IPv6 Communication - Internet Protocol version 6 (IPv6)

How the hosts communicate in IPv6?

In IPv6, broadcast mechanisms are not required as that of IPv4. In order to obtain an IP address from the DHCP or manual configuration, it is not mandatory as that of IPv4 for an IPv6. The IP can be auto-configured by IPv6 on its own.

ARP has been replaced by ICMPv6 Neighbor Discovery Protocol.

What is IPv6 Neighbor Discovery Protocol?

By using the link-local address, the host of the IPv6 can auto-configure it by joining a number of multicast groups. The multicast addresses are used for all the communications related to that segment. In IPv6, a series of states are undergone such as:

  • Neighbour Solicitation: Once all the IPv6s are configured either by DHCP server or by auto-configuration, a neighbour solicitation message is sent by the host out to FF02::1/16 multicast address for all the IPv6 addresses to convey that nobody else can occupy the same address.
  • DAD (Duplicate Address Detection): No duplicate address exists on the segment when the host does not listen anything from the segment regarding Neighbour Solicitation message.
  • Neighbour Advertisement: Once the addresses are assigned and made ready for running, a neighbour advertisement message is sent by the host to other hosts on the segment, that it has assigned those IPv6 addresses.

Once the IPv6 addresses are configured with the host, the following happen:

  • Router Solicitation: A router Solicitation multicast packet (FF02::2/16) is sent by the host onto its segment to identify the presence of any router on the segment. The host is facilitated to configure the router as default gateway. The host shifts to a new router if the default gateway router goes down and the new router becomes the default gateway.
  • Router Advertisement: When a router receives a Router Solicitation message, it response back to the host, advertising its presence on that link.
  • Redirect: A Router Solicitation request is received by the router but is considered as the best gateway for the host. In such instances, a redirect message is sent back by the router conveying that the host will send its data destined to a host which does not belong to the same segment.

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Internet Protocol version 6 (IPv6) Topics