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Remote Monitoring and
Desktop Management
Week-7
Remote Monitoring
and Desktop Management
SNMP designed for management of
a limited range of devices and a
limited range of functions
Monitoring is difficult in both WANs
and the newer switched LANs.
Remote Monitoring
SNMP network management tools
can support the monitoring of
individual devices. However, it is
difficult to learn about traffic on a
particular network using SNMP.
Protocol Analysers as Monitors
Protocol analysers can support viewing
of each packet that passes on a network.
In a network using routing or switches,
monitors will only see the traffic on their
part of the network.
Thus, the devices cannot cover whole
network.
Remote Network Monitors
Could have one monitor per subnetwork
or switched section - may be excessively
costly if use protocol analysers.
If dedicated monitoring modules are used
that report back to a network
management station, this may be
possible. This is called remote monitoring.
Remote Monitor - RMON
A range of standard functions have been
defined for remote monitoring within
SNMP - RMON.
RMON agents may be dedicated
hardware devices attached to a
subnetwork or may be software running
in networked devices (computers,
switches, routers, printers, etc)
RMON normally supports:
Off-line operation
Monitor collects statistics (packet
counts, error rates, etc) with
management station retrieving data
after some time duration.
Reduces network traffic.
RMON normally supports:
Preemptive Monitoring
Monitor runs diagnostics and collects
statistics continuously, reporting failure
to management station and supplying
diagnostic information to assist
problem resolution.
RMON normally supports:
Problem detection and reporting
Monitor passively observes its
subnetwork and reports to
management station on specific
problems that are observed.
RMON normally supports:
Value-added data
Monitor can provide information of
greater detail and with analysis that
would normally only be available to
an analyser attached to that
subnetwork - eg, hosts generating
most traffic.
RMON normally supports:
Multiple managers
Monitors may be expected to
provide support for more than one
management station.
Monitor Control
A monitor is required to perform tasks
that are more sophisticated than the
devices normally managed using SNMP
(routers, bridges, etc).
Thus it must be able to interact with a
management station to provide data and
receive commands of some complexity.
Monitor Control
SNMP was not originally intended
for this and so needs some minor
changes to support RMON.
This is done via an RMON MIB.
RMON Overview
A standard MIB
 Described in RFC 1757
 Defines MAC-layer statistics and control
objects
 Monitors basic Ethernet operations
 Powerful alarm and event mechanism
 Automatic historical data collection
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Utilisation
Collisions
Usage patterns
Planning data
RMON Architecture
Router
Router
WAN
LAN segments
LAN segments
RMON
DCM
RMON Group objects
Statistics - utilisation and error rates
history - periodic samples are stored
alarm - alarm thresholds can be set
host - traffic to/from hosts on subnetwork
hostTopN - maintains a list of highest
recorded (peak) statistics for hosts
matrix - error and utilisation data can be
returned as a matrix for all addresses of
nodes recorded
RMON Group objects
filter - permits the setup of selective
monitoring
packet capture - determines how the
monitor delivers data to the
management station
event - table of all events generated by
the RMON agent
Network Overload
RMON agents may be set to retain
information for a period of time, or to
return data immediately. In either case,
the volume of data may reduce network
performance.
However, the trade-off may be the lack
of network knowledge….
Monitoring Device Overload
The volume or detail of information
required to be accessed by RMON
agents may be so great that it may
affect monitoring device performance.
In high-volume situations (high speed
switches, etc) dedicated devices are
preferable.
Desktop Management
Desktop Management Task Force
a collection of computer industry
parties (Microsoft, Intel, etc see
www.dmtf.org ) have been working
on the development of an agent that
can reside in device to be managed.
DTMF - DMI
The DMTF developed the Desktop
Management Interface (DMI) a
standardised system to carry out the
task. Resides as a TSR (Terminate and
Stay Resident program) or as a
windows DLL.
Desktop management Interface
Initial development of the user agent
has centred around the IBMcompatible PC-style machines.
However, there is intended to be a
standard interface for all operating
environments and platforms.
A remote management station can then
provide a wide range of supportive
functions from "over-the-shoulder"
helping of the user, to taking over of the
keyboard and "becoming the user" to
run through a sequence of operations.
The management station can also
provide many remote management
functions like backup and automatic
software upgrades, independent of the
users involvement.
The management agent will be a
standardised product that is compatible
with the current and future management
standards (CMIP, SNMP).
Desktop management using a local
agent offers many advantages,
particularly in the areas of system
security and reliability and it may be
necessary for the support of network
administration in the new networking
environments.