USRE40744E1 - Method for determining the drop rate, the transit delay and the break state of communications objects - Google Patents
Method for determining the drop rate, the transit delay and the break state of communications objects Download PDFInfo
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- USRE40744E1 USRE40744E1 US09/988,789 US98878901A USRE40744E US RE40744 E1 USRE40744 E1 US RE40744E1 US 98878901 A US98878901 A US 98878901A US RE40744 E USRE40744 E US RE40744E
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- 238000000034 method Methods 0.000 title claims abstract description 46
- 238000004891 communication Methods 0.000 title claims abstract description 39
- 230000008447 perception Effects 0.000 claims abstract description 18
- 238000005070 sampling Methods 0.000 claims abstract description 11
- 238000012545 processing Methods 0.000 claims abstract description 9
- 238000007726 management method Methods 0.000 description 6
- 235000008694 Humulus lupulus Nutrition 0.000 description 4
- 238000003745 diagnosis Methods 0.000 description 4
- 230000004044 response Effects 0.000 description 4
- 238000004364 calculation method Methods 0.000 description 2
- 230000000737 periodic effect Effects 0.000 description 2
- 238000010586 diagram Methods 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
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-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L43/00—Arrangements for monitoring or testing data switching networks
- H04L43/08—Monitoring or testing based on specific metrics, e.g. QoS, energy consumption or environmental parameters
- H04L43/0805—Monitoring or testing based on specific metrics, e.g. QoS, energy consumption or environmental parameters by checking availability
- H04L43/0817—Monitoring or testing based on specific metrics, e.g. QoS, energy consumption or environmental parameters by checking availability by checking functioning
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L41/00—Arrangements for maintenance, administration or management of data switching networks, e.g. of packet switching networks
- H04L41/14—Network analysis or design
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L43/00—Arrangements for monitoring or testing data switching networks
- H04L43/08—Monitoring or testing based on specific metrics, e.g. QoS, energy consumption or environmental parameters
- H04L43/0823—Errors, e.g. transmission errors
- H04L43/0829—Packet loss
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L43/00—Arrangements for monitoring or testing data switching networks
- H04L43/08—Monitoring or testing based on specific metrics, e.g. QoS, energy consumption or environmental parameters
- H04L43/0852—Delays
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L43/00—Arrangements for monitoring or testing data switching networks
- H04L43/08—Monitoring or testing based on specific metrics, e.g. QoS, energy consumption or environmental parameters
- H04L43/0852—Delays
- H04L43/0864—Round trip delays
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L43/00—Arrangements for monitoring or testing data switching networks
- H04L43/10—Active monitoring, e.g. heartbeat, ping or trace-route
Definitions
- This method determines the drop rate, the transit delay and the break state of communications objects using the topology (connectivity) of these objects.
- a method of determining the topology of a network of objects has been filed for patent, Dawes et al, U.S. Ser. No. 08/558,729 filed Nov. 16, 1995, U.S. Ser. No. 08/599,310 filed Feb. 9, 1996 and (unknown) filed Nov. 15, 1996 incorporated herein by reference.
- a manual method or some alternative automatic method allows the connectivity of communications objects to be determined.
- the invention exploits knowledge of the detailed local topology of communicating objects.
- Communications objects such as routers have multiple communications lines. They accept frames from these lines and determine from information in each frame which line each frame should be sent out on.
- the time between the receipt of a frame and its dispatch out again is called the transit delay.
- routing or switching communications devices cannot dispatch frames as fast as they receive them and run out of memory to store the ones they receive, so they discard some.
- internal queues may fill up and for other reasons, frames get lost between acceptance and onward dispatch.
- the overall discard rate is usually called the drop rate.
- the break state for a device is true when it can neither send nor receive on any communications line, yet all the lines are ok. For example, when a device is powered down its break state is true.
- the break state is true for a line when the devices at each end are not broken and yet cannot send or receive traffic across it. For example, a line is broken when it is cut through.
