In first place if you decided to use IPV6 ip for the APs then the important point to note, You can provision an IPv6 AP in the network only if the controller interface is configured with an IPv6 address.
We are going to discuss about a scenario where the controller interface is configured with IPV4 address, but IPV6 is configured on network. When AP boots it gets an ip address from IPV6 through network but keeps failing to provision the controller and gets in to a reboot loop.
The cause for this behavior is because the controller interface is configured with an IPV4 address.
To overcome this situation we could use the following step to resolve this issue
We can set 'M’ bit - "Managed address configuration" flag to 0 or also set the ‘O’ bit - "Other configuration" flag to 1 on the network end will resolve the issue.
A DHCPv6 client will know when it wants to use DHCPv6 either based upon instruction of an attached router, or when no default gateway is present. The default gateway has two configurable bits in an Router Advertisement (RA) available for this purpose:
• ‘M’ bit - "Managed address configuration" flag. When set, it indicates that the client may use DHCPv6 to retrieve a Managed IPv6 address from a DHCPv6 server. If the M flag is set, the O flag is
redundant and can be ignored because DHCPv6 will return all available configuration information.
• ‘O’ bit - "Other configuration" flag. When set , indicates that other configuration information is available via DHCPv6. Examples of such information are DNS-related information or information on other servers within the network.
M = 0, O = 0 : Client uses RA to get non-link-local address and other settings. Even DHCPv6 server exists, client ignores it.
M = 1, O = 0 : Client uses DHCPv6 for both address and other configuration settings. This combination is known as DHCPv6 stateful, in which
M = 1, O = 1 : DHCPv6 is assigning stateful address to client. If RA includes network prefix, client also gets stateless address.
M = 0, O = 1 : Client gets stateless address from RA. DHCPv6 only assign other configuration settings to client. This combination is known as DHCPv6 stateless.