Download A Study of Mobile IP - Witchita State University

A Study of Mobile IP
Kunal Ganguly
Wichita State University
CS843 – Distributed Computing
Outline
•
•
•
•
•
Introduction
How Mobile IP works
Protocols of Mobile IP
Next Generation Mobility – Mobile IPv6
Conclusion
OUTLINE
1/19
Introduction
• IP addresses are usually associated with a fixed point of
access to the network/Internet.
• The IP protocol does not support mobility
• The Problem:
– Current network models insist on assigning a new IP address
every time a node changes its point of attachment.
– For mobile nodes, receiving data in a reliable fashion would be
impossible if its IP address changes from time to time.
INTRODUCTION 2/19
Introduction
Solving the Problem
Mobile IP (RFC 3344) uses 2 IP addresses to help a mobile
node receive uninterrupted service:
– Home Address
• Static
• Makes the mobile node appear logically connected to the home network
• Allows the mobile node to remain addressable via the home address
– Care-of Address
• Changes at every new point of attachment
• Identifies the mobile node’s point of attachment with respect to the network
topology
INTRODUCTION 3/19
How does Mobile IP manage 2 IP addresses?
Agents of Mobile IP
– Home Agent
• Gets packets intended for the mobile node and delivers them
transparently to the mobile node’s current point of attachment
– Foreign Agent
• Comes into play only if node is on a foreign network
• Receives encapsulated packets from the Home Agent,
decapsulates them, and sends them to the intended mobile node
INTRODUCTION 4/19
What does Mobile IP offer?
INTRODUCTION 5/19
How does Mobile IP work?
Successful cooperation between 3 mechanisms:
–Discovering the care-of address
–Registering the care-of address
–Tunneling to the care-of address
HOW DOES
6/19
Discovering the Care-of Address
• The Home and Foreign Agents announce their
presence using Agent advertisements at regular
intervals
• Agent advertisements:
– Same as Router Advertisements, except that some extra
information is added about the care-of addresses
– Informs of alternative encapsulation techniques
– Lets mobile node know whether it is on a Home or
Foreign network
HOW DOES
7/19
Discovering the Care-of Address
Contd.
• The mobile node listens for the Home Agent
advertisement to get its address.
• Once on a foreign network, the mobile node
listens for a Foreign Agent advertisement and
registers itself, and informs the Foreign Agent of
its Home Address.
• The Foreign Agent contacts the Home Agent and
registers the care-of address.
HOW DOES
8/19
Registering the Care-of Address
• When the Home Agent receives a registration request
for the care-of address, its adds the necessary
information to its routing table.
• It then sends a registration reply back to the Foreign
Agent.
• Registration requests:
– Contain a binding – Home address, care-of address and
Registration Lifetime (how long may the agent use the
binding).
– Allow the Home Agent to associate the care-of address with
the home address of the mobile node.
– Define parameters and flags which characterize the tunnel to
be used.
HOW DOES
9/19
Tunneling to the Care-of Address
The Home Agent and the Foreign Agent use a tunnel
to communicate.
– A tunnel defines the end-points of the route to be
followed by a IP packet.
– Start point is the Encapsulator (done by Home Agent)
– End point is the Decapsulator (done by Foreign Agent)
HOW DOES
10/19
Tunneling to the Care-of Address Contd.
Encapsulation
The default Encapsulation mechanism that must be
supported by all mobility agents using Mobile IP is
IP-within-IP.
The original IP packet is made the payload of a new
IP packet (encapsulated) whose destination field in
the header shows the care-of address.
HOW DOES
11/19
Tunneling to the Care-of Address Contd.
Decapsulation
At the end-point of the tunnel, the packet is
Decapsulated, where the Foreign Agent extracts the
payload and sends the packet to the mobile node
identified by its hardware address.
HOW DOES
12/19
Tunneling to the Care-of Address Contd.
2 kinds of Tunneling
Triangular Routing
Reverse Tunneling
HOW DOES
13/19
Protocols of Mobile IP
The Physical layer and Data-link layers support:
–
–
–
–
–
–
Signal Modulation
Encryption
Compression
Interference control
Channel Access/Selection
Modifications to allow Gratuitous or Proxy ARP
PROTOCOLS
14/19
Protocols of Mobile IP Contd.
At the Network layer, Mobile IP offers:
–
–
–
–
Addressing
Routing
Location Management
Authentication
PROTOCOLS
15/19
Protocols of Mobile IP Contd.
• Since Mobile IP is implemented at the Network
layer, no major changes are required on the layers
above (transport, session, presentation, &
application).
• However, services such as Congestion control,
Flow control and Quality of Service are
introduced at the Transport layer, and Resource
discovery and Link adaptation layer are introduced
at the application layer.
PROTOCOLS
16/19
Mobile IPv6
• Great deal of improvements over Mobile IPv4
• Stateless Address Autoconfiguration, Neighbor
Discovery mechanisms – no need for DHCP, Foreign
Agents or ARP
• Mobile IPv6 can use IPsec (IP Security Protocol) for all
actions which require security, such as authentication and
data integrity protection
• Route optimization is greatly improved in Mobile IPv6.
• Mobile IPv6 does not have a problem with ingress
filtering by routers, hence the wasteful technique of
Reverse Tunneling is not required.
• Mobile IPv6 has a special routing header, doing away
with the need for encapsulation.
IPv6
17/19
Conclusion
• Increased user acceptance of mobile devices fuels
the need for developers to provide wireless
connectivity to network services from these
devices.
• Mobile IP, already a reality with some
implementations, commercial and in academic
institutions, is definitely going to be a standard in
the devices of tomorrow.
CONCLUSION
18/19
QUESTIONS?
QUESTIONS
19/19