WO2009070070A1

WO2009070070A1 - Method for measuring network performance using intermediate measurement nodes

Info

Publication number: WO2009070070A1
Application number: PCT/SE2007/050903
Authority: WO
Inventors: Bob Melander; Christopher Flinta; Svante Ekelin; Jan-Erik MÅNGS
Original assignee: Telefonaktiebolaget Lm Ericsson (Publ)
Priority date: 2007-11-27
Filing date: 2007-11-27
Publication date: 2009-06-04

Abstract

The present invention relates to methods and arrangements to measure network performance, wherein a send specification (Sx;Sp) for each of at least one probe packet (X;P) is generated at a sending node (GGSN/A; GW/A). The probe packet is transmitted from the sending node on a communication path (A-D) in a communication network (IP; ETHERNET), towards a receiving node (GGSN/B; GW/B). The method comprises the following steps: - The probe packet (X;P) passes at least one intermediate measurement capable node (IMEN1-IMEN3) located on the path (A-D) between the sending node and the receiving node. - At least one time stamp specification (rx1-rx3, sx1-sx3; rp1-rp3, sp1-sp3) for the packet (X;P) is generated at the intermediate measurement capable node (IMEN1-IMEN3). - the probe packet is received by the receiving node (GGSN/B; GW/B) and a receive specification (Rx;Rp) is generated for the probe packet. - Network performance is estimated by utilizing generated specifications (Sx, rx1-rx3, sx1-sx3, Rx; Sp, rp1-rp3, sp1-sp3, Rp).

Description

METHOD FOR MEASURING NETWORK PERFORMANCE USING INTERMEDIATE MEASUREMENT NODES

TECHNICAL FIELD

The present invention relates to methods and arrangements for measuring communication network performance.

BACKGROUND

Measurement of network characteristics can be performed using methods which include active probing of the network, i.e. injecting dedicated probe packets for the sole purpose of the measurement method. One example is disclosed in the patent US 6,868,094 wherein an IP performance monitoring method is shown. In the US patent a timing probe data packet containing a send time stamp is sent over the network from a sender to a receiver. A receive time stamp is generated at the receiver. The probe packets sender performance is analyzed based upon the send and receive stamps. Another example is the BART method for available bandwidth estimation, developed at Ericsson AB. Aspects of

BART has been published at several conferences such as:

[1] S. Ekelin and M. Nilsson, "Continuous monitoring of available bandwidth over a network path", 2^nd Swedish National Computer Networking Workshop, Karlstad, Sweden, November 23-24, 2004. [2] S. Ekelin, M. Nilsson, E. Hartikainen, A. Johnsson, J. -E. Mangs, B.

Melander and M. Bjorkman, "Real-time measurement of end-to-end available bandwidth using Kalman filtering," in Proc. 10th IEEE/IFIP Network Operations and Management Symposium, 2006.

[3] E. Hartikainen and S. Ekelin, "Tuning the Temporal Characteristics of a Kalman-Filter Method for End-to-End Bandwidth Estimation," in

Proc. 4th IEEE/IFIP Workshop on End-to-End Monitoring Techniques and Services, 2006. [4] E. Hartikainen and S. Ekelin, "Enhanced Network-State Estimation using Change Detection," in Proc. 1st IEEE LCN Workshop on Network Measurements, 2006.

In an active probing method, each probe packet receives a time stamp as it is sent from the sending node. When reaching the receiving node it is time-stamped again, and the time stamps are fed into an algorithm in order to calculate an estimate of the characteristics parameters. When estimating available bandwidth, also the sizes of the probe packets are needed by the algorithm.

The probe packets are normally sent in pairs or in packet trains. The number of packets in a train may vary according the probing method. However, a train must consist of at least two packets. BART is essentially a packet-pair method, and in the cases where probe packet trains of length N > 2 are used, the train can essentially be seen as a sequence of N-I probe packet pairs, where all the interior packets double as being the first in one pair and the second in another.

The time interval between sent probe packets is selected by the probing algorithm in order to achieve a specific probing load on the network path. This time interval is related to the probe packet size; a smaller time interval between packets with a given packet size will give a higher probing load.

One reason for using pairs (or trains) as opposed to sending isolated probe packets is that the need for synchronization between sender and receiver is eliminated.

