A)Link-Local (FE80::/10)
When an IPv6 stack is enabled, link-local address is automatically assigned to each interface. The IPv6 link-local prefix FE80::/10 is used and the interface identifier in Extended Unique Identifier 64 (EUI-64) format is appended as the address's low-order 64-bit. Link-local addresses are only for local-link scope and must never be routed between subnets within a site.
Example
RouterA(config-if)#ipv6 address FE80:0:0:0:1001:1234:5678:00AB link-local
The link-local address is configured here. This command with the link-local argument can be used to override the default link-local address assigned by the router.
You can also enable just IPv6 on an interface without specifying an aggregatable global unicast or site-local address by using the ipv6 enable command, as shown here:
Router(config-if)#ipv6 enable
This command also automatically configures the link-local address on the interface.B)Site-Local (FEC0::/10) - Deprecated in RFC 3879 and replaced with Unique Local IPv6 Unicast Addresses fc00::/7 - RFC 4193, fd00::/8 localli assigned ULA
A site-local address is used only within a site. Site-local addresses are not enabled by default on nodes like link-local addresses, meaning that they must be assigned.
A site-local address is similar to private address spaces in IPv4. A site-local prefix and address may be assigned to any nodes and routers within a site. However, site-local addresses must never be routed on the global IPv6 Internet.
Usage:Printers,Intranet servers, Network switches, bridges, gateways, wireless access points and any servers and routers that must only be reached internally for management purposes
Example
RouterA(config-if)#ipv6 address FEC0:0:0:1001::1/64
The site-local address is configured on the interface. After the completion of this command, the link-local address is automatically configured.
In the following example, the site-local prefix FEC0:0:0:1001::/64 is used to configure the address. The site-local and link-local addresses are automatically configured:
RouterA(config-if)#ipv6 address FEC0:0:0:1::/64 eui-64
***Take note that the Site-local will appear under the Global Unicast Address field same as Aggregate Global Unicast Address, the only way to know that it is site-local is by the first 4 hexadecimal value FEC0.
C)Aggregatable Global Unicast Address
Each global unicast IPv6 address has three parts:
- Prefix received from a provider— The prefix assigned to an organization by a provider should be at least a /48 prefix. The /48 prefix represents the high-order 48-bit of the network prefix.
- Site— With one /48 prefix allocated to an organization by a provider, it is possible for that organization to enable up to 65,535 subnets (assignment of 64-bit's prefix to subnets).
- Host— The host part uses each node's interface identifier. This part of the IPv6 address, which represents the address's low-order 64-bit, is called the interface ID.
Example
RouterA(config-if)#ipv6 address 2001:0c20:0:1001:0:0:0:1abc/64
The aggregatable global unicast address is configured on the interface. After the completion of this command, the link-local address is automatically configured.
In the following example, the aggregatable global unicast prefix 2001:0c20:0:1001::/64 is used to configure the address. The aggregatable global unicast and link-local addresses are automatically configured:
RouterA(config-if)#ipv6 address 2001:0c20:0:1001::/64 eui-64
