IPv6 Neighbor Discovery (ND) is a set of messages and processes that determine relationships between neighboring nodes. ND replaces Address Resolution Protocol (ARP), Internet Control Message Protocol (ICMP) Router Discovery, and ICMP Redirect, which are used in IPv4, and provides additional functionality. ND is described in RFC 2461, "Neighbor Discovery for IP Version 6 (IPv6)."
ND is used by hosts to:
-
Discover neighboring routers.
- Discover addresses, address prefixes, and other configuration parameters.
-
Advertise their presence, host configuration parameters, and on-link prefixes.
-
Inform hosts of a better next-hop address to forward packets for a specific destination.
-
Both resolve the link-layer address of a neighboring node to which an
IPv6 packet is being forwarded and determine when the link-layer address
of a neighboring node has changed.
-
Determine whether IPv6 packets can be sent to and received from a neighbor.
| Process | Description |
|---|---|
|
Router discovery |
The process by which a host discovers the local routers
on an attached link (equivalent to ICMPv4 Router Discovery) and
automatically configures a default router (equivalent to a default
gateway in IPv4). |
|
Prefix discovery |
The process by which a host discovers the network prefixes for local destinations. |
|
Parameter discovery |
The process by which a host discovers additional
operating parameters, including the link maximum transmission unit (MTU)
and the default hop limit for outbound packets. |
|
Address autoconfiguration |
The process for configuring IP addresses for interfaces
in either the presence or absence of a stateful address configuration
server such as Dynamic Host Configuration Protocol version 6 (DHCPv6).
For more information, see IPv6 address autoconfiguration. |
|
Address resolution |
The process by which a node resolves a neighboring
node's IPv6 address to its link-layer address (equivalent to ARP in
IPv4). The resolved link-layer address becomes an entry in a node's
neighbor cache (equivalent to the ARP cache in IPv4). You can use the netsh interface ipv6 show neighbors
command to view the contents of the neighbor cache on a computer
running the Windows Server 2003 family and Windows XP. The neighbor
cache displays the interface identifier for the neighbor cache entry,
the neighboring node's IPv6 address, the corresponding link-layer
address, and the state of the neighbor cache entry. For more
information, see View the neighbor cache and Netsh commands for Interface IPv6. |
|
Next-hop determination |
The process by which a node determines the IPv6 address
of the neighbor to which a packet is being forwarded based on the
destination address. The forwarding or next-hop address is either the
destination address of the packet being sent or the address of a
neighboring router. The resolved next hop address for a destination
becomes an entry in a node's destination cache (also known as a route
cache). You can use the netsh interface ipv6 show destinationcache
command to view the contents of the destination cache on a computer
running the Windows Server 2003 family and Windows XP. The destination
cache displays the destination address, the interface identifier and
next-hop address, the interface identifier and address used as a source
address when sending to the destination, and the path MTU for the
destination. For more information, see View the destination cache and Netsh commands for Interface IPv6. |
|
Neighbor unreachability detection |
The process by which a node determines that IPv6
packets cannot be sent to and received from a neighboring node. After
the link-layer address for a neighbor has been determined, the state of
the entry in the neighbor cache is tracked. If the neighbor is no longer
receiving and sending back packets, the neighbor cache entry is
eventually removed. Neighbor unreachability detection provides a
mechanism for IPv6 to determine that neighboring hosts or routers are no
longer available on the local network segment. |
|
Duplicate address detection |
The process by which a node determines that an address
considered for use is not already in use by a neighboring node
(equivalent to the use of gratuitous ARP frames in IPv4). |
|
Redirect function |
The process by which a router informs a host of a
better first-hop IPv6 address to reach a destination (equivalent to the
function of the IPv4 ICMP Redirect message). |
IPv6 is a rapidly evolving standard. The RFCs referenced might have been made obsolete by newer RFCs.
Source:
http://www.technet.microsoft.com
Published By
S.G.Godwin Dinesh.MCA
Sr.System Administrator
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