NDP - IPv6 Neighbor Discovery Protocol

Neighbor Discovery Protocol is used by IPv6 hosts for an expansion of responsibilities referring to the local place network. further, it also works with ICMPv6 to complete some of operations. The primary duties for NDP are Router Discovery, Neighbor Discovery and copy address Discovery. It was devised specifically due to the truth that IPv6 does now not permit for announces and consequently ARP (deal with resolution Protocol) as used with IPv4 isn't in operation.

Router Discovery

although there is a model of DHCP that may be used with IPv6, another option is to locate the nearby router which can offer facts relating to DHCP servers and also provide an cope with prefix so that hosts can configure their own IP Addresses. when a number is first related to a link it mechanically multicasts a Router Solicitation message to the All Routers multicast group deal with. Any routers lively at the link will reply with a Router commercial message to the All Hosts multicast group address. The Router advertisement message can indicate a spread of information.

Contained inside the Router advertisement message is an cope with prefix or a couple of prefixes regarding subnets to be had at the nearby hyperlink. The Host then is aware of which subnet or subnets are nearby and do no longer need the help of the nearby router to reach. The Host can routinely configure it's personal IP cope with with the aid of the usage of the prefix and EUI-sixty four guidelines. This involves including an EUI-sixty four interface identifier derived from the interface MAC address to the marketed prefix. The Interface Identifier part of the IPv6 IP address is used to identify a completely unique physical interface on a link. The 48 bit MAC address is separated into 2 x 3 bytes (24 bits), with the first three bytes realize as the OUI (Organisational specific Identifier), generally referred to as the vendor wide variety. 16 additional bits are inserted between the 3rd and 4th byte, and those bits are represented by the Hexadecimal variety FFFE. The U/L bit, being the seventh bit inside the excessive order byte is ready to a cost of 1 to signify a international Scope. The system of a number robotically configuring it's IP cope with from the given prefix is known as Stateless Autoconfiguration. moreover the Router advertisement message additionally carries the default hop be counted that Hosts have to use.

Neighbor Discovery

NDP Hosts can use other Solicitation and advertisement Messages for use with neighboring Hosts, including Neighbor Solicitation and Neighbor advertisement messages:

Neighbor Solicitation messages can be utilized by Hosts on the LAN to attain MAC addresses of other Hosts, that's a characteristic supplied by using ARP with IPv4. The message is despatched to the solicited-node multicast address that is associated with a group of hosts matching the final 6 bits of the cope with.

Neighbor commercial messages are sent in response to Neighbor Solitication messages and comprise the Senders IPv6 address and MAC address. In some times Hosts can send unsolicited NA messages which would be despatched to the All Hosts multicast deal with of FF02::1.

duplicate deal with Detection

as well as sending out a Router Solicitation message when becoming a member of a hyperlink, a bunch also sends out a Neighbor Solicitation message for it's personal IP deal with to make sure no different Host is configured with the equal IPv6 address. If a number gets a response then it knows that deal with can not be used and configures some other address. that is just like the method of Gratuitous ARP, as used with IPv4.