r: =0, ignored T: reverse tunneling requested x: =0, ignored

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Mobile IP registration reply

home agent home address type = 3 lifetime 7 8 15 16 31 code identification extensions . . . Example codes: registration successful 0 registration accepted 1 registration accepted, but simultaneous mobility bindings unsupported registration denied by FA 65 administratively prohibited 66 insufficient resources 67 mobile node failed authentication 68 home agent failed authentication 69 requested Lifetime too long registration denied by HA 129 administratively prohibited 131 mobile node failed authentication 133 registration Identification mismatch 135 too many simultaneous mobility bindings

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Simultaneous Bindings

q A Mobile Node may register multiple bindings simultaneously q The Home Agent makes multiple copies of packets destined for

the mobile node, and tunnels a copy to each care-of address

q Simultaneous bindings may be used to

q facilitate seamless hand-off q avoid too frequent registrations

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Tunneling

q Packet destined to the mobile node are routed to the home

network (normal IP operation)

q Home Agent intercepts packets on the home network q Home Agent encapsulates packets, and tunnels them to the

care-of address

q At the care-of address (either Foreign Agent or co-located), the

packet is decapsulated, and delivered to the mobile node

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Packet Interception by Home Agent

q Advertise reachability of Mobile Node Home Address q Proxy and Gratuitous ARP:

l Home Agent Replies to ARP requests for the Mobile Node (Proxy ARP) l The Home Agent (or Mobile node) broadcasts a not requested ARP after a

change has occurred (Mobile Node has roamed out (or in)) (Gratuitous ARP)

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Encapsulation

• riginal IP header
• riginal data

new data new IP header

• uter header

inner header

• riginal data

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Encapsulation I

Encapsulation of one packet into another as payload

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

Record Encapsulation)

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

q 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

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Encapsulation II

Minimal encapsulation (optional) (RFC 2004)

q avoids repetition of identical fields q e.g. TTL, IHL, version, DS (RFC 2474, old: TOS) q only applicable for unfragmented 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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Generic Routing Encapsulation

• riginal

header

• riginal data

new data new header

• uter header

GRE header

• riginal data
• riginal

header Care-of address COA IP address of HA TTL IP identification GRE 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 sequence number (optional) key (optional) reserved1 (optional) checksum (optional) protocol reserved0 ver. C K S

RFC 2890

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Mobile IP with reverse tunneling

q Router accept often only “topological correct“ addresses

(firewall!)

q a packet from the MN encapsulated by the FA is now topological

correct

q furthermore multicast and TTL problems solved (TTL in the home

network correct, but MN is too far away from the receiver)

q Reverse tunneling does not solve

q problems with firewalls, the reverse tunnel can be abused to

circumvent security mechanisms (tunnel hijacking)

q optimization of data paths, i.e. packets will be forwarded through

the tunnel via the HA to a sender (double triangular routing)

q The standard is backwards compatible

q the extensions can be implemented easily and cooperate with

current implementations without these extensions

q Agent Advertisements can carry requests for reverse tunneling

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Reverse tunneling (RFC 3024)

Internet receiver

FA HA MN

home network foreign network sender

3 2 1

• 1. MN sends to FA
• 2. FA tunnels packets to HA

by encapsulation

• 3. HA forwards the packet to the

receiver (standard case)

CN

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Outline of Lecture 11

q Mobile IP Basics q 3 parts of Mobile IP:

q Advertising Care-of Addresses q Registration q Tunneling

q Mobile IPv6 q Mobile IPv6 extensions

q Hierarchical Mobile IPv6 q Fast Handover for Mobile IPv6 q Proxy Mobile IPv6

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Mobile IPv6 (RFC 6275)

Mobile IP was developed for IPv4, but IPv6 simplifies the protocols

q security is integrated and not an add-on, authentication of

registration is included

q COA can be assigned via auto-configuration (DHCPv6 is one

candidate), every node has address autoconfiguration

q no need for a separate FA, all routers perform router advertisement

which can be used instead of the special agent advertisement; addresses are always co-located

q MN can signal a sender directly the COA, sending via HA not

needed in this case (automatic route optimization)

q „soft“ hand-over, i.e. without packet loss, between two subnets is

supported

l MN sends the new COA to its old router l the old router encapsulates all incoming packets for the MN and

forwards them to the new COA

l authentication is always granted

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Outline of Lecture 11

q Mobile IP Basics q 3 parts of Mobile IP:

q Advertising Care-of Addresses q Registration q Tunneling

q Mobile IPv6 q Mobile IPv6 extensions

q Hierarchical Mobile IPv6 q Fast Handover for Mobile IPv6 q Proxy Mobile IPv6

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IP Micro-mobility support

q Micro-mobility support:

q Efficient local handover inside a foreign domain

without involving a home agent

q Reduces control traffic on backbone q Especially needed in case of route optimization

q Hierarchical Mobile IPv6 (HMIPv6) q Important criteria:

