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WO2010063104A1 - Procédé et appareil de mesure de caractéristiques de performance de réseau ip - Google Patents

Procédé et appareil de mesure de caractéristiques de performance de réseau ip Download PDF

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Publication number
WO2010063104A1
WO2010063104A1 PCT/CA2009/001735 CA2009001735W WO2010063104A1 WO 2010063104 A1 WO2010063104 A1 WO 2010063104A1 CA 2009001735 W CA2009001735 W CA 2009001735W WO 2010063104 A1 WO2010063104 A1 WO 2010063104A1
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WIPO (PCT)
Prior art keywords
packets
path
packet
sequences
sub
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English (en)
Inventor
Loki Michael Jorgenson
Christopher Robert Norris
Fredrick Klassen
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Appneta Inc
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Apparent Networks Inc USA
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Publication of WO2010063104A1 publication Critical patent/WO2010063104A1/fr
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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
    • H04L43/50—Testing arrangements
    • 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
    • H04L41/02—Standardisation; Integration
    • H04L41/0213—Standardised network management protocols, e.g. simple network management protocol [SNMP]

Definitions

  • the present invention pertains to the field of packet-based network evaluation and in particular to a method and apparatus for measuring IP network performance characteristics.
  • a typical packet-based data communication network comprises a number of packet handling devices interconnected by data links, a collection of which forms a path.
  • the packet handling devices may comprise, for example, routers, switches, bridges, firewalls, gateways, hubs or similar devices.
  • the data links may comprise physical media segments such as electrical cables of various types, fibre optic cables, and the like or transmission type media such as radio links, laser links, ultrasonic links, or similar links.
  • Various communication protocols may be used to carry data across the data links, wherein data can be carried between two points in such a network by traversing a path, which includes one or more data links connecting the two points.
  • IP networks routinely support applications which can be sensitive to network conditions such as network congestion levels.
  • Typical such applications can include real-time services such as remote login applications, gaming applications, Voice-over-IP, IPTV and other forms of audio or video streaming, for example.
  • QoE Quality of Experience
  • measuring the performance of networks can be essential to their management.
  • measuring performance can also be important for planning and assessment of a particular network's relative value to a business.
  • measurement can provide the underpinning for monitoring and diagnostic systems and also be a key consideration in the management of applications that depend on the network.
  • IP networks were not specifically designed to support measurement, however there are various techniques for making measurements that are largely based opportunistically on extant functionalities of the network. For example, statistics may be gathered at the interfaces of network devices (such as switches, routers or end-hosts) using Simple Network Management Protocol (SNMP) or Remote Monitoring (RMON). Alternately, File Transfer Protocol (FTP) may be used to transfer data across an end-to-end network path or Internet Control Message Protocol (ICMP) Echo may be used to send packets on a round-trip between devices. From these various sources of data, different analyses may extract measures such as available bandwidth, achievable capacity, latency, or jitter, among others.
  • SNMP Simple Network Management Protocol
  • RMON Remote Monitoring
  • FTP File Transfer Protocol
  • ICMP Internet Control Message Protocol Echo
  • packet dispersion techniques can be used to characterize the performance properties of an end-to-end IP-based network path.
  • Two or more packets are transmitted from an origin device to a remote device and then, depending on the implementation, these packets are usually echoed back to the origin device.
  • the packets are transmitted such that they are immediately contiguous, namely such that there is little or no gap in time between the end of a leading packet and the beginning of the subsequent packet.
  • successful application of dispersion analysis requires a high degree of control of the packet timing registration in order to detect relatively small changes in separation between packets.
  • packet pair dispersion involves the use of only two packets, wherein this is an economical approach that limits the number of packets sent out onto the networks.
  • this technique can suffer from lack of precision due to the sparseness of the timing statistics of a small number of packets.
  • packet train dispersion involves sending N packets, where N > 2. Again, there is little or no gap between the N packets and they are referred to as a "train” or a "burst".
  • trains or a "burst”.
  • burst When packets in the train pass through a bandwidth bottleneck, they are stretched out such that the time to transmit each packet increases with decreasing transfer rate. The separation between each packet is substantially zero as each packet must wait in queue while the preceding packet is transmitted. If the packets then arrive at their destination, an estimation of the bandwidth can be derived by measuring the time from the first packet to last packet, and the number of bytes contained within that burst, and evaluating the ratio of bytes transferred over time.
  • Packet train dispersion can be effective in theory and within the laboratory, however it suffers from various limitations in practice. As is known, there are many behaviours on IP networks, particularly the Internet, that obscure or interfere with the collection of the requisite data for analysis using PTD. For example, the presence of traffic on the network can introduce noise into the data. Furthermore, symptoms of network dysfunction such as loss or reordering can also obstruct the subsequent data analysis using PTD. Finally, variation and inconsistency in the implementation of networks can make the measurement results and analysis thereof unreliable or inaccurate due to the inapplicability of the underlying network models assumed for the respective analysis.
  • An object of the present invention is to provide a method and apparatus for measuring IP network performance characteristics.
  • a method for characterizing a path of a packet-based network said path including two or more nodes, wherein the path is exhibiting one or more forms of sub-optimal operation, said method comprising the steps of: generating one or more sequences of packets and transmitting the one or more sequences of packets along the path of the packet-based network, each packet of the one or more sequences of packets traversing at least a portion of said path; collecting test data representative of responses of the packet-based network to transmission of the one or more sequences of packets; generating remediated data from the test data, the remediated data generated at least in part based on the one or more forms of sub-optimal operation; and analysing the remediated data to develop one or more characterizations of the path.
  • an apparatus for characterizing a path of a packet-based network said path including two or more nodes, wherein the path is exhibiting one or more forms of sub-optimal operation
  • the apparatus comprising: a generation module configured to generate one or more sequences of packets and to transmit the one or more sequences of packets along the path of the packet-based network, each packet of the one or more sequences of packets traversing at least a portion of said path; a collection module configured to collect test data representative of responses of the packet-based network to transmission of the one or more sequences of packets; a remediation module configured to generate remediated data from the test data, the remediated data generated at least in part based on the one or more forms of sub-optimal operation; and an analysis module configured to analyse the remediated data to develop one or more characterizations of the path.
  • a computer readable medium having recorded thereon statement and instructions which, when executed by a computer processor, cause the processor to execute a method for characterizing a path of a packet-based network, said path including two or more nodes, wherein the path is exhibiting one or more forms of sub-optimal operation, said method comprising the steps of: generating one or more sequences of packets and transmitting the one or more sequences of packets along the path of the packet-based network, each packet of the one or more sequences of packets traversing at least a portion of said path; collecting test data representative of responses of the packet-based network to transmission of the one or more sequences of packets; generating remediated data from the test data, the remediated data generated at least in part based on the one or more forms of sub-optimal operation; and analysing the remediated data to develop one or more characterizations of the path.
