SLAAC Only Method
The SLAAC only method is enabled by default when the ipv6 unicast-routing command is configured. All enabled Ethernet interfaces with an IPv6 GUA configured will start sending RA messages with the A flag set to 1, and the O flag and M flag set to 0
The A = 1 flag suggests to the client that it create its own IPv6 GUA using the prefix advertised in the RA. The client can create its own Interface ID using either *Extended Unique Identifier method (EUI-64) or have it *Randomly Generated.
The O=0 and M=0 flags instruct the client to use the information in the RA message exclusively. The RA includes the prefix, prefix-length, DNS server, MTU, and default gateway information. There is no further information available from a DHCPv6 server.
- Randomly generated – The 64-bit interface ID is randomly generated by the client operating system. This is the method now used by Windows 10 hosts.
- EUI-64 – The host creates an interface ID using its 48-bit MAC address and inserts the hex value of fffe in the middle of the address. Some operating systems default to the randomly generated interface ID instead of the EUI-64 method, due to privacy concerns. This is because the Ethernet MAC address of the host is used by EUI-64 to create the interface ID.
IPv6 SLAAC Configuration
Enable IPv6 Unicast Routing
R1(config)# ipv6 unicast-routing
Enter interface configuration mode
R1(config)# interface [interface]
Configure an IPv6 address
R1(config-if)# ipv6 address [ipv6-address/prefix-length]
Configure an IPv6 Link-Local address
R1(config-if)# ipv6 address [ipv6-address] link-local
Enable the Interface
R1(config-if)# no shutdown R1(config-if)# exit R1(config)#
IPv6 SLAAC Only Complete Configuration example
R1> enable R1# configure terminal R1(config)# ipv6 unicast-routing R1(config)# interface fa0/0 R1(config-if)# ipv6 address 2001:db8:cafe:1::1/64 R1(config-if)# ipv6 address fe80::1 link-local R1(config-if)# no shutdown R1(config-if)# exit R1(config)#