In this ppt you'll learn about the packet delivery. How the Ip packet is delivered from transmitter to receiver when the Mobile node is in the Foreign network. Also you'll be able to learn all definitions like What is mobile node, correspondent node, Home agent, Foreign Agent, Tunneling, Encapsulation, COA(care of address) etc. After that you'll learn about the Agent advertisement and registering of care of address including different steps.

1. IP PACKET DELIVERY
SOURABH KUMAR
(ECE)
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2. MOBILE IP TERMINOLOGY
 MOBILE NODE (MN): A mobile node is an end-system or router that can change its point of
attachment to the internet using mobile IP.
 The MN keeps its IP address and can continuously communicate with any other system in the
internet as long as link-layer connectivity is given.
 Correspondent Node (CN): communication partner
 Home Network: The home network is the subnet the MN belongs to with respect to its IP address.
No mobile IP support is needed within the home network.
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3. MOBILE IP TERMINOLOGY
 Home Agent (HA): router in the home network of the MN, which registers the location of the MN,
tunnels IP datagrams to the COA when MN is away from home.
 Foreign Network: The foreign network is the current subnet the MN visits and which is not the home
network
 Foreign Agent (FA): router in the current visited network of the MN, which forwards the tunneled
datagrams to the MN, also acts as the default router for the registered MN.
 FA can also provide security services because they belong to the foreign network as opposed to the MN
which is only visiting.
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4. MOBILE IP TERMINOLOGY
 Care Of Address (COA): The COA defines the current location of the MN from an IP point of view.
 Foreign Agent COA: The COA could be located at the FA, i.e., the COA is an IP address of the FA.
 The FA is the tunnel end-point and forwards packets to the MN.
 Many MN using the FA can share this COA as common COA.
 Co-LOCated COA: The COA is co-lOCated if the MN temporarily acquires an additional IP address
which acts as COA. CO-LOCATED ADDRESSES CAN BE ACQUIRED USING SERVICES LIKE DHCP
(DYNAMIC HOST CONFIGURATION PROTOCOL)
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5. IP PACKET DELIVERY 5

6. IP PACKET DELIVERY(STEP1)
 One of the requirements of mobile IP was to support hiding the mobility of the MN. CN does not need to
know anything about the MN’s current location and sends the packet as usual to the IP address of MN. This
means that CN sends an IP packet with MN as a destination address and CN as a source address. The
internet, not having information on the current location of MN, routes the packet to the router responsible
for the home network of MN. This is done using the standard routing mechanisms of the internet.
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7. IP PACKET DELIVERY(STEP2)
 The HA now intercepts the packet, knowing that MN is currently not in its home network. The packet is not
forwarded into the subnet as usual, but encapsulated and tunneled to the COA. A new header is put in front
of the old IP header showing the COA as new destination and HA as source of the encapsulated packet
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8. IP PACKET DELIVERY(STEP3)
 The foreign agent now decapsulates packet, i.e., removes the additional header, and forwards the original
packet with CN as source and MN as destination to the MN. Again, for the MN mobility is not visible. It
receives the packet with the same sender and receiver address as it would have done in the home network.
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9. IP PACKET DELIVERY(STEP4)
 The IP datagram from MN to CN travels directly across the network, using CN’s IP address as the
destination address AND MN’S ADDDRESS(FIXED IP ADDRESS) AS SOURCE ADDRESS AS
USUALLY IT DOES.
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10. AGENT ADVERTISEMENT
 One initial problem of an MN after moving is how to find a foreign agent. How does the MN discover
that it has moved? For this purpose mobile IP describes two methods: agent advertisement and agent
solicitation.
 THERE ARE THREE MAIN STEPS TO DISCOVER AND REGISTER:
 Discovery - A mobile node uses a discovery procedure to identify prospective home agents and foreign
agents.
 Registration - A mobile node uses a registration procedure to inform its home agent of its care-of
address.
 Tunneling - Tunneling procedure is used to forward IP datagrams from a home address to a care of
address.
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11. AGENT ADVERTISEMENT
 foreign agents and home agents advertise their presence periodically using special agent advertisement
messages.
 An agent advertisement message has one or more care-of-addresses and a flag indicating whether it is a
home agent or foreign agent.
 For these advertisements Internet control message protocol (ICMP) messages are used with some mobility
extensions.
 The agent advertisement packet with the extension for mobility is shown IN NEXT SLIDE. The upper part
represents the ICMP packet while the lower part is the extension needed for mobility.
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12. AGENT ADVERTISEMENT 12

13. Mobile-IP extension
 Type = 16
 Length = number of COA provided with the message. It is equal to 6+4*(no. of addresses)
 Registration lifetime = maximum lifetime specified by the agent in seconds which the node can request
during registration.
 Sequence No. = total no. of advertisements sent during initialization.
 The flags after registration lifetime explain the features of advertisement. They are described as:
 R-bit: registration with this agent is required even when the mobile node uses a collocated COA.
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14. Mobile-IP extension
 B-bit: The Foreign agent is busy to take any registrations
 H-bit: Agentis home agent
 F-bit: Agent is foreign agent
 M-bit: Minimal encapsulation is used for encapsulation
 G-bit: Generic routing encapsulation is used
 r-bit: was initially set to V in first version of mobile IP (RFC 2002) suggested use of header compression
and should be ignored.
 T-bit: reverse tunneling.
 The foreign agent should advertise at least one CoA.
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15. Agent advertisement
 Allows for the detection of mobility agents
 Lists one or more available care-of addresses
 Informs the mobile node about special features
 Mobile node selects its care-of address
 Mobile node checks whether the agent is a home agent or foreign agent
 Once the care-of-address is achieved the mobile node registers it with its Home agent and informs
about the current location where the packets intended for it can be forwarded.
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16. Registering the care-of-address
 If the mobile node travels to a foreign network, it registers with the foreign agent by sending a registration
request message which includes the permanent IP address of the mobile host and the IP address of its home
agent.
 The foreign agent in turn performs the registration process on behalf of the mobile host by sending a
registration request containing the permanent IP address of the mobile node and the IP address of the
foreign agent to the home agent.
 When the home agent receives the Registration Request, it updates the mobility binding by associating the
care-of-address of the mobile node with its home address.
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17. Registering the care-of-address
 The home agent then sends an acknowledgement to the foreign agent.
 The foreign agent in turn updates its visitors list by inserting the entry for the mobile node and relays the
reply to the mobile node
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18. Registering the care-of-address 18

19. THANK YOU
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