U.S. patent application number 11/334466 was filed with the patent office on 2006-06-01 for method and apparatus for processing requests for statistics in a communication network.
Invention is credited to Wlodek Olesinski, Rashid Qureshi, Mark Woodward.
Application Number | 20060114837 11/334466 |
Document ID | / |
Family ID | 25264666 |
Filed Date | 2006-06-01 |
United States Patent
Application |
20060114837 |
Kind Code |
A1 |
Olesinski; Wlodek ; et
al. |
June 1, 2006 |
Method and apparatus for processing requests for statistics in a
communication network
Abstract
A method and apparatus of initiating a plurality of requests for
statistics to be sent to an associated plurality of nodes in a
segment of a communication network is provided. One or more
requests are associated with an individual node. Each node has one
or more node attributes. The method includes defining a sequence
for initiating the requests to be sent to the nodes. The sequence
is based on a value of a selected node attribute of each node. The
method also includes initiating the requests according to the
sequence.
Inventors: |
Olesinski; Wlodek; (Nepean,
CA) ; Qureshi; Rashid; (Ottawa, CA) ;
Woodward; Mark; (Carp, CA) |
Correspondence
Address: |
MCCARTHY TETRAULT LLP
BOX 48, SUITE 4700,
66WELLINGTON STREET WEST
TORONTO
ON
M5K 1E6
CA
|
Family ID: |
25264666 |
Appl. No.: |
11/334466 |
Filed: |
January 19, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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09833531 |
Apr 11, 2001 |
|
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11334466 |
Jan 19, 2006 |
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Current U.S.
Class: |
370/252 ;
370/401 |
Current CPC
Class: |
H04L 29/06 20130101;
H04L 41/0213 20130101 |
Class at
Publication: |
370/252 ;
370/401 |
International
Class: |
H04J 1/16 20060101
H04J001/16 |
Claims
1. A method for collecting statistics from nodes of a communication
network having a plurality of heterogeneous nodes, comprising:
defining for the network a node level limitation pertinent to
statistics collection; for each node involved in statistics
collection, mapping a respective value of the node level limitation
to a corresponding node identification; and, sending statistics
requests to each node based on the respective value, wherein each
node processes a number of requests according to the respective
value.
2. The method of claim 1 wherein the node level limitation includes
a maximum number of outstanding packets to be transmitted from each
node.
3. The method of claim 1 wherein the node level limitation includes
a maximum number of requests per second that can be processed by
the node.
4. The method of claim 1 wherein the defining includes determining
the respective value from node information retrieved from the
network.
5. The method of claim 1 wherein the defining includes determining
the respective value for each node based on network level
limitations pertinent to statistics collection.
6. The method of claim 1 wherein each node includes a respective
number of statistics collecting counters, each counter for
maintaining statistics pertinent to a node attribute.
7. The method of claim 1 and further comprising, for maximizing
collection of statistics over a predetermined time interval:
defining for each node a set of attributes for which statistics
need to be collected; mapping a set of attributes collectable for
each node to the corresponding node identification and generating a
table with the mapping; storing in the table for each node
identification a default value for each attribute in the set of
attributes based on past performance of each node; ordering the
statistics requests in a sequence of statistics requests according
to a predetermined ranking calculated from the table; and, pooling
the nodes each time interval according to the sequence of
statistics requests for updating the table with current values of
the attributes.
8. The method of claim 7 wherein the predetermined ranking is
re-calculated for each time interval.
9. The method of claim 7 wherein criteria for the predetermined
ranking is one or more of: per node attributes, a number of
subcomponents on a node, a number of requests per node, an average
response time for a node, and a number of timeouts per node.
10. A system for collecting statistics from nodes of a
communication network having a plurality of heterogeneous nodes,
comprising: a computer coupled to the communication network; and, a
program executed on the computer, the program including: a module
for defining for the network a node level limitation pertinent to
statistics collection; a module for, for each node involved in
statistics collection, mapping a respective value of the node level
limitation to a corresponding node identification; and, a module
for sending statistics requests to each node based on the
respective value, wherein each node processes a number of requests
according to the respective value.
11. The system of claim 10 wherein the node level limitation
includes a maximum number of outstanding packets to be transmitted
from each node.
12. The system of claim 10 wherein the node level limitation
includes a maximum number of requests per second that can be
processed by the node.
13. The system of claim 10 wherein the module for defining includes
a module for determining the respective value from node information
retrieved from the network.
14. The system of claim 10 wherein the module for defining includes
a module for determining the respective value for each node based
on network level limitations pertinent to statistics
collection.
15. The system of claim 10 wherein each node comprises a respective
number of statistics collecting counters, each counter for
maintaining statistics pertinent to a node attribute.
16. The system of claim 10 wherein the program further includes,
for maximizing collection of statistics over a predetermined time
interval: a module for defining for each node a set of attributes
for which statistics need to be collected; a module for mapping a
set of attributes collectable for each node to the corresponding
node identification and generating a table with the mapping; a
module for storing in the table for each node identification a
default value for each attribute in the set of attributes based on
past performance of each node; a module for ordering the statistics
requests in a sequence of statistics requests according to a
predetermined ranking calculated from the table; and, a module for
pooling the nodes each time interval according to the sequence of
statistics requests for updating the table with current values of
the attributes.
17. The system of claim 16 wherein the predetermined ranking is
re-calculated for each time interval.
18. The system of claim 16 wherein criteria for the predetermined
ranking is one or more of: per node attributes, a number of
subcomponents on a node, a number of requests per node, an average
response time for a node, and a number of timeouts per node.
Description
[0001] This application is a continuation of U.S. patent
application Ser. No. 09/833,531, filed Apr. 11, 2001, and
incorporated herein by reference.
FIELD OF THE INVENTION
[0002] The invention relates generally to data communications, and
more particularly to a method and apparatus for processing requests
for statistics in a communication network.
