HP Serviceguard Aggregatable Global Unicast Addresses, Link-Local Addresses, Site-Local Addresses

::ffff:192.168.0.1

Aggregatable Global Unicast Addresses

The global unicast addresses are globally unique IPv6 addresses. This address format is very well defined in the RFC 2374 (An IPv6 Aggregatable Global Unicast Address Format). The format is:

3	13	8	24	16	64 bits
FP	TLA ID	RES	NLA ID	SLA ID	Interface ID

where: FP = Format prefix. Value of this is “001” for Aggregatable Global unicast addresses. TLA ID = Top-level Aggregation Identifier.

RES = Reserved for future use.

NLA ID = Next-Level Aggregation Identifier.

SLA ID = Site-Level Aggregation Identifier. Interface ID = Interface Identifier.

Link-Local Addresses

Link-local addresses have the following format:

10 bits	54 bits	64 bits
1111111010	0	interface ID

Link-local address are supposed to be used for addressing nodes on a single link. Packets originating from or destined to a link-local address will not be forwarded by a router.

Site-Local Addresses

Site-local addresses have the following format:

10 bits	38 bits	16 bits	64 bits
1111111011	0	subnet ID	interface ID

Link-local address are supposed to be used within a site. Routers will not forward any packet with site-local source or destination address outside the site.

Multicast Addresses

A multicast address is an identifier for a group of nodes. Multicast addresses have the following format:

8 bits	4 bits	4 bits	112 bits
11111111	flags	scop	group ID

“FF” at the beginning of the address identifies the address as a multicast address.

The “flgs” field is a set of 4 flags “000T”. The higher order 3 bits are reserved and must be zero. The last bit ‘T’ indicates whether it is permanently assigned or not. A value of zero indicates that it is permanently assigned otherwise it is a temporary assignment.

The “scop” field is a 4-bit field which is used to limit the scope of the multicast group. For example, a value of ‘1’ indicates that it is a node-local multicast group. A value of ‘2’ indicates that the scope is link-local. A value of “5” indicates that the scope is site-local.

The “group ID” field identifies the multicast group. Some frequently used multicast groups are the following:

380 IPv6 Network Support