  • Figure 1 illustrates a Van Jacobson diagram which schematically illustrates packet transmission through a network bottleneck.
  • Figure 2 is a schematic view of an example path through a network from a first location to a second location according to one embodiment of the present invention.
  • Figure 3 is a schematic representation of a sequence of packets configured as a burst load of packets according to one embodiment of the present invention.
  • Figure 4 is a schematic representation of a sequence of packets configured as a stream of packets according to one embodiment of the present invention.
  • Figure 5 is a schematic representation of an analysis system in accordance with one embodiment of the present invention.
  • Figure 6 is a schematic representation of a received sequence of packets and the remediated data derived therefrom according to one embodiment of the present invention.
  • Figure 7 is a schematic representation of a transmitted sequence of packets, received sequences of packets having packet loss and remediated data derived therefrom according to one embodiment of the present invention.
  • Figure 8 is a schematic representation of datagram remediation of the timings associated with a sequence of packets for determination of capacity, according to one embodiment of the present invention.
  • Figure 9 is a schematic representation of timing remediation using a datagram configured as a primer packet associated with a sequence of packets, wherein the remediated data enables determination of capacity, according to one embodiment of the present invention.
  • Figure 10 is a schematic representation of datagram remediation of the timings associated with a sequence of packets for determination of capacity, according to one embodiment of the present invention.
  • Figure 1 1 is a schematic representation of estimated capacity as a function of the number of packets in a sequence of packets, according to one embodiment of the present invention.
  • sequence of packets is used to define datagrams, bursts of packets, streams of packets, or other configuration of packets.
  • datagrams can be single packets transmitted with relatively large inter-packet separations in time.
  • bursts can be groups of packets transmitted with relatively small inter-packet spacing and relatively large inter-burst separations.
  • streams can be sequences of datagrams or bursts transmitted with a relatively fixed separation therebetween. Other configurations of sequences of packets would be readily understood by a worker skilled in the art.
  • path is used to define a packet transfer route within a network, typically defined between a source host and a destination host.
  • the source host is the location of the source of the one or more sequences of packets and the destination host is the desired destination of the one or more sequences of packets.
  • a path can be defined as a one way path, namely a one way route within the network which is defined between the source host and the destination host.
  • a path can be also be defined as a closed loop type path, wherein the path defines an outgoing route from the source host to the destination host and further defines a return route from the destination host to the source host.
  • the outgoing route can be the same as the return route and in other embodiments, the outgoing route can be different from the return route.
  • packet handling device is used herein to describe devices on a packet- switched network which accept packets or sequences of packets and reply or forward the packets.
  • packet handling devices include routers, switches, bridges, firewalls, gateways, hubs or similar devices.
  • Packet handling devices typically function using one or more predetermined sets of protocols on at least OSI layers 3 and below, or other compatible layer in another packet based network model.
  • a packet handling device may also refer to an OSI layer 2 device, or similar device, such as an Ethernet switch for handling frames.
  • sub-optimal operation is used to define a characteristic of a network or path of a network, which is representative of a potential problem or condition associated with the network or path.
  • a characteristic of a network or path that can be indicative of sub-optimal operation can be a hardware or software implementation of one or more of the packet handling devices or network links associated with the network or path or other physical or configuration aspect of the network or path.
  • a characteristic of a network or path that can be indicative of sub-optimal operation can be a transient condition of network operation, and can be for example associated with traffic on the network.
  • instances of packet loss, jitter, latency, packet reordering, unsymmetric capacities and half-duplex operation are examples of sub-optimal operation of a network or path.
  • Other characteristics of a network or path that can be associated with sub-optimal operation would be readily understood by a worker skilled in the art.
  • capacity total capacity
  • data transfer capacity data transfer capacity
  • capacity or total capacity of a network path can be synonymous with bandwidth or maximum achievable bandwidth or linespeed or throughput.
  • available capacity is used to define the amount of the total capacity of a network path available for data transfer at a given time, with respect to existing traffic or other limiting factors.
  • the ratio of [(total capacity minus available capacity) to total capacity] is defined as the utilization of the network path, which may be expressed as a percentage or other applicable format.
  • duplex is used to define a characteristic of the network path that corresponds with simultaneous transfer of data in both directions between a first node and a second node of the network. This typically applies to the measurable capacity of a given network interface or network path or segment that is the sum of both directions and potentially limited by one direction in the case where the capacities in each direction are not symmetric. Duplex measurement in general typically cannot distinguish contributions from each direction and typically treats the measure or characteristic as a conflated value. [0038] The term “simplex” is used to define a characteristic of the network path that corresponds with the transfer of data in only one direction between a first node and a second node of the network. Measurements may be taken that are specific to the flow of data in each direction.
  • simplex is used to define a methodology which enables the separation or dissemination of one or more characteristics of the outgoing path and the returning path of the path between the first node and second node. Furthermore, simplex can be used to define a methodology which enables the determination of one or more characteristics of only the outgoing path or the returning path.
  • the term "about” refers to a +/- 10% variation from the nominal value. It is to be understood that such a variation is always included in any given value provided herein, whether or not it is specifically referred to.
  • the present invention provides a method and apparatus for characterizing a path of a packet-based network, and in particular for characterizing a path in the presence of one or more forms of sub-optimal operation of the path.
  • the method and apparatus generates one or more sequences of packets and transmits these one or more sequences of packets along the path of the packet-based network, such that each packet of the one or more sequences of packets traverses at least a portion of said path.
  • These one or more sequences of packets are configured in order to elicit one or more responses from the packet-based network.
  • the method and apparatus collects test data representative of responses of the packet-based network to the transmission of the one or more sequences of packets.
  • this collected test data is subsequently remediated and converted into remediated data.
  • the manner in which the remediation of the test data is conducted is at least in part based on the one or more forms of sub-optimal operation of the packet-based network.
  • the remediated data is subsequently analysed in order to develop one or more characterizations of the path.
  • the analysis of the remediated data may be performed using packet train dispersion techniques or packet pair dispersion techniques or other analysis techniques as would be readily understood by a worker skilled in the art.
  • the remediation of the test data is performed in order alleviate the impact of one or more sub-optimal operations of the packet based network or path on the subsequent analysis of the collected responses to the initial transmission of the one or more sequences of packets.
  • This remediation of the test data is essentially performed in order to reconfigure the initially collected test data, in order that this collected information can be suitably used with the respective analysis technique, which is based on particular underlying assumptions for the operation and functionality of a path of the network being assessed.
