1. Mobile Networking through Mobile IP
Presenter: Guimin Zhang

2. Truly Mobile Networking
Provide confident access to the Internet anytime, anywhere
Reconnection occurs automatically and noninteractively
Mobility transparent to applications and higher level protocols such as TCP

3. Today’s Internet Protocol
Packets are routed to destinations based on IP address

4. Apply to Mobile Networking

5. Apply to Mobile NetworkingX

6. Mobile IP Approach Mobile IP uses two IP addresses:
Home address: The IP address assigned to the mobile node, making it logically appear attached to its home network.
Care-of address: An IP address at the mobile node's current point of attachment to the Internet, when the mobile node is not attached to the home network.

7. Mobile Network Terminology (1)
Home network: The network at which the mobile node seems reachable, to the rest of the Internet, by virtue of its assigned IP address.
Foreign network: The network to which the mobile node is attached when it is not attached to its home network, and on which the care-of address is reachable from the rest of the Internet.

8. Mobile Network Terminology (2)
Home agent: A router on the home network that effectively causes the mobile node to be reachable at its home address even when the mobile node is not attached to its home network.
Foreign agent: A router on the foreign network that can assist the mobile node in receiving datagrams delivered to the care-of address.

9. How Mobile IP Works HA

10. How Mobile IP Works Discovering the care-of address
Registering the care-of address
Tunneling to the care-of address
Register HA FA
Discovery

11. Agent Discovery Protocol
Extends ICMP Router Discovery protocol
ICMP Router Discovery Protocol enables hosts attached to multicast or broadcast networks to discover the IP addresses of their neighboring routers.
Agent advertisements: The mobile agent broadcast agent advertisements at regular intervals.
Agent solicitation: The mobile node broadcast or multicast a solicitation that will be answered by any foreign agent or home agent that receives it.

12. Advertisement Message Formats
ICMP Router Advertisement
Agent Advertisement extension
Type: 16
R: register required
B: busy
H: home agent
F: foreign agent
M: minimum encapsulation
G: GRE encapsulation
V: Van Jacobson header compression

13. Advertisement Message Formats
ICMP Router Advertisement
Prefix Length extension
Type: 19
Prefix Length:network number of the corresponding Router Address listed in the ICMP Router Advertisement portion of the message.

14. Mobile Node Move Detection
Lifetime based
The mobile node record the Lifetime of advertisement message. If it fails to receive another advertisement from the same agent until the the Lifetime expires, it considers to find a new agent.
Network prefixes based
The Prefix-length extension is used to determine if the newly received advertisement is in the same subnet as the mobile node’s current care-of-address.

15. Registration
Exchange of Registration Request and Registration Reply messages: UDP using well-known port 434
MH: mobile host; FA: Foreign Agent; HA: Home Address

16. Foreign Agent Consideration
Each foreign agent must be configured with a care of address
For each pending or current registration, the foreign agent maintains a visitor list entry containing:
Link-layer source address of the mobile node
The mobile node’s Home Address
The Home Agent address
The identification field
The requested registration Lifetime
The remaining Lifetime of the pending or current registration

17. Security Considerations in Registration
Danger: Registration Request works remotely to the home agent to affect the home agent's routing table
Security:
Authentication: Home agents and mobile nodes perform authentication using MD5 algorithm and key size of 128 bits.
Replay Protection: The Identification field is used to verify that a registration message has been freshly generated.
timestamp , random number

18. Tunneling to the Care of Address

19. Changes with IP Version 6
Route Optimization
When it knows the mobile node's current care-of address, a correspondent node can deliver packets directly to the mobile node's home address without any assistance from the home agent
Security
Strong authentication and encryption features are included in IP V6

20. Problems Facing Mobile IP
Security issues
Routing inefficiency
Triangle routing
Ingress filtering
User perceptions of reliability
Competition from other protocols

21. Mobile IP Related Projects
The CMU Monarch Project: Protocols for Adaptive Mobile and Wireless Networking
Portland State Secure Mobile Networking Project
State University of New York, Binghamton's Linux-Mobile IP
Stanford's Operating Systems and Networking Group's MosquitoNet
BBN Technologies' Mobile IP Security page

22. Reference
"Mobile Networking through Mobile IP," C. Perkins, IEEE Internet Computing, Vol. 2, No. 1, 1998.
"Mobile IP ,"  C. Perkins, IEEE Communications Magazine, Vol. 35, No. 5, 1997.