chap 9

• Available IPv4 addresses (Classes A, B and C) are approximately 3.7 billion.
• Temporary solution for IPv4 addressing

  • Sharing of IP Addresses
  • Network Address Translation (NAT)
• Long term solution

  IPv6
• IP addresses are assigned by IANA, through the Regional Internet Registries (RIRs).
• IANA

  Internet Assigned Numbers Authority
• RIRs world-wide

  • AfriNIC
  • APNIC
  • ARIN
  • LACNIC
  • RIPE NCC
• Depletion of IPv4 address space has been the main reason for moving to IPv6.
• IPv6 addresses

  Use 128 bits
• 128 bits give 2^128 = 3.4x10^38 IPv6 addresses.
• IPv6 addresses are too long to be expressed in dotted-decimal format.

  
• Hexadecimal Numbering System

  A system used to represent IPv6 addresses
• IPv6 addresses use hexadecimal numbering system.
• Hextet


  Each group of 16-bit sections in IPv6 addresses
• Each hextet represents 16 binary bits.
• IPv6 can be written in both uppercase or lowercase.

  
• Leading 0's in any hextet

  Can be omitted
• A double colon (::) can replace any single, contiguous string of one or more 16-bit segments consisting of all 0’s.
• Double colon (::) can only be used once within an address, otherwise the address will be ambiguous.
• Rules for making IPv6 addresses shorter

  • Omitting leading 0's
  • Using double colon for contiguous 0's
  • Double colon can only be used once
• Answer to the exercise is 2055:8888::70:0:33.
• Answer to the exercise is ::1.
• Re-write the IPv6 address with all 0’s in the compressed format is ::.

  
• IPv6 addresses are divided into Network Portion and Host Portion.
• Prefix Length

  Indicates the network portion of an IPv6 address
• Answer is 2001:3456:CAFE.
• Types of IPv6 addresses

  • Unicast
  • Multicast
  • Anycast
• IPv6 does not have broadcast addresses.

  
• Types of IPv6 Unicast addresses

  • Global Unicast
  • Link-Local
  • Loopback
  • Unspecified Address
  • Unique Local
  • Embedded IPv4
• This module will only discuss the first 4 types of IPv6 Unicast addresses.
• Global Unicast Address

  Similar to a public IPv4 address, which is internet-routable.
• Global Unicast Address

  • Globally unique
  • Can be static or dynamic
  • ICANN allocates IPv6 address blocks to the 5 RIRs
• Currently, only global unicast addresses with the first three bits of 001 are being assigned.
• The first hextet is 0010 or 0011.
• IPv6 address is 2000::/3.
• Link-Local Unicast Address


  For communication with other devices on the same subnet.
• Link-Local Unicast Address is confined to a subnet, not routable beyond the subnet.
• Link-local addresses are FE80::/10.
• Every IPv6-enabled network interface is required to have a link-local address.
• Types of IPv6 Addresses

  • Global Unicast Address
  • Link-Local Unicast Address
  • Loopback
  • Unspecified Address
• Global Unicast Address

  • Similar to a public IPv4 address, which is internet-routable
  • Globally unique, no two devices should have identical global unicast address
  • Can be static (manual) or dynamic (e.g. DHCPv6)
  • ICANN allocates IPv6 address blocks to the 5 RIRs
  • Currently, only global unicast addresses with the first three bits of 001 are being assigned
  • The first hextet is 0010 or 0011
  • IPv6 address is 2000::/3