In the basic version of BART, no feedback from receiver to sender is assumed. The algorithm can be considered to be running at the receiver, and all input needed must then be accessible at the receiver. One possibility is probing end-to-end, i.e. from one sending host to one receiving host. Another scenario is probing edge-to-edge, i.e. from one aggregating node to another aggregating node. A problem with existing probing methods is that an operator often has many interconnected "network islands" and may want to determine network status more in detail, for example determining bottlenecks inside such network.

SUMMARY

The present invention relates to problems with insufficient precision when estimating network performance.

The problem is solved by the invention by using measurement capable nodes traversed on an end-to-end network path to produce intermediate bandwidth (or other metrics) estimates in addition to the end-to-end estimate.

The solution to the problems more in detail is a method of measuring network performance, wherein a send specification for each of at least one probe packet is generated at a sending node. The probe packet is transmitted from the sending node on a communication path in a communication network, towards a receiving node. The method comprises the following further steps:

At least one intermediate measurement capable node located on the path between the sending node and the receiving node is passed by the probe packet.

At least one time stamp specification for the packet is generated at the intermediate measurement capable node . The probe packet is received by the receiving node and a receive specification for the probe packet is generated.

Network performance is estimated by utilizing generated specifications.

In one embodiment of the invention, generated time stamp specifications and if appropriate, bandwidth estimates, are incorporated in the probe packet before the packet is forwarded, while in another embodiment generated time stamp specifications and bandwidth estimates are incorporated in a List packet that is forwarded subsequent the probe packet.

In one aspect of the invention the time stamp specification generated at the intermediate measurement capable node, represents a receive time stamp that is incorporated in the probe packet (or List packet) before the packet is forwarded. In this case the intermediate measurement capable node forwards the probe packet directly after the probe packet (or the List packet) has been augmented with the receive time stamp/characteristics estimate. The send time stamp is assumed to be equal to the receive time.

In another aspect of the invention a second time stamp specification, generated at the intermediate measurement capable node, represents a send time stamp. In this case received probe packets are buffered in the node and later dispatched from the node in an appropriately chosen send pattern. In this case both the receive and send times from the node are included in the probe packet (or the List packet) .

A purpose of the invention is to enhance network characteristic measurement methods to include segment characteristics of the probed network path. This purpose and others are achieved by methods, arrangements, nodes, systems and articles of manufacture.

An advantage of the invention is that end-to-end measurement accuracy may improve and that not only the end-to-end estimate but also estimates for two or more segments of the probed network path can be obtained. An example where segmented measurements could be useful is when an operator has many interconnected "network islands". The operator could then position intermediate measurement capable nodes at suitable locations in its networks to measure performance within the islands and between the islands in one single measurement. The operator can then more easily determine if a bottleneck is inside that operator' s network or in some traversed network.

The invention will now be described more in detail with the aid of preferred embodiments in connection with the enclosed drawings .

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 discloses a block schematic illustration of probe packets sent between WCDMA networks over an IP network.

Figure 2 discloses a block schematic illustration of a list packet and probe packets sent between Enterprise networks over an Ethernet network.

Figure 3 discloses a flow chart illustrating some essential method steps of the invention.

Figure 5 schematically discloses a system that can be used to put the invention into practice. DETAILED DESCRIPTION

Figure 1 discloses a system that is used to put a first embodiment of the invention into practice. In figure 1 an Internet Protocol IP network system is shown in which probe packets are sent. Two access networks WCDMA/A, WCDMA/B of the type Wideband Code Division Multiple Access mobile communication systems are shown in figure 1. A mobile terminal/subscriber MSA is located in the WCDMA/A network and communicates via a Radio Base Station RBS. Packets from MSA are hereby sent from the RBS to a Radio Network Controller RNC in the WCDMA/A. The RNC is the main element in a Radio Network Subsystem that controls the use and the reliability of the radio resources. Packets arriving from terminal MSA are forwarded from the RNC to a Gateway GPRS Support Node GGSN/A in packet domain. The GGSN/A supports the edge routing function of the GPRS network. GGSN/A performs the task of an IP router to external packet data networks. In this example, as indicated in figure 1, dedicated probe packets are injected for the sole purpose of measurement, and sent from GGSN/A via the IP network to a Gateway GPRS Support Node GGSN/B. Packets hereby passes several intermediate measurement capable nodes IMEN1-IMEN3 on the path in the IP network between WCDMA/A and WCDMA/B. A mobile terminal/subscriber MSB is located within the WCDMA/B network that is attached to the IP network via the Gateway GPRS Support Node GGSN/B. In this example probe packets are sent between GGSN/A and GGSN/B, but as an alternative the probe packets can be sent/received from any node between MSA and MSB.

