Chapter 9 - Using Snmp; About Snmp And Smartna-X - Network Critical SmartNA-X User Manual

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This chapter describes how to use SNMP (Simple Network Management Protocol) to monitor SmartNA-X
temperature, traffic high/low, power on/off, system restarts, TAP module insertion/removal, and other conditions
requiring administrator attention. The chapter covers the following major topics:
• About SNMP and SmartNA-X, page 58
• Configuring SNMP, page 61

About SNMP and SmartNA-X

SNMP is an interoperable standards-based protocol for network management. SNMP is an application-layer
protocol that provides a message format for communication between SNMP managers and SNMP agents. The
SNMP manager can be part of your existing Network Management System (NMS).
Both agent and management information base (MIB) reside on the device that is being managed, in this case
SmartNA-X. An agent has local knowledge of management information and translates that information to or from
an SNMP specific form. A manager can request a value from the agent or store a value into the agent. The agent
can also respond to a manager's requests to get or set data.
MIBs describe the structure of the management data of a device subsystem; they use a hierarchical namespace
containing object identifiers (OID).
Unsolicited messages, or notifications, alerting the SNMP manager to a condition on the managed device can also
be sent from the agent to the manager. Notifications can be sent for improper authentication, system restarts, TAP
modules withdrawn or inserted, link status up or down, and other significant events.
Supported versions
The SNMP agent used by SmartNA-X supports SNMP versions v1,v2c and v3. These versions essentially provide
three different security models. Table 9-1 identifies what the combinations of security models and levels within
these different security models mean. By a combination of authenticating and encrypting packets, SNMPv3 is the
most secure. SNMPv3 increases security to levels far beyond the simple community string method used by
SNMPv1/v2c by adding:
• packet encryption to prevent snooping by an unauthorized source
• integrity checks to ensure that a packet has not been tampered with in transit
• authentication checks to verify a message is from a valid source
SNMPv3 also adds View-based Access Control Method (VACM), which has the responsibility of checking
whether a specific type of access to a specific managed object is allowed. Access control occurs in the agent when
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