Site-local IPv6 Address

Site-local IPv6 address is similar to private IPv4 address defined in RFC 1918. This site-local address is for private network. It cannot be used on public IPv6 network, only routable within private network. Site-local IPv6 address is started with 1111 1110 1100, is denoted as FEC0::/10.

To prevent Site-local IPv6 address on public, you can filter FEC0:10 on your egress filtering of WAN link.

Cisco_IPv6_1(config)# interface fastethernet0/0
Cisco_IPv6_1(config-if)# ipv6 address FEC0::/64 eui-64

Cisco_IPv6_1# show ipv6 interface brief
FastEthernet0/0            [up/up]
    FE80::CE00:3BFF:FE85:0
    FEC0::CE00:3BFF:FE85:0
FastEthernet0/1            [administratively down/down]
 

Pinging to site-local IPv6 address from other site of router.

Cisco_IPv6_2# ping ipv6  FEC0::CE00:3BFF:FE85:0

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to FEC0::CE00:3BFF:FE85:0, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 4/4/4 ms