The IP network is divided into four segments A, B, C, D. Segment A is located between the GGSN/A and IMENl, segment B is located between IMENl and IMEN2, segment C is located between IMEN2 and IMEN3 and segment D is located between IMEN3 and GGSN/B. The probe packets X and Y are in this example sent from GGSN/A, via the IP network to GGSN/B. As will be explained more in detail below, send time stamps representing packet's send time of day may be generated in nodes when packets are sent. In the same way receive time stamps representing packet's receive time of day may be generated in nodes when packets are received.

A method of measuring network performance according to the invention will now be explained together with figure 1. The method comprises the following steps:

• Probe packets X and Y are prepared to be sent from GGSN/A to GGSN/B.

• Send specifications that in this example are send time stamps Sx and Sy are generated in the sending node GGSN/A. A send time stamp indicates a packet's intended send time of day from a sending node, in this case from the GGSN/A. Sx belongs to packet X and Sy belongs to packet Y.

• The send time stamp Sx is incorporated in packet X while the send time Sy is incorporated in packet Y.

SEGMENT A

• The probe packets X and Y are transmitted one by one from the sending node GGSN/A on their respective intended send time, via the Internet Protocol network IP on segment A, towards the receiving node GGSN/B.

• The probe packets X and Y are received, one by one, to a first intermediate measurement capable node IMENl . • The probe packets are receive time stamped at IMENl. A receive time stamp rxl is hereby incorporated in the probe packet X and a receive time stamp ryl is incorporated in the probe packet Y before the packets are forwarded. In this case the IMENl forwards the probe packets directly after they have been augmented with the receive time stamps. The send times are hereby assumed to be equal the receive times, i.e. sxl=rxl and syl=ryl (so no additional send time is generated and added to the probe packet before sending) .

SEGMENT B

• The probe packets X and Y are transmitted one by one from the sending node IMENl, via the Internet Protocol network IP on segment B, towards the receiving node GGSN/B.

• The probe packets X and Y are, one by one, received to and receive time stamped by, a second intermediate measurement capable node IMEN2.

• The probe packets are buffered in IMEN2 for further evaluation. IMEN2 is pre-configured to buffer and evaluate received probe packets. A receive time stamp indicates a packet's receive time of day to IMEN2. The packets X and Y have both been time stamped and a receive time stamp rx2 is generated for packet X and a receive time stamp ry2 is generated for packet Y. Both time stamps rx2 and ry2 are stored in the IMEN2. The time difference between the received packets X and Y, i.e. the time difference Tr = ry2-rx2, is calculated in the

IMEN2. The send time difference between the packets X and Y when sent from IMENl, i.e. the time difference Ts = syl-sxl that was received to IMEN2 in the packets X and Y, is also stored in the IMEN2. The time differences Tr and Ts are handled in an algorithm to create a BART estimate of available bandwidth in the network segment B between IMENl and IMEN2. The BART method for available bandwidth estimation is well known to those skilled in the art. Aspects of BART have been published at several conferences, see for example those mention in the BACKGROUND part of this application. To be observed is that the BART method is just one example and not the only method that can be used to estimate network performance by using the invention.

• The received probe packets are, as already mentioned, buffered in the node IMEN2 and later dispatched from the node in an appropriately chosen send pattern (so as to optimize the measurement performance) . Send times from the IMEN2 is appended to each probe packet before sending the packet further. A send time stamp sx2 is hereby incorporated in the probe packet X and a send time stamp sy2 is incorporated in the probe packet Y before the packets are sent further. The created network characteristics estimate for the segment B is also incorporated in both or in one of the packets X and Y.

SEGMENT C

• The probe packets X and Y are transmitted one by one from the sending node IMEN2, via the Internet Protocol network IP on segment C, towards the receiving node GGSN/B. • The probe packets X and Y are received, one by one, to a third intermediate measurement capable node IMEN3.

