FORM 2
The Patent Act 1970
(39 of 1970)
&
The Patent Rules, 2005

COMPLETE SPECIFICATION
(SEE SECTION 10 AND RULE 13)

TITLE OF THE INVENTION

“External loopback diagnostic test for asymmetric digital subscriber line”

Name Nationality Address
Alcatel Lucent France 3, avenue Octave Gréard 75007 Paris,
France.

The following specification particularly describes and ascertains the nature of this invention and the manner in which it is to be performed:-

TECHNICAL FIELD
1. The present invention relates to asymmetric digital subscriber lines and, more particularly, to loopback test in asymmetric digital subscriber lines.

BACKGROUND
2. Telecommunication networks employ Asymmetric Digital Subscriber Line (ADSL) technology for high speed digital communications. ADSL converts existing twisted pair telephone lines into access pair for digital communication and multimedia services. ADSL operates on frequency division multiplexing techniques, in which, the frequency spectrum is allocated for both voice and data paths. ADSL connections have the ability to dynamically adapt to the line conditions and hence, the ADSL connections have to be fully evaluated using traffic generation. Traffic generation schemes may be employed for both upstream and downstream to stress the ADSL circuit to obtain throughput measurements as an overall measure of its performance. Furthermore, conventional traffic generation schemes provided with network interface cards generate traffic at the rate of 24 Mbps for testing ADSL. However, in such cases the traffic needs to be generated on the ADSL unit itself and generating required number of packets per second poses a difficulty.
3. The ADSL is an asymmetric link and has different speeds in the upstream and downstream direction. For example, in case of ADSL 2+ mode the upstream speed is 1.5Mbps and the downstream speed is 24Mbps. This speed difference between the upstream and downstream is not sufficient for looping transmitter signal back into the receiver using external loopback cable i.e., the speed difference does not permit feeding back the signal to the receiver in order to achieve sufficient speeds difference in both the directions. Owing to the speed limitation external loopback diagnostics techniques cannot be employed for ADSL interface. Thus, there is no means to determine if end-to-end interfaces in ADSL are functioning accurately.
4. Although there are some line loopback tests, they test only the analog side rather than end-to-end interface connectivity. Tests such as Board Production Test (BPT) test may be employed for testing ADSL connections. However, BPT tests only analog side of the ADSL hardware. In this test, the transmit signal is looped into the receiver through an external loopback cable connected to RJ-11 ADSL port. Further, the output signal is measured. The quality and strength of the output indicates how well the analog front end device is functioning. A successful execution of the BPT test indicates proper functioning of front end devices. However, the test does not guarantee that the digital interfaces are functioning correctly too. Most importantly, the test does not allow running the stress test in upstream and downstream direction. In addition, the BPT does not provide any information on the connectivity aspects of the end-to-end interfaces. Further, the upstream and down stream of the ADSL that operate on frequency division multiplexing may interact and interfere with each other resulting in reducing the maximum available throughput of the network. The throughput of the ADSL circuit therefore must be measured with respect to the traffic generated both in upstream and downstream directions simultaneously in order to stress the ADSL circuit. So some existing systems employ two test instruments that operate in tandem at each end of the ADSL circuit. However, this adds to the overall cost of the system.

