Mobility And Mobile I Pv4


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Unit 3 Of ACN

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Mobility And Mobile I Pv4

  1. 1. Mobility issues
  2. 2. Support for Mobility in IP Internetworks <ul><li>Routing done with IP address </li></ul><ul><li>IP address of device tied to a network </li></ul><ul><li>No redirection possible for mobile node </li></ul><ul><li>Routing by </li></ul><ul><ul><li>Manual configuration </li></ul></ul><ul><ul><li>Unique address for nodes </li></ul></ul>
  3. 3. Mobility support in IPv4 <ul><li>Seamless Device Mobility Using Existing Device Address </li></ul><ul><li>No New Addressing or Routing Requirements </li></ul><ul><li>Interoperability </li></ul><ul><li>Layer Transparency </li></ul><ul><li>Limited Hardware Changes . </li></ul><ul><li>Scalability </li></ul><ul><li>Security </li></ul>
  4. 4. Mobility overview <ul><li>Implementing a forwarding system for mobile devices </li></ul><ul><li>When a mobile unit is on its “home” network, it functions normally </li></ul><ul><li>When it moves to a different network, datagrams are sent from its home network to its new location </li></ul><ul><li>This allows normal hosts and routers that don't know about Mobile IP to continue to operate as if the mobile device had not moved </li></ul><ul><li>Special services required to implement Mobile IP: </li></ul><ul><ul><li>Letting a mobile device determine where it is </li></ul></ul><ul><ul><li>Telling the home network where to forward messages etc </li></ul></ul><ul><li>Mobile IP was designed under the specific assumption that the attachment point would not change more than once per second </li></ul>
  5. 5. Message forwarding <ul><li>The mobile node’s home router serves as home agent (HA) in Home Network (HN) </li></ul><ul><li>the router in Foreign Network (FN) as the foreign agent (FA) </li></ul><ul><li>The mobile has been assigned a temporary, “care-of” address to use while in FN </li></ul><ul><li>In step #1, the remote client sends a datagram to the mobile using its home address, as before. </li></ul><ul><li>It arrives in HN as usual. </li></ul><ul><li>In step #2, the HA encapsulates that datagram in a new one and sends it to the mobile node in FN. </li></ul>
  6. 6. Mobile IP operation
  7. 7. Mobile IP Devices & Roles <ul><li>Mobile Node: Node on the move </li></ul><ul><li>Home Agent: This is a router on the home network </li></ul><ul><li>Foreign Agent: This is a router on the network to which the mobile node is currently attached </li></ul><ul><li>The HA receives datagrams destined for the MN’s normal IP address and forwards them to the MN’s current location, either directly or by sending to the FA. </li></ul><ul><li>The HA and FA are also responsible for various communication and setup activities that are required for Mobile IP to work. </li></ul>
  8. 8. Gen operation of Mobile IP <ul><li>Agent Communication </li></ul><ul><ul><li>Agent Discovery process </li></ul></ul><ul><ul><ul><li>Listens for Agent Advertisement messages </li></ul></ul></ul><ul><ul><ul><li>Agent Solicitation message </li></ul></ul></ul><ul><li>Network Location Determination by Mobile node </li></ul><ul><ul><li>by looking at the information in the Agent Advertisement message. </li></ul></ul><ul><li>Care-Of Address Acquisition </li></ul><ul><ul><li>From the foreign Agent Advertisement message </li></ul></ul><ul><ul><li>Or other means </li></ul></ul><ul><li>Agent Registration </li></ul><ul><ul><li>informs the HA on its HN of its presence on the FN </li></ul></ul><ul><ul><li>registering with the HA </li></ul></ul><ul><ul><li>This may be done either directly between the MN and the HA, or indirectly using the FA as a conduit. </li></ul></ul><ul><li>Datagram Forwarding: directly or through FA </li></ul>
  9. 9. Home and care of addresses <ul><li>Home address </li></ul><ul><ul><li>This is the address used by the device on its home network </li></ul></ul><ul><li>Care-Of Address </li></ul><ul><ul><li>A secondary, temporary address used by a MN while it is 'traveling” away from its HN </li></ul></ul><ul><li>Mobile IP Care-Of Address Types </li></ul><ul><ul><li>Foreign Agent Care-Of Address </li></ul></ul><ul><ul><ul><li>This is a care-of address provided by a foreign agent in its Agent Advertisement message </li></ul></ul></ul><ul><ul><ul><li>In fact it is the address of foreign agent itself </li></ul></ul></ul><ul><ul><ul><li>HA forwards MN’s message to FA </li></ul></ul></ul><ul><ul><li>Co-located Care-of Address </li></ul></ul><ul><ul><ul><li>MN acquires by manually in the FN </li></ul></ul></ul><ul><ul><ul><li>MN acquires from DHCP in FN </li></ul></ul></ul>
