WO1998002992A1

WO1998002992A1 - A secure signalling protocol emulator system

Info

Publication number: WO1998002992A1
Application number: PCT/SE1997/001008
Authority: WO
Inventors: Kim Laraqui
Original assignee: Telia Ab
Priority date: 1996-07-15
Filing date: 1997-06-10
Publication date: 1998-01-22
Also published as: SE515055C2; SE9602774D0; SE9602774L

Abstract

The invention provides a secure signalling protocol emulator system for an integrated services digital network including a plurality of customer premises equipments for users of the network, a user network interface, a user-to-network-interface signalling protocol, and a network management protocol, characterised in that said system includes a protocol emulator overlaying said management protocol (e.g. SNMP), said emulator being adapted to transform signalling frames (e.g. UNI signalling frames) generated by a customer premises equipment into management protocol operations. The protocol emulator is preferably interposed between the signalling protocol (e.g. a Q931/Q2931 protocol) and the management protocol.

Description

A SECURE SIGNALLING PROTOCOL EMULATOR SYSTEM

The invention relates to a secure signalling protocol emulator system (SSPES) for an integrated services digital network (ISDN/BISDN), nn TSDN/BISDN including a S5PF. , nnri a method for secure signalling protocol emulation on a management protocol, such as SNMP.

The signalling protocol emulator on SNMP consists of a small layer between a Q931/Q2931 protocol, which is used for ISDN (Integrated Services Digital Network), or BISDN (Broadband ISDN) , user-to-network-interface signalling, and SNMP. The signalling protocol emulator system (SPES) facilitates the deployment of a very economical protocol stack for exchange of signalling messages between users of ISDN/BISDN services and an operator providing such services. With SPES, the operator who provides the ISDN/BISDN service may implement a secure exchange of signalling information without deploying the standard and very complex signalling protocols that would otherwise be required. A secure signalling protocol emulator system (SSPES) can be deployed as a means to implement TINA connection management and a much more robust DAVIC/DSM-CC user-network configuration and session management.

It is generally understood that a management protocol is inherently slower than a signalling protocol. The basis of this understanding is that signalling protocols are typically given higher processing priority than network management protocols. From a structural point of view, processing a SNMPv2 (SNMP version 2) protocol data unit (PDU) is much simpler and thus faster than processing a Q2931 signalling frame. Furthermore, as IP, which is the traditional technology across which management messages are exchanged, evolves towards being able to provide real-time services, SNMP could be guaranteed delay and delivery qualities .

Current solutions for control of resources across an ISDN/BISDN user network interface (UNI) require the deployment of numerous protocols and suites on customer premises equipment (CPE) as well as on equipment in local exchanges. The main problem with protocols is that they contribute largely to the complexity inflation of networks, i.e. the protocols:

consume resources on platforms, including scarce user terminal memory by requiring a special set of protocols, for example, SSCOP and MTP3;

require special purpose OAM (Operations, Administration, and Maintenance) support to work properly; and

- require a substantial set of business support systems in order to keep track of which signalling protocol is being deployed and where it is being deployed, for example, software distribution and change management tools.

Thus, before deploying protocols, an operator should give consideration to, and compare the merits of, the available protocol architectures. In particular, the protocols required to be installed, by an operator, on local telephone exchanges and, by subscribers, on their CPEs (Customer Premises Equipments), should be compared against one another from a functional perspective.

Current trends in UNI protocol configurations can be summarized as follows:

Internet SNMP will normally be supplied with all

_ _ HUBs, Routers, and bridges.

all CPEs with BISDN UNIs will be equipped with SNMP, partly because this is required by the Asynchronous Transfer Mode (ATM) Interim Local Management Interface (ILMI) mechanisms. Among many things, ILMI allows an ATM UNI CPE to register to a local telephone exchange. For example, an operator, such as Telia, will have to deploy ILMI on all its UNIs for configuration management of CPEs attaching to the TCS (Telia

City Services) .

signalling will offer standard means for CPEs and an operator, such as Telia, to interact over BISDN.

