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Intro to IP Tunneling

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• Normal network comminication
  • Normal network communication:

    In normal network communication (that we have studied so far): User data is put inside an level 3 (network layer) packet The level 3 (network layer) packet is sent inside a physical network frame Example:

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• Tunneling
  • Tunneling:

    Tunneling = an encapsulation technique where: a network-level data unit (packet) is transmitted as payload (= data) inside another network-level data unit (packet) Graphically explained:

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• IP tunneling
  • IP tunneling:

    IP tunneling = the encapsulation technique where one IP packet is transmitted as payload (= data) inside another network-level packet Graphically explained:

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• IP-in-IP tunneling

  • IP-in-IP tunneling:

    IP-in-IP tunneling = the encapsulation technique where one IP packet is transmitted as payload (= data) inside another IP packet Graphically explained:

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• Applications that make use of tunneling
  • Use of tunnels:

    The create a virtual private network (VPN) This is the most commonly used application of tunneling To provide novel network services Examples: IP multicast (the MBone was constructed using tunnels) To connect two or more non-common networks using a common network Example: When IPv6 was first introduced, the small number of IPv6 networks were connected through IPv4 tunnels

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• Dictatic notes
  • The IP tunneling feature was introduced in in 1995 to the Internet Standard

    The tunneling feature is documented in the Internet RFC 1853: click here

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  • NOTE:

    I will use IP-in-IP to explain the tunneling concept

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• Encapsulation
  • Tunneling is a form of:

    encapsulation !!!! The outer IP packet is used to transfer (= "tunnel") the inner IP packet to the "processing location" !!!

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  • You have seen encapsulation before - it was used in routers: click here

    Encapsulation was used to: Transmit a (virtual) IP packet inside a (real) Physical (Ethenet) frame