Ipv6

  • Introduction of IPv6 (IPv6 vs. IPv4) [1]
  • Handover management
    for mobile nodes in IPv6 networks [2][3]

motivation

  • Addresses
  • Asian countries, especially China, Japan and South Korea
  • Uniquely address every molecule in the solar system
  • World’s population is growing
  • IoT
 

IPV4 vs. IPV6

  • Addresses:
    • IPv4 - 32 bit (4 bytes)  addressing and  allows 4,294,967,296 unique addresses 
    • IPv6 -  128-bit (16 bytes)  addressing and  allows 340 undecillion  unique addresses.
      (340,282,366,920,938,463,463,374,607,431,768,211,456 ) VS. (4,294,967,296)
  • Checksum: 
    • IPv4 - header includes checksum 
    • IPv6 - header doesn’t contains checksum 
  • Fragmentation
    • IPv4 - Both routers and senders fragment the data 
    • IPv6 - only Senders can fragment data packets.

IPv4 - [7]

IPv6 - [5]

  • Version                      - 4 -bit Internet Protocol version number = 6
  • Traffic Class           - 8  -bit traffic class field - QoS?
  • Flow Label              - 20-bit flow label - May be used for special handling
  • Payload Length   - 16-bit unsigned integer
  • Next Header         - 8   -bit selector
  • Hop Limit                 - 8   -bit unsigned integer (TTL)

IPv6 Addresses Format [5]

  • IPv6 defines three types of addresses. 
    • Unicast address specifies a single host  ( 1 to 1).
    • Multicast is like a broadcast that can cross subnets, Nodes have to subscribe to a multicast group to receive information (One/Many to Many).
    • Anycast address is one that is assigned to more than a single interface (Many to Few).
    • There is no broadcast address in IPv6
  • IPv6 addresses example:
    • FF04:19:5:ABD4:187:2C:754:2B1
    • FF01:0:0:0:0:0:0:5A  ==  FF01::5A
    • Hybrid - 0:0:0:0:0:0:199.182.20.17  ==  ::199.182.20.17

ICMPv6 - Internet Control Message Protocol [6][8]

  • ICMPv6 error messages are:
    • Destination Unreachable:   packet cannot be  delivered for reasons other than  congestion.
    • Packet Too Big: Sent by a router when it has a packet that it cannot forward because the packet is larger than the MTU of the outgoing link.
    • Time Exceeded:
      • Sent by a router that when the packet's  Hop Limit reaches zero.
      • If all fragments of a datagram  are not received within the fragment reassembly time.
    • Parameter Problem: inability to process the header.

IPv6 Extension Headers

  •   What are Extension Headers?  
  •   How are they identified in the IPv6 Header?
  •   Extension Header Order

IPv6 Extension Headers [4]

  • 0 - Hop-by-Hop Options header
    • must be examined by every node along the path.
    • Jumbo Payload option "jumbograms" less the 4GB [9]
  • 60 - Destination Options header (note 1)
  • 43 - Routing header
    • list one or more intermediate nodes to be "visited" on the way to a packet's destination.
  • 44 - Fragment header
  • 51 - Authentication header (note 2) [10]
  • 50 - Encapsulating Security Payload header (note 2) [11]
  • 60 - Destination Options header (note 3)
  • 59 - Upper-layer header - (e.g., 6 for TCP, or 17 for UDP)

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Mobile IPv6 Terms

  • mobile node ( MN ) : A node that can change its point of attachment from one link to another.
  • correspondent node: A peer node with which a mobile node is communicating.
  • home address: A unicast address assigned to a mobile node.
  • home subnet prefix: The IP subnet prefix corresponding to a mobile node's home address.
  • home link: The link on which a mobile node's home subnet prefix is defined.
  • home agent: A router on a mobile node's home link with which the mobile node has registered its current care-of address

more TERMS

  • Foreign subnet prefix: Any IP subnet prefix other than the mobile node's home subnet prefix.
  • Foreign link: Any link other than the mobile node's home link.
  • Handover: A process by which the mobile node changes from one link-layer connection to another L2 + L3.
  • Care-Of Address: A unicast routable address associated with a mobile node while visiting a foreign network.
  • binding: The association of the home address with a care-of address (lifetime)
  • Binding Update: A Binding Update is used by a mobile node to notify the correspondent node or the home agent of its current binding.

mobile IPv6 - MIPv6

PROBLEM? 


