In SNMPv3, security is paramount and each SNMP entity (client or agent) needs to have a user with a security name (username) and optionally, a security level which determines whether authentication and encryption are used. When configuring SNMPv3 users on network infrastructure devices, it is essential to match the username, authentication (auth) algorithm, authentication key (auth key), privacy (priv) algorithm, and privacy key (priv key) exactly as they are configured on the SNMP server to ensure successful communication.

This is because the SNMPv3 security model relies on a combination of a username and a pair of keys (authentication and privacy keys) to uniquely identify and secure communication between the agent and the manager. The keys are used to verify the integrity (auth key) and confidentiality (priv key) of the messages. Using the same algorithms ensures that the messages can be properly encrypted and decrypted on both ends.