SUMMARY
5. In view of the foregoing, an embodiment herein provides a system for conducting external loopback test of an asymmetric digital subscriber line in a communication network. The communication network comprising at least one asymmetric digital subscriber line module, at least one digital subscriber line access module and a Point-to-Point Protocol over Ethernet server. Further, the asymmetric digital subscriber line module is configured for generating packets by employing a packet generator and sending the generated packets between the asymmetric digital subscriber line and the Point-to-Point Protocol over Ethernet server. The digital subscriber line access module is configured for receiving the packet from the asymmetric digital subscriber line module and sending the packet to the Point-to-Point Protocol over Ethernet server over an Ethernet link. The Point-to-Point Protocol over Ethernet server configured for checking if the service name of the packet matches with the stored service name, generating duplicates of the packet and sending the duplicated packets to the asymmetric digital subscriber line module through the digital subscriber line access module. The system is configured for generating the packet where the packet is a point-to-point protocol active discover initiation packet. The system is configured for duplicating the packets where the duplicate packets are point-to-point protocol active discovery offer response packets. The system is configured for duplication of the packets and further the duplication factor may be controlled by providing an argument at the Point-to-Point Protocol over Ethernet server. The system is configured for determining the speed of end-to-end interface connectivity by verifying the integrity of the duplicated packets on receiving the duplicated packets, verifying packet loss, if any, using counters at transmit and receive points and computing the speed achieved in upstream and downstream directions.
6. Embodiments further disclose at least one asymmetric digital subscriber line module for packet generation in a communication network. The module is configured for generating packets by employing a packet generator and sending the generated packet over an asymmetric digital subscriber line link to a digital subscriber line access module. The asymmetric digital subscriber line module is further configured for calculating data loss from received duplicate packets to determine the speed in transmission. A host processor that resides within the asymmetric digital subscriber line module is configured to generate the packet.
7. Also disclosed herein is a method for conducting external loopback test of an asymmetric digital subscriber line in a communication network. The network comprising an asymmetric digital subscriber line module, at least one digital subscriber line access module and a Point-to-Point Protocol over Ethernet server. Further, the method comprising the asymmetric digital subscriber line module generating at least one packet for establishing a Point-to-Point Protocol over Ethernet session with the Point-to-Point Protocol over Ethernet server, the digital subscriber line access module receiving the packet from the asymmetric digital subscriber line module, the digital subscriber line access module sending the packet to the Point-to-Point Protocol over Ethernet server over an Ethernet link, the Point-to-Point Protocol over Ethernet server checking if the service name of the packet matches with a stored service name, the Point-to-Point Protocol over Ethernet server generating duplicates of the packet, if the service name matches with the stored name on the Point-to-Point Protocol over Ethernet server. The Point-to-Point Protocol over Ethernet server sending the duplicated packets to the asymmetric digital subscriber line module through the digital subscriber line access module and the asymmetric digital subscriber line module determining the speed of the network from the duplicated packets where the duplicated packets are sent by the digital subscriber line access module. The speed of the network is determined by verifying the integrity of the duplicated packets on receiving the duplicated packets, verifying packet loss, if any, using counters at transmit and receive points and computing the speed achieved in upstream and downstream directions. The packet is a point-to-point protocol active discover initiation packet. The duplicate packet is a point-to-point protocol active discover offer response packet. The duplication of the packet is controlled by a duplication factor, wherein the duplication factor may be controlled by providing an argument at the Point-to-Point Protocol over Ethernet server.
8. Embodiments herein also disclose a Point-to-Point Protocol over Ethernet server in a communication network. The server configured for checking if service name of a packet matches the stored service name on receiving the packet from a digital subscriber line access module, sending a signal to a packet duplication module for duplication of the packet, producing a plurality of duplicates of the packet based on a duplication factor and sending the duplicated packets to a digital subscriber line access module. The Point-to-Point Protocol over Ethernet server is configured for performing packet duplication by employing a packet duplication module. The Point-to-Point Protocol over Ethernet server is configured for controlling the duplication factor by providing an argument to the server.
9. These and other aspects of the embodiments herein will be better appreciated and understood when considered in conjunction with the following description and the accompanying drawings.

BRIEF DESCRIPTION OF THE FIGURES
10. The embodiments herein will be better understood from the following detailed description with reference to the drawings, in which:
11. FIG. 1 illustrates the architecture of the system employed for conducting loopback test, according to an embodiment as disclosed herein;
12. FIG. 2 illustrates an Asymmetric Digital Subscriber Line (ADSL) module, according to an embodiment as disclosed herein;
13. FIG. 3 illustrates a Digital Subscriber Line Access Module (DSLAM), according to an embodiment as disclosed herein; and
14. FIG. 4 is a flow chart depicting the process of conducting loopback test, according to an embodiment as disclosed herein.

