1. RFC 3775 IPv6 Mobility Support
Geller Bedoya
Joe Contreras
Stephen Ward
Michael Yue

2. Why is Mobile IPv6 Needed?
Mobile devices with Internet connectivity increasingly common
Mobile phones are becoming Internet capable
Global Internet Mobility
All in

3. Mobile IPv6 IPv6 Mobility is based on core features of IPv6
The base IPv6 was designed to support Mobility
Minimal changes from IPv6 to Mobile IPv6:
A new Type 2 Routing header
A set of mobility options to include in mobility messages
New Internet Control Message Protocol for IPv6 (ICMPv6) messages
Changes to router discovery messages and options and additional Neighbor Discovery options
A new Home Address option for the Destination Options header
Main bullets

4. Terminology
Mobile node (MN) is a mobile device with an IPv6 home address
Correspondent node (CN) is a computer with which mobile node communicates using its home address
Home Agent (HA) helps MN to manage its mobility
Mobile node can always be reached at its home address
Bullet by bullet

5. Correspondent and Mobile node Communications
There are two ways to handle packet forwarding between CNs and MNs:
Bidirectional mode (Triangular Routing)
Route optimization mode

6. Uses type 2 routing header
Requires MIPv6 functionality on the CN
Initial packets are routed from the CN to the MN via the HA
MN replies to CN directly, and CN does a binding cache update for MN's new CoA
Subsequent packets between CN and MN are routed directly with no interaction needed on the HA

7. Type-2 Routing Header
Allows for routing directly from Corresponding Node to Mobile Node Care-of Address
Home Address is kept in routing header until retrieval by Mobile Node
Different Header type from traditional IPv6 routing type allows for different firewall rules
The general idea is following: some mobile node having a permanent address (so called home address) is travelling at present. It is connected to some strange network and obtained a temporary (care-of) address. The goal is to deliver datagrams to the care-of address, but to hide its existence from the upper layers.
So when a datagram is sent to the mobile node, the care-of address is used as the destination in basic IPv6 header. However, a routing header Type 2 is attached containing the home (permanent) address of the mobile node. When the datagram arrives at the target, the addresses are swapped and the home address is presented as the destination to upper layers.

8. Mobility Header
Used for communications between the Corresponding Node, Home Agent, and Mobile Node
 Ensures all binding commands are taken care of
Attaches onto the IPv6 Option header

9. Mobility Options Option types 6-27 are defined in later RFCs
Option types that are not understood by the receiver are ignored, but the receiver must still process the mobility header.

10. Mobility Header Types Binding Refresh Request Binding Error Message
Binding Update/Binding Acknowledgement
Care-of Test initialization message/Care-of  Test Message
Home Test initialization message/Home test message
Triangular routing employs only BU/BA/BE messages

11. Dynamic Home Agent Address Discovery (DHAAD)
Router on a link acting as a Home Agent maintains a Home Agents List
Building a Home Agents List
DHAAD Exchange starts
Request  Reply
Mobile Prefix Solicitation  Mobile Prefix Advertisement
Process on page 100
Neighbor discovery, IPv6 equivalent of proxy ARP in IPv4

12. Dynamic Home Agent Address Discovery (DHAAD)
 Home Agents listen for DHAAD Request on a subnet anycast address with identifier 0x7E (decimal 126)
Mobile Nodes then listen for DHAAD Reply with a message containing a Home Agent Preference value(s)
Mobile node then sends Binding Update and Care-of-address to the Home Agent
Process on page 100
Anycast is one at a time
Neighbor discovery, IPv6 equivalent of proxy ARP in IPv4

13. Dynamic Home Agent Address Discovery (DHAAD)CN
Process on page 100
Anycast is one at a time
Neighbor discovery, IPv6 equivalent of proxy ARP in IPv4
DHAAD Request
DHAAD Reply

14. New ICMP Messages Home Agent Address Discovery Request
 Implementation of Dynamic Home Agent Address Discovery
Home Agent Address Discovery Request
Home Agent Address Discovery Reply
Mobile Prefix Solicitation
Mobile Prefix Advertisement

15. Home Agent Address Discovery Request
Source IP = MN's CoA Destination IP = anycast address
Type = 144         Code = 0        ICMPv6 Checksum
Identifier = aid in matching a future Reply to this Request
Reserved = 0 (unused)
Mobile node requests Home Agent addresses

16. Home Agent Address Discover Reply
Source IP = HA's IP        Destination IP = MN's CoA
Type = 145        Code = 0         ICMPv6 Checksum
Identifier = same one used in Request message
Reserved = 0 (unused)
List of Home Agent Addresses
The number of addresses presented in the list is indicated by the remaining length of the IPv6 packet carrying the Home Agent Address Discovery Reply message.

