Cisco Systems 3750E manual Snmp Versions, 33-2

Chapter 33 Configuring SNMP

Understanding SNMP

These sections contain this conceptual information:

•SNMP Versions, page 33-2

•SNMP Manager Functions, page 33-3

•SNMP Agent Functions, page 33-4

•SNMP Community Strings, page 33-4

•Using SNMP to Access MIB Variables, page 33-4

•SNMP Notifications, page 33-5

•SNMP ifIndex MIB Object Values, page 33-6

SNMP Versions

This software release supports these SNMP versions:

•SNMPv1—The Simple Network Management Protocol, a Full Internet Standard, defined in RFC 1157.

•SNMPv2C replaces the Party-based Administrative and Security Framework of SNMPv2Classic with the community-string-based Administrative Framework of SNMPv2C while retaining the bulk retrieval and improved error handling of SNMPv2Classic. It has these features:

–SNMPv2—Version 2 of the Simple Network Management Protocol, a Draft Internet Standard, defined in RFCs 1902 through 1907.

–SNMPv2C—The community-string-based Administrative Framework for SNMPv2, an Experimental Internet Protocol defined in RFC 1901.

•SNMPv3—Version 3 of the SNMP is an interoperable standards-based protocol defined in

RFCs 2273 to 2275. SNMPv3 provides secure access to devices by authenticating and encrypting packets over the network and includes these security features:

–Message integrity—ensuring that a packet was not tampered with in transit

–Authentication—determining that the message is from a valid source

–Encryption—mixing the contents of a package to prevent it from being read by an unauthorized source.

Note To select encryption, enter the priv keyword. This keyword is available only when the cryptographic (encrypted) universal software image is installed.

Both SNMPv1 and SNMPv2C use a community-based form of security. The community of managers able to access the agent’s MIB is defined by an IP address access control list and password.

SNMPv2C includes a bulk retrieval mechanism and more detailed error message reporting to management stations. The bulk retrieval mechanism retrieves tables and large quantities of information, minimizing the number of round-trips required. The SNMPv2C improved error-handling includes expanded error codes that distinguish different kinds of error conditions; these conditions are reported through a single error code in SNMPv1. Error return codes in SNMPv2C report the error type.

SNMPv3 provides for both security models and security levels. A security model is an authentication strategy set up for a user and the group within which the user resides. A security level is the permitted level of security within a security model. A combination of the security level and the security model determine which security mechanism is used when handling an SNMP packet. Available security models are SNMPv1, SNMPv2C, and SNMPv3.

Catalyst 3750-E and 3560-E Switch Software Configuration Guide

33-2 OL-9775-02