eap_config::eap_fast_a_id field

eap_fast_a_id - EAP-FAST authority identity (A-ID) If EAP-FAST is not used, this can be set to %NULL. In theory, this is a variable length field, but due to some existing implementations requiring A-ID to be 16 octets in length, it is recommended to use that length for the field to provide interoperability with deployed peer implementations.