Snmp Protocol Version; Mib Overview - H3C S5500-EI series Operation Manual

Operation Manual – SNMP-RMON
H3C S5500-EI Series Ethernet Switches
SNMP provides the following four basic operations:
Get operation: NMS gets the value of a certain variable of Agent through this
operation.
Set operation: NMS can reconfigure certain values in the Agent MIB (Management
Information Base) to make the Agent perform certain tasks by means of this
operation.
Trap operation: Agent sends Traps to the NMS through this operation.
Inform operation: NMS sends Traps to other NMSs through this operation.

1.1.2 SNMP Protocol Version

Currently, SNMP agents support SNMPv3 and are compatible with SNMPv1 and
SNMPv2c.
SNMPv1 authenticates by means of community name, which defines the
relationship between an SNMP NMS and an SNMP Agent. SNMP packets with
community names that did not pass the authentication on the device will simply be
discarded. A community name performs a similar role as a key word and can be
used to regulate access from NMS to Agent.
SNMPv2c authenticates by means of community name. Compatible with SNMPv1,
it extends the functions of SNMPv1. SNMPv2c provides more operation modes
such as GetBulk and InformRequest; it supports more data types such as
Counter64 and Counter32; and it provides various error codes, thus being able to
distinguish errors in more detail.
SNMPv3 offers an authentication that is implemented with a User-Based Security
Model (USM). You can set the authentication and privacy functions. The former is
used to authenticate the validity of the sending end of the authentication packets,
preventing access of illegal users; the latter is used to encrypt packets between
the NMS and Agent, preventing the packets from being intercepted. USM ensures
a more secure communication between SNMP NMS and SNMP Agent by
authentication with privacy, authentication without privacy, or no authentication no
privacy.
Successful interaction between NMS and Agent requires consistency of SNMP
versions configured on them. You can configure multiple SNMP versions for an Agent
to interact with different NMSs.

1.1.3 MIB Overview

Any managed resource can be identified as an object, which is known as the managed
object. Management Information Base (MIB) is a collection of all the managed objects.
It defines a set of characteristics associated with the managed objects, such as the
object identifier (OID), access right and data type of the objects. Each Agent has its
own MIB. NMS can read or write the managed objects in the MIB. The relationship
between NMS, Agent and MIB is shown in Figure 1-1.
1-2
Chapter 1 SNMP Configuration