  • the sub-optimal operation of the path results in packet reordering.
  • the remediation of the test data is performed in order to alleviate the effect that packet reordering has on the subsequent analysis used for evaluation of characteristics of the path of the network.
  • the test data is collected and subsequently converted into remediated data.
  • the remediation process for generation of the remediated data is configured and accordingly performed in a manner that the remediated data is substantially compatible with the analysis subsequently performed to determine one or more characteristics of a path of the network, thereby substantially alleviating the effect of packet reordering thereon.
  • the sub-optimal operation of the path results in packet loss.
  • the test data is collected and subsequently converted into remediated data, wherein the remediation of the test data is performed in order to alleviate the effect that packet loss has on the subsequent analysis used for evaluation of characteristics of the path of the network.
  • the remediated data is substantially compatible with the analysis subsequently performed which enables the determination of one or more characteristics of a path of the network, thereby substantially alleviating the effect of packet loss thereon.
  • the sub-optimal operation of the path results in a path exhibiting unsymmetrical characteristics.
  • the characteristics of the network path exhibited from a source host to a destination host are different from the characteristics of the network path exhibited from the destination host to the source host.
  • the test data is collected and subsequently converted into remediated data, wherein the remediation of the test data is performed in order to separate information indicative of the outgoing path from the source host to the destination host and the return path from the destination host to the source host.
  • the remediated data is substantially compatible with the analysis subsequently performed, while enabling the determination of one or more characteristics of the outgoing path and/or one or more characteristics of the return path, thereby substantially alleviating the effect of unsymmetrical operation of the network.
  • the sub-optimal operation of the path results in a path exhibiting unsymmetrical characteristics.
  • the collected test data reflective of the timings associated with one or more sequences of packets which includes multiple packets in a burst type configuration, is remediated using collected test data reflective of the timings associated with one or more sequences of packets, which include a single packet or datagram.
  • the conversion of the test data into remediated data enables the subsequent evaluation of the capacity of the path exhibiting unsymmetrical characteristics, and thus this capacity is indicative of the rate at which sustained two-way information traffic can flow along the path.
  • the sub-optimal operation of the path results in a path exhibiting unsymmetrical characteristics.
  • the collected test data is reflective of the timings associated with one or more sequences of packets, wherein each of the one or more sequences of packets includes multiple packets in a burst type configuration, preceded by a packet or datagram by a predetermined amount of time.
  • the test data is collected and subsequently converted into remediated data, wherein the remediation of the test data is performed in order to separately evaluate capacity indicative of the outgoing path from the source host to the destination host and capacity of the return path from the destination host to the source host.
  • the sub-optimal operation of the path results in the path exhibiting an undesired level of variability of its determined capacity characteristics.
  • the collected test data is reflective of the timings associated with one or more sequences of packets, wherein each of the one or more sequences of packets includes multiple packets in a burst type configuration, preceded by a packet or datagram.
  • the conversion of the test data into remediated data enables the subsequent evaluation of the capacity of the path having a desired limited variability.
  • the present invention provides for active probing, which can comprise configuring and transmitting one or more sequences of packets into a network along a network path and observing a response, which may vary according to the mechanisms implemented along the network path.
  • Network responses can be collected as test data by the source host, destination host, or other host.
  • the conversion of the test data into the remediated data and optionally the analysis of the remediated data can be performed by a computing device located at or associated with the source host, destination host or other host.
  • active probing can be configured to elicit responses from one or more packet handling devices such as ICMP messages, ICMP Echo Reply packets, packet acknowledgements, and the like.
  • ICMP messages may include Destination Unreachable messages such as Host or Port Unreachable, Time Exceeded messages such as TTL expired in transit, and the like.
  • Packet acknowledgements may be generated by sending packets according to a specific protocol, such as TCP or UDP at Layer 3 or Ethernet or PPP at Layer 2, and observing the receipt of these packets either directly or via generated acknowledgements for protocols supporting reliable packet delivery.
  • At least part of the active probing of the network path is modified based at least in part on the sub-optimal operation of the path.
  • the protocol, size or other characterization of the one or more sequences of packets being generated for active probing may at least in part be based on the sub-optimal operation of the path.
  • a particular remediation action is required and in order for this remediation action to be performed, the transmission and collection of test data indicative of specific formats of one or more sequences of packets may be required.
  • the transmission of the one or more sequences of packets and/or the collection of the responses to the one or more sequences of packets as test data may be modified based at least in part on the sub-optimal operation of the path.
  • Figure 2 illustrates an example of a portion of a network 10, wherein the network comprises an arrangement of network devices 14 interconnected by data links 16.
  • the network devices may comprise, for example, routers, switches, bridges, hubs, gateways and the like.
  • the data links may comprise physical media segments such as electrical cables, fibre optic cables, or the like or transmission type media such as radio links, laser links, ultrasonic links, or the like.
  • an analysis system 17 is connected to the network 10.
  • path 34 is a closed loop, wherein packets originate at a test packet sequencer 20, travel along the path 34 to a reflection point 18, and then propagate back to the test packet sequencer 20.
  • the path does not need to be a closed loop, for example, an open path may be configured such that the mechanism for dispatching the one or more sequences of packets may be separated from the mechanism that receives the packets after they have traversed the path.
  • the packets of the one or more sequences of packets being sent along a path during the active probing can be of varying sizes, wherein the largest size of packet is defined by the MTU supported by the path to the selected end host or destination host. For example, if a packet larger than the MTU is transmitted during an active probing session, a fragmentation response will typically be received by the test packet sequencer 20.
  • these one or more sequences of packets transmitted during the active probing can be datagrams, bursts or streams, for example.
  • Datagrams can be single packets with large inter-packet separations in time, for example the separation between the single packets can be in the range of hundreds of milliseconds.
  • tight datagrams can be datagrams transmitted with relatively small inter-packet spacings.
  • Bursts can be groups of a number of packets that are separated by small or virtually zero inter-packet separations. The inter-burst separation in time can be relatively large and can be in the range of hundreds of milliseconds.
  • a burstload can be an extended burst of many packets back-to-back, which can typically be more than an order of magnitude larger than a burst.
  • a burstload can comprise in the order of hundreds of packets.
  • streams can be sequences of bursts of for example a fixed size and number wherein there is a fixed separation of time between bursts.
  • Other configurations of sequences of packets would be readily understood by a worker skilled in the art. Each of these configurations of sequences of packets can be used alone or in combination to actively sample a path of a network in order to characterise its end-to-end performance, however the level of characterisation can be dependent on the form of the sequences of packets used during the active probing session.
  • the test packet sequencer 20 can record information about the times at which the one or more sequences of packets are dispatched and times at which returning packets are received.
