S
IMPLE
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ETWORK
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ANAGEMENT
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ROTOCOL
3-47
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 clients. 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 software such as
SMC EliteView. 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 using 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