SLAAC Option (Router Advertisement only)

SLAAC is the default option on Cisco routers. Both the M flag and the O flag are set to 0 in the RA, as shown in the figure.

This option instructs the client to use the information in the RA message exclusively. This includes prefix, prefix-length, DNS server, MTU, and default gateway information. There is no further information available from a DHCPv6 server. The IPv6 global unicast address is created by combining the prefix from RA and an Interface ID using either EUI-64 or a randomly generated value.

RA messages are configured on an individual interface of a router. To re-enable an interface for SLAAC that might have been set to another option, the M and O flags need to be reset to their initial values of 0. This is done using the following interface configuration mode commands:

Router(config-if)# no ipv6 nd managed-config-flag

Router(config-if)# no ipv6 nd other-config-flag