SNMP Foundations and Concepts
Simple Network Management Using Net-SNMP and ftlSNMP
8-15
SNMP, applications developed for any SNMP implementation tend to be easily
adaptable and useful with other SNMP implementations.
Conceptually, every managed object on a network is uniquely identifiable. SNMP uses
ISO Abstract Syntax Notation Standard 1 (ASN.1) to place every SNMP object within
the internet hierarchy of managed objects. All these unique managed objects can be
managed by their defined characteristics in the MIB. While in the theoretical schema
there is only one MIB, it is usual to refer to any file that provides SNMP MIB definitions
as a MIB. MIBs can be formally registered and entered into defined namespace or used
locally as experimental MIBs.
An SNMP server only knows of objects for which it has definitions. This allows
distributed SNMP services to co-exist on networks without interfering with each other.
SNMP agents can, however, interact. SNMP agents can act as subagents of a master
agent. A managed object can be a host computer or subsystem, an arbitrary interactive
device, or a software application (including an operating system), basically anything
whose interactivity over the network can be defined in a MIB so that it can be interfaced
via SNMP.
Extensions and Fault-Tolerant SNMP Operation
While Net-SNMP supports the security features of SNMPv3, it can also interact
compatibly with distributed SNMP services that use SNMPv1 and SNMPv2. Net-SNMP
is the most widely-adopted open source SNMP utility package. This facilitates
interfacing the Net-SNMP and ftlSNMP implementations with other servers deploying
Net-SNMP-based distributed SNMP services and service management utilities in a
heterogeneous network environment. Net-SNMP has been ported to Linux, UNIX, and
other operating systems, such as Windows NT and Stratus VOS. Note, however, that
the Net-SNMP and ftlSNMP combined packages provide support only for ftServer
systems running a supported Linux
distribution together with
Express Builder
.
The Net-SNMP and ftlSNMP packages encourage deployment of distributed SNMP
services on heterogeneous networks featuring both ftServer systems running a
supported Linux
distribution together with
Express Builder
, and Express5800/
ftServer
hosts
running other supported operating systems.
The Net-SNMP and ftlSNMP packages interact with and manage networked objects
defined in MIB files. The ftlSNMP package includes the SRA-ftLinux-MIB file
(SRA-ftLinux-MIB.txt) to support fault-tolerant Express5800/
ftServer
systems.
Net-SNMP also supports MIB-II and Host Resource MIB features. The ftlSNMP
package follows the SNMP master/agent daemon management model, and extends
the basic model using AgentX subagents. This allows the subagents associated with
different MIBs to be kept separate so that failure of one does not bring down the others.
Also, the
ftltrapsubagent
was kept separate from the
ftlsubagent
to avoid
blocking on serious traps. AgentX extensions are defined in RFC2741,
Agent
Extensibility (AgentX) Protocol version 1
. RFC2741 defines a standardized framework
