Explain the “M” and “O” bit in IPv6 DHCP server configuration. What are the associated flags ?
This article applies to Aruba Mobility Controllers running ArubaOS version 18.104.22.168.
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:
redundant and can be ignored because DHCPv6 will return all available configuration information.
When a router sends an RA with ‘O’ bit set, but does not set the ‘M’ bit, the client can do Stateless Address Autoconfiguration (SLAAC) to obtain its IPv6 address, and use DHCPv6 for obtaining additional information. (An example of additional information is DNS). This mechanism is well known as Stateless DHCPv6, because the DHCPv6 server does not need to keep track of the client address bindings.
- In the Router Advertisement the fags M = 0, O = 1 is set as below