To allow down-level devices to participate in a network controlled by a protocol including CGAS or ECGAs, the CGA or ECGA authentication may be made optional to allow the down-level devices to execute non-CGA or non-ECGA versions of network protocols, while at the same time allowing the use of CGA- and/or ECGA-authenticated versions of the same protocols. To identify non-cryptographic addresses (e.g., non-CGA and non-ECGA), the address bits of a non-CGA or non-ECGA such that the address cannot be or is probably not an encoding of the hash of a public key. In this manner, a receiving node may properly identify the capabilities of the sending node, perform an appropriate authentication of the message containing the non-cryptographic address, and/or prioritize processing of information contained in the message with the non-cryptographic address.