DETAILED DESCRIPTION OF EMBODIMENTS
15. The embodiments herein and the various features and advantageous details thereof are explained more fully with reference to the non-limiting embodiments that are illustrated in the accompanying drawings and detailed in the following description. Descriptions of well-known components and processing techniques are omitted so as to not unnecessarily obscure the embodiments herein. The examples used herein are intended merely to facilitate an understanding of ways in which the embodiments herein may be practiced and to further enable those of skill in the art to practice the embodiments herein. Accordingly, the examples should not be construed as limiting the scope of the embodiments herein.
16. The embodiments herein disclose a mechanism for conducting external loopback test for asymmetric digital subscriber line by providing systems and methods thereof. Referring now to the drawings, and more particularly to FIGS. 1 through 4, where similar reference characters denote corresponding features consistently throughout the figures, there are shown embodiments.
17. A method for conducting external loopback test in asymmetric digital subscriber line is disclosed. The method determines the end-to-end connectivity of the Asymmetric Digital Subscriber Line (ADSL) interface by conducting loopback tests on ADSL. The method employs a mechanism where the network traffic is generated in both upstream and downstream directions on the ADSL and the end-to-end connectivity on ADSL link is verified. The method allows testing the upstream and downstream speed of the ADSL link at the highest possible speeds.
18. A packet generator is employed within the ADSL module. The packet generator generates the packets. The packets generated are sent to the ADSL engine that further sends the packets to a Digital Subscriber Line Access Module (DSLAM) over the ADSL interface. The DSLAM on receiving the packets forwards the packets to the Ethernet interface of DSLAM. The Ethernet interface of the DSLAM is connected to a host machine i.e., a Point-to-point Protocol over Ethernet (PPPoE) server. In the PPPoE server, the received packets are duplicated. For every packet received, the PPPoE server may produce ‘n’ duplicates. Further, the duplicated packets may be sent to the ADSL module through the DSLAM. At the ADSL module, the integrity of the data packets is verified. In addition, transmit and receive counters may be employed to measure the speed of the packets sent and received. Also, packet loss data may be determined and thus, the speed achieved in upstream and downstream transmission may be calculated. The method determines the end-to-end interface connectivity of ADSL interface.
19. FIG. 1 illustrates the architecture of the system employed for conducting loopback test, according to an embodiment as disclosed herein. The embodiment depicts the architecture of an ADSL network for which the external loopback test is performed. In an embodiment herein, the system comprises of an ADSL module 101, a DSLAM 102 and a PPPoE server 103.
20. The ADSL module 101 is provided with a host processor and an ADSL engine. The host processor further comprises a packet generator. The ADSL module 101 is responsible for generation of the packets in order to build the traffic on the ADSL connection. The traffic helps in determining the speed of the end-to-end interfaces on the ADSL connection. The packet generator on the host processor generates a Point-to-point Active Discover Initiator (PADI) packet. On generation of the PADI packet, the packet is sent to an ADSL engine. The ADSL engine sends the PADI packet to the DSLAM 102 on an ADSL link.
21. Further, when the ADSL module 101 receives the duplicated packets from the DSLAM 102, the ADSL module 101 performs integrity check on the duplicated packets. During this check, transmit and receive counters may be employed to determine packet loss, rate of transmission and the speed achieved in upstream and downstream directions. Thus, the connectivity and performance of the end-to-end interfaces of the ADSL connection may be verified. In an embodiment, there is no additional configuration required on the ADSL module 101. A default configuration of device on VPI/VCI mode, bridged mode, and ADSL mode will suffice. In an embodiment, a plurality of ADSL modules 101 may be connected to ports on the DSLAM 102.
