Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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Dynamically Adaptive Network Element Telemetry System
Field of the Invention
The present invention relates to the monitoring of network elements comprising
a high speed managed data network, and more particularly to a dynamically
adaptive
network element telemetry system.
Background of the Invention
A network needs to be monitored for the existence, disappearance, reappearance
and status of traditional network devices such as routers, hubs and bridges
and more
recentlyhigh speed switching devices such as ATM, Frame Relay, DSL, VoIP and
Cable
Modems.
In order to generate meaningful performance reports a network management
system is required to collect and process primarily two types of data. Network
Topology
Data and Performance Data. Network Topology Data defines what each object is
and
where it is located in the network hierarchy, while Performance Data are
scalar values
representing the management variable for each object at specified time
intervals.
Network monitoring is traditionally achieved through the polling of the
elements.
A typical initial installation configuration of a management system known in
the art
results in the network element polling rate being set at a fixed default
level, typically 15
minutes. With the timing of samples and delays associated with data
processing, this
results in the management system being able to generate reports within a
couple of
polling cycles.
Periodically, there is a need to increase this default polling rate by
decreasing the
polling interval on specific network elements to allow for closer scrutiny of
the network
under management. The problem is that most existing systems are unable to
change
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polling parameters "on-the-fly". Instead, it has been necessary to perform
labourious
manipulations for each desired change, followed by a disruption of polling
activity to
allow for the transmission of the resulting changes, and finally having to
wait for a couple
of polling cycles to occur in order to generate reports based on the changes.
This results in delays in the availability of information, delays typically in
excess
of the time this information is required. The solution to this problem
therefore, must
comprise a method for rapidly modifying not only the polling rate of specific
elements,
but any operational parameter required for network telemetry such as a fall
back
parameter that controls the retry behaviour of a transaction that fails due to
network
congestion.
For the foregoing reasons, there is a need for a method of network element
telemetry that provides for the localized, low-latency re-configuration and
reporting of
monitoring transactions without a disruption of polling activity.
Summary of the Invention
The present invention is directed to a dynamically adaptive network element
telemetry system that satisfies this need. The system, leveraging the
functionality of a
high speed communications network comprising a network element telemetry
infrastructure comprised of at least one Performance Monitor (PM) server
computer and
at least one, and preferably a plurality of Data Collection (DC) node
computers
comprising a Data Collection Process (DCP) comprising a command handler, the
system
further comprises a Single Distributed Arena (SDA) encompassing the network
element
telemetry infrastructure to form a single large parallel virtual application
wherein the
DCP further comprises a run time telemetry parameter operational change
application.
The SDA further comprises a telemetry control and collected data filter
application
providing the primary interface between the DCP and the SDA and a performance
telemetry controller to enable the suspension, resumption or change of the
parameters of
performance telemetry for any network element.
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In an aspect of the invention, there is a defined maximum interval of time for
which any element can be fast-polled more often than the default rate. At
programmed
intervals the server will traverse the list of known network elements and any
elements
that have been polled longer than permissible will be restored to the
background rate.
Permissible time is calculated from the first rate change request and is not
reset for
subsequent requests.
In an aspect of the invention, limits on the number of concurrent fast-polls
per
managed device is enforced.
In an aspect of the invention, provision is made in the protocol for clients
to
specify formulae containing more than one telemetric parameter. This allows a
client to
monitor more than one separately generated statistic derived from data
received in the
same probe to minimize measurement traffic to the managed device.
As well, measurement traffic to the managed device is not increased with
additional subscribing clients on the same element since these additional
clients get their
information from the same data stream.
The invention provides for more granular monitoring of identified trouble
spots
in the network than that under the default background polling rate and without
a
disruption of polling activity. By enabling the user to increase the frequency
of polling
for specific network elements, more information can be generated over a
shorter period
of time relating to what is happening.
Near real-time access to the management telemetry stream provides the user
with
a tight watch on possible troubled areas of the network by making increased
telemetry
available for any managed element that the system has flagged as performing
outside the
normative range.
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The invention enables rapid and dynamic control of the operational parameters
of
management transactions conducted by the DC node computer on behalf of the PM
server
computer.
As well, the invention safeguards against over-management of delicate or
heavily
loaded devices.
