1. Mobile IP

2. IP
Internet
IP address is used by router to direct data packet to it’s destination. IP address works well if user is static.
If User is moving while active session, How to handle it?
Cellular Network

3. Addressing
The IP addresses are designed to work with stationary hosts because part of the address defines the network to which the host is attached.
Mobile IP

4. Addressing Keep Up – address and update routing tables. Get a New IP
Possible Solution
Keep Up – address and update routing tables.
Not feasible to update all routers every time whenever host moves to a new network
Get a New IP
This requires that configuration files are changed. Ongoing transmission will be interrupted.
Two addresses
- Home address
- Care 0f address
Mobile IP

5. Mobile IP Home Address: Mobile host original home address.
/16
/24
Internet
/16
/24
Care of address: Mobile host original home address.
Mobile IP

6. Mobile IP
Mobile IP adds mobility support to the Internet network layer protocol IP.
The Internet started at a time when no-one had a concept of mobile computers.
The Internet of today lacks mechanisms for the support of users traveling through the world.
IP is the common base for thousands of applications and runs over dozens of different networks; this is the reason for supporting mobility at the IP layer.

7. Addressing Mobile IP has two addressing The home address is permanent;
The care-of address changes as the mobile host moves from one network to another.
Mobile IP

8. Terminology Mobile Node (MN) Home Agent (HA) Foreign Agent (FA)
system (node) that can change the point of connection to the network without changing its IP address
Home Agent (HA)
system in the home network of the MN, typically a router registers the location of the MN, tunnels IP datagrams to the COA
Foreign Agent (FA)
system in the current foreign network of the MN, typically a router forwards the tunneled datagrams to the MN, typically also the default router of the MN
Care-of Address (COA)
address of the current tunnel end-point for the MN (at FA or MN)
actual location of the MN from an IP point of view
Correspondent Node (CN)
communication partner

9. Addressing How these addresses are converted into each other?
Who will handle these addressing to provide communication services without interruption?
Mobile IP

10. Agent Agent provide transparent change in address. Home Agent.
Foreign Agent.
Mobile IP

11. Home Agent & Foreign Agent
Mobile IP

12. Communication Example network HA MN FA CN home network
(physical home network
for the MN)
router HA
router FA
foreign network MN
Internet
router
end-system CN
(current physical network for the MN)

13. Data transfer to the mobile system
Communication
Data transfer to the mobile system
home network
foreign
network HA 2 FA MN
receiver 3 1
Internet
sender CN
1. Sender sends to the IP address of MN,
HA intercepts packet
2. HA tunnels packet to COA, here FA,
by encapsulation
3. FA forwards the packet to the MN

14. Data transfer from the mobile system
Communication
Data transfer from the mobile system
home network
foreign network HA FA 1 MN
sender
Internet
receiver CN
1. Sender sends to the IP address of the receiver as usual, FA works as default router

15. Mobile host to Remote host communication
To communicate with remote host, mobile host requires three phases.
1. Agent Solicitation
2. Registration
3. Data Transfer
Mobile IP

16. Mobile host to Remote host communication
Mobile IP

17. Mobile host to Remote host communication
Agent Advertisement
HA and FA periodically send advertisement messages into their physical subnets
MN listens to these messages and detects, if it is in the home or a foreign network (standard case for home network)
MN reads a COA from the FA advertisement messages
Registration (always limited lifetime!)
MN signals COA to the HA via the FA, HA acknowledges via FA to MN these actions have to be secured by authentication
Advertisement
HA advertises the IP address of the MN (as for fixed systems), i.e. standard routing information
Routers adjust their entries, these are stable for a longer time (HA responsible for a MN over a longer period of time)
Packets to the MN are sent to the HA, independent of changes in COA/FA

18. Remote host to mobile host communication
Mobile IP

19. Inefficiency in Mobile IP-Double Crossing
Communication involving mobile IP can be inefficient. The inefficiency can be severe or moderate. The severe case is called double crossing or 2X . The moderate case is called triangle routing or dog-leg routing.
Mobile IP

20. Inefficiency in Mobile IP-Triangle routing
Sender sends all packets via HA to MN higher latency and network load
Solutions – optimization HA informs a sender about the location of MN . Sender learns the current location of MN
direct tunneling to this location
big security problems!
Mobile IP

21. Questions Q. Explain when mobile IP is needed
Q. Why and where is encapsulation needed for mobile IP?
Q. Explain packet flow if two mobile nodes communicate and both are in foreign networks. What additional routes do packets take if reverse tunnelling is required?
Q. What is meant by tunnelling? Explain how tunnelling works for mobile IP using IP-in-IP.
Discuss the advantages and disadvantages of this method.
Q. Name the inefficiencies of mobile IP regarding data forwarding from a correspondent node to a mobile node. What are optimizations and what additional problems do they cause?
 Q. What are general problems of mobile IP regarding security?
 Q. What is the basic purpose of DHCP? Name the entities of DHCP.
 Q. How can DHCP be used for mobility and support of mobile IP?