22. The DSLAM 102 acts as intermediate for sending the packets between ADSL module 101 and the PPPoE server 103. The PADI packets generated on the ADSL module 101 are sent to the DSLAM 102 on an ADSL link. The DSLAM 102 on receiving the PADI packet bridges the packet to the Ethernet interface of the DSLAM 102. Further, the Ethernet interface of the DSLAM 102 is connected to a PPPoE server 103. The DSLAM 102 may be connected to the PPoE server 103 using a fast Ethernet or a gigabit Ethernet link. In an embodiment, the PPPoE server 103 may be a Linux host machine. The PADI packets may be then transferred to the PPPoE server 103. In an embodiment, the host machine may be other machine than a Linux host machine.
23. The PPPoE server 103 is responsible for duplication of the received PADI packets for generation of the traffic in downstream direction. On receiving the PADI packets from the DSLAM 102, the PPPoE server 103 makes a check if the service name of the packet matches with the service name stored on it. In an embodiment, the service name may be ‘GLOG’ that is fixed in PADI packets and hence PPPoE server 103 must be started with the same service name. In case the service name does not match, the PPPoE server 103 may not respond with PADO packets and hence there will be no downstream traffic.
24. On confirmation of the service name, the PPPoE server 103 generates duplicates of the PADI packet. The PPPoE server 103 signals the packet duplication module to produce duplicates of the PADI packets received. The packet duplication module then generates ‘n’ duplicates PADO packets for each PADI packet. The packet duplication factor ‘n’ depends on the traffic that needs to be generated in the downstream direction, the bandwidth of Ethernet interface, and capacity of the PPPoE server 103. The number of packets to be duplicated may be configured by the service provider by providing an argument at the time of starting the PPPoE server 103.
25. In an embodiment, data is transferred over ADSL link in form of Asynchronous Transfer Mode (ATM) cells. The ATM cell is fixed 53-byte in size and contains 48 byte of payload and 5 bytes of ATM header. Due to this even 64-byte Ethernet packet generates two ATM cells and actual bytes transferred on ATM link is 106 bytes (53 * 2). All upstream and downstream throughput calculations are done based on number of ATM cells transferred.
26. FIG. 2 illustrates an Asymmetric Digital Subscriber Line (ADSL) module, according to an embodiment as disclosed herein. The ADSL module comprises a host processor 201, an ADSL engine 202 and an encoder/ decoder 203. Further, the host processor 201 comprises of a packet generator.
27. The host processor 201 is responsible for generation of the PADI packets by initiation of the packet generation process by the packet generation module. The host processor 201 sends an indication to the packet generator to generate the PADI packets. On receiving the indication, from the host processor 201, the packet generator generates PADI packets in order to create upstream traffic on ADSL. The host processor 201 is also responsible for carrying out the processing activities of the ADSL module 101.
28. The ADSL engine 202 receives the responses from the host processor and sends the response to the appropriate destination. The ADSL engine 202 obtains the PADI packets generated and bridges the ADSL interface using the PADI packets. Further, the ADSL engine 202 forwards the PADI packets to the DSLAM 102 over the Ethernet interface.
29. The encoder/ decoder 203 are responsible for performing encoding or decoding operations on the data received by the ADSL module 101. The request received by the ADSL module 101 is decoded by the encoder/ decoder 203 and then sent to the appropriate module to address the request. In case of responses, the responses may be encoded in the required format and sent to the external destination.
30. FIG. 3 illustrates a Point-to-Point Protocol over Ethernet server, according to an embodiment as disclosed herein. The PPPoE server 103 is responsible for the duplication of the packets in order to maintain the network traffic in both upstream and downstream directions. In an embodiment, the PPPoE server may be a Linux host machine. The PPPoE server 103 comprises different sub modules including a packet duplication module 301, an interface 302 and an encoder/ decoder 303.
31. The packet duplication module 301 is responsible for duplication of packets received by the ADSL module 101. When the PADI packets are received by the PPPoE server 103, it sends intimation to the packet duplication module 301. Further, the packet duplication module 301 starts packet duplication process. For every PADI packet, the packet duplication module 301 produces ‘n’ number of PADO packets. The factor ‘n’ is termed as duplication factor and the factor may be pre-configured. The duplication factor may be controlled by providing an argument while starting the PPPoE server 103. Further, the duplication factor also depends on the ADSL mode that is being employed. The actual duplication being achieved depends on the capacity of the PPPoE server 103 and the bandwidth of Ethernet interface between the PPPoE server 103 and DSLAM 102.
