IPAM type. The following types are supported:
(1) For underlay_l2, overlay_l2, and vpc-router networking, only the default value distributed_l2 is supported.
(2) For underlay_ipvlan networking, the default value is distributed_l2. In the CCN scenario, only null and fixed are supported. In the CCE and FST 5G core scenarios, only null and distributed_l2 are supported.
(3) For phy-direct and dpdk-direct networking, the default value is l2, and optional values are null and distributed_l2. In the FST 5G core scenario, only null and distributed_l2 are supported.
If the value is out of the range (for example, host-local), Canal automatically sets the value to the default value and no error is returned.
null: Canal is not used to manage IP addresses.
fixed: fixed IP address, which is used in the CCN scenario.
l2: This value is not used in any scenario.
distributed_l2: The distributed small subnet is used to manage IP addresses.