Mobility And Mobile I Pv4
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Mobility And Mobile I Pv4



Unit 3 Of ACN

Unit 3 Of ACN



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    Mobility And Mobile I Pv4 Mobility And Mobile I Pv4 Presentation Transcript

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