Chapter 5: Simple Network Management Protocol
Simple Network Management Protocol (SNMP) is a communication protocol
designed specifically for managing devices on a network. Equipment comm only
managed with SNMP includes switches, routers and host comp uters. SNMP is
typically used to configure these devices for proper operation in a network
environment, as well as to monitor them to evaluate performance or detect poten tial
problems.
Managed devices supporting SNMP contain software, which runs locally on the
device and is referred to as an agent. A defined set of variables, known as man age d
objects, is maintained by the SNMP agent and used to manage t he device. Th ese
objects are defined in a Management Information Base (MIB) that provides a
standard presentation of the information controlled by the agent. SNMP defines both
the format of the MIB specifications and the protoc ol used to a ccess this i nform ation
over the network.
The switch includes an onboard agent that supports SNMP vers ions 1, 2c, and 3 .
This agent continuously monitors the status of the switch ha rdware, as well as t he
traffic passing through its ports. A network management station can a ccess th is
information using software such as HP OpenView. Access to the onboard agent
from clients using SNMP v1 and v2c is controlled by community strings. To
communicate with the switch, the management station must fi rst submit a valid
community string for authentication.
Access to the switch using from clients using SNMPv3 provide s additional secu rity
features that cover message integrity, authentication, and encryption; as well as
controlling user access to specific areas of the MIB tree.
The SNMPv3 security structure consists of security models, with each mo del ha vi ng
it’s own security levels. There are three security models defined, SNMPv1,
SNMPv2c, and SNMPv3. Users are assigned to “groups” that are defined by a
security model and specified security levels. Each group also has a define d security
access to set of MIB objects for reading and w riting, whi ch are known as “views .”
The switch has a default view (all MIB objects) and default groups def ined for
security models v1 and v2c. The following table shows the se curity m odels and
levels available and the system default settings.

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