1. Networking Applications
Dr. Ayman A. Abdel-Hamid
College of Computing and Information Technology
Arab Academy for Science & Technology and Maritime Transport
Mobility
Mobility
© Dr. Ayman Abdel-Hamid, Networking Applications

2. © Dr. Ayman Abdel-Hamid, Networking Applications
Outline
Mobile Computing
Mobile IP
Mobility
© Dr. Ayman Abdel-Hamid, Networking Applications

3. © Dr. Ayman Abdel-Hamid, Networking Applications
Mobile Computing
Access to data anywhere, anytime, using any means of connectivity
Nomadic access
Cellular-like access
Mobile ad hoc networks
Mobility
© Dr. Ayman Abdel-Hamid, Networking Applications

4. Host Mobility Problem 1/2
An IP address reflects a host’s point of attachment to the network
Example: TCP connection identified by a 4-tuple
< source IP address, source TCP port,
destination IP address, destination TCP port >
if either host move, and acquire a new IP address, the TCP connection breaks
Fundamental Problem
an IP address serves dual purpose
Transport and application layer perspective: end-point identifier
Network Layer: routing directive
Mobility
© Dr. Ayman Abdel-Hamid, Networking Applications

5. Host Mobility Problem 2/2
Subnet R
Packets to Mobile Host routed to home network
Mobile Host
Stationary
Host
Subnet R
Internet
Mobile Host
Mobility
© Dr. Ayman Abdel-Hamid, Networking Applications

6. Host Mobility Problem Solutions
Network layer solutions
-IETF Mobile IP (MIPv4 and MIPv6)
uses “Mobility agents”
hides a change of IP address, when a mobile host is moving between IP networks.
Application layer solutions
-Mobility support using “Session Initiation Protocol”
used for real-time mobile communications
problem with TCP connections, suggests using mobile IP for TCP connections
End-to-End Host Mobility support
Relies on DNS secure dynamic updates
TCP option for connection migration (suspend TCP connection and reactivate it from another IP address)
Mobility
© Dr. Ayman Abdel-Hamid, Networking Applications

7. Network Layer Solutions Model
two-level addressing architecture
home address & care-of address
key mechanisms
address translation
map home address to care-of address
packet forwarding
tunnel packets to care-of address
location management
update mobile host’s location
Mobility
© Dr. Ayman Abdel-Hamid, Networking Applications

8. © Dr. Ayman Abdel-Hamid, Networking Applications
IETF Mobile IPv4 1/4
Assigned a unique IP address on home network
Foreign Network
Home Network MH
Obtains a co-located care of address in the foreign network MH
3. registration reply HA
Foreign Network
4. registration reply MH
2. registration
request FA
1. Registration request
HA:Home Agent
FA: Foreign Agent
MH: Mobile Host
Provides a care-of address to MH in the foreign network
Home Registration Process
Mobility
© Dr. Ayman Abdel-Hamid, Networking Applications

9. © Dr. Ayman Abdel-Hamid, Networking Applications
IETF Mobile IPv4 2/4
Home Network
Foreign Network
2. Datagram intercepted by HA (through ARP) and tunneled to care-of address (FA)
3. Datagram detunneled and delivered to MH
Triangular Routing
tunnel HA FA MH
1. Datagram to MH arrives on home network via standard IP routing
4. Datagrams sent by MH are delivered through standard IP routing. In this case FA is MH's default router CH
CH: Correspondent Host
Unicast datagram routing to the MH’s care-of address
Mobility
© Dr. Ayman Abdel-Hamid, Networking Applications

10. © Dr. Ayman Abdel-Hamid, Networking Applications
IETF Mobile IPv4 3/4
3. CH caches MH care-of address and uses it for any subsequent datagrams destined to MH
1. Datagram to MH arrives on home network via standard IP routing
Home Network
Old tunnel CH
2. Binding Update
HA informs CH about MH current care-of address
FA1
Foreign Network MH HA
Route optimization
FA2
new tunnel MH
Forwarding pointer
Previous FA notification
inform previous FA of the new care-of address for MH. Previous FA tunnels in-flight packets, and packets from CH with out-of-date location cache entries to new FA. (Handoff)
Cache
Mobility
© Dr. Ayman Abdel-Hamid, Networking Applications

11. © Dr. Ayman Abdel-Hamid, Networking Applications
IETF Mobile IPv4 4/4
Problems
triangular routing (sub-optimal routing)
tunneling overhead
use of route optimization solves the triangular routing problem, BUT requires change in the IP stack of CH
large signaling overhead (registration) , if movement within the same domain (local-area mobility). MH has to inform the HA whenever it changes its point of attachment.
Mobility
© Dr. Ayman Abdel-Hamid, Networking Applications

12. © Dr. Ayman Abdel-Hamid, Networking Applications
Outline
MIPv4 Micro-mobility solutions
Mobility
© Dr. Ayman Abdel-Hamid, Networking Applications

13. Local-area Mobility Solutions
Within the Mobile IP framework
Regional Registration Framework (MIP_RR)
Local and Indirect Registration
Host-based forwarding schemes
Cellular IP (Columbia University)
HAWAII (Bell Labs)
Multicast-based schemes
Assign MH a scoped multicast address within the foreign domain
Mobility
© Dr. Ayman Abdel-Hamid, Networking Applications