- the network management center is the computer which is operating the software that performs this method. It also either performs interrogation of devices to provide data for the method below or receives such data to use in the method.
- the NMC periodically requests from each device in a communications network the amount of traffic flowing in and out of each interface and the line status (OK or OFF) on the line for each interface on that device. This request should result in a set of replies from each device returned to the NMC. Not all devices need report the OK or OFF line status values or do so correctly.
- the NMC may detect four changes. First that it now receives no replies to its requests of this device. Second that it receives no replies from devices lying beyond this device and which are only reachable through this device. Third no traffic will now be detected flowing in any lines to or from this device. Four the line status bits on lines connected to this broken device will change (e.g. from ok to off). Any subset of two or more of these four changes will be adequate to determine that the device is broken.
- the drop rate in a device is the difference between the mean drop rate measured to devices just beyond it (and connected to it) and the mean drop rate measured to devices just before it (and connected to it), where closeness is measured in terms of the number of hops to the NMC. Devices diagnosed as broken should not be included in any part of this calculation.
- the mean frame transit delay in a device is the difference between the mean round trip time measured to devices just beyond it (and connected to it) and the mean round trip time measured to devices just before it (and connected to it), where closeness is measured in terms of the number of hops to the NMC. Devices diagnosed as broken should not be included in any part of this calculation.
- a method for determining the mean transit delay of frames through one or more communications devices which receive and forward frames.
- a method for determining the mean drop rate of frames through one or more communications devices which receive and forward frames.
- a method for determining the break state of one or more communications devices and interfaces or lines to and from communications devices.
- a method of analyzing a communication network comprising determining a break state of communications devices connected in the network, by polling each device from a network management computer (NMC) which is in communication with the network, and processing signals in the NMC in accordance with at least one of
- NMC network management computer
- FIG. 1 is an illustration of a portion of a network
- FIG. 2 is a block diagram of a structure for supplementing the invention.
- the method described below is general, is independent of device type and does not require a device to respond to management requests (e.g. SNMP). Moreover, the method described below works even on objects or sets of objects not responding to management requests (e.g. a portion of the network managed by some supplier of communications services).
- the drop rate in ‘x’ is the difference between the mean drop rate measured to ‘C’ and ‘B’ and the mean drop rate measured to ‘D’.
- the mean drop rate measured to ‘D’ is the fraction of the requests for information sent by the NMC to ‘D’ to which no replies have been received.
- the mean drop rates to ‘C’ and ‘B’ are computed similarly.
- the mean frame transit delay ‘x’ is the difference between the mean round trip time measured to ‘C’ and ‘B’ and the mean round trip time to ‘D’.
- the software executing the method runs as a software module within the same main software process that executes the methods described in the aforenoted patent applications.
- This process receives device replies from a further software process that periodically requests the traffic and status information from all managed devices in the network.
- the main software uses these relies to determine the topology, and once the topology is known, also passes the replies to the logic module that executes the method. Changes in break state of any object and the current drop and delay values are recorded periodically in a database. The NMC operator can now observe these changes in information by operating a software tool that examines this database.
- FIG. 2 describes a structure for implementing the methods described below.
- the mean frame drop rate is the probability that a frame will get dropped in attempting to transit through a device.
- the drop rate in a device is the difference between the mean drop rate measured to devices just beyond it (and connected to it) and the mean drop rate measured to devices just before it (and connected to it), where closeness is measured in terms of the number of hops to the NMC. Note that in equation 2 the value of D(x) is half the difference between L+ and L ⁇ , as L+ and L ⁇ refer to round trip as opposed to one way trip drops.
- the mean frame transit delay is how long it takes the average frame to transit through this device.
- the mean frame transit delay in device ‘x’ is 0.021 seconds.
- the NMC may detect four changes. First that it now receives no replies to its requests of this device. Second that it receives no replies from devices lying beyond this device and which are only reachable through this device. Third no traffic will now detected flowing in any lines to or from this device. Fourth that the line status bits on lines connected to this broken device will change (e.g. from ok to off). Any subset of two or more of these four changes will be adequate to determine that the device is broken.