BACKGROUND OF THE INVENTION
[0003] Communication networks comprise a plurality of nodes, or
switches, which are interconnected to form a web of nodes. Users
communicate with other users in the network by transmitting
messages and data through the network. Data is routed or switched
through a path of connected nodes from the node associated with the
sender to node associated with the recipient.
[0004] Each node may maintain a set of statistics relating to the
network traffic passing therethrough. Statistics include
performance, usage or billing data collected from a communication
network. The statistics may be used for billing purposes,
evaluation of network performance at a node and fault diagnostics
that may be present about a node. Typically, statistics are tracked
using software modules which track aspects of the statistics in
counters or registers internal to the nodes. The counters may be
embodied in hardware or software using techniques known in the art.
Generally, to conserve resources, the counters maintain only recent
data. Further, the counters may be configured to be reset after a
predetermined time period or interval. Typical reset intervals are
5 minutes, 15 minutes, 60 minutes and 24 hours. The counter
occupies a portion of memory on the node to store data from the
previous interval while compiling data for the current interval. At
the end of the current interval, interval data is written over the
memory contents for the previous interval. The counter for the
current interval is reset and then begins to track data for the
current interval. As such, statistics must be collected in every
interval in order to retain timely statistics.
[0005] In prior art systems, there are statistics collection
systems for a communication network which typically send statistics
requests to the network using the known simple network management
protocol (SNMP) or other protocols appropriate for the nodes. The
statistics collection system typically communicates with the
network using a separate device, a statistics collection unit. The
statistics collection unit is typically external to the network and
is connected to the network using a dedicated network management
functionality communication link.
[0006] It will be appreciated that statistics collection requires
resources. Processing a request for statistics collection from the
statistics collection unit by a node requires that the node utilize
its processing resources, thereby diverting resources from
processing switching or routing traffic. Accordingly, nodes
typically are not optimized for statistics collection processing
and generally commit only limited resources thereto. The statistics
collection unit is also resource limited because of the vast number
of nodes in the network to be queried.
[0007] There are two limitations that may limit the capacity in the
network for statistics collection: system level limitations and
per-node limitations. System level limitations include: (i) time
required for building requests and managing responses, (ii) upper
bound on the number of items that can be transmitted with a single
request and (iii) upper bound on outstanding requests in a segment
of the network given capacity of the links in the segment and the
number of expected responses. Per-node limitations include: (i)
node response time, (ii) node resource limitations and (iii) upper
bound on the number of outstanding requests for the node given that
the node must divert switching resources to respond to such
requests. An outstanding request is a request for which a response
from the node has not yet been communicated to the statistics
collection unit.
[0008] In prior art systems, requests for statistics for a specific
interval are sent to the network in blocks which are not modelled
for bandwidth or other efficiencies. As such, the system and
per-node constraints may combine to defer requests to a node so
that statistics collection is not maximized for a given interval.
This may result in a loss of statistical data. Timely polling of
the counters in a node must occur or the overall statistics
collection process will produce incomplete or inaccurate
results.
[0009] Additionally, in the prior art, a statistics collection unit
may use an overly conservative constraint for the number of
outstanding requests allowed for a particular node. A typical
conservative constraint used is the smallest number of outstanding
requests allowed for the nodes in the segment or network as the
constraint for every node in the segment or network. This may
underutilize a given node and defer further requests for that node
until the current outstanding requests are answered. Deferring
requests to the node may result statistics collection not being
maximized for a given interval resulting in a loss of statistical
data.
[0010] There remains a need for a system and method which improves
upon the use of available resources in processing requests for
statistics to nodes in a network.
SUMMARY OF THE INVENTION
[0011] In a first aspect of the invention, a method of defining an
order for sending a plurality of requests for statistics to an
associated plurality of nodes of a communication network is
provided. One or more requests are associated with an individual
node. Each node has one or more node attributes. The method
includes defining a sequence for sending the requests to be sent to
the nodes. The sequence is based on a value of a selected node
attribute of each node. The method also includes initiating each of
the requests according to the sequence.
[0012] The method may define for each node a translated value
related to the value of the selected node attribute prior to
defining the sequence and base the sequence on a ranking of all of
the translated values.
[0013] The method may select two or more node attributes and for
each of these node attributes, refine the ranking of the nodes
based on the value of each of those node attributes.
[0014] The method may receive data regarding a plurality of
responses from the nodes which received requests. The method may
track a number of outstanding requests in a segment of the
communication network. The segment includes the associated nodes.
The number of outstanding requests relates to a number of requests
in the segment for which responses have not been received. The
number of outstanding requests is associated with an upper bound
number. The method may also initiate each of the requests by
comparing the number of outstanding requests in the segment with
the upper bound number and initiate one request when the number of
outstanding requests in the segment is less than the upper bound
number.
[0015] The method may receive data regarding a plurality of
responses from each node which received the requests. The method
may track a number of outstanding requests for each node. The
number of outstanding requests for each node relates to a number of
requests for which responses have not been received for each node.
Each number of outstanding requests is associated with an upper
bound number. The method may, for each node, initiate the requests
when the number of said outstanding requests is less than the upper
bound number, each request being sent independently to its
associated node.
[0016] The method may separately define the upper bound number for
each node in the segment.
[0017] The method may select a selected node attribute which has a
value representing a number of requests to be initiated for each
node in a time interval. The method may define the sequence by
ranking the nodes in descending order utilizing each of the values
of the selected node attribute of the nodes.
[0018] The method may select a selected node attribute which is a
response time of each of the nodes to previous requests. The method
may define the sequence by ranking the nodes in descending order
utilizing each of the values of the selected node attribute of the
of nodes.
[0019] The method may select a selected node attribute which
identifies an operating characteristic of each of the nodes. The
method may define the sequence by ranking the nodes in a
predetermined order utilizing each of the values of the selected
node attribute of the nodes.
[0020] The method may utilize an operating characteristic which
indicates wireless and non-wireless transmission technologies
associated with each of the nodes. The method may define the
sequence by ranking the nodes utilizing values of the operating
characteristic and ranking nodes having wireless transmission
technologies with a higher priority.
