Course: https://www.internetsociety.org/tutorials/introduction-to-ipv6/module-1-introduction/

Module 1: Introduction to iPv6

• IETF = Internet Engineering Task Force (IETF)
• Problems addressed when transitioning to iPv6:
  • iPv4 address exhaustion
  • need for simpler auto-configuration and re-numbering
  • requirement for security at IP level
  • improved protocol design
  • new possibilities of managing flow
• iPv4 only has 2 billion IP addresses available, iPv6 encompasses 340 trillion trillion trillion
• Since iPv6 is a huge amount to address space, the subnet sizes are huge as well
  • At ISP level (/32), there are 79 septillion addresses assigned
  • Largest block of iPv6 addresses allocated to France Telecom and Deutsche Telekom > allocation is /19 block, equivalent to 35, 000 billion
• Most of the internet becoming dual stack because iPv4 and iPv6 are not compatible
• Difficulty and cost of obtaining iPv4 address space will increase, inevitable that in the future some sites will only support iPv6
• Workarounds: Network Address Translation
• Adopting MAT technology will help systems maintain iPv4 service while moving to iPv6 (bust costly in long-term)
• Steps to move to iPv6:
  • Learn more about iPv6
  • Get network iPv6 ready

Module 2: Understanding iPv6 Addresses

• iPv6 addresses are 128 bits
  • broken into sixteen 8 bit sections
  • example of address: 128.91.45.157.220.40.0.0.0.252.87.212.200.32.255
  • can be converted to hex
• To convert iPv6 from binary address to hexadecimal:
  • Break binary into 8 blocks of 16 bits
  • Split each block of 16 bits into 4 segments
  • Convert each segment into a hexadecimal (0-F)

• zero compression – consecutive blocks of zeros
  • if there is more than 1 consecutive block where characters are all zeroes, you can compress to ::
  • zero compression can only be used ONCE in an address
• zero suppression – leading 0’s
  • remove all leading 0s (front part) in each segment (cannot remove if after a non-zero in a segment)
  • each segment must contains at least a single digit if not using zero compression

• iPv6 prefixes
  • iPv6 is hierarchical, addresses can be sub-netted for performance and security reasons in the same way as iPv4
  • all devices whose IP addresses have the same prefix share the same network component of address and are part of a subnet
  • larger subnet = smaller # after dash
    • /32 subnet (means network is only 32 bits, whereas subnet contains up to 96 bits left for specific addresses)
    • /48 subnet has 80 bits left for specific addresses
    • /32 is a bigger subnet than /48
  • iPv6 address types
    • iPv6 addresses identify an interface/group of interfaces
    • 3 main types of iPv6 addresses:
      • Unicast (2000::)
        • Most common type of iPv6
        • Identifies a single interface
        • Communication between single sender and single receiver over network
        • Every machine should have at least open global unicast address assigned to each interface
        • Global unicast addresses all begin with same prefix: 2000::/3
      • Anycast
        • Anycast addresses identify groups of interfaces
        • Packets for anycast addresses are sent to nearest interface in a group
        • Facilitates communication between any sender and nearest group of receivers in a network
        • Allocated from unicast address space (2600::), not distinguishable from unicast address
      • Multicast (ff00::)
        • Identifies a group of interfaces, belonging to different nodes
          • Packages sent to multicast addresses are delivered to all interfaces in the group
          • Facilitate communication between single sender and multiple receivers
          • Multicast replaces broadcast addresses in iPv4
          • Prefix: ff00::/8
          • Format:
            • Indicator: Always 11111111 (aka FF), indicates multicast
            • Scope: indicates how broadly multicast packets will spread
              • 4 possible values:
                • Node-local
                • Link-local
                • Site-local
                • Global
              • Group ID: multicast group within the given scope
                • All nodes, all-routers, OSPF, NTP
              • Special iPv6 Addresses
                • Unspecified (::/128)
                  • All zeros, refers to host when host doesn’t know own address
                  • Used for devices seeking to have iPv6 address assigned
                • Loopback (::1/128)
                  • Has single address for loopback function
                • IPv4 Mapped (::ffff:0:0/96)
                  • Prefix is 96 bits, 32 bits hold the embedded iPv4 addresses
                  • Used to represent iPv4 address as an iPv6 address
                  • Address helps to transition from iPv4 to iPv6
                • Unique Local Unicast (ULA) (fc00::/7)
                  • For local use, within a site or group of sites
                  • Not routable on the global internet
                • Link-Local Unicast (fe80::/10)
                  • Unicast addresses to be used on a single link
                  • Used for neighbor discovery, automatic address configuration, when no routers are present