32. The interface 302 is the first point of contact for all the messages sent to the PPPoE server 103. The interface receives the requests and directs it to the appropriate modules that address the function.
33. The encoder/decoder 303 is responsible for encoding or decoding the responses and requests. In case of responses, the responses may be encoded in the required format and sent to the external destination. The encoder/ decoder 303 may also be configured to make a check for the service name on receiving a PADI packet from the DSLAM. If the service name matches with the name stored on the server then a response may be produced and PADO packets may be produced. On the other hand, if the service name does not match the stored service name on the server the server will not respond and there will be no downstream traffic.
34. FIG. 4 is a flow chart depicting the process of conducting loopback test, according to an embodiment as disclosed herein. At the beginning of the test the user configures (401) the parameters required to perform the test on the network devices. Configurations may be performed on the network devices involved in the test such as the ADSL module 101, DSLAM 102 and PPPoE server 103. The ADSL mode on the device may be set to auto which also indicates the default settings. At the DSLAM 102, the port to which ADSL link is connected is configured in bridged mode. The VPI/ VCI of the DSLAM port are set to 0/32. The service name ‘GLOG’ may be defined at the PPPoE server 103. The ADSL module 101 invokes the host processor 201 on it. The host processor 201 houses a packet generation module. The packet generation module generates (402) PADI packets. The PADI packets generated are then sent to the ADSL engine 202 in order to forward the packets over the ADSL interface to the DSLAM 102. The PADI packets are sent (403) to the DSLAM over the ADSL link. The DSLAM 102 bridges the Ethernet interface and sends (404) the PADI packets to the PPPoE server 103. On receiving the PADI packets, the PPPoE server 103 checks (405) for the service name in the packets. In case the service name matches (406) with the name stored on the PPPoE server 103 then the process moves further, else there is no response from the PPPoE server 103 and thus downstream traffic is not generated. The process then performs (407) no action. When there is a match in the service name, the packet duplication module 301 is informed. The packet duplication module 301 then generates (408) duplicates of the PADI packet and produces the specified number of PADO packets. The number of PADO packets duplicated depends on the duplication factor that is configured on the PPPoE server 103. The duplicated packets may then be sent (409) to the DSLAM 102. The DSLAM 102 then sends the PADO packets to the ADSL module 101 over the Ethernet interfaces. The ADSL module 101 may perform (410) analysis on the data packets received in order to determine the functioning of the Ethernet interfaces. The ADSL module 101 may also employ additional transmit and receive counters in order to verify any packet loss, and compute speed achieved in upstream and downstream directions. The various actions in method 400 may be performed in the order presented, in a different order or simultaneously. Further, in some embodiments, some actions listed in FIG. 4 may be omitted.
35. In an embodiment, the invention offers various benefits such as it does not require any configuration of ADSL interface except some default setting on the device (VPI/VCI, bridged mode, ADSL mode). Further, the system allows end-to-end verification with line rate traffic in upstream and downstream directions. It requires only VPI/VCI setting and bridge mode configuration on DSLAM port. In addition, it requires only open source PPPoE server on Linux host. Also, runs tests on multiple ADSL chassis simultaneously by connecting them to different ports on DSLAM. In case of extension of the method for VDSL and SHDSL devices the method works without any changes for higher speed interfaces.
36. The embodiments disclosed herein can be implemented through at least one software program running on at least one hardware device and performing network management functions to control the network elements. The network elements shown in Fig. 1, 2 and 3 include blocks which can be at least one of a hardware device, or a combination of hardware device and software module.
37. The foregoing description of the specific embodiments will so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the claims as described herein.