[0021] The method may be embodied in a computer program.
[0022] The method may be repeated in a cyclic time interval.
[0023] The method may track a second number of other outstanding
requests for each of the nodes. The second number of other
outstanding requests for each of the associated nodes relates to a
number of requests for each of the nodes for which responses have
not been received. Each second number of other outstanding requests
is associated with a nodal upper bound number. The method may
initiate each request when the number of outstanding requests for
the segment is less than the upper bound number and the second
number of other outstanding requests is less than the nodal upper
bound number for the individual node associated with each
request.
[0024] In a second aspect of the invention, a statistics collection
unit associated with a communication network is provided. The
communication network includes a plurality of nodes and each of the
nodes has one or more node attributes. The statistics collection
unit includes a computer and a program executed on the computer.
The program includes a sequencing module defining a sequence for
sending requests for statistics to be sent to an associated
plurality of nodes. One or more requests are associated with an
individual node. The sequence is based on a value of a selected
node attribute of each node. The program also includes an
initiating module initiating each of the requests according to the
sequence.
[0025] In a third aspect of the invention, an apparatus for use in
a statistics collection unit in a communication network is
provided. The communication network includes a plurality of nodes.
The apparatus includes a device defining a sequence for sending the
requests for statistics to be sent from the statistics collection
unit to an associated plurality of nodes in the segment.
[0026] In a fourth aspect of the invention, a computer executable
program for use on a communication network is provided. The
communication network includes a plurality of nodes. The computer
executable program executes the step of defining a sequence for
sending a plurality of requests for statistics to be sent to an
associated plurality of nodes. One or more requests are associated
with an individual node. Each node has one or more node attributes.
The sequence is based on a value of a selected node attribute of
each of the nodes. The computer executable program also executes
the steps of initiating each of the requests according to the
sequence.
[0027] In other aspects, the invention provides various
combinations and subsets of the aspects described above.
BRIEF DESCRIPTION OF THE DRAWINGS
[0028] The foregoing and other aspects of the invention will become
more apparent from the following description of specific
embodiments thereof and the accompanying drawings which illustrate,
by way of example only, the principles of the invention. In the
drawings, where like elements feature like reference numerals (and
wherein individual elements bear unique alphabetical suffixes):
[0029] FIG. 1 is a block diagram of a communication network
including a statistics collection unit in accordance with an
embodiment of the invention;
[0030] FIG. 2 is a block diagram of a node and its subcomponents in
the communication network of FIG. 1;
[0031] FIG. 3 is a block diagram illustrating sets of node
attributes for nodes for the communication network of FIG. 1;
[0032] FIG. 4 is a block diagram of another communication network
including a statistics collection unit in accordance with the
embodiment of the invention;
[0033] FIG. 5A is a table exemplary of node attributes for nodes
for the communication network of FIG. 4;
[0034] FIG. 5B is a timeline comparing performance of an embodiment
to performance of a prior art system using the node attributes of
FIG. 5A;
[0035] FIG. 6A is a table examplary of upper bounds for outstanding
requests for nodes in another communication network; and
[0036] FIG. 6B is a block diagram comparing performance of an
embodiment to performance of a prior art system using the example
of FIG. 6A.
DETAILED DESCRIPTION OF AN EMBODIMENT
[0037] The description which follows, and the embodiments described
therein, are provided by way of illustration of an example, or
examples, of particular embodiments of the principles of the
present invention. These examples are provided for the purposes of
explanation, and not limitation, of those principles and of the
invention. In the description which follows, like parts are marked
throughout the specification and the drawings with the same
respective reference numerals.
[0038] The foregoing embodiment relates to a method and apparatus
for processing requests for statistics to be sent to the nodes in
the network in a defined sequence. The manner of defining the
sequence in this embodiment is configurable. Therefore, the
requests may be sent in an intelligent manner, utilizing
information gathered from the network to define a sequence in which
to initiate the requests, providing efficient use of the bandwidth
resources of the connection to the network and of the nodes
themselves. Alternatively, the sequence may be defined to minimize
the number of selected resource tracking statistics which may be
reset before their data is retrieved.
[0039] First, a description of a communications system associated
with an embodiment is provided. Referring to FIG. 1, data
communication network 105 provides the capability for compiling
statistics that are recorded by various nodes included within data
communication network 105. Data communication network 105 comprises
network cloud 110 that includes a plurality of interconnected
nodes, or switches, 161-171.
[0040] It will be appreciated that network cloud 110 may be any
packet switched network. For example, network cloud 110 may utilize
asynchronous transfer mode (ATM) protocol for communication. In an
ATM network, nodes 161-171 may be ATM nodes or switches.
[0041] Nodes 161-171 in network cloud 110 are grouped into
segments, or subnets, 112-114. First segment 112 includes nodes
161-164; second segment 113 includes nodes 165-168; and third
segment 114 includes nodes 169-171.
[0042] End users 181-184 may be connected to network cloud 110 via
routers 190 and 191, allowing data to be transmitted amongst end
users 181-184 through nodes 161-171 in network cloud 110. For
example, a packet may be sent from end user 184 to end user 181,
from user 184, to router 190, to network cloud 110, to router 191
and finally to end user 181.
[0043] As is illustrated, each of node segments 112-114 operably
communicates with its associated statistics collection unit
141-143. Statistics collection units 141-143 may communicate to
node segments 112-114 via dedicated network management
functionality communication links 154-156. Each statistics
collection unit 141-143 is responsible for gathering the
appropriate statistics within its associated node segment 112-114.
Statistics collection units 141-143 typically use a general purpose
computer with specialized network management software operating
thereon which gathers statistics from their segments 112-114.
[0044] The following description of an embodiment will refer to
statistics collection unit 143, link 156, segment 114, and nodes
169-171 to illustrate aspects of the embodiment within a segment of
network cloud 110. It will be appreciated that the same general
description will apply to statistics collection unit 141, link 154,
segment 112, and nodes 161-164 and statistics collection unit 142,
link 155, segment 113, and nodes 165-168.
