Page 322 - Optical Communications Essentials

Network Management

312 Chapter Eighteen

Figure 18.4. Basic simple network management protocol (SNMP) archi-
tecture.

central network management console. To alleviate some of this stress, the
Internet Engineering Task Force (IETF) developed the remote monitoring
(RMON) scheme.
The RMON set of standards extends and improves the SNMP framework.
The main document is the RFC 1757 Ethernet RMON MIB, which describes the
framework for remote monitoring of a MIB. The basic purpose of the RMON
MIB specification is to readily implement a distributed management system
consisting of an RMON manager and an RMON probe. The probe is responsible
for collection of management data. It may be a stand-alone piece of equipment,
or it could be a software application that is embedded within the managed
device. The function of the manager is to retrieve the RMON information,
process it, and then present it to the system administrator.
The RMON specifications give network administrators greater freedom to
select network monitoring probes and consoles that meet the needs of a particu-
lar network. By defining a set of statistics and functions that can be exchanged
between RMON-compliant consoles and network probes, the specifications pro-
vide the administrators with comprehensive fault diagnosis, planning, and per-
formance-tuning information.
Management applications do not communicate directly with the managed
device itself, but instead go through an RMON agent in the probe by using
SNMP. This setup makes it easier to share information among multiple man-
agement stations. The RMON MIB specifications define how the information
should be categorized in a common format so that the manager and the probe
can exchange data. They do not define explicitly how the probe should collect
the data or how the manager should format these data for presentation.

18.4. Optical Layer Management
To deal with standardized management functions in the optical layer, in
February 2001 the ITU-T defined a three-layer model. The document is ITU-T
Recommendation G.709, Network Node Interface for the Optical Transport
Network (OTN), which also is referred to as the Digital Wrapper standard. Just

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