RFC 9792: Prefix Flag Extension for OSPFv2 and OSPFv3

Each OSPF prefix can be advertised with an 8-bit field to indicate specific properties of that prefix. However, all the OSPFv3 Prefix Options bits have already been assigned, and only a few bits remain unassigned in the Flags field of the OSPFv2 Extended Prefix TLV. This document solves this problem by defining a variable-length Prefix Extended Flags sub-TLV for OSPF. This sub-TLV is applicable to OSPFv2 and OSPFv3.