The Handover Procedure


  • MN detects  that it has moved to a new subnet.
    • Router advertisement
    • Router solicitation
  • Router advertisement  allows to create a new care-of address
    • Stateless - each host to determine its address.
    • Stateful address autoconfiguration - DHCPv6.

THE HANDOVER PROCEDURE


  • The MN performs duplication address detection (DAD)
    • The MN has to send one or several neighbor solicitation(s) to its new address and wait for a response for at least 1 s
  • The MN must update the binding cache in its home agent and correspondent(s) by sending a binding update.

    Suggestions for Enhancement?

    • The MN should perform DAD in parallel.  
    • Choose not to perform it.

    Handover Enhancement

    • MN can be reachable through multiple wireless links from physically neighboring APs. 
      • If these APs are on different subnets
        • One of them must be a primary  for a default AR.
      • If the default AR becomes unreachable
        •  the  MN can use a new default AR for which it  already has a care-of address  In addition.
        • the packets sent by the correspondent nodes are lost until they receive the  binding update.
    • MN  can switch between two ARs several times (ping-ponging).

    HANDOVER ENHANCEMENT

    • Mobile IPv6 requires that the MN to create and register a new care-of address after each movement.
    • Bicasting allows the MN to simultaneously register with several ARs. 
      • All the packets intended for the MN are then duplicated in several potential localizations.
    • Bicasting performed by the home agent
      • generates lots of traffic on both the wired and wireless links.

    HIERARCHICAL MOBILE IPV6 - HMipv6[12]

    • Designed to minimize  signaling to correspondent(s) and to the home  agent.
    • The global Internet is divided in regions defining local area mobility. [13]
    • mobility anchor point:  is an AR with a publicly routable IP address at the top of several ARs. 
    • Regional Care-of Address (RCoA):   RCoA is an address allocated by the MAP to the mobile node.
    • On-Link Care-of Address ( LCoA ) :   LCoA is configured on a mobile node’s  interface, based on the prefix advertised by its default router.

    When the Mobile node first enters a domain

    • Make a regional registration to advertise to its home agent and correspondent(s).
    • After each movement between ARs in the same domain, the mobile node needs to send a local registration to the mobility anchor point to update its on-link care-of address.
    • All mobile node movements within the domain are hidden from the home agent and correspondent(s).

    Two Modes of Hierarchical MIPv6

    • Basic mode:
      • MN has two addresses:
        • Regional care-of address based on the mobility anchor point prefix.
        • On-link care-of address based on the current AR prefix.
      • In this scheme, the mobility anchor point acts as a home agent.

    Two Modes of Hierarchical MIPv6

    • Extended mode: 
      • MN one address: 
        • Regional care-of address is (one of)  the mobility anchor point unique address(es).
      • The mobility anchor point keeps a binding table with the current on-link care-of address of an MN matched with the MN home address  == on-link care-of address.
      • When it receives packets destined to an MN, it detunnels and retunnels them to the on-link care-of address.
      • This implies that each packet must contain the MN home address.

    fmipv6 - fast handover Protocol  [14]

    • Allows an AR to offer services to MN in order to anticipate the L3 handover.
    • The movement anticipation is based on the L2 triggers.
    • The main L2 triggers used are the following:
      • Link Up - MN has established a connection with an AP.
      • Link Down - MN has lost  a connection with an AP.
      • L2 Handover Start - MN  starts an L2 handover to attach to a new AP.
    • Fast Handover uses these L2 triggers to optimize the MN movements in two methods:
      • Anticipated handover 
      • Tunnel-based handover


    Fast Handover – Tunnel-Based Handover

    • It only performs an L2 handover and continues to use its old care-of address in the new subnet. 
    • The MN does not need to exchange any packets: the two ARs set up a bidirectional tunnel from the L2 triggers without interacting with the MN.

    ?

    referances

    notes

    • 1: For options to be processed by the first destination that appears in the IPv6 Destination Address field plus subsequent destinations listed in the Routing header.
    •  2: Additional recommendations regarding the relative order of the Authentication and Encapsulating Security Payload headers are given in [RFC-2406].
    • 3: For options to be processed only by the final destination of the packet.

    Bicasting in Hierarchical Architecture

    • bicasting performed by the mobility anchor point.
      • can generate too much delay in packet delivery.
    • Packets are only duplicated within  the domain.
    •   Subjects that are still under discussion since it causes problems:
      • Discovery  of the other mobility anchor point(s).
      • Selection  of one mobility anchor point by the MN.
      • Load balancing among multiple mobility anchor  points.

    IPv6

    By Asaf

    IPv6

    seminar

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