LevelOne GEL-5261, Руководство пользователя

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Chapter 13
| Basic Administration Protocols
Simple Network Management Protocol
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Simple Network Management Protocol
Simple Network Management Protocol (SNMP) is a communication protocol
designed specifically for managing devices on a network. Equipment commonly
managed with SNMP includes switches, routers and host computers. 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
potential 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 managed
objects, is maintained by the SNMP agent and used to manage the device. These
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 protocol used to access this
information over the network.
The switch includes an onboard agent that supports SNMP versions 1, 2c, and 3.
This agent continuously monitors the status of the switch hardware, as well as the
traffic passing through its ports. A network management station can access this
information using network management software. 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 first submit a valid
community string for authentication.
Access to the switch from clients using SNMPv3 provides additional security
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 model having
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 defined security access to set of
MIB objects for reading and writing, which are known as “views.” The switch has a
default view (all MIB objects) and default groups defined for security models v1 and
v2c. The following table shows the security models and levels available and the
system default settings.