Communication in IPV6

In IPV6 we dont have any broadcast technique for delivering message and data.

The IPV6 can not be dependent on the DHCP Dynamic Host Control Protocol for the configuration , it also auto configure its own IP.

ARP has been replaced by ICMPv6 Neighbor Discovery Protocol.

Neighbor Discovery Protocol

A terminal in the IPV6 network can perform auto-configuring with a unique address. As soon it gets the IP address , it will join the multicast group. All the communication then will be made by using that multicast address.

• Neighbor Solicitation:After auto configuration all the IPV6 terminals in the network the host will send a message called as solicitation message to all the nodes for informing that this particular address is occupied by me no one else occupies it.

• DAD (Duplicate Address Detection): When the host does not listen from anything from the segment regarding its Neighbor Solicitation message, it assumes that no duplicate address exists on the segment.

• Neighbor Advertisement: After assigning the addresses to its interfaces and making them up and running, the host once again sends out a Neighbor Advertisement message telling all other hosts on the segment, that it has assigned those IPv6 addresses to its interfaces.

Once a host is done with the configuration of its IPv6 addresses, it does the following things:

• Router Solicitation: A host sends a Router Solicitation multicast packet out on its segment to know the presence of any router on this segment. It helps the host to configure the router as its default gateway. If its default gateway router goes down, the host can shift to a new router and makes it 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: This may be the situation where a Router receives a Router Solicitation request but it knows that it is not the best gateway for the host. In this situation, the router sends back a Redirect message telling the host that there is a better ‘next-hop’ router available. Next-hop is where the host will send its data destined to a host which does not belong to the same segment.