  • a first mechanism for example a test packet sequencer
  • a second mechanism can be positioned at the destination host, and can be used to receive the sequence of packets.
  • the first and second mechanisms would collect timings related to the departure and receipt of a sequence of packets.
  • a sequence of packets is a burstload, an example configuration of which is illustrated in Figure 3.
  • a burstload 310 comprises a plurality of packets for example N packets 360, wherein these packets have an interpacket spacing 300 of approximately a zero interpacket spacing.
  • each packet has been identified as having a size S 350, however in alternate configurations of a burstload the size of the packets can vary within the burstload.
  • the number of packets in a burstload is typically an order of magnitude greater than the number of packets within a burst.
  • a burstload can comprise about 100, 200, 400 or other large number of packets.
  • this format of a sequence of packets represents a type of network response sampling that is unique to specific applications.
  • a stream is a parameterized sampling that substantially corresponds to a network load generated by real-time application traffic, for example VoIP traffic.
  • this example of a stream comprises M bursts, 410, 420 and 430, each composed of N packets 460 having a size 5, 440, and approximately a zero inter-packet spacing within a burst. Each burst is separated by a fixed timing equal to t, 450.
  • the parameterization of the values selected for M, N, S and t can be mapped to the choices of codec being used for an associated real-time application, for example VoIP and the number of simultaneous real-time connections.
  • appropriate values of the parameters for packet size, 5, and burst separation timing, t are defined by the codec being used, and the number of simultaneous real-time connections provides an appropriate value for the burst size, N.
  • the number of bursts, M can be specific to the resolution of the statistics that are required for a particular active sampling procedure. In one embodiment, the number of bursts used in a sampling procedure is approximately 50, however this can vary depending on the desired detail of path evaluation. Other configurations of streams would be readily understood by a worker skilled in the art.
  • the test packet sequencer 20 that dispatches one or more sequences of test packets 30 each comprising one or more test packets 32 is connected to the network 14.
  • the path 34 extends from the test packet sequencer 20 through routers 14A, 14B, and 14C to a computer 19 from where the packets are routed back through routers 14C, 14B, and 14A to return to test packet sequencer 20.
  • the packets 32 may comprise Internet Control Message Protocol (ICMP) ECHO packets directed to end host 19 which will automatically generate an ICMP ECHO REPLY packet in response to each ICMP ECHO packet or alternately an ICMP ECHO packet may result in an ICMP TTL Expiry packet being created in response at some mid-path device.
  • packets 32 could be another type of packet protocol, such as packets formatted according to the Transmission Control Protocol (TCP) or User Datagram Protocol (UDP) protocol wherein packets of these protocols are port specific and may generate a ICMP Port Unreachable packet from an end host or an ICMP TTL Expiry packet from a mid-path device, for example.
  • TCP Transmission Control Protocol
  • UDP User Datagram Protocol
  • Such packets could be sent to end host 19 and then returned to test packet sequencer 20 by software or hardware at end host 19, for example UDP echo daemon software, in the form of a UDP ECHO packet.
  • the sequence of packets can comprise packets of a single configuration or packets of varying configurations.
  • a sequence of packets can include some packets configured using ICMP, while other packets of the same sequence of packets are configured using UDP.
  • Other configurations of a sequence of packets would be readily understood by a worker skilled in the art.
  • packets 32 may be delayed by different amounts and some packets 32 may be lost in transit.
  • Various characteristics of the network devices 14 and data links 16 along path 34 can be determined by observing how the transmission characteristic data derived from different packets in the sequences varies, which can include measures relating to latency, capacity, delay variation, packet loss among others, for example.
  • Analysis system 17 receives the test data 33, wherein the analysis system may comprise a programmed computer. Analysis system 17 may be hosted in a common device or located at a common location with test packet sequencer 20 or may be separate therefrom. As long as analysis system 17 can receive test data 33, its precise location is a matter of convenience. Furthermore, the analysis system can be configured as a single mechanism for remediation of the test data and analysis thereof and equally may comprise multiple modules, wherein a particular module is configured to perform a specific task. In addition, the analysis system can be configured as a single computing device, and equally may comprise multiple computing devices communicatively linked in order to perform the required tasks.
  • the analysis system 558 includes a generation module 550, which is configured to generate and transmit one or more sequences of packets and a collection module 552, which is configured to collect the test data resulting from the transmission.
  • the analysis system 558 comprises a remediation module 554, which is configured to remediate the test data into remediated data and an analysis module 556 which is configured to perform one or more analyses on the remediated data in order to determine one or more characteristics of the network path being evaluated.
  • each of these modules can be interconnected either to one another directly or indirectly through another module.
  • Test data 33 comprises information regarding packets which have traversed path 34.
  • Test data 33 may comprise information regarding one or more of the sequence of packets transmitted including variables such as packet size (the number of bytes in a packet), burst size (the number of packets in a burst), and initial inter-packet separation (the time between packets in a burst at transmission).
  • packet size the number of bytes in a packet
  • burst size the number of packets in a burst
  • initial inter-packet separation the time between packets in a burst at transmission.
  • ICMP messages collected as test data such as ICMP Echo Reply, TTL Expiry, or Port Unreachable, may contain in their payload the header information, including the packet that triggered the ICMP message, at the point that the ICMP message was triggered.
  • test data 33 may include derivatives of one or more of these variables, for example packet sequence can be derived from inter-packet separation. Higher order variables may also be derived as admixtures of these variables, for example through the use of sequences of packets having a distribution of packet sizes within a distribution of inter-packet separations.
  • the analysis system 17 furthermore determines remediated data that can be determined directly or indirectly using the test data and in light of the one or more forms of sub-optimal operation of the path. In addition, the analysis system further determines one or more characteristics of the path from the remediated data.
  • the remediation of the test data is performed in order alleviate the impact of one or more sub-optimal operations of the packet based network or path on the subsequent analysis of the collected responses to the initial transmission of the one or more sequences of packets.
  • This remediation of the test data is essentially performed in order to reconfigure the initially collected test data, in order that this collected information can be suitably used with the respective analysis technique, which is based on particular underlying assumptions for the operation and functionality of a path of the network being assessed.
  • the collected and unremediated test data may not be suitable for the respective analysis technique, due to the sub-optimal operation of the path violating one or more particular underlying assumptions for the operation and functionality of a path which is relied upon by the analysis technique.
  • the analysis technique may result in a null, false, incorrect or inaccurate determination of one or more characteristics of the path.
  • the remediation of the test data is performed in order alleviate the impact of one or more sub-optimal operations of the packet based network or path on the subsequent analysis of the collected responses to the initial transmission of the one or more sequences of packets.
