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A MIB view represents a set of MIB objects (or MIB object hierarchies) with certain access privileges and
is identified by a view name. The MIB objects included in the MIB view are accessible while those
excluded from the MIB view are inaccessible.
A MIB view can have multiple view records each identified by a
view-name oid-tree
pair.
You control access to the MIB by assigning MIB views to SNMP groups or communities.
SNMP operations
SNMP provides the following basic operations:
•
Get
—NMS retrieves the SNMP object nodes in an agent MIB.
•
Set
—NMS modifies the value of an object node in an agent MIB.
•
Notification
—SNMP agent sends traps or informs to report events to the NMS. The difference
between these two types of notification is that informs require acknowledgment but traps do not.
Traps are available in SNMPv1, SNMPv2c, and SNMPv3, but informs are available only in
SNMPv2c and SNMPv3.
Protocol versions
SNMPv1, SNMPv2c, and SNMPv3 are supported for high encryption in non-FIPS mode. Only SNMPv3
is supported in FIPS mode. An NMS and an SNMP agent must use the same SNMP version to
communicate with each other.
•
SNMPv1
—Uses community names for authentication. To access an SNMP agent, an NMS must use
the same community name as set on the SNMP agent. If the community name used by the NMS
differs from the community name set on the agent, the NMS cannot establish an SNMP session to
access the agent or receive traps from the agent.
•
SNMPv2c
—Uses community names for authentication. SNMPv2c is compatible with SNMPv1, but
supports more operation types, data types, and error codes.
•
SNMPv3
—Uses a user-based security model (USM) to secure SNMP communication. You can
configure authentication and privacy mechanisms to authenticate and encrypt SNMP packets for
integrity, authenticity, and confidentiality.
Access control modes
SNMP uses the following modes to control access to MIB objects:
•
View-based Access Control Model
—The VACM mode controls access to MIB objects by assigning
MIB views to SNMP communities or users.
•
Role based access control
—The RBAC mode controls access to MIB objects by assigning user roles
to SNMP communities or users.
{
An SNMP community or user with a predefined user role network-admin, mdc-admin, or level-15
has read and write access to all MIB objects.
{
An SNMP community or user with a predefined user role network-operator or mdc-operator has
read-only access to all MIB objects.
{
An SNMP community or user with a user role specified by the
role
command accesses MIB
objects through the user role rules specified by the
rule
command.