- a line which has more than two ends is treated as a device from the point of view of breaks.
- the methods described above can be performed as a single method of partitioned into two or three methods. They can record and/or report the change or current state of the devices and interfaces under consideration to a database or file, to another software element or elements within the same cpu or not, directly or remotely to a screen or screens, to one or more NMCs, or in other ways. They can operate in a single cpu or distributed in multiple cpus. Each method can consider one or more devices, either serially or in parallel. The methods can share a common input of responses from the NMC or can have different input forms, and the methods can be integrated within a single NMC, istributed among several NMC or performed partially or wholly by other cpus.
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- Engineering & Computer Science (AREA)
- Computer Networks & Wireless Communication (AREA)
- Signal Processing (AREA)
- Environmental & Geological Engineering (AREA)
- Data Exchanges In Wide-Area Networks (AREA)
- Small-Scale Networks (AREA)
Abstract
D(x)=((L+(x)−L−(x))/2,
and L(x)=1−A(x)
where
-
- A(x): the fraction of poll requests from the NMC to device x for which the NMC receives replies (measured over the last M sampling periods), (wherein x must not be broken),
- D(x): the mean frame drop rate in device x,
- L(c): NMC's perception of the loss rate to device x and back,
- L−(x): the NMC's perception of the mean value of L(z) for all devices z connected to device x, closer to the NMC than device x and which are not broken, and
- L+(x): the NMC's perception of the mean value of L(z) for all devices z connected to device x, further away from the NMC than device x and which are not broken.
Description
D(x)=((L+(x)−L−(x))/2,
and L(x)=1−A(x)
where
-
- A(x): the fraction of poll requests from the NMC to device x for which the NMC receives replies (measured over the last M sampling periods), (wherein device x must not be broken),
- D(x): the mean frame drop rate in device x,
- L(c): NMC's perception of the loss rate to device x and back,
- L−(x): the NMC's perception of the mean value of L(z) for all devices z connected to device x, closer to the NMC than device x and which are not broken, and
- L+(x): the NMC's perception of the mean value of L(z) for all devices z connected to device x, further away from the NMC than device x and which are not broken.
T(x)=((w+(x)−W−(x))/2
where
-
- T(x): the mean frame transit delay for device x, (wherein device x must not be broken),
- W(x): the mean round trip time taken between a poll request from the NMC to device x and the receipt of the reply by the NMC (measured over the last N sampling periods),
- W−(x): The NMC's perception of the mean value of W(z) for all devices z connected to device x, closer to the NMC than device x and which are not broken,
- W+(x): The NMC's perception of the mean value of W(z) for all devices z connected to device x, further away from the NMC than device x and which are not broken.
-
- (a) (i) receiving no replies to polling signals directed to a device,
- (ii) receiving no replies from devices lying beyond said device,
- (iii) detecting no traffic flowing in any lines to or from said device,
- (iv) detecting changes to line status bits on lines connected to said device;
- (b) (i) determining zero traffic on a line and a device being otherwise determined as not being broken, declaring the line as being broken,
- (ii) declaring a line as being broken in step (b)(i) after a predetermined period of time,
- and
- (c) processing steps (a) and (b) with lines having more than two ends, as if it were a single device from the point of view of breaks.
- (a) (i) receiving no replies to polling signals directed to a device,
- M: how many sampling periods the drop rate is averaged over (e.g. 10). A sampling period is the interval between periodic requests for traffic and status values from interfaces (e.g. 30 seconds).
- A(x): the fraction of poll requests from the NMC to ‘x’ for which the NMC receives replies (measured over the last M sampling periods). ‘x’ must be not be broken.
- D(x): the mean frame drop rate in device ‘x’.
- L(c): NMC's perception of the loss rate to ‘x’ and back.
