IPv6 Network Prefixes

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• IPv6 address is divided into two parts:
  • network ID
    • first 64 bits
  • interface ID
    • second 64-bits
      • always the same length unlike IPv4

• network addresses are written using classless notation
  • /nn is the length of the network prefix in bits
  • network ID is used to determine whether two addresses belong to the same IP network
    • E.g., if prefix is /48, then if the first 48 bits are the same, they would be part of same network
    • an org’s network can be represented by a global routing prefix 48-bits long
      • have 16 bits left to subnet

Example

• 2001:db8:3c4d::/48
  • represents a network address
• 2001:db8:3c4d:0001::/64
  • represents a subnet within that network address

• IPv6 can use
  • unicast
  • multicast
  • anycast
• there is no broadcast addressing