  10. 10. Agent Discovery Process <ul><li>Agent/Node Communication </li></ul><ul><li>Orientation </li></ul><ul><li>Care-Of Address Assignment </li></ul>
  11. 11. Mobile IP Messages <ul><li>Agent Advertisement </li></ul><ul><ul><li>This is a message transmitted regularly by a router acting as a Mobile IP agent. </li></ul></ul><ul><ul><li>It consists of a regular Router Advertisement message that has one or more extensions added that contain Mobile-IP-specific information for mobile nodes </li></ul></ul><ul><li>Agent Solicitation Messages </li></ul><ul><ul><li>This message can be sent by a mobile IP device to nudge a local agent to send an Agent Advertisement. </li></ul></ul>
  12. 12. Mobile IP Mobility Agent Advertisement Extension Format
  13. 13. Registration <ul><li>Direct Registration ( co-located care-of address ) </li></ul><ul><ul><li>Mobile node sends Registration Request to home agent. </li></ul></ul><ul><ul><li>Home agent sends Registration Reply back to mobile node. </li></ul></ul><ul><li>Indirect Registration ( FA care-of address ) </li></ul><ul><ul><li>Mobile node sends Registration Request to foreign agent. </li></ul></ul><ul><ul><li>Foreign agent processes Registration Request and forwards to home agent. </li></ul></ul><ul><ul><li>Home agent sends Registration Reply to foreign agent. </li></ul></ul><ul><ul><li>Foreign agent processes Registration Reply and sends back to mobile node. </li></ul></ul>
  14. 14. Registration messages <ul><li>Registration is performed by the mobile node sending a Registration Request message </li></ul><ul><li>the home agent returns a Registration Reply . </li></ul><ul><li>The foreign agent may be required to act as a “middleman” to facilitate the transaction, but is otherwise not involved </li></ul>
  15. 15. Mobile IP Data Encapsulation <ul><li>The home agent will intercept datagrams intended for the mobile node as they are routed to its home network and forward them to the mobile node. </li></ul><ul><li>This is done by encapsulating the datagrams and then sending them to the node's care-of address. </li></ul><ul><li>IP-in-IP is default encapsulation </li></ul>
  16. 16. Mobile IP data Delivery tunnel <ul><li>The start of the tunnel is the home agent </li></ul><ul><li>The end of the tunnel depends on what sort of care-of address is being used: </li></ul><ul><ul><li>Foreign Agent Care-Of Address:- FA </li></ul></ul><ul><ul><li>Co-located care-of Address:- Mobile Node </li></ul></ul>
  17. 17. Triangle delivery path <ul><li>Normally, the tunnel is used only for datagrams that have been sent to the mobile node and captured by the home agent. </li></ul><ul><li>When the mobile nodes wants to send a datagram, it doesn't tunnel it back to the home agent; this would be needlessly inefficient. </li></ul><ul><li>Instead it just sends out the datagram directly using whatever router it can find on its current network, which may or may not be a foreign agent. </li></ul><ul><li>When it does this, it uses its own home address as the source address for any requests it sends. </li></ul><ul><li>As a result, any response to those requests will go back to the home network. </li></ul><ul><li>This sets up a “triangle” of sorts for these kinds of transactions </li></ul>
  18. 18. Mobile tunneling Triangle path
  19. 19. Mobile IP Reverse Tunneling <ul><li>A reverse tunnel is set up between the mobile node and the home agent, or between the foreign agent and the home agent, depending on care-of address type. </li></ul><ul><li>All transmissions from the mobile node are tunneled back to the home network where the home agent transmits them over the internetwork </li></ul><ul><li>A more symmetric operation rather than the “triangle” path </li></ul><ul><li>This is needlessly inefficient, because it means each communication requires four steps. </li></ul><ul><li>Thus, it is used only when necessary. </li></ul>
  20. 20. Situation for reverse tunneling <ul><li>where network where the mobile node is located has implemented certain security measures that prohibit the node from sending datagrams using its normal IP address. </li></ul><ul><li>In particular, a network may be set up to disallow outgoing datagrams with a source address that doesn’t match its network prefix. </li></ul><ul><li>This is often done to prevent “spoofing” (impersonating another’s IP address.) </li></ul>