  • remediation of the test data into remediated data can be performed in order to alleviate the impact of for example, packet reordering, packet loss, unsymmetrical path configurations and network capacity.
  • packet reordering remediation packet loss remediation, simplex measurement remediation, datagram remediation, datagram remediation using a primer packet and remediation based on network capacity.
  • multiple remediation techniques may be applied to the test data, under appropriate conditions, in order to determine the remediated data, for example, packet reordering remediation may be applied as well as packet loss remediation, or simplex measurement remediation may be applied together with packet reordering remediation or datagram remediation using a primer packet or other combination of two or more remediation techniques, as would be readily understood by a worker skilled in the art.
  • the sub-optimal operation of the path results in packet reordering.
  • the remediation of the test data is performed in order to alleviate the effect that packet reordering has on the subsequent analysis used for evaluation of characteristics of the path of the network.
  • the test data is collected and subsequently converted into remediated data.
  • the remediation process for generation of the remediated data is configured and accordingly performed in a manner that the remediated data is substantially compatible with the analysis subsequently performed to determine one or more characteristics of a path of the network, thereby substantially alleviating the effect of packet reordering thereon.
  • the most typical cause of reordering is the presence of a multi-channel link somewhere in the end-to-end path of the network, which can include cases such as: 1) certain router architectures; 2) certain operating system architectures; 3) multi-channel links between mid-path routers; 4) per-packet load-sharing without session or connection identification; and the like as would be readily understood by a worker skilled in the art.
  • the effective capacity of the multiple channels can be appropriately represented by the overall timing of a burst that passes through them.
  • the effective bulk transfer rate of the path is equivalent to the time for all packets of the sequence of packets to arrive.
  • the timings of an arriving burst containing reordering can be re- arranged, ranked in order of arrival time, and then re-numbered in a manner such that the first packet to arrive is labelled as number one, the second packet to arrive is labelled as number two, and so on, regardless of each of the packets original transmission time.
  • FIG. 6 An example of this embodiment of the present invention is illustrated in Figure 6, wherein a sequence of packets includes a total of seven packets, numbered 1 to 7, which indicates the initial order in which in the packets were transmitted.
  • This sequence of packets can be originally transmitted such that all seven of the packets are transmitted with substantially no inter-packet separation.
  • the order of the packets 500 has changed and there is also temporal separations 505 between these packets.
  • the arrival time in relation to the original order to the transmission of the packets is also illustrated 510, and this can be considered to represent a portion of the test data.
  • the generation of the remediated data from the test data results in the sequence of packets being renumbered 520 in sequential order, regardless of their actual reception order, with their reception times being according rearranged 530.
  • the present invention with reordered packet sequences rearranged in order of reception, and thereby converted into remediated data, they can be analyzed according to PTD analysis.
  • the resulting capacity estimate for the path can subsequently be interpreted as: 1) the effective transfer rate of the multi-channel link, if it is the smallest bottleneck in the path, as experienced by an application and 2) representative of the smallest bottleneck, if it is other than the multi-channel link, since the packets entering the bottleneck would retain their order while in transit of a serial link.
  • the remediated data representative of the de-ordered timings of the sequence of packets can be mapped directly to a virtual best burst according to the order of the packets of the sequence of packets upon reception.
  • the sub-optimal operation of the path results in packet loss.
  • the test data is collected and subsequently converted into remediated data, wherein the remediation of the test data is performed in order to alleviate the effect that packet loss has on the subsequent analysis used for evaluation of characteristics of the path of the network.
  • the remediated data is substantially compatible with the analysis subsequently performed which enables the determination of one or more characteristics of a path of the network, thereby substantially alleviating the effect of packet loss thereon.
  • bursts that include packet loss must be excluded from the PTD analysis. This reasoning is based on the assumption that if a packet is lost in transit, subsequent contiguous packets can at times have a gap separating them that is smaller than otherwise possible due to the presence of the otherwise missing packet. As such, the burst cannot be assumed to have passed the same number of bytes through a constraining bottleneck and so the timings are not reliable, for the subsequent analysis using PTD.
  • packet loss associated with the transmission of one or more sequences of packets can be disregarded and a PTD analysis can still be applied to determine a network capacity.
  • N K
  • the requirement that there be no loss within the entire sequence of packets can be relaxed when: 1) loss within the sequence of packets results in a sub-set of the packets within the sequence of packets being received contiguously, namely there is no intervening packet loss; 2) the number of packets sent in a sequence of packets is sufficiently large and/or the packet loss is sufficiently low that the number of packets in a contiguous sub-set is sufficiently large, for example typically 5 or greater; 3) only a sequence of packets containing loss after the contiguous sub-set of packets received can be used, wherein the contiguous sub-set must start with the first packet transmitted; and 4) timings from any sub-set of packets within a sequence of packets
  • the remediated data can include multiple sub- set sequences of packets which include one or more sequences of packets for example, each comprising from about 5 packets up to the largest contiguous number of packets available in the sequence of packets, for example 10 packets or more.
  • This remediated data can subsequently be used to construct one or more virtual best bursts having a minimum size of 5 packets up to the largest contiguous number of packets available in the sequence of packets, for example 10 packets or more.
  • Figure 7 illustrates an originally transmitted sequence of packets 600 configured as a burst of packets. This figures also illustrates possible configurations of the received packets 610 of the sequence of packets, wherein packet loss may have occurred.
  • Figure 7, further illustrates sub-sets of sequences of packets 620, which may be determined based on the format of the packet loss associated with the received one or more sequences of packets. For example, arrows 625, illustrate the different sub-sets of packets 620, which may be associated with each of the configurations of the received sequences of packets 610 which may or may not include packet loss.
  • the third configuration of received packets is representative of multiple packets being lost.
  • the highest measurement for the capacity of all sub-set virtual best bursts is assumed to be the optimal value to be derived from a set of sequences of packets containing loss insofar as each sub-set represents a value from a distribution of values with a maximum.
  • a variation on this packet loss remediation can allow for sub-sets of sequence of packets to be used even after loss has appeared.
  • This approach requires assumptions to be made that are not consistent with the virtual best burst approach.
  • the filtering of the test data by minimum RTT cannot be used to select out the best values, as timings for a given packet in a sequence of packets vary according to any loss preceding it.
  • the above defined packet loss remediation approach may provide a means for estimating achievable capacity with some changes to the analytic approach. For example, virtual best bursts could be composed for sequences of packets, which have the loss at the same point in the sequence.
  • all sequences of packets which have lost the second packet could be used to compose a special virtual best burst for the balance of the sequence of packets, or sub-set of packets. Subsequently, the analysis could assume that the special case of the second packet being lost and adjust the PTD analysis to model this case accordingly.