• The probe packets are receive time stamped at IMEN3. A receive time stamp rx3 is hereby incorporated in the probe packet X and a receive time stamp ry3 is incorporated in the probe packet Y before the packets are sent further. In this case the IMEN3 forwards the probe packets directly after they have been augmented with the receive time stamps. The send times are assumed to be equal to the receive times i.e. rx3=sx3 and ry3=sy3.

SEGMENT D

• The probe packets X and Y are transmitted one by one from the sending node IMEN3, via the Internet

Protocol network IP on segment D, towards the receiving node GGSN/B.

• The probe packets X and Y are received, one by one, to the receiving node i.e. to the Gateway GPRS Support Node GGSN/B.

• The probe packets are receive time stamped Rx, Ry at the receiving node GGSN/B.

• The probe packets are buffered in GGSN/B for further evaluation. GGSN/B is pre-configured to buffer and evaluate received probe packets. Both time stamps Rx and Ry are stored in the GGSN/B.

• A further investigation of segment D is desired. The time difference between the received packets X and Y, i.e. the time difference Tr = Ry-Rx, is calculated and stored in the GGSN/B. The send time difference between the packets X and Y when sent from IMEN3, i.e. the time difference Ts = sy3-sx3 is also stored in the GGSN/B. The time differences Tr and Ts are handled in an algorithm to create a BART estimate of available bandwidth in the network segment D between IMEN3 and GGSN/B.

• A further investigation of the complete path, i.e. all segments A-D, is also desired. The send time difference between the packets X and Y when sent from GGSN/A, i.e. the time difference Ts = Sy-Sx is stored in the GGSN/B. The time differences Tr (=Ry-

Rx) and Ts are handled in an algorithm to create a BART estimate of available bandwidth in the "whole" network between GGSN/A and GGSN/B.

• The already created BART estimate of available bandwidth in the network segment B between IMENl and IMEN2 received from the packets A and/or B is stored in the receiving node GGSN/B.

To summarize, available bandwidth in the IP network has been estimated for the following three network segments and brought together in GGSN/B for potential further analysis:

• Segment B (the estimate was calculated in IMEN2 and forwarded to GGSN/B) .

• Segment D (the estimate was calculated in GGSN/B) .

• Segment A-D (the estimate was calculated in

GGSN/B) .

Figure 2 discloses a second embodiment of the invention. In figure 2, two Enterprise networks ENTERPRISE/A/B are shown that communicates via an ETHERNET based network. In the computer industry, the term Enterprise is often used to describe any large organization that utilizes computers. An intranet, for example, is an example of an enterprise computing system. Ethernet comprises Local Area Network architecture. Ethernet uses a bus or star topology and currently supports data transfer rates from 10 Mbps to 10 Gbps. The Ethernet specification served as the basis for the IEEE 802.3, which specifies the physical and lower software layers.

In figure 2 a terminal/subscriber Tl is attached to ENTERPRISE/A. Subscriber Tl communicates via a Gateway node GW/A with the ETHERNET based network. In the same way, a terminal/subscriber T2 is attached to ENTERPRISE/B that communicates via a Gateway node GW/B with the ETHERNET. In figure 2 probe packets P and Q can be seen in the ETHERNET network. The probe packets are sent from GW/A, via the ETHERNET network to the GW/B. In this embodiment a third packet, a so called List packet L, is also sent between GW/A to GW/B. The List packet collects and transport generated time stamp specifications. The List packet will be further explained below when the second embodiment of the invention is explained.

A method of measuring network performance according to the second embodiment of the invention will now be explained together with figure 2. The method comprises the following steps :

• The probe packets P and Q are prepared to be sent from GW/A to GW/B.

• Send specifications that in this example are send time stamps Sp and Sq are generated in the sending node GW/A. A send time stamp indicates a packet's intended send time of day from a sending node, in this case from the GW/A. Sp belongs to packet P and Sq belongs to packet Q.

• The send time stamps Sp and Sq are incorporated in the List packet L.

SEGMENT A

• The probe packets P and Q are transmitted one by one from the sending node GW/A on their respective intended send time, via the ETHERNET on segment A, towards the receiving node GW/B.

• The List packet L is sent subsequent the probe packets P and Q towards the receiving node GW/B.