Brief Description of the Drawings
These and other features, aspects, and advantages of the present invention
will
become better understood with regard to the following description, appended
claims, and
accompanying drawings where:
Figure 1 is an overview of the dynamically adaptive network element telemetry
system;
Figure 2 shows client computers connected to the network;
Figure 3 shows the suspend or restore telemetry for an element command;
Figure 4 shows the fast-poll duration limner;
Figure 5 shows the fast-poll concurrency limner;
Figure 6 shows the clients specifying formulae containing more than one
telemetric parameter; and
Figure 7 shows the poll rate maintenance mechanism.
Detailed Description of the Presently Preferred Embodiment
As shown in figure 1, the present invention is directed to a dynamically
adaptive
network element telemetry system. The system, leveraging the functionality of
a high
speed communications network comprising a network element telemetry
infrastructure
comprised of at least one Performance Monitor (PM) server computer 10 and at
least one,
and preferably a plurality of Data Collection (DC) node computers 12
comprising a Data
Collection Process (DCP) 16 comprising a command handler 18. The system
further
comprises a Single Distributed Arena (SDA) 20 encompassing the network element
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telemetry infrastructure 14 to form a single large parallel virtual
application wherein the
DCP 16 further comprises arun time telemetryparameter operational change
application
22. The SDA 20 further comprises a telemetry control and collected data filter
application
24 providing the primary interface between the DCP 16 and the SDA 20 and a
5 performance telemetry controller 26 to enable the suspension, resumption or
change of
the parameters of performance telemetry for any network element 28.
The SDA 20 is embodied in a software application that permits a heterogeneous
collection of computers to be combined for use as a single large parallel
virtual
application.
The SDA 20 provides an environment whereby the PM server computer 10 and
the DC node computers 12 can establish communications in a way that does not
affect
the normal flow of information between them during polling rate changes.
As shown in figure 2, in preferred embodiments of the invention, the system
further comprises at least one client computer 30 connected to the network to
communicate remotely with the PM server computer 10 to initiate and view
telemetry
changes.
A client application 30 specifies a desired polling rate in its initial
subscription
message. If the client 30 requests the default background polling rate it will
receive
updates at the current normative frequency and no rate adjustment functions
occur.
If a client 30 requests a rate faster than the default the system checks the
normative rate for the element 28 requested. If required and permissible, a
rate
adjustment message is dispatched to the responsible control filter 24 in its
DC node
computer 12.
In an embodiment of the invention, a provided 'suspend or restore telemetry
for
an element command 32 provides suspension and restoration functionality which
causes
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the process to stop or resume performance telemetry to an element 28 given by
name as
well as any existing sub-elements. This functionality is automatic, therefor
no response
is required from either the user or the system. To receive confirmation, the
user reads
back the normative configuration using the report command. State rules are not
affected
by a suspension.
To avoid over-management the invention provides certain safeguards against
unacceptably aggressive polling of a managed device 34.
As shown in figure 3, in an embodiment of the invention, the system is further
comprised of a fast-poll duration limiter 36 for defining a maximum interval
of time for
which any element 28 can be polled more often than the default rate or 'fast-
polled'. At
programmed intervals the system will traverse the list of known elements 28
and any
elements 28 that have been polled longer than permissible will be restored to
the
background rate. This permissible time is calculated from the first rate
change request
and is not reset for subsequent requests.
As well, as shown in figure 4, in an embodiment of the invention, the system
is
further comprised of a fast-poll concurrency limiter 38 for enforcing a
maximum number
of concurrent fast-polls per device 34. Concurrent fast polls are defined as
fast polls
occurring at the same time.
Policing this constraint is delegated to the control filter 24 which
internally tracks
the number of fast-polls scheduled for each managed device 34. Once the limit
has been
reached on a device 34 the filter 24 will balk at attempts to schedule
additional elements
28 of the device 34 for fast-polling.
When the system determines that there are no remaining fast-polling clients 30
subscribed for a particular device 34, a default rate control message is sent
to the
responsible control filter 24. For this determination the system only
considers whether
it has an known active fast-polling client 30 for the device 34. Whether or
not a client 30
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has signed off gracefully is not considered in order to ensure that fast-
polling will not be
conducted unnecessarily.
The invention is designed to handle the considerable application and
measurement
traffic that can be generated. Data from the DCP 16 is filtered at the DC node
computer
12 using efficient hashing algorithms to ensure that only client 30 requested
data is
released into the management band. No double polling is done, the data the
near real-time
client 30 sees is obtained from the same management transaction that feeds the
reporting
database.
