MOBILE IP

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MOBILE IP

• Presented by-
• Praveen Kumar
• Final year (8th sem)
• (Elect. Comm. Engg.)

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Overview

• What is Mobile IP?
• Mobile IP Operation
• Mobile Addressing Details
• Foreign Agent Discovery
• Agent Registration

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What is Mobile IP?

• IETF standard protocol
• Designed to allow mobile users to move from one
  network to another while maintaining their
  permanent IP address.
• Described in IETF RFC 3344

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Mobile IP Operation

• What is the Biggest Challenge?
• Biggest challenge is allowing a host to retain
  its address without requiring routers to learn
  host-specific routes.
• Mobile IP solves the problem by
• Allowing a computer to hold two addresses
  simultaneously
• A permanent and fixed PRIMARY ADDRESS
• And a SECONDARY ADDRESS that is temporary

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Mobile IP

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Mobile IP Entities

• Mobile Node (MN)
• The entity that may change its point of
  attachment from network to network in the
  Internet
• Detects it has moved and registers with best FA
• Assigned a permanent IP called its home address
  to which other hosts send packets regardless of
  MNs location
• Since this IP doesnt change it can be used by
  long-lived applications as MNs location changes
• Home Agent (HA)
• This is router with additional functionality
• Located on home network of MN
• Does mobility binding of MNs IP with its COA
• Forwards packets to appropriate network when MN
  is away
• Does this through encapsulation (IP in IP
  Tunneling)

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Mobile IP Entities

• Foreign Agent (FA)
• Another router with enhanced functionality
• If MN is away from HA the it uses an FA to
  send/receive data to/from HA
• Advertises itself periodically
• Forwards MNs registration request
• Decapsulates messages for delivery to MN
• Care-of-address (COA)
• Address which identifies MNs current location
• Sent by FA to HA when MN attaches
• Usually the IP address of the FA
• Correspondent Node (CN)
• End host to which MN is corresponding (eg. a web
  server)

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Foreign Agent Discovery

• Uses ICMP router discovery mechanism
• Routers periodically send ICMP router
  advertisement messages
• Hosts may send an ICMP router solicitation to
  prompt for the advertisement
• A Mobile may also multicast to the all agents
  group (224.0.0.11)
• If the router acts as a foreign agent then in its
  reply it will append a mobility agent extension
• The message type is the same as for ICMP router
  advertisements except that if the datagram length
  specified in the IP header is greater than the
  length specified in the ICMP router discovery
  message, then the extension is present

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Communicating with a Foreign Agent

• Foreign Agent may use its address as the
  secondary address for the Mobile Host
• How can the foreign agent communicate with the
  Mobile host when it does not have a unique
  address?
• The Mobile host supplies its hardware address
  during the registration.
• The foreign agent will use the hardware address
  and home IP address to communicate with the
  Mobile host

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Communicating with Home Network

• When a host is at a foreign site the home agent
  can intercept datagrams that arrive from external
  sources and forward them without problems
• A special case arises when the Mobile is at a
  foreign site and hosts from the home network
  attempt to forward datagrams to the Mobile unit
• Those datagrams will be sent via direct delivery
  and not be intercepted by the home agent
• Therefore the home agent must arrange to
  intercept the ARP requests on behalf of the
  Mobile host which acts as a proxy

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Agent Registration

• Before it can receive datagrams at the foreign
  location a Mobile host must register with an
  agent
• Registration is done via UDP
• The procedure allows a host to
• Register with a foreign agent
• Register with the home agent to arrange
  forwarding
• Renew a registration that is due to expire
• Deregister with the home agent

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Mobile IP Tunneling

• Across Internet

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Security in Mobile IP

• Authentication can be performed by all parties
• Only authentication between MN and HA is required
• MD5 is the default
• Replay protection
• Timestamps are mandatory
• HA and FA do not have to share any security
  information.

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THANK YOU