[0045] As described earlier, traffic transmitted through network
cloud 110 may be monitored using counters. As such, each of nodes
161-171 comprise a number of counters for storing a set of
statistics relating to traffic flow through the nodes and possibly
other characteristics of the node. Again, the counters may be
embodied in hardware, software or other means known in the art.
Typically, the counters are reset after a predetermined time
interval regardless as to whether or not their data has been
collected. If the data from the counters is not collected in each
interval, some data will be lost and the overall statistics
collection process will produce incomplete or inaccurate
results.
[0046] Referring to FIG. 2, each node 161-171 may include a number
of subcomponents. The hierarchical structure of each node 161-171
may include a number of cards 204a, 204b, . . . 204n, where the
cards may process communications utilizing a number of devices
206a, 206b, . . . , 206n, and where the devices may each support a
number of connections, 208a, 208b, . . . 208n. A card is a physical
entity having a number of devices. A device (or port) is a physical
or logical entity that groups connections. Connections carry user
data and are made between devices. There may be many connections
per device. Each of these hierarchical components may include
specific counters 220 for collecting statistics for that particular
hierarchical component. As such, statistics requests from
statistics collection unit 143 may be targeted at a particular
counter 220 within a particular hierarchical component within each
associated node 161-171 of each request.
[0047] Referring to FIG. 1, statistics management block 120
receives network statistics configurations 122 that are generated
by an automatic billing routine or some other entity that may
request a particular statistic or set of statistics. Any network
statistics configurations 122 received by statistics management
block 120 must be processed and parsed to generate statistics
collection configuration information which is provided to
statistics collection units 141-143. The parsing performed by
statistics management block 120 is based on the distribution of
nodes 161-171 that contain the requested statistics amongst the
various node segments 112-114.
[0048] The statistics collection configuration information contains
information concerning the nodes and their subcomponents required
to respond to network statistics configuration 122 which is used to
determine the protocol, frequency of polling and other parameters
needed for the requests. Statistics management block 120 sends each
set of statistics collection configuration information to its
associated statistics collection unit 141-143.
[0049] When statistics collection unit 143 receives statistics
collection configuration information from statistic management
block 120, statistics collection unit 143 will form and send
statistics requests to nodes 169-171 in node segment 114. Each
individual request from statistics collection unit 143 is
associated with, i.e. addressed to, a node 169-171 in segment 114
from which it requests statistics. It will be appreciated that
statistics requests sent to the various nodes in network cloud 110
may be sent using SNMP or other polling protocols. It will be
appreciated that statistics collection unit 143 may use software
and/or hardware to process the initiation and processing of
requests to nodes 169-171 in its segment 114. As described
previously, statistics collection unit 143 in the embodiment uses a
general purpose computer with specialized network management
software operating thereon. However, other embodiments may have
hardware embodied in customized circuitry, an ASIC, a
microcontroller, and other electronics. The software may be
embodied in one or more computer programs executing on one or many
pieces of the hardware.
[0050] Statistics are sent from nodes 169-171 to statistics
collection unit 143 in response to scheduled polling and event
driven collection. In scheduled polling, the statistics collection
unit 143 periodically sends requests to nodes 169-171 to respond
with the required data. The requests may be sent at regular or
irregular intervals. In event driven collection, requests are not
sent by statistics collection unit 143.
[0051] An example of the type of statistics that may be tracked is
the number of data packets being sent through network cloud 110
from end user 181 to either of end users 183 and 184. Statistics
management block 120 receives network statistic configuration 122
relating to this requirement and generates statistics collection
configuration information. The statistics collection configuration
information is passed to each statistics collection unit 141-143.
In this example, the individual requests are sent to a number of
nodes 161-171 in a number of segments 112-114 in network cloud 110.
Each statistics collection unit 141-143 collects the statistics
corresponding to traffic sent by end user 181 from its associated
nodes 161-171 via sending individual requests to one or more of
nodes 161-171. It will be appreciated that the sequence in which
the individual requests are sent by statistics collection unit 143
may affect how much data is gathered from each of nodes 169-171 in
each interval since both system and per-node limitations can defer
the arrival of individual requests for statistics or the responses
thereto.
[0052] As described earlier, there are limitations in processing
requests. System level limitations include the time required for
building a request, the number of items that can be transmitted
with a single request and the upper bound on outstanding requests
in segment 114 given the capacity of links in segment 114 and the
number of expected responses from nodes 169-171. Per-node
limitations include the response time for each of nodes 169-171,
computational processing limitations for nodes 169-171 and the
upper bound on the number of outstanding requests for each of nodes
169-171 that marks when each node must divert switching resources
to respond to such requests. An outstanding request is a request
for which a response from its associated node 161-171 has not yet
been communicated to its statistics collection unit 141-143.
[0053] The embodiment utilizes algorithms to initiate requests in a
sequence to make efficient use of available resources, including
bandwidth, of the node and the network. Alternatively, the sequence
can be defined so that the number of requests to specific counters
(chosen by the network operator) is maximized. It will be
appreciated that, in some circumstances, resource usage may be
managed by defining the sequence for initiating requests using a
time-response algorithm that allows response to a greater number of
requests from all nodes. In other circumstances, resource usage may
be managed by defining the sequence on a hierarchical node ordering
system, collecting data from specific nodes first.
[0054] Referring to FIG. 3, information that may be used to define
the sequence for initiating the requests to nodes 169-171 is stored
in sets of node attributes 369-371. Similarly, the information that
may be used to define the sequence for initiating the requests to
nodes 161-164 and nodes 165-168 is stored in sets of node
attributes 361-364 and sets of node attributes 365-368,
respectively. Each set of node attributes 361-371 comprises data
gathered from nodes 161-171 during previous requests for
statistics, information obtained from network 110 and information
derived from that data. An example of information which may be
contained in sets of node attributes 361-371 for nodes 161-171 is
presented in table 300, where each row of table 300 represents a
set of node attributes 361-371 for nodes 161-171. Statistics
collection unit 143 is able to access the information contained in
sets of node attributes 369-371 for nodes 169-171 in segment 114.