WE CLAIM:-
1. A system for conducting external loopback test of an asymmetric digital subscriber line in a communication network, said communication network comprising at least one asymmetric digital subscriber line module, at least one digital subscriber line access module and a Point-to-Point Protocol over Ethernet server, further
said asymmetric digital subscriber line module configured for:
generating packets by employing a packet generator;
said digital subscriber line access module configured for:
receiving said packet from said asymmetric digital subscriber line module; and
sending said packet to said Point-to-Point Protocol over Ethernet server over an Ethernet link;
said Point-to-Point Protocol over Ethernet server configured for:
checking if the service name of said packet matches with the stored service name;
generating duplicates of said packet; and
sending said duplicated packets to said asymmetric digital subscriber line module through said digital subscriber line access module.

2. The system as in claim 1, wherein said system is configured for generating said packet where said packet is a point-to-point protocol active discover initiation packet.

3. The system as in claim 1, wherein said system is configured for duplicating said packets where said duplicate packets are point-to-point protocol active discover offer response packets.

4. The system as in claim 1, wherein said system is configured for duplication of said packets and further said duplication factor may be controlled by providing an argument at said Point-to-Point Protocol over Ethernet server.

5. The system as in claim 1, wherein said system is configured for determining the speed of end-to-end interface connectivity by
verifying the integrity of said duplicated packets on receiving said duplicated packets;
verifying packet loss, if any, using counters at transmit and receive points; and
computing the speed achieved in upstream and downstream directions.

6. An asymmetric digital subscriber line module for packet generation in a communication network, said module is configured for
generating packets by employing a packet generator; and
sending said generated packet over an asymmetric digital subscriber line link to a digital subscriber line access module.

7. The asymmetric digital subscriber line module as in claim 6, wherein said module is further configured for calculating data loss from received duplicate packets to determine the speed in transmission.
8. The asymmetric digital subscriber line module as in claim 6, wherein a packet generator is within a host processor that resides within said asymmetric digital subscriber line module.

9. A method for conducting external loopback test of an asymmetric digital subscriber line in a communication network, said network comprising an asymmetric digital subscriber line module, at least one digital subscriber line access module and a Point-to-Point Protocol over Ethernet server, further said method comprising
said asymmetric digital subscriber line module generating packets;
said digital subscriber line access module receiving said packet from said asymmetric digital subscriber line module;
said digital subscriber line access module sending said packet to said Point-to-Point Protocol over Ethernet server over an Ethernet link;
said Point-to-Point Protocol over Ethernet server checking if the service name of said packet matches with a stored service name;
said Point-to-Point Protocol over Ethernet server generating duplicates of said packet, if said service name matches with said stored name on said Point-to-Point Protocol over Ethernet server;
said Point-to-Point Protocol over Ethernet server sending said duplicated packets to said asymmetric digital subscriber line module through said digital subscriber line access module; and
said asymmetric digital subscriber line module determining the speed of said network from said duplicated packets, where said duplicated packets are sent by said digital subscriber line access module.

10. The method as in claim 9, wherein said speed of said network is determined by
verifying the integrity of said duplicated packets on receiving said duplicated packets;
verifying packet loss, if any, using counters at transmit and receive points; and
computing the speed achieved in upstream and downstream directions.

11. The method as in claim 9, wherein said packet is a point-to-point protocol active discover initiation packet.

12. The method as in claim 9, wherein said duplicate packet is a point-to-point protocol active discover offer response packet.

13. The method as in claim 9, wherein said duplication of said packet is controlled by a duplication factor, wherein said duplication factor may be controlled by providing an argument at said Point-to-Point Protocol over Ethernet server.

14. A Point-to-Point Protocol over Ethernet server in a communication network, said server configured for
checking if service name of a packet matches the stored service name on receiving said packet from a digital subscriber line access module;
sending a signal to a packet duplication module for duplication of said packet;
producing a plurality of duplicates of said packet based on a duplication factor; and
sending said duplicated packets to a digital subscriber line access module.

15. The Point-to-Point Protocol over Ethernet server as in claim 14, wherein said Point-to-Point Protocol over Ethernet server is configured for performing packet duplication by employing a packet duplication module.

16. The Point-to-Point Protocol over Ethernet server as in claim 14, wherein said Point-to-Point Protocol over Ethernet server is configured for controlling said duplication factor by providing an argument at said server.

Dated 20th of Aug, 2010

Nishant Kewalramani
Patent Agent