• The probe packets P and Q and the List packet L are received, one by one, to a first intermediate measurement capable node IMENl .

• The probe packets are receive time stamped at

IMENl. In this case the IMENl forwards the probe packets directly after reception. The send times are hereby assumed to be equal the receive times, i.e. spl=rpl and sql=rql (so no additional send time is generated and added to the probe packet before sending) .

• Receive time stamps rpl (=spl) and rql (=sql) are incorporated in the List packet L before the packet is forwarded.

SEGMENT B

• The probe packets P and Q and the List packet L are transmitted one by one from the sending node IMENl, via the ETHERNET on segment B, towards the receiving node GW/B. • The probe packets P and Q are, one by one, received to and receive time stamped by, a second intermediate measurement capable node IMEN2.

• The probe packets are buffered in IMEN2 for further evaluation. Like in the first embodiment, the time differences Tr and Ts are handled in an algorithm to create an estimate of available bandwidth in the network segment B between IMENl and IMEN2.

• The received probe packets are, as already mentioned, buffered in the node IMEN2 and later dispatched from the node. A send time stamp sp2 is hereby generated for the probe packet P and a send time stamp sq2 is generated for the probe packet Q when the packets are sent further.

• The generated send time stamps sp2 and sq2 and the created network characteristics estimate for the segment B is incorporated in the List packet L.

SEGMENT C

• The probe packets P and Q and the List packet L are transmitted one by one from the sending node IMEN2, via the ETHERNET on segment C, towards the receiving node GW/B.

• The probe packets P and Q are received, one by one, to a third intermediate measurement capable node IMEN3. The probe packets are receive time stamped with rp3 and rq3 at IMEN3. In this case the IMEN3 forwards the probe packets directly after reception. The send times are assumed to be equal to the receive times i.e. rp3=sp3 and rq3=sq3. • The receive time stamps rp3 and rq3 are incorporated in the List packet before the packet is sent further towards the receiving node GW/B.

SEGMENT D

• The probe packets P and Q, and the List packet L are transmitted one by one from the sending node IMEN3, via the ETHERNET on segment D, towards the receiving node GW/B.

• The probe packets P, Q and the List packet L are received, one by one, to the receiving node i.e. to the Gateway GPRS Support Node GW/B.

• The probe packets are receive time stamped Rp, Rq at the receiving node GW/B.

• The probe packets and the List packet are buffered in GW/B for further evaluation. Both time stamps Rp and Rq are stored in the GW/B.

• A further investigation of the complete path, i.e. all segments A-D, is desired. The send time difference between the packets P and Q when sent from GW/A, i.e. the time difference Ts = Sq-Sp is stored in the GW/B. The time differences Tr (=Rq- Rp) and Ts are handled in an algorithm to create a BART estimate of available bandwidth in the "whole" network between GW/A and GW/B.

• The already created BART estimate of available bandwidth in the network segment B between IMENl and IMEN2, received in the List packet L, is stored in the receiving node GW/B. To summarize, available bandwidth in the IP network has been estimated for the following network segments and brought together in GW/B for potential further analysis:

• Segment B (the estimate was calculated in IMEN2 and forwarded in the List packet L to GW/B) .

• Segment A-D (the estimate was calculated in GW/B by using specifications forwarded in the List packet L) .

Figure 3 discloses a flow chart in which some of the more important steps of the invention are shown. The flowchart is to be read together with the earlier shown figures. The flowchart comprises the following steps:

- Probe packets are transmitted from a sending node (GGSN/A; GW/A) via a communication network (IP; ETHERNET) towards a receiving node (GGSN/B; GW/B) . A time specification for each of the transmitted probe packets is generated at the sending node (GGSN/A; GW/A) . This step is disclosed in figure 3 with a block 101.

- Probe packets are received one by one, by at least one intermediate measurement capable node IMEN. At least one time specification for each of the received probe packets is generated at the IMEN. This step is disclosed in figure 3 with a block 102.

- Probe packets are received one by one, by the receiving node. A time specification for each of the received probe packets is generated at the receiving node. This step is disclosed in figure 3 with a block 103.

Generated send time stamp specifications and generated receive time stamp specifications are joined together and compared. This step is disclosed in figure 3 with a block 104.