To do so efficiently, sets of node attributes 369-371 are stored in
an area that is readily accessible to statistics collection unit
143. In the present embodiment, node attributes for their
respective segments 112-114 are stored in the memory associated
with each statistics collection unit 141-143. It will be
appreciated that sets of node attributes 369-371 may be stored in
random access memory, data registers, a hard disk, a floppy disk
and any other read/write storage media accessible by statistics
collection unit 143.
[0055] The network operator selects a particular node attribute
312-316 to be the selected node attribute for segment 114 or
network cloud 110. The network operator may base this selection on
the past performance of nodes 169-171. Choices for the selected
node attribute may include: (i) the number of requests sent to
nodes 169-171 in an interval (node attribute 312), (ii) the average
response time for receiving a response from nodes 169-171 (node
attribute 313), (iii) the class of node associated with the request
(node attribute 314), (iv) the number of timeouts per node (node
attribute 315) and (v) the number of counters on nodes 169-171 from
which to collect data (node attribute 316). It will be appreciated
that node attributes are not limited to those identified above and
may be any information accessible about the node, its past
performance in the network, information available from the network,
previously gathered statistics and other attributes that may be
derived from this information.
[0056] Once a selected node attribute has been selected, statistics
collection unit 143 defines a sequence in which to initiate
statistics requests to nodes 169-171 within segment 114.
Representations of nodes 169-171 in segment 114 are ordered by the
value of their selected node attributes according to the
predetermined ranking algorithm. In this way, the sequence is based
on the value of the selected node attributes of nodes 169-171. The
requests are then initiated in the sequence based on the ranking of
the representation of their associated nodes 169-171. It will be
appreciated that initiating the requests is subject to system and
per-node constraints that may affect the sequence in which they are
sent.
[0057] The algorithm used to define the sequence is executed on the
hardware that comprises statistics collection unit 143. This
hardware is part of the device which defines the sequence and
initiates the requests within statistics collection unit 143. The
device may be a central processing unit, a piece of hardware
specially hardwired for this task, a microcontroller, or a general
purpose computer, among other things. Alternatively, it will be
appreciated that a device separated from statistics collection unit
143 may be provided with hardware and software to access sets of
node attributes 369-371 and define a sequence for initiating the
requests in segment 114. The device then communicates the sequence
to its associated statistics collection unit 143 to initiate the
requests based on that sequence, subject to system and per-node
constraints that may affect the sequence of the requests.
[0058] Defining the sequence of requests is illustrated by the
following example. First, the network operator selects node
attribute 312 as the selected node attribute for segment 114 and
wishes to define the sequence for initiating requests in ascending
order of this value. Statistics collection unit 143 accesses sets
of node attributes 369-371 for the value of node attribute 312 for
nodes 169-171. The values for node attribute 312 are 9, 2 and 6 for
nodes 169, 170 and 171 respectively. In this example, the algorithm
defines the sequence as initiating requests to node 170, node 171
and node 169, in that order, subject to system and per-node
constraints. Therefore, statistics collection unit 143 will
initiate requests in this sequence subject to these
constraints.
[0059] The network operator may select two or more node attributes
312-316 to be selected node attributes. When two or more node
attributes 312-316 are selected as selected node attributes, the
network operator also specifies the order in which the selected
node attributes will be used to define the sequence. Selecting more
than one selected node attribute results in a ranking that is
iteratively refined where the first selected node attribute is used
to rank the representation of its associated node and then
representations with the same value or range of values of the
selected node attribute for the first ranking are ranked by the
next selected node attribute. The representations with the same
values or ranges of values for the selected node attributes for all
of the previous rankings are then ranked by the next selected node
attribute. This continues until the representations have been
ranked by all of the selected node attributes.
[0060] For example, network operator chooses node attributes 314
and 315 as selected node attributes. The values of node attributes
314 and 315 are to be ranked in ascending numerical and
alphabetical order and node attribute 315 is to be used to rank the
representations of nodes 169-171 before node attribute 314. The
algorithm ranks the representations for nodes 169 and 171 before
node 170 when ranking by node attribute 315. The algorithm then
refines the ranking for each group of representations with the same
value for previous node attributes, nodes 169 and 171 and node 170
by node attribute 314. This results in a sequence for initiating
requests for node 171, node 169 and node 170, in that order.
[0061] Algorithms used to rank the representations of nodes 169-171
by the value of their selected node attributes may differ depending
on the information in the selected node attribute and the method
for defining the sequence for initiating the requests. For example,
ranking by the value of node attribute 312 by statistics collection
unit 143 may rank the representations in ascending or descending
order, depending upon the desired result. If the selected node
attribute contains a character string, as does node attribute 314,
the algorithm may rank the by the value of the selected node
attribute alphabetically. Alternatively, the algorithm may rank by
the value of the selected node attributes in a predetermined order
based on the possible values for the selected node attributes. For
example, the algorithm may sequence class "B" attributes first,
followed by class "C" and class "A", in that order. It will be
appreciated that an operating characteristic of the nodes may be
this class distinction. An example of such an operating
characteristic may be the distinction between nodes which
correspond to wireless transmission technologies and nodes that do
not. A network operator may cause the algorithm to rank the
wireless class of nodes before other types of nodes thus giving a
higher priority to the wireless class of nodes.
[0062] The algorithm used to define the sequence for initiating the
requests may translate the selected node attributes into values
that are more readily sortable prior to ranking them. The
translated value for nodes 169-171 is a function of the value of
their selected node attributes. The algorithm then uses the
translated value to define the sequence for initiating the
requests. For example, a selected node attribute containing a real
number may be converted to an integer. Another example is an
algorithm that translates node attribute 314 having a value of
class "A" to the integer 1, class "B" to 2 and class "C" to 3 and
ranking them in ascending order. The translation portion of the
algorithm may also define the values for selected node attributes
within a certain range to have the same value for their translated
values. Whether a translation occurs depends on the type of
information found in the selected node attribute and how the
algorithm is used to define the sequence based on those values.
