Cisco Catalyst 3560-X Series, Software Configuration Manual

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Catalyst 3750-X and 3560-X Switch Software Configuration Guide
OL-25303-03
Chapter 1 Configuring SNMP
Understanding SNMP
These sections contain this conceptual information:
• SNMP Versions, page 1-2
•
SNMP Manager Functions, page 1-3
• SNMP Agent Functions, page 1-4
•
SNMP Community Strings, page 1-4
• Using SNMP to Access MIB Variables, page 1-4
•
SNMP Notifications, page 1-5
• SNMP ifIndex MIB Object Values, page 1-5
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.
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.