- Network performance is estimated by utilizing corresponding time stamp specifications of the joined time stamps. This step is disclosed in figure 3 with a block 105.

An example of a system used to put the invention into practice is schematically shown in figure 4. The block schematic constellation corresponds to the ones disclosed in figures 1 and 2 but is by no means limited to these two examples. Figure 4 discloses a probe packet transmitter TRl on a sending side. TRl is connected to a Time Stamp Generator TSGl on the sending side. The TSGl forwards generated send time stamps for the probe packet either back into the probe packet or to a List packet LIST. To be noted is that the List packet uses the same transmitters and receivers as the probe packet in this example but is for the sake of clarity drawn separately in the figure. TRl transmits the probe packet

("PACKET") and where appropriate, i.e. when a List packet is used also the List packet, towards a receiving side.

A receiver RIl located in an intermediate measurement capable node IMEN between the sending and receiving side, receives the probe packet and the List packet. A Time Stamp Generator TSGIl in the IMEN is connected to the receiver and forwards receive time stamps for the probe packet either back into the probe packet or to a List packet LIST. An algorithm handler ALG that is connected to the Time Stamp Generator TSGIl may also receive stamps for the probe packet or data received in the List packet. ALG handles received information and creates a bandwidth estimate that is sent either back into the probe packet or to the List packet LIST. A probe packet transmitter TIl aimed to forward the packet is located in the intermediate measurement capable node IMEN. TIl is connected to a Time Stamp Generator TSG12. The TSG12 forwards generated send time stamps for the probe packet either back into the probe packet or to the List packet LIST. TIl transmits the probe packet and possibly the List packet towards the receiving side. When receiving the packets to the receiving side, to a receiver R2, a Time Stamp Generator TSG2 connected to the receiver, generates a receive time stamp for the probe packet and forwards the time stamp to an analyzing unit ANY. Also the content of the List packet is forwarded to the analyzing unit. In case no List packet is used and the probe packet has forwarded generated time stamps and bandwidth estimate, information is transferred from the probe packet to the analyzing unit. To obtain network characteristics, the ANY handles receive time stamp, send time stamps and bandwidth estimate received in the LIST.

Items are shown in the figures as individual elements. In actual implementations of the invention however, they may be inseparable components of other electronic devices such as a digital computer. Thus, actions described above may be implemented in software that may be embodied in an article of manufacture that includes a program storage medium. The program storage medium includes data signal embodied in one or more of a carrier wave, a computer disk (magnetic, or optical (e.g., CD or DVD, or both), non-volatile memory, tape, a system memory, and a computer hard drive.

The invention is not limited to the above described and in the drawings shown embodiments but can be modified within the scope of the enclosed claims. The systems and methods of the present invention may be implemented for example on any of the Third Generation Partnership Project (3GPP) , European Telecommunications Standards Institute (ETSI), American National Standards Institute (ANSI) or other standard telecommunication network architecture. Other examples are the Institute of Electrical and Electronics Engineers (IEEE) or The Internet Engineering Task Force (IETF) . The description, for purposes of explanation and not limitation, sets forth specific details, such as particular components, electronic circuitry, techniques, etc., in order to provide an understanding of the present invention. But it will be apparent to one skilled in the art that the present invention may be practiced in other embodiments that depart from these specific details. In other instances, detailed descriptions of well-known methods, devices, and techniques, etc., are omitted so as not to obscure the description with unnecessary detail. Individual function blocks are shown in one or more figures. Those skilled in the art will appreciate that functions may be implemented using discrete components or multi-function hardware. Processing functions may be implemented using a programmed microprocessor or general- purpose computer.

The invention is in other words not limited to the above described and in the drawings shown embodiments but can be modified within the scope of the enclosed claims.

Claims

1. Method of measuring network performance, wherein a send specification (Sx; Sp) for each of at least one probe packet (X; P) is generated at a sending node (GGSN/A;

GW/A) , which probe packet is transmitted from the sending node on a communication path (A-D) in a communication network (IP; ETHERNET), towards a receiving node (GGSN/B; GW/B) , the method being c h a r a c t e r i z e d by

- passing, by the probe packet (X; P), at least one intermediate measurement capable node (IMEN1-IMEN3) located on the path (A-D) between the sending node and the receiving node;

- generating at the intermediate measurement capable node (IMEN1-IMEN3) , at least one time stamp specification (rxl-rx3, sxl-sx3; rpl-rp3, spl-sp3) for the packet (X; P);

- receiving the probe packet by the receiving node

(GGSN/B; GW/B) and generating a receive specification (Rx;Rp) for the probe packet;

estimating network performance by utilizing generated specifications (Sx, rxl-rx3, sxl-sx3, Rx; Sp, rpl-rp3, spl-sp3, Rp) .