- L−(x): The NMC's perception of the mean value of L(z) for all devices ‘z’ connected to ‘x’, closer to the NMC than ‘x’ and which are not broken.
- L+(x): The NMC's perception of the mean value of L(z) for all devices ‘z’ connected to ‘x’, further away from the NMC than ‘x’ and which are not broken.
L(x)=1−A(x) eqn 1
D(x)=(L+(x)−L−(x))/2 eqn 2
- A(B)=0.95 i.e. The NMC gets replies to 95% of its traffic info requests from ‘B’.
- A(C)=0.94 i.e. The NMC gets replies to 94% of its traffic info requests from ‘C’.
- A(D)=0.96 i.e. The NMC gets replies to 96% of its traffic info requests from ‘D’.
Therefore: - L(B)=1−0.95=0.05
- L(C)=1−0.94=0.06
- L(D)=1−0.96=0.04
- L−(x)=L(D)=0.04
- L+(x)=(L(C)+L(B))/2=0.055
- D(x)=((L(C)+L(B))/2−L(D))/2=(0.055−0.04)=0.007
- M: how many sampling periods the transit delay is to be averaged over (e.g. 4) A sampling period is the interval between periodic requests for traffic and status values from interfaces (e.g. 30 seconds). T(x): the mean frame transit delay for device ‘x’. ‘x’ must not be broken.
- W(x): the mean round trip time taken between a poll request from the NMC to ‘x’ and the receipt of the reply by the NMC (measured over the last N sampling periods).
- W−(x): The NMC's perception of the mean value of W(z) for all devices ‘z’ connected to ‘x’, closer to the NMC than ‘x’ and which are not broken.
- W+(x): The NMC's perception of the mean value of W(z) for all devices ‘z’ connected to ‘x’, further away from the NMC than ‘x’ and which are not broken.
T(x)=(W+(x)−W−(x))/2 eqn 3
- W(B)=0.100 i.e. The NMC gets replies from ‘B’ on average 0.100 seconds after it sends ‘B’ a request.
- W(C)=0.104 i.e. The NMC gets replies from ‘C’ on average 0.104 seconds after it sends ‘C’ a request.
- W(D)=0.081 i.e. The NMC gets replies from ‘D’ on average 0.081 seconds after it sends ‘D’ a request.
Therefore: - W−(x)=W(D)=0.081
- W+(x)=(W(B)+W(C))/2=(0.100+0.104)/2=0.102
- T(x)=(W+(x)−W(x))/2=(0.102−0.081)/2=0.010
Claims (3)
D(x)=((L+(x)−L−(x))/2,
and L(x)=1−A(x)
T(x)=((w+(x)−W−(x))/2
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US09/988,789 USRE40744E1 (en) | 1997-01-28 | 2001-11-20 | Method for determining the drop rate, the transit delay and the break state of communications objects |
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
CA002196133A CA2196133C (en) | 1997-01-28 | 1997-01-28 | Method for determining the drop rate, the transit delay and the break state of communications objects |
US09/014,687 US6084860A (en) | 1997-01-28 | 1998-01-28 | Method for determining the drop rate, the transit delay and the break state of communications objects |
US09/988,789 USRE40744E1 (en) | 1997-01-28 | 2001-11-20 | Method for determining the drop rate, the transit delay and the break state of communications objects |
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US09/014,687 Reissue US6084860A (en) | 1997-01-28 | 1998-01-28 | Method for determining the drop rate, the transit delay and the break state of communications objects |
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USRE40744E1 true USRE40744E1 (en) | 2009-06-16 |
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US09/014,687 Ceased US6084860A (en) | 1997-01-28 | 1998-01-28 | Method for determining the drop rate, the transit delay and the break state of communications objects |
US09/988,789 Expired - Lifetime USRE40744E1 (en) | 1997-01-28 | 2001-11-20 | Method for determining the drop rate, the transit delay and the break state of communications objects |
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US09/014,687 Ceased US6084860A (en) | 1997-01-28 | 1998-01-28 | Method for determining the drop rate, the transit delay and the break state of communications objects |
