The address type of this interface. This entry along with the ifIndex value acts as the index to the mgmdRouterInterface table. A physical interface may be configured in multiple modes concurrently, e.g. in IPv4 and IPv6 modes connected to the same interface, however the traffic is considered to be logically separate.
Sources for this description
D-Link official switch MIBsD-Link MIB copies (LibreNMS/Observium Community)