Nat & IPv6

• As 2^32 addresses ien't enough, network address translation (NAT) and IPv6 were made

NAT

• All devices in one local network share one IPv4, as far as the outside world is concerned
• All datagrams leaving local network have same source NAT IP, but different source ports
• Datagrams w/ source/destination in an example home network have 10.0.0/24 address for src/destination

IPv6

• Instead of 32-bit addresses, IPv6 has 128-bit addresses 4 sets of 32 bits
• Typically expressed with hexadecimal addresses
• No checksum
• Difficult to change the entire internet

IPv4 -> IPv6

• Not all routers can be simultaneously updated
  • IPv4 and IPv6 routers are mixed

- Tunneling: IPv6 datagram carried as payload in IPv4 datagram, among IPv4 routers ("packet within a packet")