Cisco IE 4000, Software Configuration Manual

Page: 532 / 1066

528
Configuring SNMP
Information About SNMP
Information About SNMP
SNMP
The Simple Network Management Protocol (SNMP) is an application-layer protocol that provides a message format for
communication between managers and agents. The SNMP system consists of an SNMP manager, an SNMP agent, and
a MIB. The SNMP manager can be part of a network management system (NMS) such as CiscoWorks. The agent and
MIB reside on the switch. To configure SNMP on the switch, you define the relationship between the manager and the
agent.
The SNMP agent contains MIB variables whose values the SNMP manager can request or change. A manager can get a
value from an agent or store a value into the agent. The agent gathers data from the MIB, the repository for information
about device parameters and network data. The agent can also respond to a manager’s requests to get or set data.
An agent can send unsolicited traps to the manager. Traps are messages alerting the SNMP manager to a condition on
the network. Traps can mean improper user authentication, restarts, link status (up or down), MAC address tracking,
closing of a TCP connection, loss of connection to a neighbor, or other significant events.
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—Ensures that a packet was not tampered with in transit.
— Authentication—Determines that the message is from a valid source.
— Encryption—Mixes the contents of a package to prevent it from being read by an unauthorized source.
To select encryption, enter the priv keyword. This keyword is available only when the cryptographic (encrypted)
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.