Country Status (4)
Country | Link |
---|---|
US (2) | US6084860A (en) |
AU (1) | AU5745098A (en) |
CA (1) | CA2196133C (en) |
WO (1) | WO1998033300A1 (en) |
Families Citing this family (3)
Publication number | Priority date | Publication date | Assignee | Title |
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US6584072B1 (en) * | 1998-01-28 | 2003-06-24 | Loran Network Management Ltd. | Method for determining the drop rate, the transit delay, and the break state of communications objects |
EP2802112B8 (en) * | 2013-05-08 | 2020-04-01 | Sandvine Corporation | System and method for managing a downstream bitrate on networks |
US9154431B2 (en) | 2013-05-08 | 2015-10-06 | Sandvine Incorporated Ulc | System and method for managing bitrate on networks |
Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO1993010495A1 (en) * | 1991-11-22 | 1993-05-27 | Cabletron Systems, Inc. | Method and apparatus for monitoring the status of non-pollable devices in a computer network |
US5559955A (en) * | 1990-09-17 | 1996-09-24 | Cabletron Systems, Inc. | Method and apparatus for monitoring the status of non-pollable device in a computer network |
US5668800A (en) * | 1994-05-02 | 1997-09-16 | International Business Machines Corporation | Path testing in communications networks |
US5933416A (en) * | 1995-11-16 | 1999-08-03 | Loran Network Systems, Llc | Method of determining the topology of a network of objects |
-
1997
- 1997-01-28 CA CA002196133A patent/CA2196133C/en not_active Expired - Fee Related
-
1998
- 1998-01-27 WO PCT/CA1998/000053 patent/WO1998033300A1/en active Application Filing
- 1998-01-27 AU AU57450/98A patent/AU5745098A/en not_active Abandoned
- 1998-01-28 US US09/014,687 patent/US6084860A/en not_active Ceased
-
2001
- 2001-11-20 US US09/988,789 patent/USRE40744E1/en not_active Expired - Lifetime
Patent Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5559955A (en) * | 1990-09-17 | 1996-09-24 | Cabletron Systems, Inc. | Method and apparatus for monitoring the status of non-pollable device in a computer network |
WO1993010495A1 (en) * | 1991-11-22 | 1993-05-27 | Cabletron Systems, Inc. | Method and apparatus for monitoring the status of non-pollable devices in a computer network |
US5668800A (en) * | 1994-05-02 | 1997-09-16 | International Business Machines Corporation | Path testing in communications networks |
US5933416A (en) * | 1995-11-16 | 1999-08-03 | Loran Network Systems, Llc | Method of determining the topology of a network of objects |
Non-Patent Citations (5)
Title |
---|
"Dyanmic QoS Control of Multimedia Applications Based on RTP", Busse et al. vol. 1, pp. 49-58, 1966. * |
"Fuzzy Routing", W. Arnold et al., Fuzzy Sets and Systems, vol. 2, pp. 131-153; Jan. 23, 1997. * |
"Performance evaluation of PC routers using a single-server multi-queue system with a reflection technique", A. Jirachiefpattana et al., Computer Communications, vol. 1, No. 20, pp. 1-10, Jan. 1997. * |
"Structure and use of signalling in B-ISDNs", R.O. Onvural et al, Computer Networks and ISDN Systems, vol. 3, pp. 307-323, 1996. * |
N. Dawes et al., Network Diagnosis by Reasoning in Uncertain Nested Evidence Spaces, IEEE Transaction on Communication, vol. 43, N. 2/3/4, pp. 466-476, Apr. 1995. * |
Also Published As
Publication number | Publication date |
---|---|
CA2196133A1 (en) | 1998-07-28 |
AU5745098A (en) | 1998-08-18 |
US6084860A (en) | 2000-07-04 |
CA2196133C (en) | 2002-07-16 |
WO1998033300A1 (en) | 1998-07-30 |
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