[0063] In the embodiment described, the algorithm ranks the
representations of the nodes only in ascending order and maps
selected node attribute values to an integer value used for this
ranking. The desired sequence for initiating the requests will
affect how this translation occurs. For example, referring to FIG.
3, ranking the representations for nodes 169-171 in segment 114 by
the quickest response time first, node attribute 323, may require a
translation of the value of node attribute 323 to an integer. One
method of achieving this result is to truncate the values to
integers. That will produce "10", "5" and "6" for the translation
of the values of node attribute 323 for nodes 169, 170 and 171,
respectively. Ranking the translated selected node attributes in
ascending order results in a sequence for initiating requests for
node 170, node 171 and node 169, in that order. Ranking by the
slowest response time first in segment 114 will also require a
translation of the value of node attribute 323 to an integer but
the translation must also reverse the order of the values of node
attribute 323. One method of achieving this result is to truncate
the values to integers and take the negative as the translated
value. That will produce "-10", "-5" and "-6" for the translation
of node attribute 323 for nodes 169,. 170 and 171, respectively.
Ranking the translated selected node attributes in ascending order
results in a sequence of requests for node 169, node 171 and node
170, in that order.
[0064] In the embodiment, the requests themselves are not ranked
but representations of the nodes with which they are associated are
ranked. The ranked representations are used to determine the order
in which nodes should be polled. The sequence of requests is
defined by sending requests for the nodes in the order of this
ranking. The association of requests with the representations of
their nodes may be maintained using an array of pointers. It will
be appreciated that the requests themselves may be stored in a
sequenced order to accomplish the same goal of initiating the
requests in a defined sequence. Also, it will be appreciated that
it may not be necessary for the representations of nodes to be
stored in a sequenced order prior to sending the requests to those
nodes. This may be accomplished through an array of pointers to the
representations of the nodes where the array of pointers indicates
the sequence of nodes to which requests will be sent.
[0065] Referring to FIG. 1, it will be appreciated that in other
embodiments statistics collection unit 143 may send requests in an
order other than that of the defined sequence due to system and
per-node constraints. For example, a statistics collection system
typically has other constraints preventing statistics collection
unit 143 from sending too many requests without receiving responses
for those requests.
[0066] One such constraint is the limit on the capacity of the
links in segment 114, for example, the capacity of link 156 for
statistics collection unit 143. Each link in segment 114 is able to
receive only a predefined number of messages at a time, therefore,
there is an upper bound on the number of outstanding requests in
segment 114 to prevent the links from being overloaded with
messages. It will be appreciated that the value of this upper bound
may be different in each segment 112-114 and may be some number
other than the actual upper bound.
[0067] To track statistics related to the upper bound in the
segment, a counter is maintained by statistics collection unit 143
to count the number of outstanding requests in segment 114. The
counter value is incremented for every request sent and decremented
for each response received. Before a request is sent, the counter
is compared with the segment upper bound. If the counter has not
yet reached the segment upper bound, the request is sent. If the
counter has reached the segment upper bound, the request is not
sent. This ensures that the segment upper bound will not be
exceeded before sending a request for segment 114. It will be
appreciated that this counter may be embodied in hardware or
software using techniques known in the art.
[0068] There may also be an upper bound on the number of
outstanding requests that exist for each node 169-171. This upper
bound exists for each node 169-171 because nodes 169-171 must
divert resources away from their switching functions to respond to
the requests for statistics. Exceeding this upper bound for nodes
169-171 may cause traffic interruptions and loss of service for the
node. Therefore, this upper bound should not be exceeded.
Statistics collection unit 143 maintains a separate counter for
each node 169-171 in segment 114. The upper bound for each node
169-171 is compared with its counter in the same manner as the
segment upper bound. It will be appreciated that these counters may
also be embodied in hardware or software using techniques known in
the art.
[0069] Constraints such as those noted above may cause statistics
collection unit 143 to send requests in an order other than the
sequence defined by the described method. Typically, the upper
bounds for the number of outstanding requests for each segment
112-114 are much larger than the upper bound for the number of
outstanding requests for any given node 161-171 in network cloud
110.
[0070] In the embodiment, the methods for ensuring the segment and
the per-node upper bound for outstanding requests are not exceeded
are both performed by statistics collection unit 143. It will be
appreciated that, in other embodiments, statistics collection unit
143 may perform only one of the methods of checking the upper
bounds or may not perform any method of checking the upper
bounds.
[0071] When nodes 169-171 within node segment 114 respond to the
outstanding sent statistics requests, the responses are collected
by statistics collection unit 143. When statistics collection unit
143 sends requests to segment 114, it may do so through a standard
interface known in the art, such as a socket. Statistics collection
unit 143 stores appropriate structures to receive responses from
each request. The structures are associated with the socket
corresponding to its request. Each response arrives on the same
socket on which it was sent. Statistic collection unit 143 combines
the information from the responses with the other statistics
received from segment 114 and stores this information in its
corresponding structure. It provides these relevant statistics to
statistics aggregation block 130.
[0072] It will be appreciated that this process of defining a
sequence for sending requests will be repeated for each set of
statistics collection configuration information sent to each
statistics collection unit 141-143. This may occur on a cyclic time
interval since statistics collection configuration information may
be in response to scheduled polling from statistics management
block 120.
[0073] Statistics collection unit 143 may also update the
information stored in sets of node attributes 369-371 (FIG. 3) to
be used to define a sequence for future requests for statistics.