Dynamic control of polling parameters is achieved by modifying the DCP 16 to
allow for runtime variations of the operational parameters without a
disruption of polling
activity.
The command handlers 18 within the DCP 16 include functionality to recognize
a listen class command to adjust the poll rate of a given element 28. This
command takes
effect unequivocally.
As well, a provided 'report telemetry parameters' command causes the DCP 16
to report the telemetry parameters of any element 28 given by name. The
response will
be either a list of probe configuration data or an assertion that the element
28 is not
known at this DCP 16.
Communication between the PM server computer 10 and its DC node computers
12 is accomplished via Internet Datagram Sockets using an expression
interpreter
embedded in the system.
Client computer 30 tasks communicate with the system via a lightweight
datagram-based protocol. The DCP 16 uses the User Datagram Protocol (UDP) to
the end
client 30 thereby providing scalability, simplicity and speed. UDP has always
been an
excellent choice when an extremely large client base must be kept very up-to-
date with
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data whose currency is transient by nature. The client 30 protocol that is
overlaid onto the
UDP is correspondingly lightweight and tolerant of disruption.
Status history is sent with each client 30 update so that the UDP server need
only
emit packets when new data is available. Even with this history information
included the
packet size is small, typically less than 512 bytes.
An indefinite number of clients 30 can be actively receiving processed
telemetry
at any given time. In embodiments of the invention, provision is made for
specialized
control clients that are intended as integration hooks for non-SDA
applications.
The invention provides for more granular monitoring of identified trouble
spots
in the network than that under the default background polling rate and without
a
disruption of polling activity. By enabling the user to increase the frequency
of polling
for specific network elements 28 more information can be generated over a
shorter period
of time relating to what is happening.
Near real-time access to the management telemetry stream provides the user
with
a tight watch on those identified troubled areas of the network by making
increased
telemetry available for any managed element 28 that the system has flagged as
performing outside of its normative range.
The invention allows rapid and dynamic control of the operational parameters
of
management transactions conducted by the DC node computer 12 on behalf of the
PM
server computer 10.
As well, the invention safeguards against over-management of delicate or
heavily
loaded devices.
Collected data can be filtered, processed and transported to a web-based or
other
client 30 at a much faster rate.
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Measurement traffic to the managed device 34 is not increased with additional
subscribing clients 30 on the same element 28 since these additional clients
30 get their
information from the same data stream.
Easily understood message/reply sets make the system extremely portable. Any
system or language that has bindings to open an Internet Datagram Socket, or
can proxy
one, can have a client 30. Foreign systems can integrate either with the SDA
20 control
system or at the UDP client 30 level.
The design is simple to maintain and horizontally scalable to an arbitrary
degree.
As shown in figure 5, in an embodiment of the invention, provision is made in
the
protocol for clients 30 to specify formulae 40 containing more than one
telemetric
parameter 42. This allows a client 30 to monitor more than one separately
generated
statistic derived from data received in the same probe to minimize measurement
traffic
to the managed device 34.
As shown in figure 6, in another embodiment of the invention, a poll rate
maintenance mechanism 44 is provided as an error feedback control scheme. The
collection time associated with each sample received from a control filter 24
is examined
and the effective polling rate is calculated. This measured value is compared
against the
normative rate for the implicated element 28. If the measurement does not
conform to the
normative rate for the element 28 additional rate change commands are sent to
the control
filter 24 to bring the rate in line. Since the measured rate will rarely be
exactly equal to
the normative rate the feedback control scheme uses a heuristic formula to
determine if
the rate is close enough. Changes to the normative polling rate are naturally
enforced as
the system continually seeks equilibrium.
Although the present invention has been described in considerable detail with
reference to certain preferred versions thereof, other versions are possible.
Therefore, the
CA 02345530 2001-04-26
spirit and scope of the appended claims should not be limited to the
description of the
preferred versions contained herein.
All the features disclosed in this specification (including any accompanying
5 claims, abstract, and drawings) may be replaced by alternative features
serving the same,
equivalent or similar purpose, unless expressly stated otherwise. Thus, unless
expressly
stated otherwise, each feature disclosed is one example only of a generic
series of
equivalent or similar features.
