Identification of priority faults in a transport network

1. A system for prioritising faults in a transport network comprising a plurality of network elements arranged to transport data signals comprising respective overhead data and payload data, the system comprising:

at least one first network element arranged to include in said overhead data a priority indicator indicating the relative importance of the respective payload data; and

at least one second network element arranged to examine the respective priority indicator of data signals,

the system being arranged to prioritise each fault detected in respect of a data signal using at least the value of the respective priority indicator wherein the priority indicator is included in said overhead data in a synchronous transport network.

2. A system as claimed in claim 1 , wherein said at least one first network element is arranged to receive said payload data, to create said overhead data and to incorporate said created overhead data and said payload data into a data signal suitable for transportation across said network.

3. A system as claimed in claim 1 , wherein said at least one second network element is arranged to terminate data signals.

4. A system as claimed in claim 1 , wherein said at least one second network element is arranged to receive data signals from, and forward data signals to, one or more other of said network elements.

5. A system as claimed in claim 1 , wherein each of said network elements is arranged to serve as a first and a second network element.

6. A system as claimed in claim 1 , further including a management apparatus arranged for communication with said at least one first network element in order to provide respective values at which to set said priority indicator thereto, and arranged for communication with said at least one second network element in order to receive respective values of examined priority indicators therefrom.

7. A system as claimed in claim 6 , in which said at least one second network element is arranged to receive from said management apparatus a respective expected value for said priority indicators, wherein said at least one second network element is arranged to compare said respective expected priority indicator values with the respective examined priority indicator values and to detect a signal fault upon determination of a mismatch.

8. A system as claimed in claim 1 , wherein said priority indicator is included in overhead data associated with the path taken by the respective data signal across said transport network.

9. A system as claimed in claim 1 , wherein said priority indicator is included in overhead data associated with a section of said transport network.

10. A system as claimed in claim 1 , wherein said transport network comprises a synchronous transport network.

11. An apparatus for use in prioritising faults in a transport network comprising a plurality of network elements arranged to transport data signals comprising respective overhead data and payload data, said overhead data including a priority indicator indicating the relative importance of the respective payload data, wherein the apparatus is arranged to determine the priority indicator of a data signal in respect of which a fault is detected and to communicate the value of the priority indicator to a management apparatus wherein the priority indicator is included in said overhead data in a synchronous transport network.

12. An apparatus as claimed in claim 11 , arranged to receive, from a management apparatus, a respective value at which to set said priority indicator, and being further arranged to include the priority indicator in said overhead data.

13. An apparatus as claimed in claim 11 , wherein the apparatus is arranged to receive, from a management apparatus, a respective expected value for said priority indicator, to compare said respective expected priority indicator value with a respective examined priority indicator value, and to detect a signal fault upon determination of a mismatch.

14. An apparatus as claimed in claim 11 , wherein the apparatus is arranged to receive, from a management apparatus, a respective expected value for said priority indicator, wherein, upon detection that a data signal has failed to reach said apparatus, said apparatus is arranged to communicate to said management apparatus said failure and said respective expected value.

15. An apparatus as claimed in claim 11 , wherein said priority indicator is included in overhead data associated with the path taken by the respective data signal across said transport network.

16. An apparatus as claimed in claim 11 , wherein said priority indicator is included in overhead data associated with a section of said transport network.

17. An apparatus as claimed in claim 11 , wherein said transport network is a synchronous transport network and said apparatus includes a trail termination source function (TT_So) arranged to include said priority indicator in said overhead data.

18. An apparatus as claimed in claim 11 , wherein said transport network is a synchronous transport network and said apparatus includes a trail termination sink function (TT_Sk) arranged to examine said priority indicator.

19. An apparatus as claimed in claim 11 , wherein said transport network is a synchronous transport network and said apparatus includes a trail termination sink monitoring function (m_TT_Sk) arranged to examine said priority indicator.

20. A method of prioritising faults in a transport network comprising a plurality of network elements arranged to transport data signals comprising respective overhead data and payload data, the method comprising:

including in said overhead data a priority indicator indicating the relative importance of the respective payload data; examining, in respect of a data signal for which a fault is detected, the respective priority indicator; and prioritising said detected fault using at least the value of said respective priority indicator wherein the priority indicator is included in said overhead data in a synchronous transport network.

21. A system for prioritising faults in a transport network in which a data signal is transported across the network along a path comprising one or more network elements, the data signal comprising overhead data and payload data, the system comprising a management apparatus arranged to associate with said data signal a priority indicator the value of which indicates the relative importance of the payload data and being further arranged to communicate the priority indicator to one or more network elements in said path, wherein, upon detection by a network element in said path that said data signal has failed to reach said network element, said network element is arranged to communicate said failure and the value of said priority indicator to said management apparatus wherein the priority indicator is included in said overhead data in a synchronous transport network.

22. A system for prioritising faults in a transport network in which a data signal is transported across the network along a path comprising one or more network elements, the data signal comprising overhead data and payload data, the system comprising a management apparatus arranged to associate with said data signal a priority indicator the value of which indicates the relative importance of the payload data and being further arranged to communicate the priority indicator to one or more network elements in said path, wherein, upon detection by a network element in said path of a fault in said data signal, said network element is arranged to communicate the value of said priority indicator to said management apparatus wherein the priority indicator is included in said overhead data in a synchronous transport network.

23. A system as claimed in claim 22 , wherein said management apparatus is arranged to cause said priority indicator to be included in the respective overhead data of data signals and wherein, upon receipt by said network element of a data signal in respect of which a fault is detected, said network element determines the value of said priority indicator from the respective overhead data.

24. A system as claimed in claim 22 , wherein, in the event that said fault causes said data signal to fail to reach said network element, said network element determines the value of said priority indicator from the respective priority indicator communicated to it by the management apparatus.