Statistics aggregation block 130 communicates with each of
statistics collection units 141-143 to aggregate the segment
statistics to produce compiled statistics 132. These are provided
as a response to the network statistics configuration 122 received
by statistic s management block 120. In the embodiment, statistics
collection unit 143 has software to control and process various
statistics collection and processing functions. These include
defining the sequence of initiating requests, accessing and
processing node attributes 369-371, ranking the representations of
nodes 169-171, translating values of node attributes 369-371,
checking counters, effecting communicating with nodes 169-171,
statistics management block 120 and statistic aggregation block 130
and gathering and processing statistics, among other things. It
will be appreciated that the programs may be embodied in one
computer program or many computer programs executing on one or many
hardware devices. The software may be stored in random access
memory, read only memory, a hard disk, a floppy disk, and any other
storage media accessible by statistics collection unit 143.
Statistics collection unit 143 may use a central processing unit, a
custom hardware device, a microcontroller, or a general purpose
computer, among other things, to do any or all of the tasks
involved in sending requests to nodes 169-171.
[0074] Referring to FIGS. 4, 5A and 5B, an example using the method
initiating requests in a defined sequence as described above for
network 425 of FIG. 4 is shown. In FIG. 4, network cloud 425 is
shown having segment 415 with seven nodes 401-407. Statistics
collection unit 420 communicates with nodes 401-407 in segment 415
through link 430. For this example, it is assumed that the
responses to requests to nodes 401-406 take exactly one second to
arrive back to statistics collection unit 420 and the requests to
node 407 take three seconds. The example also imposes upper bounds
of one outstanding request per node and two outstanding requests in
segment 415.
[0075] Referring to FIG. 5A, table 500 shows values for node
attributes for seven nodes 401-407. Each row 501-507, in table 500
represents a separate node. There are three columns in table 500
representing node attributes which are monitored for this example.
The node attributes shown are the element identifiers (node
attribute 510) shown in column 520, the number of requests to be
made to each of nodes 401-407 in the next interval (node attribute
512) shown in column 522 and the expected response time based on
previous responses from nodes 401-407 (node attribute 514) shown in
column 524.
[0076] Referring to FIG. 5B, parts (i) and (ii) show timelines 528
and 529 measured in seconds along the horizontal axis. The number
of outstanding requests in segment 415 is shown along the vertical
axis. Each box on timelines 528 and 529 represents one of requests
531-538, each request 531-538 made to the node whose element
identifier, node attribute 510, is contained within the box. The
areas of each of the boxes on timelines 528 and 529 represent the
bandwidth in link 430 used by requests 531-538 represented by each
box.
[0077] FIG. 5B(i) shows the results of initiating requests using a
prior art method, which initiates requests without defining a
sequence. Here the order of initiating requests coincides with node
attribute 510 (the element identifier for nodes 401-407) as shown
in column 520 in table 500. The requests will be initiated for
nodes 401-407 in ascending order of their element identifiers,
subject to stated constraints.
[0078] FIG. 5B(i) shows that at 0 seconds, request 531 is sent for
the statistics from node 401. As the requests to be sent for node
401 have been exhausted, request 532 is sent for node 402, i.e. the
node with the next element identifier. At this point, the upper
bound on the number of outstanding requests in segment 415 has been
reached and no further requests are sent. At 1 second, requests 531
and 532 have received a response and new requests may be sent.
Accordingly, requests 533 and 534 are sent at 1 second. Thereafter,
the upper bound on the number of outstanding requests in segment
415 has been reached and no further requests are sent. Statistics
collection unit 420 continues to initiate requests by receiving
responses from requests 533 and 534 and by sending requests 535 and
536 at 2 seconds. At 3 seconds, responses have been received from
requests 535 and 536 and statistics collection unit 420 sends
request 537 for node 407. After request 537 is sent for node 407,
no further requests may be sent. This is because while there is a
remaining request 538, also for node 407, the upper bound for
outstanding requests for node 407 has been reached. Therefore,
request 538 will not be sent until a response is received for
request 537. The response for request 537 returns at 6 seconds, at
which point, request 538 is sent. Request 538 returns at 9 seconds.
The timeline in FIG. 5B(i) shows that this method of initiating
requests results in responses returning for all requests 531-538 in
9 seconds. The unused bandwidth for link 430 in network 425 using
this method is indicated on timeline 528 by shaded portion 540.
[0079] FIG. 5B(ii) shows the results of a method of the embodiment
defining a sequence for initiating the requests using node
attribute 512, the number of requests for the nodes, shown in
column 522 of table 500. The sorting algorithm selected for this
example defines the sequence by the number of requests for the
interval for its associated node in descending order. This sequence
will attempt to initiate requests for node 407 prior to requests
for the other nodes, subject to the stated constraints.
[0080] At 0 seconds, using the sequencing algorithm described
earlier, request 537 is sent for the statistics to node 407,
therefore, no further requests may be sent for node 407 since the
upper bound for outstanding requests for node 407 has been reached.
Request 538 will not be sent until request 537 returns a response.
Since request 538 will not be sent at 0 seconds, request 531 is
sent for node 401. At this point, the upper bound for the number of
outstanding requests in segment 415 has been reached and no further
requests are sent. At 1 second, request 531 has received a response
and new requests may be sent. Request 532 is sent at 1 second.
Again the upper bound for the number of outstanding requests in
segment 415 has been reached and no further requests are sent. At 2
seconds, request 532 has received a response and request 533 for
node 403 is sent. At 3 seconds, responses have been received from
requests 533 and 537. Request 538 for node 407 is then sent at 3
seconds, along with request 534 for node 404. This process
continues with requests 535 and 536 being sent at 4 and 5 seconds
respectively.
[0081] The timeline in FIG. 5B(ii) shows that this method of
defining a sequence for initiating the requests results in
responses returning for all requests 531-538 in 6 seconds. This is
an improvement over the method of FIG. 5B(i) which required 9
seconds. The method of FIG. 5B(i) runs the risk of not sending some
requests in time to obtain the statistics required before the
statistics recorded for the interval are discarded by the
counters.
[0082] The elements of FIG. 5B(ii) also illustrate an example using
the response time, node attribute 514, as the selected node
attribute, shown in column 524 of table 500. The algorithm selected
for this example defines a sequence for initiating the requests for
the nodes by the longest response time for the interval in
descending order. The sequence of requests will attempt to send
requests for node 407 first, followed by nodes 401, 402, 403, 404,
405 and 406. Similarly, this method of initiating requests results
in responses returning for all requests 531-538 in 6 seconds.
