Techniques are disclosed for a link state routing protocol adjacency state machine. The adjacency state machine ensures that first and second logical links using different networking protocols are established on a single physical link between two network devices prior to indicating adjacency between the network devices. In some examples, the adjacency state machine determines that both the first and second links are active in response to determining that hello messages are generated by both network devices for both links. In some examples, the adjacency state machine determines that both the first and second logical links are active upon expiration of a predetermined time corresponding to a time required for a duplicate address detection (DAD) operation to complete. In some examples, the first and second logical links use Internet Protocol version 4 (IPv4) and Internet Protocol version 6 (IPv6), respectively.