Managing Serviceguard Nineteenth Edition, Reprinted June 2011

::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:
64 bits16248133
Interface IDSLA IDNLA IDRESTLA IDFP
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:
64 bits54 bits10 bits
interface ID01111111010
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:
64 bits16 bits38 bits10 bits
interface IDsubnet ID01111111011
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:
112 bits4 bits4 bits8 bits
group IDscopflags11111111
“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:
366 IPv6 Network Support