[0083] In the example of FIGS. 5A and 5B, the network operator
utilized a selected node attribute for the interval resulting in a
maximized number of requests sent and responses received over a
time interval. However, a network operator may want to impose a
specific sequence using this mechanism to give a particular node or
message type the highest priority even though this may not be the
most efficient sequence for initiating requests. Also, it is
possible for the prior art method of sending requests to nodes in a
network to produce the optimum result in that all requests receive
a response in each interval. However, allowing the network operator
to configure the sequence in which requests are initiated allows
the network operator to select and rank relevant factors when
polling the network.
[0084] It will be appreciated that the device defining the sequence
for initiating the requests may alternatively employ a
self-teaching method of defining a sequence for initiating requests
without having the network operator select a selected node
attribute. The self-teaching method could define the sequence based
on a number of pre-programmed factors to optimize the collection of
statistics from certain nodes or all of the nodes in the segment or
network. The pre-programmed factors may be based on the results
from previous collections performed with different sequencing
methods. The self-teaching method may be performed in a simulated
environment and the optimal method recommended to network
operators.
[0085] An additional feature of the embodiment described above is
the use of individual upper bounds for the upper bound on the
number of outstanding requests allowed for the nodes in the
network.
[0086] Referring to FIG. 6B(i) and (ii), network 610 is shown
having segment 609 with three nodes 601-603. Statistics collector
606 collects statistics from nodes 601-603 through link 608.
Referring to FIG. 6A, table 600 provides a row for each of nodes
601-603 in network 610. Column 604 of table 600 gives the upper
bound for the number of outstanding requests that each node 601,
602 and 603 can process at any one time.
[0087] In prior art systems, statistics collection unit 606
typically uses an overly conservative constraint for the number of
outstanding requests for a node, such as the smallest number for
all nodes 601-603, as the constraint for each of nodes 601-603 in
segment 609 or network 610. In the example presented, the smallest
upper bound from column 604 is one outstanding request.
[0088] FIG. 6B(i) shows the requests sent in network 610 using a
prior art system. While the prior art system avoids overloading
nodes 601-603 with requests to which they cannot respond, one or
more of nodes 601-603 may be underutilized. This may contribute to
a deferral in requesting and receiving responses for statistics
since statistics collection unit 606 may have to wait for a
response before initiating more requests to a node although the
node is able to process more requests immediately. FIG. 6B(i) shows
that this example results in a large amount of unutilized bandwidth
in link 608, represented by shaded portion 614. The amount of
bandwidth in link 608 used by each of nodes 601, 602 and 603 is one
outstanding request, respectively represented by shaded portions
611, 612 and 613. The values for column 604 from table 600 in FIG.
6A shows that node 603 can process two more outstanding requests,
using some of the unutilized bandwidth in shaded portion 614 of
link 608.
[0089] Referring to FIG. 6B(ii), in the embodiment, the network
operator separately defines the upper bound for the outstanding
requests for each of nodes 601-603 in network 610 given the upper
bounds from column 604 of table 600 in FIG. 6A. The data contains a
mapping between the node address of nodes 601-603 and the upper
bound value for that node. The statistics collection unit 606 reads
and updates these upper bounds on the direction of the network
operator. It will be appreciated that the separately defined upper
bound need not be the values given in column 604 but may be other
suitable numbers chosen by the network operator. The network
operator, in this example, defines the individual upper bound as
equal to the upper bound from column 604 of table 600. Statistics
collection unit 606 maintains a counter for each node 601-603 in
segment 609. The counter value is incremented for a node 601-603 if
statistics collection unit 606 sends a request for that node
601-603. The counter value is decremented for a node 601-603 if
statistics collection unit 606 receives a response from that node
601-603. Before sending a request for a node 601-603, statistics
collection unit 606 compares the counter for that node 601-603 with
the separately defined upper bound for outstanding requests for
that particular node 601-603. If the counter has not yet reached
the node upper bound, the request is sent. If the counter has
reached the node upper bound, the request is not sent.
[0090] Using the individual upper bounds for each node 601-603, the
amount of bandwidth in link 608 used by each of nodes 601, 602 and
603 is now one outstanding request for each of nodes 601 and 602,
respectively represented by shaded portions 621 and 622 and three
outstanding requests for node 603, represented by shaded portion
623. This allows node 603 in FIG. 6B(ii) to use more of the
unutilized bandwidth, the new amount of unutilized bandwidth shown
in shaded portion 624 of link 608.
[0091] Using the method of defining a sequence for initiating
requests described with reference to FIG. 1, statistics collection
unit 143 initiates a request after determining that the upper bound
for segment 114 and the per-node upper bound for the number of
outstanding requests will not be exceeded with a further request
for the particular node in segment 114. Determining that the
per-node upper bound for outstanding requests will not be exceeded
uses the separately defined upper bound for each individual node
169-171 rather than the overall constraint typical in the prior
art. For efficient operation, the separately defined upper bounds
for nodes 169-171 in segment 114 are stored in an area that is
readily accessible to statistics collection unit 143. It will be
appreciated that individual upper bounds may be stored in random
access memory, a hard disk, a floppy disk, and any other storage
media accessible by statistics collection unit 143. In the
embodiment, the upper bounds are stored within each statistics
collection unit 141-143. Similarly, statistics collection unit 141
determines that the upper bounds for nodes 161-164 and segment 112
will not be exceeded before sending a request and statistics
collection unit 142 determines that the upper bounds for nodes
165-168 and segment 113 will not be exceeded before sending a
request.
[0092] It will also be appreciated that in another embodiment an
algorithm may be used to define the sequence which is a hybrid of
algorithms described herein.
[0093] It is noted that those skilled in the art will appreciate
that various modifications of detail may be made to the embodiments
described herein, which would come within the spirit and scope of
the invention as defined in the following claims.
* * * * *