2. Method of measuring network performance according to claim 1, which method comprises the following further steps : - a bandwidth estimate is calculated in the intermediate measurement capable node (IMEN1-IMEN3) by utilizing selected generated specifications.

3. Method of measuring network performance according to claim 1 or 2, whereby the generated specifications (Sx, rxl-rx3, sxl-sx3) and/or the bandwidth estimate is included in the probe packet (X) .

4. Method of measuring network performance according to claim 1 or 2, whereby the generated specifications (Sp, rpl-rp3, spl-sp3) and/or the bandwidth estimate is included in a List packet (L) that subsequently passes the same nodes (GW/A, IMEN1-IMEN3, GW/B) as the probe packet (P) .

5. Method of measuring network performance according to any of the previous claims, whereby the generated specifications (Sx, rxl-rx3, sxl-sx3; Sp, rpl-rp3, spl- sp3) and/or the bandwidth estimate is forwarded to the receiving node (GGSN/B; GW/B) .

6. Method of measuring network performance according to any of the claims 1-3, whereby the time stamp specification generated in the intermediate measurement capable node ( IMENl-IMEN3 ), is a receive specification (rxl-rx3) , which method comprises the following further step: including the receive specification (rxl-rx3) in the probe packet (X) ;

forwarding the probe packet (X) from the intermediate measurement capable node (IMEN1-IMEN3) on the path (A-D) towards the receiving node (GGSN/B; GW/B) .

7. Method of measuring network performance according to any of the claims 1-3, whereby the probe packet (X) is buffered in the intermediate measurement capable node ( IMENl-IMEN3) .

8. Method of measuring network performance according to claim 7, whereby the time stamp specification generated in the intermediate measurement capable node (IMENl-

IMEN3) , is a send specification (sxl-sx3) , which method comprises the following further step:

including the send specification (sxl-sx3) in the probe packet (X) ;

- forwarding the buffered probe packet (X) from the intermediate measurement capable node (IMEN1-IMEN3) on the path (A-D) towards the receiving node (GGSN/B; GW/B) .

9. A method of measuring network performance wherein at least two probe packets (X, Y; P, Q) have been transmitted from the sending node to the receiving node according to any of the previous claims.

10. Method of measuring network performance according to any of the previous claims wherein buffered probe packets are sent in an appropriately chosen send pattern.

11. An arrangement in a communication network to measure network performance, wherein a send specification (Sx; Sp) for each of at least one probe packet (X; P) is generated at a sending node (GGSN/A; GW/A) , which probe packet is transmitted from the sending node on a communication path (A-D) in the communication network

(IP; ETHERNET), towards a receiving node (GGSN/B;

GW/B) , the arrangement being c h a r a c t e r i z e d by

- means to receive the probe packet (X; P) by at least one intermediate measurement capable node (IMENl- IMEN3) located on the path (A-D) between the sending node and the receiving node;

- means to generate at the intermediate measurement capable node (IMEN1-IMEN3) , at least one time stamp specification (rxl-rx3, sxl-sx3; rpl-rp3, spl-sp3) for the packet (X; P);

- means to receive the probe packet by the receiving node (GGSN/B; GW/B) and means to generate a receive specification (Rx;Rp) for the probe packet;

- means to estimate network performance by utilizing generated specifications (Sx, rxl-rx3, sxl-sx3, Rx; Sp, rpl-rp3, spl-sp3, Rp) .

12. An arrangement to measure network performance according to claim 11, which arrangement further comprises means in the intermediate measurement capable node (IMENl- IMEN3) to calculate a bandwidth estimate by utilizing selected generated specifications.

13. An arrangement to measure network performance according to claim 11 or 12, which arrangement further comprises means to include the generated specifications (Sx, rxl- rx3, sxl-sx3) and/or the bandwidth estimate in the probe packet (X) .