  • sub-sets of packets following loss could be analyzed without resorting to PTD.
  • alternate methods for estimating capacity could be used such as local mode identification using histograms or kernel density estimation. These methods instead rely on correlations in the statistical distribution to identify trends in multiple samples.
  • the sub-optimal operation of the path results in a path exhibiting unsymmetrical characteristics.
  • the characteristics of the network path exhibited from a source host to a destination host are different from the characteristics of the network path exhibited from the destination host to the source host.
  • the test data is collected and subsequently converted into remediated data, wherein the remediation of the test data is performed in order to separate information indicative of the outgoing path from the source host to the destination host and the return path from the destination host to the source host.
  • the remediated data is substantially compatible with the analysis subsequently performed, while enabling the determination of one or more characteristics of the outgoing path and/or one or more of the return path, thereby substantially alleviating the effect of unsymmetrical operation of the network.
  • UDP user datagram protocol
  • ICMP Port Unreachable the returning packets are much smaller than those transmitted, which is different from the basic case where the packets are of the same size. This difference in packet sizes in the two directions along the path can make it possible to distinguish the bottlenecks in one direction along the path from those in the other direction.
  • a means for measuring the performance of an end-to-end path when the destination host has been instrumented with software to echo back packets in a specific manner In this embodiment, a sequence of packets can be sent from a source host to a destination host and echoed back to the source host. Timestamps can be taken at each end of the path and the effect of any dispersion accumulated along the outgoing path, namely from the source host to the destination host, is removed by the destination host before sending the sequence of packets back to the source host.
  • the test data collected in this manner can be converted into remediated data such that the timestamps of the packets transmitted and received are considered.
  • this general methodology may be considered similar to the extant 2-way or "duplex" approach in how it samples and analyzes, and therefore this embodiment of the present invention, can provide a simple extension of that 2-way methodology to a 1-way or "simplex" measurement.
  • simplex sampling and measurement can be initialized such that one or more sequences of packets can be sent from the source host to the destination host in order to synchronize the clocks thereof.
  • simplex sampling and measurement can be performed following the subsequent steps. Initially, the source host can be implemented to perform duplex sampling wherein it sends a sequence of packets of maximum size with no gap between the packets, to the destination host, wherein the destination host echoes the sequence of packets back to the source host immediately as each packet arrives and the source host subsequently timestamps each of the returning packets as they arrive.
  • the source host sends another sequence of packets of maximum size with no gap between the packets to the destination host, wherein this sequence of packets may be marked for simplex handling at the destination host.
  • the destination host receives each packet of the sequence of packets and holds them and records the timestamp of the arrival of each of the packets of the sequence of packets, according to the local clock.
  • the destination host prepares a sequence of packets to echo back to the source host, wherein these packets are the same size and have the same contents as the arriving sequence of packets, but without any dispersion gap between the packets of the sequence of packets.
  • the destination host prior to the destination host transmitting this sequence of packets, the destination host includes the previously recorded arrival timestamps of the packets within the payload of one or more of the packets being sent to the source host. In addition, the destination host holds all of the packets of the prepared sequence of packets for a holding period of time, which is also recorded in the payload(s) of one or more of the packets, before transmitting the sequence of packets back to the source host.
  • the period of time may be determined based on: 1 ) at least being greater than the time taken to prepare the sequence of packets for transmission to the source host; 2) an amount of time to receive the incoming sequence of packets, write the arrival timestamps into the payload(s) of the sequence of packets for the reply, prepare the sequence of packets for reply, and plus a fixed interval; or 3) an amount of time to receive the incoming sequence of packets, write the arrival timestamps into the payload(s) of the sequence of packets for the reply, prepare the sequence of packets for reply, for example send reply as soon as possible.
  • the source host records the arrival timestamps of the returning packets of the sequence of packets, and also decodes the arrival timestamps and holding period of time from the packet payload(s) that were placed there by the source host.
  • This sequence of transmission between the source host and the destination host can be repeated a sufficient number of time in order to generate a set of timestamps from multiple sequences of packets such that an adequate analysis can be performed.
  • the set of timestamps that can be explicitly found or derived from the above noted test data for each sample, which is indicative of the remediated data can include: 1 ) transmit timestamps for each packet from the originating host defined in local source host time; 2) arrival timestamps for each packet at the destination host, in non-local time, namely destination host time, and subsequently relative timing between arriving packets at the destination host; 3) the holding period of time of the sequence of packets before echoed back from the destination host, defined in absolute time; and 4) arrival timestamps for each packet of the sequence of packets at the source host, in local source host time.
  • RTT round trip time
  • a reduced RTT can be calculated that excludes the holding period of time and can be effectively equivalent to a normal round trip time.
  • this reduced RTT may be calculated for one or more packets, or for the entire sequence of packets.
  • an optimal sequence of packets with the shortest round trip time can be identified, or a virtual best burst can be constructed composed of the times for each packet with the least round trip time.
  • the sequence of packets with the shortest round trip time, or the related best virtual burst can be assumed to have completed the end-to-end round trip with the minimum possible time as it may be considered that this sequence of packets did not encounter any cross-traffic or be otherwise delayed beyond the amount that will be common to every packet making that trip.
  • the packet dispersion recorded at each end of the path namely at the destination host and the source host, can be assumed to be representative of the bottlenecks inherent to the path.
  • PTD can then be applied to the relative time of the arriving bursts at the destination host to determine the outgoing path capacity and similarly, PTD can be applied to the arriving bursts at the source host to determine the return path capacity.
  • the available capacity or achievable capacity in each direction of the path can be measured.
  • Selecting the preferred timestamps according to minimum RTT remains a desired approach, however, without synchronizing the clocks of the source host and the destination host, it becomes necessary to remediate the available test data to reveal the best choice.
  • the minimum RTT travel time for both the sequence of packets travelling the outgoing path and the sequence of packets travelling the return path is an adequate filter, where the overall trip time for both is measured in the local time of the source host.
  • the overall trip time also includes holding period of time at the destination host that is recorded as a time difference.
  • the intra-burst dispersion namely the time the first and last packets in each sequence of packets, which is known for both the outgoing path and the return path can be analyzed by PTD to determine capacity in each direction.
  • the above remediated data indicative of simplex sampling when taken in combination with the duplex samples that also may be sent between the source host and destination host, the measured capacity for duplex or the two way, return transmission of packets, may be compared with each of the simplex capacity measures in the outgoing and incoming directions, in order to assess the degree to which the path is unsymmetric, the presence of half-duplex, and the like along the path, or the like.
  • the sub-optimal operation of the path results in a path exhibiting unsymmetrical characteristics.
