Error detection/correction and fault detection/recovery – Pulse or data error handling – Digital data error correction
Reexamination Certificate
2001-03-29
2004-02-03
Tu, Christine T. (Department: 2133)
Error detection/correction and fault detection/recovery
Pulse or data error handling
Digital data error correction
C714S057000, C714S033000, C714S046000
Reexamination Certificate
active
06687869
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method for evaluating a presentation layer data unit, which contains application-oriented messages, coded according to a predefined coding protocol, for at least one application process running on a Q3 platform. The presentation layer data unit is received by the Q3platform via an association established on a Q3interface between the Q3 platform and a partner Q3platform, where:
the format of the data unit is checked for compliance with the predefined coding protocol;
the user data contained in the data unit is decoded (provided there are no errors in the coding);
the application-oriented messages are determined;
these messages are forwarded to the appropriate application process(es).
The invention equally relates a Q3 platform with at least one Q3 interface, on which associations with a partner Q3 platform can be established, with an application layer for application processes running on the Q3 platform, and a presentation machine to receive presentation layer data units via the associations. The data units contain application-oriented messages for at least one of the application processes, and these messages are coded according to a predefined coding protocol. The presentation machine, which evaluates these data units, is configured
to check the format of the data unit for compliance with the predefined coding protocol;
to decode the user data contained in the data unit (provided there are no errors in the coding);
to determine the application-oriented messages; and
to forward these messages to the appropriate application processes.
Q3 platforms and Q3 interfaces are used in the context of a so-called control network, in accordance with various standards specified by the International Telecommunications Union (ITU), and particularly the Recommendations M.3010 and M.3100. There follows a brief explanation of the main concepts of the control network, since these are required in order to understand the invention. Further information about this subject can be found in the aforementioned ITU Recommendations M.3010 and M.3100, and in ITU
2. Description of the Prior Art
Modern telecommunication networks generally comprise a large number of switching and transmission components. These are subsequently referred to as network elements (NE), in accordance with the aforementioned ITU recommendations. In order to provide comprehensive overall control of the network elements in a telecommunications network, with regard to operations, administration and maintenance (OAM), the Standards M.3010 and M.3100 propose an independent control network for processing information, and this is referred to as a telecommunications management network (TMN). Among other components, the TMN includes the network elements as terminal stations, and accesses the network elements via standardized interfaces and protocols. The TMN receives control-oriented reports from the network elements, which it controls. The control network includes an operations center, also known as an operations system or OS (of which there may be more than one), which allows centralized OAM control of the telecommunication network, as well as operation and monitoring of the control network by maintenance staff via terminals.
Switching centers in the telecommunication network are directly connected to the operations center via a so-called Q3 interface. The term Q3 platform refers to a network node that has one or more Q3 interfaces and is part of a control network. In particular, this includes the aforementioned switching centers with Q3 interfaces and the operations center of the control network. Another example of an interface type, which is not particularly important for the present invention, is the so-called Q2 interface. This is less complex, is intended for simpler network elements, and is used to connect network elements to the operations center indirectly via intermediate stations.
In accordance with ITU Recommendations X.710 and X.711, a common management information service (CMIS) is used at the Q3 interfaces in a control network, to exchange messages and commands relating to network control. A connection established between a control center and a network element is called an association. The operations center can use an association to send commands from the CMIS service, otherwise known as CMISE operations (common management information service element), to the network element. In this context, a single association can be used to transfer CMISE operations for a number of processes belonging to CMIS applications, which may be running concurrently on the same Q3 platform.
For the purposes of the association, and in particular the CMIS service, message transfers are based on the protocol layer architecture as defined in the OSI 7-layer model (cf. ITU Recommendation X.200) The present invention is only concerned with the top two layers of the OSI 7-layer model, namely layer 6 (the ‘presentation layer’) and layer 7 (the ‘application layer’). According to the OSI 7-layer model, the application layer contains the application-specific processes, in particular the CMISE operations, and relies on the functions of the presentation layer for this purpose. The presentation layer is used to generate a common coding for participating Q3 platforms on the basis of functions in layer 5, otherwise known as the ‘session layer’ which provides communication control functions. The present invention is not concerned with layers 1 to 5.
When transferring CMISE operations via an association with the partner platform, the operations are passed from the application layer to the presentation layer. A so-called PPM (presentation-layer protocol machine) is provided on each Q3 platform to perform the data transfer at the presentation layer. Messages are exchanged between PPMs on the Q3 platforms in the form of so-called PPDUs (presentation-layer protocol data units). The structure of PPDUs and the procedure for transferring messages based on PPDUs are specified by a predefined coding protocol. In accordance with the standards for the Q3 interface, the coding protocol is defined by the so-called ‘basic encoding rules’ as per ITU Recommendation X.209, and by syntax based on the so-called ASN structure as per ITU Recommendation X.208. PPDUs received over the association are checked and decoded by the PPM in accordance with the coding protocol (provided there are no errors). The data for the application processes is then determined, and the application-oriented messages thus obtained are passed to the application layer. Here, they are forwarded to the appropriate application processes.
However, if the PPM detects a contravention of the predefined coding rules or deviation from the predefined syntax during the transfer and subsequent decoding of a PPDU, then the PPDU concerned is flagged as invalid. In this case, the specified standards stipulate that a termination report should be displayed at the application layer, and the association should be shut down by sending a so-called ARP-PPDU (abnormal release provider PPDU) to the PPM on the partner platform. In this context, it is of no importance to the presentation layer whether the deviation from coding rules or syntax in the PPDU relates to the parameters required for processing within the presentation layer, or only concerns user data (data in the application layer); e.g., payload data in CMISE commands. Consequently, even if an attribute of the user data in a single application-layer operation is “incompatible” with the coding protocol, this will result in the whole association being terminated. In particular, this connection termination includes the termination of other CMIS application processes running over this association, loss of the messages and acknowledgments being transferred over the association, and delay in the transmission of further operations, since a new association has to be established for this purpose. The reason for the connection termination, and in particular the original operation on the Q3 interface
Bell Boyd & Lloyd
Tu Christine T.
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