IPv4
Internet Protocol version 4 (IPv4) is the fourth version in the development of the Internet protocol (IP) the Internet, and routes most traffic on the Internet. IPv4 is a connection-less protocol for use on packet-switched networks. It operates on a best offers delivery model, in that it does not guarantee delivery, nor does it assure proper sequencing or avoidance of duplicate delivery. These aspects, including data integrity, are addressed by an upper layer transport protocol, such as the Transmission Control Protocol(TCP). IPv4 (Internet Protocol version 4) is currently the most widely-used network protocol.

IPv4 Header
ipv4_packet

IPv6
Internet Protocol version 6 (IPv6) is the latest revision of the Internet Protocol (IP), the communications protocol that provides an identification and location system for computers on networks and routes traffic across the Internet. IPv6 quadruples the number of network address bits from 32 bits (in IPv4) to 128 bits, which provides more than enough globally unique IP addresses for every network device on the planet.

IPv6 Header

ipv6

Comparison between IPv4 and IPv6 Headers

  • The header length field is removed from IPv6 because of header is fixed.
  • The service type field is eliminated from IPv6 because the priority and flow control combined works as service field.
  • Total length field is eliminated in IPv6 variable is only payload length.
  • The TTL field is replaced by hop limit.
  • The protocol field is replaced is by the next header field.
  • There is no header checksum is IPv6 because header fixed.

Transition from IPv4 and IPv6

  • Dual Stack
  • Tunneling
  • Header Translation

Dual Stack : It is recommended that all posts before migrating completely to IPv6 has a dual stack of protocols. In other words, a station must run IPv4 and IPv6 simultaneously until all the internet uses IPv6

Tunneling : It is a strategy when two computers using IPv6 want to communicate with each other and the packet must pass through region that uses IPv4. To pass through this region the packet must have an IPv4 address. So IPv6 packet is encapsulated in the IPV4 packet when it exits the region

Header Translation : It is necessary when majority of internet has moved to IPv6 but some system still use IPv4. The sender wants to use IPv6 but receiver dose not understand IPv6. The tunneling dose not work in this situation because the packet must be in the IPv4 format to be understood by the receiver. In this case the header format must be totally changed through translation process.

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