  • the collected test data reflective of the timings associated with one or more sequences of packets, which includes multiple packets in a burst type configuration is remediated using collected test data reflective of the timings associated with one or more sequences of packets, which includes a single packet or datagram.
  • the conversion of the test data into remediated data enables the subsequent evaluation of the capacity of the path exhibiting unsymmetrical characteristics, and thus this capacity is indicative of the rate at which sustained two-way information traffic can flow along the path.
  • remediation of the test data into remediated data can be provided such that the PTD method can be applied and such that an automatic and accurate assessment of the capacity according to duplex can be determined, wherein the evaluated capacity is sensitive to the presence of half-duplex mode along the path.
  • the remediation of the test data can also account for other unsymmetric conditions that may be present along the path.
  • unsymmetric conditions For example, even in a full-duplex environment, there may be various unsymmetric conditions between the outgoing path and return path of the path being evaluated that are half-duplex-like. That is, the capacities in one direction may be limited compared to the other due to design, dysfunction, or other circumstance.
  • NICs network interface cards
  • the remediation of the test data is enabled by the collection of test data relating to the timing measurements of one or more sequences of packets configured as a duplex datagram together with timing measurements of one or more sequences of packets configured as bursts.
  • This combination of the collected timings is used to remediate this test data prior to applying PTD analysis to derive capacity of a path, such that this evaluation of the capacity is sensitive to the presence of half-duplex mode along the path.
  • each iteration of of the probative packets comprises at least of one instance of a datagram of large size and a burst of packets of that same large size.
  • the best overall burst timestamps are selected.
  • the criteria for “best” can be variable, however in one embodiment "best” may be assumed to be the shortest time for the round trip of all packets in the burst.
  • the best overall datagram timing is selected, and in one embodiment "best” may be assumed as the shortest round trip time.
  • Other criteria for the selection of "best" burst and “best” datagram would be readily understood by a worker skilled in the art.
  • the round-trip time for the first packet of the "best" burst is compared to the round-trip time for the "best" datagram.
  • the minimum value for the round-trip time is used to represent the round-trip time for the first packet in the burst. This is illustrated in Figure 8, wherein the round trip time for the datagram 710 is used to represent the round trip time associated with the first packet of the burst 700.
  • the capacity of the path can subsequently be calculated as the ratio of the number of bytes in the burst, less the first packet, over the time between the first and last packet in the burst.
  • the payload of the first packet does not contribute to the total number of bytes transmitted, as the time of arrival of each packet is measured from the time it is fully arrived including payload, not from when its header initially is received.
  • the datagram 710 round-trip time is much less than that of the first packet in the burst 700. This type of difference in round trip time is typical when a half-duplex interface is present at the destination host. In this example, the datagram is immediately sent back by to the source from the destination host once it received. In contrast when operating in half-duplex mode, the interface at the destination host must hold the first packet of the burst while it continues receiving the subsequent packets.
  • the first packet is typically not echoed back until most or all packets of the burst have arrived, thereby increasing the time for the first packet's round-trip.
  • the overall time that the burst is held up is commensurate with its size, and thus related to the data transfer rate of the interface at the destination host.
  • the destination host's interface is set to full-duplex, the first packet of the burst will be returned immediately.
  • the round-trip timing for the first packet of the burst will typically be comparable to the round trip timing of the datagram.
  • the presence of half-duplex is automatically included in the analysis.
  • the capacity of a path is reduced by a factor of 2 for half-duplex, due to the influence of the datagram's shorter round trip time.
  • This representation of the capacity substantially accurately reflects the rate at which sustained two-way traffic can flow along the path evaluated.
  • any significant difference between the datagram timing and the first burst packet timing acts as a clear indication that half-duplex is present somewhere along the path between the source host and the destination host.
  • the sub-optimal operation of the path results in a path exhibiting unsymmetrical characteristics.
  • the collected test data is reflective of the timings associated with one or more sequences of packets, wherein each of the one or more sequences of packets includes multiple packets in a burst type configuration, preceded by a packet or datagram by a predetermined amount of time.
  • the test data is collected and subsequently converted into remediated data, wherein the remediation of the test data is performed in order to separately evaluate capacity indicative of the outgoing path from the source host to the destination host and capacity of the return path from the destination host to the source host.
  • the combined datagram and burst timings may be applied to detect the presence of half-duplex and calculate the two-way capacity of a path from a source host to a destination host.
  • this method for detecting duplex configuration cannot be suitably applied to simplex or one way measurements.
  • a sequence of packets can be configured as a probative burst using both a datagram and a burst at the same time.
  • the datagram can be referred to as a "primer packet" and precedes the burst by a predetermined amount of time.
  • the primer packet is essentially configured in this manner in order to optimize the path between the source host and the destination host by "priming" all of the interfaces just prior to the transmission of the probative burst. In this manner, delays in processing the burst packets due to interfaces being inactive or otherwise unprepared may be mitigated. Nominally the primer packet is transmitted some fixed time prior to the burst.
  • this fixed time can be selected such that the primer packet has substantially no interaction with the subsequently transmitted sequence of packets, while being sufficiently short enough such that interfaces being "primed” do not return to an inactive or otherwise unprepared state prior to transmission of the sequence of packets.
  • the fixed time can be 8ms, or other suitable predetermined amount of time as would be readily understood.
  • the primer packet can also be used in simplex measurements of a path.
  • the use of a primer packet may be further extended to overcome some of the challenges of time synchronization between the source host and the destination host, as without time syncing, transit times cannot be properly measured between the source host and the destination host. As such, datagram transit times cannot be directly compared to burst packet transit times in either direction.
  • the primer packet may be treated as if it is a datagram, wherein its transmission timing relative to the burst can be used to provide timing information between the datagram and first packet of the burst. Since the difference in transmission timing between the primer packet and the first packet of the burst is fixed, it can be monitored at the destination host for change.
  • the combination of the burst and primer which is received with the minimum overall round-trip time can be selected for use with the simplex measurement remediation as defined above.
  • This minimum round trip time of this particular combination of the burst and primer packet can be indicative of the optimal conditions along the path, for example, the least amount of or no cross-traffic, which may be encountered during transmission along the path.
  • the timings for the sequence of packets including the primer packet and the burst which were recorded at the destination host for the selected burst and primer combination can be examined to determine the separation between the primer packet and the first burst packet. If the gap at reception exceeds the original fixed transmission gap, for example 8 ms, it can be presumed that the additional gap represents the extra time required for transmission of the burst packet.
  • the timing measure and associated with that of the first packet in the burst can be replaced by the timing of the primer timing however subtracting the fixed gap time period.
  • Figure 9 illustrates this embodiment of the present invention, wherein the timing of the primer packet 810, minus the 8ms, replaces the timing of that recorded for the first packet of the burst 800.