14. Regional Registration Framework (MIP_RR) 1/3
Home registration
Regional registration 10
GFA HA 4 3 9
FA2
FA3 2 8 6
FA4
FA5
FA6
FA7
Advertises {FA7, FA3, FA1} 7 5 1 MH MH MH
{1, 2, 3, and 4}: Home registration when the MH first enters the foreign domain.
{5, 6}: Regional registration with a local handoff from FA7 to FA6.
{7, 8, 9, and 10}: Home registration involving a local handoff from FA6 to FA5.
Mobility
© Dr. Ayman Abdel-Hamid, Networking Applications

15. Regional Registration Framework (MIP_RR) 2/3
The old FA relays the BU message, received from the new FA, upwards in the hierarchy (to its father FA) specifying itself as the care-of address of the MH.
The father FA performs the following steps
delete its MH’s visitor entry,
create a binding cache entry for the MH with care-of address the child FA that sent the BU message,
relay the BU message upwards in the hierarchy, and
send back a binding acknowledge message to its child FA
Mobility
© Dr. Ayman Abdel-Hamid, Networking Applications

16. Regional Registration Framework (MIP_RR) 3/3
Tunneling consistency mechanism to clear visitor entries in old path
Reg. Req. BU
Reg. Req. with PFANE
Crossover FA MH
FA2
FA4
FA5
FA3
FA7
Regional registration request
Binding update message
GFA
FA6
Mobility
© Dr. Ayman Abdel-Hamid, Networking Applications

17. Local and Indirect Registration
HA:Home Agent
FA: Foreign Agent
Home Network
Secure tunnel
Anchor FA
Foreign Network MH HA FA 1 4 3 2
Local
Registration
Home Network
Secure tunnel
Anchor FA
Foreign Network MH HA FA 1 2 3 4 5 6
Indirect
Registration
Mobility
© Dr. Ayman Abdel-Hamid, Networking Applications

18. Cellular IP 1/2 Cellular IP and Mobile IP
Global Internet with Mobile IP
Mobile IP
Global mobility
Cellular IP
Wireless access network
Wireless access network
Local handoffs
Local handoffs HA
Wireless access network model
Gateway Router BS FA MH
tunnel
Mobility
© Dr. Ayman Abdel-Hamid, Networking Applications

19. © Dr. Ayman Abdel-Hamid, Networking Applications
Cellular IP 2/2
MH: from B
MH: from F
A, D have paging caches
Gateway Router
paging update packets A D B E FA G F C
Paging update packet (routed hop-by-hop towards the GW) MH
paging packet routed to MH using paging caches
MH: from B
MH: from F
Gateway Router A D B E FA
MH responds with a route-update packet which configures routing caches along the way to the GW G F C
Data packets for MH MH
Mobility
© Dr. Ayman Abdel-Hamid, Networking Applications

20. © Dr. Ayman Abdel-Hamid, Networking Applications
HAWAII 1/2
Handoff-Aware Wireless Access Internet Infrastructure
Uses specialized path setup schemes which install host-based forwarding entries in specific routers to handle intra-domain micro-mobility
defaults to using mobile IP for inter-domain macro-mobility
requires that MH obtains a co-located care of address within a domain, nevertheless MH is required to register with a BS within the domain to be able to better handle handoffs
MH sends path setup update messages during power up and after handoffs HR FR MH
Home Domain
Foreign Domain
HA notified of co-located care of address R HA
HR: Home Domain Root Router
FR: Foreign Domain Root Router
domain model within HAWAII
Mobility
© Dr. Ayman Abdel-Hamid, Networking Applications

21. © Dr. Ayman Abdel-Hamid, Networking Applications
HAWAII 2/2
Router 0
Router 0
(0):  B
(3):  C
(0):  B
(4):  C A C B A C B 4 3 4 5
Router 1
Router 2
Router 1
Router 2
ACK
(0):  B
(4):  A A C B A C B
(0): Default  A
(2):  B
(0):  B
(3):  A A C B A C B
(0): Default  A
(5):  B 2 5 6 6 3
Old BS
New BS 2
Old BS
New BS A B A B A B A B
(0):  B
(5):  A
(0): Default  A
(1):  B
(0):  B
(2):  A
(0): Default  A
(6):  B 1 1 7 7 MH
IP: MH
IP:
Non-Forwarding path setup scheme
(MH can listen/transmit to multiple BS)
Forwarding path setup scheme
(MH can listen/transmit to only one BS)
Mobility
© Dr. Ayman Abdel-Hamid, Networking Applications

22. Multicast and Mobility 1/3
The Deadalus Approach (Berkeley, 1995)
maintains the HA concept of Mobile IP
MH pre-assigned a multicast address by HA
HA encapsulates any packets destined to MH and forwards them over the pre-assigned multicast group
MH informs nearby Base Stations about multicast group and controls forwarding/buffering of packets at BSs through a control protocol
Mobility
© Dr. Ayman Abdel-Hamid, Networking Applications

23. Multicast and Mobility 2/3
A Multicasting-based Mobility Solution (1997)
multicast sole mechanism to provide addressing and routing services to MHs
each MH is assigned a unique multicast IP address (globally unique)
approach affects a number of existing protocols such as TCP, ICMP, ARP, IGMP
Mobility
© Dr. Ayman Abdel-Hamid, Networking Applications

24. Multicast and Mobility 3/3
Fast Handoffs for Wireless Networks (1999)
foreign domain arranged as a two level hierarchy with a domain FA at the root and base stations as leafs.
MH assigned a multicast address within the foreign domain by the domain FA (centralized server)
domain FA becomes forwarding agent for all MHs (single point of failure, bottleneck)
does not discuss details of multicast address allocation or effects on multicast routing
Mobility
© Dr. Ayman Abdel-Hamid, Networking Applications