14. An arrangement to measure network performance according to claim 11 or 12, which arrangement further comprises means to include the generated specifications (Sp, rpl- rp3, spl-sp3) and/or the bandwidth estimate in a List packet (L) that subsequently passes the same nodes (GW/A, IMEN1-IMEN3, GW/B) as the probe packet (P) .

15. An arrangement to measure network performance according to any of the claims 11-14, which arrangement further comprises means to forward the generated specifications (Sx, rxl-rx3, sxl-sx3; Sp, rpl-rp3, spl- sp3) and/or the bandwidth estimate to the receiving node (GGSN/B; GW/B) .

16. An arrangement to measure network performance according to any of the claims 11-13, whereby the time stamp specification generated in the intermediate measurement capable node ( IMENl-IMEN3 ), is a receive specification (rxl-rx3) , which arrangement further comprises:

- means to include the receive specification (rxl- rx3) in the probe packet (X) ;

- means to forward the probe packet (X) from the intermediate measurement capable node (IMEN1-IMEN3) on the path (A-D) towards the receiving node (GGSN/B; GW/B) .

17. An arrangement to measure network performance according to any of the claims 11-13, which arrangement further comprises means to buffer the probe packet (X) in the intermediate measurement capable node (IMEN1-IMEN3) .

18. An arrangement to measure network performance according to claim 17, whereby the time stamp specification generated in the intermediate measurement capable node (IMEN1-IMEN3) , is a send specification (sxl-sx3) , which arrangement comprises:

- means to include the send specification (sxl-sx3) in the probe packet (X) ;

- means to forward the buffered probe packet (X) from the intermediate measurement capable node (IMENl- IMEN3) on the path (A-D) towards the receiving node (GGSN/B; GW/B) .

19. An arrangement to measure network performance according to any of the claims 11-18 comprising means to send buffered probe packets in an appropriately chosen send pattern.

20. An intermediate measurement node (IMEN1-IMEN3) in a communication network capable to measure network performance, wherein a send specification (Sx; Sp) for each of at least one probe packet (X; P) is generated at a sending node (GGSN/A; GW/A) , which probe packet is transmitted from the sending node on a communication path (A-D) in the communication network (IP; ETHERNET), towards a receiving node (GGSN/B; GW/B) , the intermediate measurement node being c h a r a c t e r i z e d by

- means to receive the probe packet (X; P);

- means to generate at least one time stamp specification (rxl-rx3, sxl-sx3; rpl-rp3, spl-sp3) for the packet (X;P);

- means to forward the probe packet.

21. An intermediate measurement node (IMEN1-IMEN3) in a communication network according to claim 20, whereby the generated time stamp specification is a receive specification (rxl-rx3) , which node further comprises:

22. An intermediate measurement node (IMEN1-IMEN3) in a communication network according to claim 20, which node further comprises means to buffer the probe packet (X) .

23. An intermediate measurement node (IMEN1-IMEN3) in a communication network according to claim 22, whereby the time stamp specification, is a send specification (sxl-sx3) , which arrangement comprises:

- means to include the send specification (sxl-sx3) in the probe packet (X) ;

24. An intermediate measurement node (IMEN1-IMEN3) in a communication network according to any of the claims 20-23 comprising means to send buffered probe packets in an appropriately chosen send pattern.

25. Article of manufacture comprising a program storage memory having computer readable program code embodied therein to measure network performance, wherein a send specification (Sx; Sp) for each of at least one probe packet (X; P) is generated at a sending node (GGSN/A; GW/A) , which probe packet is transmitted from the sending node on a communication path (A-D) in the communication network (IP; ETHERNET), towards a receiving node (GGSN/B; GW/B) , the program code being c h a r a c t e r i z e d by computer readable program code in at least one intermediate measurement capable node (IMEN1-IMEN3) located on the path (A-D) between the sending node and the receiving node, able to generate at the intermediate measurement capable node ( IMENl-IMEN3 ), at least one time stamp specification (rxl-rx3, sxl-sx3; rpl-rp3, spl-sp3) for the packet (X; P), and by computer readable program code able to estimate network performance by utilizing generated specifications (Sx, rxl-rx3, sxl-sx3, Rx; Sp, rpl-rp3, spl-sp3, Rp) .