Information Technology Reference
In-Depth Information
Ta b l e 9 - 3
IPv6 Prefix Allocation
Binary Prefix
Hexadecimal/Prefix
Allocation
1110
E000::/3
Unassigned
1111 0
F000::/5
Unassigned
1111 10
F800::/6
Unassigned
1111 110
FC00::/7
Unique Local Unicast
1111 1110 0
FE00::/9
Unassigned
1111 1110 10
FE80:/10
Link-local unicast addresses
1111 1110 11
FEC0::/10
Unassigned; was site-local unicast addresses
(deprecated)
1111 1111
FF00::/8
Multicast addresses
An unspecified address is all 0s: 0:0:0:0:0:0:0:0. It signifies that an IPv6 address is not
specified for the interface. Unspecified addresses are not forwarded by an IPv6 router.
The IPv6 loopback address is 0:0:0:0:0:0:0:1. This address is similar to the IPv4 loopback
address of 127.0.0.1.
IPv6 Unicast Address
The IPv6
unicast
(one-to-one) address is the logical identifier of a single-host interface.
With a unicast address, a single source sends to a single destination. It is similar to IPv4
unicast addresses. Unicast addresses are divided into
Key
To p i c
Link-local address scope
■
Unique-local address scope
■
Global aggregatable address scope
■
IPv4-compatible IPv6 addresses
■
Global Unicast Addresses
IPv6 global addresses connect to the public network. These unicast addresses are globally
unique and routable. This address format is initially defined in RFC 2374. RFC 3587 pro-
vides updates to the format.
The original specification defined the address format with a three-layer hierarchy: public
topology, site topology, and interface identifier. The
public topology
consisted of service
providers that provided transit services and exchanges of routing information. It used a
top-level aggregator (TLA) identifier and a next-level identifier. A site-level aggregator
(SLA) was used for site topology. The
site topology
is local to the company or site and
