HP Cisco Nexus 5000 Cisco Nexus 5000 Series Switch CLI Software Configuration - Page 422

SNMP Notifications Information About SNMP The Cisco Nexus 5000 Series switch supports SNMPv1, SNMPv2c and SNMPv3. Both SNMPv1 and SNMPv2c use a community-based form of security. SNMP is defined in RFC 3410 (http://tools.ietf.org/html/rfc3410), RFC 3411 (http://tools.ietf.org/html/rfc3411), RFC 3412 (http://tools.ietf.org/html/rfc3412), RFC 3413 (http://tools.ietf.org/html/rfc3413), RFC 3414 (http://tools.ietf.org/html/rfc3414), RFC 3415 (http://tools.ietf.org/html/rfc3415), RFC 3416 (http://tools.ietf.org/html/rfc3416), RFC 3417 (http://tools.ietf.org/html/rfc3417), RFC 3418 (http://tools.ietf.org/html/rfc3418), and RFC 3584 (http://tools.ietf.org/html/rfc3584). SNMP Notifications A key feature of SNMP is the ability to generate notifications from an SNMP agent. These notifications do not require that requests be sent from the SNMP manager. Notifications can indicate improper user authentication, restarts, the closing of a connection, loss of connection to a neighbor router, or other significant events. Cisco NX-OS generates SNMP notifications as either traps or informs. Traps are less reliable than informs because the SNMP manager does not send any acknowledgment when it receives a trap. The switch cannot determine if the trap was received. An SNMP manager that receives an inform request acknowledges the message with an SNMP response protocol data unit (PDU). If the Cisco Nexus 5000 Series switch never receives a response, it can send the inform request again. You can configure Cisco NX-OS to send notifications to multiple host receivers. Related Topics • Configuring SNMP Notification Receivers, page 380 SNMPv3 SNMPv3 provides secure access to devices by a combination of authenticating and encrypting frames over the network. The security features provided in SNMPv3 are the following: • Message integrity-Ensures that a packet has not been tampered with in-transit. • Authentication-Determines the message is from a valid source. • Encryption-Scrambles the packet contents to prevent it from being seen by unauthorized sources. SNMPv3 provides for both security models and security levels. A security model is an authentication strategy that is set up for a user and the role in which the user resides. A security level is the permitted level of security within a security model. A combination of a security model and a security level determines which security mechanism is employed when handling an SNMP packet. Security Models and Levels for SNMPv1, v2, v3 The security level determines if an SNMP message needs to be protected from disclosure and if the message needs to be authenticated. The various security levels that exist within a security model are as follows: • noAuthNoPriv-Security level that does not provide authentication or encryption. • authNoPriv-Security level that provides authentication but does not provide encryption. • authPriv-Security level that provides both authentication and encryption. Three security models are available: SNMPv1, SNMPv2c, and SNMPv3. The security model combined with the security level determine the security mechanism applied when the SNMP message is processed. Cisco Nexus 5000 Series Switch CLI Software Configuration Guide 376 OL-16597-01