  • the timing of the first burst packet remains unchanged.
  • the subsequently combined burst timing can be used to calculate the capacity. In the event that the primer timing decreases the first burst packet timing, the capacity will be reduced.
  • the sub-optimal operation of the path results in the path exhibiting an undesired level of variability of its determined capacity characteristics.
  • the collected test data is reflective of the timings associated with one or more sequences of packets, wherein each of the one or more sequences of packets includes multiple packets in a burst type configuration, preceded by a packet or datagram. The conversion of the test data into remediated data enables the subsequent evaluation of the capacity of the path having a desired limited variability.
  • NICs network interface cards
  • NICs may perform packet handling by grouping transmitted or received packets and processing them together. For example, if a NIC is performing packet handling based on groups of packets, during the collection of test data, a smaller datagram may appear to arrive as quickly as a larger datagram, or a first packet of a sequence of packets may appear to arrive later than a single packet or datagram, or several packets of a sequence of packets may appear to arrive at the same time.
  • this operational functionality of the NIC may result in timings for a single packet, for example a datagram, being significantly different from that of the first packet in a sequence of packets.
  • An example of this type of group processing of packets 905 of a sequence of packets by a NIC is illustrated in Figure 10, wherein packets of a sequence of packets are processed in groups of four.
  • using a datagram 915, for example a large datagram, and its associated timing instead of the timing parameters for a first packet of a sequence of packets, can alleviate the variability of the capacity determination for the network path being evaluated.
  • the capacity of a network path can be evaluated based on the determination of an asymptotic limit of a curve reflective of the estimated capacity versus the number of packets in a sequence of packets which was used for the estimated capacity determination.
  • Figure 1 1 illustrates an example of a curve 1005 having an asymptotic limit 1007 which may be derived for the sampling points 1002, wherein each sampling point is reflective of the estimated capacity of the network path based on the sequence of packets comprising a particular number of packets.
  • this limiting value or asymptotic limit can represent an idealized estimate wherein the number of packets in a sequence of packets approaches infinity, which substantially reproduces the effect of the method of flooding for the determination of capacity.
  • the estimated capacity curve resulting from this process of capacity estimation can be fitted with a suitable function using one or a plurality of curve fitting functions and/or statistical methods for example least squares or other method as would be readily understood by a worker skilled in the art.
  • a series of sequences of packets having different numbers of packets are sent along the network path under consideration, wherein an estimate of capacity can be determined for these varying the size of the sequences of packets. For example, and with further reference to Figure 1 1 , as there are a total of 17 sampling points, these estimates of capacity may have been determined by sending 17 sequences of packets which had packet numbers ranging from 2 to 18 packets.
  • sequences of packets comprising the largest number (N) of packets desired can be sent along the path, and the capacity can be determined based on the responses of the first predetermined number (n) of packets in the sequence of packets, where n ⁇ N.
  • N the number of packets in the sequence of packets
  • the determination of an appropriate expression for the estimated capacity curve can depend upon the specific circumstances.
  • a suitable function for fitting the illustrated data can be defined as follows:
  • Capacity(n) A (Bn - I )
  • A is the asymptotic limit value
  • B describes the rate at which the curve converges to A
  • n is the number of packets in the sequence of packets.
  • probing and evaluation can be repeated continuously over long, or effectively indefinite, periods of time. That case is sometimes referred to as "continuous monitoring”. Where evaluations over finite-periods may provide an instantaneous snapshot of the current condition, continuous monitoring may allow for on-going comparison of network conditions according to different sequence of packet configurations. This can be of interest as traffic conditions are often highly transient, with peak loads happening at certain times of the day, or due to changing network circumstances or application usage.
  • each step of the method may be executed on any general computer, such as a personal computer, server or the like and pursuant to one or more, or a part of one or more, program elements, modules or objects generated from any programming language, such as C++, Java, PL/1 , or the like.
  • each step, or a file or object or the like implementing each said step may be executed by special purpose hardware or a circuit module designed for that purpose.

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Abstract

La présente invention porte sur un procédé et un appareil destinés à caractériser un trajet d'un réseau à base de paquets en la présence d'une ou plusieurs formes de fonctionnement sous-optimal de celui-ci. Une ou plusieurs séquences de paquets sont transmises le long du trajet de telle manière que chaque paquet de la ou des séquences de paquets parcourt au moins une partie dudit trajet. Cette ou ces séquences de paquets sont configurées de façon à provoquer une ou plusieurs réponses du réseau à base de paquets. Des données de test représentatives de réponses du réseau à base de paquets à la transmission de la ou des séquences de paquets sont collectées, ces données de test étant ensuite corrigées au moins en partie sur la base de la ou des formes de fonctionnement sous-optimal du réseau à base de paquets et converties en données corrigées et les données corrigées étant analysées pour développer une ou plusieurs caractérisations du trajet.
PCT/CA2009/001735 2008-12-02 2009-12-02 Procédé et appareil de mesure de caractéristiques de performance de réseau ip Ceased WO2010063104A1 (fr)

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WO2012066371A1 (fr) * 2010-11-18 2012-05-24 Telefonaktiebolaget L M Ericsson (Publ) Systèmes et procédés de mesure de capacité disponible et de capacité de liaison serrée de chemins ip partant d'un seul point d'extrémité
CN103299583A (zh) * 2010-11-18 2013-09-11 瑞典爱立信有限公司 测量源于单个端点的ip路径的可用容量和紧链路容量的系统和方法
US9094315B2 (en) 2010-11-18 2015-07-28 Telefonaktiebolaget L M Ericsson (Publ) Systems and methods for measuring available capacity and tight link capacity of IP paths from a single endpoint
EP2953296A1 (fr) * 2010-11-18 2015-12-09 Telefonaktiebolaget L M Ericsson (publ) Systèmes et procédés de mesure de capacité disponible et capacité de liaison étanche de chemins ip à partir d'un seul terminal
CN103299583B (zh) * 2010-11-18 2016-10-19 瑞典爱立信有限公司 测量源于单个端点的ip路径的可用容量和紧链路容量的系统和方法
US9742650B2 (en) 2010-11-18 2017-08-22 Telefonaktiebolaget Lm Ericsson (Publ) Systems and methods for measuring available capacity and tight link capacity of IP paths from a single endpoint
WO2014054032A1 (fr) * 2012-10-05 2014-04-10 Telefonaktiebolaget Lm Ericsson (Publ) Procédé et système pour superposer des données radio dans des mesures ip
US9628358B2 (en) 2012-10-05 2017-04-18 Telefonaktiebolaget Lm Ericsson (Publ) Method and system for piggybacking radio data in IP measurements

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