currently supports the implementation of this capability and prefers to use this address for outgoing communication, because the address has a short lifetime and is regenerated periodically. Web Links RFC 3041
ftp://ftp.rfc-editor.org/in-notes/rfc3041.txt

Content 8.3 Dynamic IPv6 Addresses 8.3.5 IPv6 over Data Link Layers Although the redistribution command is available for all IP routing protocols, it behaves differently depending on the actual IP routing protocols involved. However, the underlying principles are the same. Therefore, the examples in this section can be used as a starting point for any redistribution scheme. The data link layer defines how IPv6 interface identifiers are created and how neighbor discovery deals with data link layer address resolution. IPv6 is defined on most of the current data link layers, including the following:

Ethernet*
PPP*
High-Level Data Link Control (HDLC)*
FDDI
Token Ring
Attached Resource Computer Network (ARCNET)
Nonbroadcast multiaccess (NBMA)
ATM**
Frame Relay***
IEEE 1394

* Cisco supports these data link layers.
** Cisco supports only ATM permanent virtual circuit (PVC) and ATM LAN Emulation (LANE).
*** Cisco supports only Frame Relay PVC.

An RFC describes the behavior of IPv6 in each of these specific data link layers, but Cisco IOS software does not necessarily support all of them.

Content 8.3 Dynamic IPv6 Addresses 8.3.6 IPv6 Multicasting A multicast address identifies a group of interfaces. Traffic sent to a multicast address travels to multiple destinations at the same time. An interface may belong to any number of multicast groups. Multicasting is extremely important to IPv6, because it is at the core of many IPv6 functions. The format of the multicast address is as follows:

IPv6 multicast addresses are defined by the prefix FF00::/8. The second octet defines the lifetime (flag) and the scope of the multicast address.
- The flag parameter is equal to 0 for a permanent, or well-known, multicast address. For a temporary multicast address, the flag is equal to 1.
- The scope parameter is equal to 1 for the scope of the interface (loopback transmission), 2 for the link scope (similar to unicast link-local scope), 3 for subnet-local scope where subnets may span multiple links, 4 for admin-local scope (administratively configured), 5 for the site scope, 8 for the organizational scope (multiple sites), and E for the global scope. For example, a multicast address starting with FF02::/16 is a permanent multicast address with a link-local scope.
The multicast group ID consists of the lower 112 bits of the multicast address.

Multicast is frequently used in IPv6 and replaces broadcast. There is no broadcast in IPv6. There is no Time to Live (TTL) in IPv6 multicast. The scoping is defined inside the address. Web Links Implementing IPv6 Multicast
http://cisco.com/en/US/products/sw/iosswrel/
ps5187/products_configuration_guide_chapter
09186a00801d6618.html

Content 8.3 Dynamic IPv6 Addresses 8.3.7 Permanent Multicast Addresses The multicast addresses, FF00:: to FF0F::, are reserved. Within that range, the following are some examples of assigned addresses. Assignments are tracked by IANA.

FF02::1 — All nodes on link (link-local scope).
FF02::2 — All routers on link.
FF02::9 — All IPv6 Routing Information Protocol (RIP) routers on link.
FF02::1:FFXX:XXXX — Solicited-node multicast on link, where XX:XXXX is the rightmost 24 bits of the corresponding unicast or anycast address of the node. (Neighbor solicitation messages are sent on a local link when a node wants to determine the link-layer address of another node on the same local link, similar to Address Resolution Protocol [ARP] in IPv4.)
FF05::101 — All Network Time Protocol (NTP) servers in the site (site-local scope).

The site-local multicast scope has an administratively assigned radius and has no direct correlation to the (now deprecated) site-local unicast prefix of FEC0::/10.

Content 8.3 Dynamic IPv6 Addresses 8.3.8 Addresses That Are Not Unique In very rare cases, the rightmost 24 bits of the unicast address of the target is not unique on the link. Solicited–node multicast addresses are used in IPv6 for address resolution of an IPv6 address to a MAC address on a LAN segment. For example, consider two nodes with addresses 2001:DB8:200:300:400:500:aaaa:bbbb and 2001:DB8:200:300:400:501:aaaa:bbbb, where the link prefix is 2001:DB8:200:300::/64. These two nodes would be listening to the same solicited-node multicast address. Each would receive the multicast packet, but only the node whose full address matched the full target address of the multicast packet (embedded in the data field of the multicast packet) would respond with a neighbor advertisement (which includes the actual MAC address). The other node would receive the multicast packet, but upon inspection of the embedded target address would realize that it was not the intended recipient of the request and would not respond. The following describes how this situation works. Node A has this characteristic:

Address 2001:DB8:200:300:400:500:1234:5678

Node B has these characteristics:

Address 2001:DB8:200:300:500:AAAA:BBBB
Solicited-node multicast address FF02:0:0:0:0:1:FFAA:BBBB (the same as node C)

Node C has these characteristics:

Address 2001:DB8:200:300:501:AAAA:BBBB
Solicited-node multicast address FF02:0:0:0:0:1:FFAA:BBBB (the same as node B)

Node A desires to exchange packets with node B. Node A sends a neighbor discovery packet to the solicited-node multicast address of B, FF02:0:0:0:0:1:AAAA:BBBB. Inside the packet, in addition to other data, is the full IPv6 address that node A is looking for (2001:DB8:200:300:500:AAAA:BBBB). This is called the target address.
Both node B and node C are listening to the same multicast address, so they both receive and process the packet.
Node B sees that the target address inside the packet is its own and responds.
Node C sees that the target address inside the packet is not its own and does not respond.

In this manner, nodes can have the same solicited-node multicast address on the link without causing neighbor discovery, neighbor solicitation, or neighbor advertisement to malfunction.

Content 8.3 Dynamic IPv6 Addresses 8.3.9 Anycast An IPv6 anycast address is a global unicast address that is assigned to more than one interface. When a packet is sent to an anycast address, it is routed to the “nearest” interface having that address. In a WAN scope, the nearest interface is found according to the measure of distance of the routing protocol. In a LAN scope, the nearest interface is found according to the first neighbor that is learned about. The following describes the characteristics of an anycast address:

Anycast addresses are allocated from the unicast address space, so they are indistinguishable from the unicast address. When assigned to a node interface, the node must be explicitly configured to know that the address is an anycast address.
The idea of anycast in IP was proposed in 1993. For IPv6, anycast is defined as a way to send a packet to the nearest interface that is a member of the anycast group, which enables a type of discovery mechanism to the nearest point.
There is little experience with widespread anycast usage. A few anycast addresses are currently assigned, including the router-subnet anycast and the Mobile IPv6 home agent anycast.
An anycast address must not be used as the source address of an IPv6 packet.

Content 8.3 Dynamic IPv6 Addresses 8.3.10