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

• 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 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 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.

•   What are Extension Headers?  

•   How are they identified in the IPv6 Header?

•   Extension Header Order

• 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)

• 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

• 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.
  

• 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 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.

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

• 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).

• 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.
  

• 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.
  

• 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).

• 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.

• 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.
  

• 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

• 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.

• [1]  Gupta, Meenakshi. "IPV4 vs. IPV6."
  
• [2] Johnson, David, Charles Perkins, and Jari Arkko. "Mobility support in IPv6." (2004): 2004
• [3] Montavont, Nicolas, and Thomas Noel. "Handover management for mobile nodes in IPv6 networks." Communications Magazine, IEEE 40.8 (2002): 38-43.
• [4] Deering, Stephen E. "Internet protocol, version 6 (IPv6) specification." (1998).
• [5] Hinden, Robert M., and Stephen E. Deering. "Internet protocol version 6 (IPv6) addressing architecture." (2003).

• [6] Conta, Alex, and Mukesh Gupta. "Internet control message protocol (icmpv6) for the internet protocol version 6 (ipv6) specification." (2006).
  
• [7] Postel, Jon. "RFC 791: Internet protocol." (1981).
• [8] Deering, S., and R. Hinden. "RFC 2460: Internet Protocol, Version 6 (IPv6) Specification (1998).
• [9] Borman, David A., Stephen E. Deering, and Robert M. Hinden. "IPv6 Jumbograms." (1999).
• [10] Kent, Stephen, and Randall Atkinson. "RFC 2402: IP authentication header." (1998).
• [11] RFC2406, E. S. P. "IP Encapsulating Security Payload (ESP)." S. Kent, R. Atkinson (1998).
• [12] Soliman, Hesham, et al. "Hierarchical mobile IPv6 (HMIPv6) mobility management." (2008).

• 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.