17. Mobile Prefix Solicitation
Source IP = MN's CoA Destination IP = HA's IP
Type = 146         Code = 0        ICMPv6 Checksum
Identifier = aid in matching a future Advertisement to this  solicitation
Reserved = 0 (unused)
Mobile node solicits Advertisement
Purpose: solicit advertisement.
HA should be on link to learn Prefix Info

18. Mobile Prefix Advertisement
Source IP = HA's IP        Destination IP = soliciting MN's CoA Type = 147         Code = 0       ICMPv6 Checksum
Identifier = same one used in Solicitation message
Reserved = 0 (unused)
M = 1 bit Managed Address Configuration flag
O = 1 bit Other Stateful Configuration flag
Prefix Information of Home Network
With Prefix Info, update and configure stored Home Network info : Home Addresses.
Unsolicited messages can only be sent to MN's registered on the network
M=1 then address autoconfiguration is done by host
O=1 then non-address autocnfiguration done by host

19. Binding Messages
Binding Update Message - used by a mobile node to notify other nodes of a new care-of address for itself
Binding Acknowledgement Message - used to acknowledge receipt of a Binding Update
Binding Error Message - used by the correspondent node to signal an error related to mobility, such as an inappropriate attempt to use the Home Address destination option without an existing binding

20. Mobile IPv6 Security Overview

21. Security with Mobile IPv6
Security Threats:
Route Optimization INCREASES the number of Binding Updates (BU)
Malicious or unauthenticated BUs can cause:
False Binding Update Attacks
Man-in-the-Middle Attacks
Denial of Service Attacks
Mitigation Techniques Mitigation Techniques:
RFC Using IPsec to Protect Mobile IPv6 Signaling between Mobile Nodes and Home Agents
The return routability procedure authorizes registrations by the
use of a cryptographic token exchange
Return Routability Protocol: The Return Routability pro-
tocol (RR protocol) presented in [2] enables a correspondent
node (CN) to obtain some reasonable assurance that a mobile
node (MN) is in fact addressable at its claimed care-of address
(CoA) as well as at its home address (HA). Only with this
assurance is the correspondent node able to accept Binding
Updates from the mobile node which would then instruct the
correspondent node to direct that mobile node’s data traffic
to its claimed care-of address. In the RR protocol, the two
cookies are exchanged to verify that a valid mobile node is
alive at its home address HoA and care-of address CoA.The
eventual binding update messages are protected using a keyed
hash function with the session key kBU obtained by hashing
the concatenation of the two cookies CH and CC.

22. IPsec Primer

23. Binding Updates Protection
BU/BA to Home Agents MUST be secured through IPsec
ESP encapsulation of Binding Updates and Acknowledgements between the mobile node and home agent MUST be supported and MUST be used
ESP encapsulation of the Home Test Init and Home Test messages tunneled between the mobile node and home agent MUST be supported and SHOULD be used
ESP encapsulation of the ICMPv6 messages related to prefix discovery MUST be supported and SHOULD be used

24. Mobile Prefix Discovery
Mobile Node and the Home Agent SHOULD use an IPsec security association to protect the integrity and authenticity of the Mobile Prefix Solicitations and Advertisements

25. Payload Packets
Payload packets exchanged with NM can follow the same protection as other IPv6 hosts
For traffic tunneled via the HA, additional IPsec ESP encapsulation may be supported

26. Conclusion
IPv6 mobility support has been on the list of required features from the beginning 
The Mobile IPv6 specification is on its way to becoming a standard so it is expected that virtually all IPv6 deployments will include at least the minimal mobile IP
An efficient and deployable protocol for handling mobility with IPv6

27. Questions?