Security Efficiency, Scalability, Transparency, Manageability

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Hierarchical Mobile IPv6 (HMIPv6) (RFC 5380)

Operation:

q Network contains mobility anchor point

(MAP)

l mapping of regional COA (RCOA) to link

COA (LCOA)

q Upon handover, MN informs

MAP only

l gets new LCOA, keeps RCOA

q HA is only contacted if MAP

changes MAP Internet AR MN AR MN HA binding update RCOA LCOAold LCOAnew

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Hierarchical Mobile IPv6 (2)

Advantages:

q Handover requires minimum number

• f overall changes to routing tables

q Integration with firewalls / private address support possible

Potential problems:

q Not transparent to MNs q Handover efficiency in wireless mobile scenarios:

l Complex MN operations l All routing reconfiguration messages

sent over wireless link

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Mobile IPv6 Fast Handovers (1)

Sources of delay in Mobile IPv6 handover:

• 1. Change of link
• 2. Movement detection
• 3. Address acquisition
• 4. Home agent update
• 5. Return routability procedure
• 6. Binding updates

q 4, 5, and 6 can be reduced/eliminated using

Hierarchical Mobile IPv6 (RFC 5380)

q For 2 and 3, a new mechanism is proposed:

Mobile IPv6 Fast Handovers (RFC 5568)

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Mobile IPv6 Fast Handovers (2)

q Mobile Node gets address for

(possible) new network from its current (previous) access router.

q Handover is initiated on the

previous network

q Previous and New Access

Routers tunnel and buffer packets

q Handover is completed on new

network. Note: This is still a hard handover, i.e., mobile node has a link to

• nly one access router at a

time.

Internet

Previous Access Router

MN

New Access Router

MN

tunnel

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Mobile IPv6 Fast Handovers: predictive handover

MN PAR NAR | | | |------RtSolPr------->| | |<-----PrRtAdv--------| | | | | |------FBU----------->|--------HI--------->| | |<------HAck---------| | <--FBack---|--FBack---> | | | | disconnect forward | | packets===============>| | | | | | | connect | | | | | |--------- UNA --------------------------->| |<=================================== deliver packets | | RtSolPr - Router Solicitation for Proxy Advertisement PrRtAdv - Proxy Router Advertisement FBU – Fast Binding Update HI - Handover Initiate HAck - Handover Acknowledge FBack - Fast Binding Acknowledgment UNA – Unsollicited Neighbor Advertisement

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Mobile IPv6 Fast Handovers: reactive handover

MN PAR NAR | | | |------RtSolPr------->| | |<-----PrRtAdv--------| | | | | disconnect | | | | | | | | connect | | |-------UNA-----------|--------------------->| |-------FBU-----------|---------------------)| | |<-------FBU----------)| | |----------HI--------->| | |<-------HAck----------| | |(HI/HAck if necessary)| | forward | | packets(including FBAck)=====>| | | | |<=================================== deliver packets | |

RtSolPr - Router Solicitation for Proxy Advertisement PrRtAdv - Proxy Router Advertisement UNA – Unsollicited Neighbor Advertisement FBU – Fast Binding Update HI - Handover Initiate HAck - Handover Acknowledge FBack - Fast Binding Acknowledgment

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Proxy Mobile IP (PMIPv6)

• IETF Network-based Mobility Management protocol

(RFC 5213 / RFC 6543)

• Hides IP-layer mobility from Mobile Node (MN)
• Mobile access gateway (MAG) emulates MN’s home link on

access link

• Packet are tunneled between MAG and Local Mobility Anchor

(LMA) using proxy Care-of Address

• Handover: New MAG sends Proxy Binding Update (PBU) to

LMA on behalf of MN

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PMIPv6 domain

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PMIPv6 message exchange

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MN MAGold MAGnew LMA Disconnect Connect Connect Disconnect PBU PBAck Rtr Adv Rtr Sol