In view of the trends, referred to above, an operator could obtain distinct benefit from a solution in which signalling protocols can be deployed without adding to the already complex protocol configurations that yield from BISDN/ATM and from services such as Local Area Network (LAN) emulation, Video-On-Demand etc.

Furthermore, it is considered that the future offers little space for special purpose protocol stacks. Instead, it is highly likely that future systems will thrive on cooperation in utilization of common protocol stacks, security mechanisms and management solutions. This trend is evident from projects such as TINA-C, DSM-CC, DAVIC, CORBA (Common Object Request Broker Architecture), DCE (Data Circuit Terminating Equipment) and so on.

It is also considered that the systems solution which is the subject of the present invention, will enable a smooth transition from pure signalling protocols to real- time object-oriented network management protocols, i.e. in line with TINA. However, whereas TINA departs frorr a totally uncorroborated approach for call management, the secure signalling protocol emulator system (SSPES) of the present invention will enable modelling to be effected on he basis of ATM Forum UNI 3 and <_ .

The present invention provides a secure signalling protocol emulator system for an integrated services digital network including a plurality of customer premises equipments for users of the network, a user network interface, a user-to-network-interface signalling protocol, and a network management protocol, characterised in that said system includes a protocol emulator overlaying said management protocol, said emulator being adapted to transform signalling frames generated by a customer premises equipment into management protocol operations.

The protocol emulator may be interposed between said signalling protocol and said management protocol. The management protocol may be SNMP and the signalling protocol ma be a Q931/Q2931 protocol.

The protocol emulator may be adapted to transform UNI signalling frames, for example, UNI Q931/Q2931 signalling frames, into SNMP operations.

The protocol emulator may be adapted to transform IINI signalling frames into SNMP operations.

In a preferred system, the management protocol m v p

SNMP, and the protocol emulator may be adapted to transtoim

UNI signalling into SNMP operations, said transformation yielding at least one table for each type of signalling message frame and at least one table for IEs. The said at least one frame-table may be for a connect message, or an alert message, or any other message.

The said at least one IE-table and the said at least one frame-table may be related by means of internal indexes.

Each element of the said at least one IE-table may be indexed using an index number identical to a call reference value of a frame, frames relating to the same call being indexed by the same inder value.

The said at least one frame-table may be indexed by means of at least a call reference value, or by means of a call reference, a protocol discriminator, and an nid I _> IE-tables, which index may be used to index individual rows of said IE-tables that pertain to the message type of a particular call.

The said at least one frame-table may optionally include a further field to enable explicit commitment of a signalling message so that individual fields of the message can be written asynchronously.

Thus, according to the present invention, a secure signalling protocol emulator system is provided for

ISDN/BISDN, including a plurality of CPEs for users of the network, a user network interface, a Q931/Q2931 signalling protocol for user-to-network-interface signalling, and SNMP, characterised in that said system includes a protocol emulator overlaying SNMP, said emulator being interposed between said Q931/Q2931 signalling protocol and SNMP, and adapted to transform signalling frames generated by a CPE into SNMP operations. The protocol emulator may be adapted to transform UNI Q931/Q2931 signalling frames, or NNI signalling frames, into SNMP operations. In the case of UNI

Q931/Q2931 signalling frame transformation into SNMP operations, the transformation yields at least one frame- table for each type of signalling message frame and at least one IE-table for IEs, in which said at least one frame-table is for a connect message, or an alert message, in which said at least one IE-table and said at least one frame-table are related by means of internal indexes, in which each element of said at least one IE-table is indexed using an index number identical to a call reference value of a frame, frames relating to the same call being indexed by the same index value, and in which said at least one frame-table is indexed by means of at least a call reference, a protocol discriminator, and an index to IE-tables.

The invention further provides an integrated services digital network including a plurality of customer premises equipments for users of the network, a user network interface, a user-to-network-interface signalling protocol, a network management protocol, and a secure signalling protocol emulator system as claimed in any one of the preceding claims. The network may be a broadband network.

The invention further provides, in an integrated services digital network including a plurality of customer premises equipments for users of the network, a user network interface, a user-to-network-interface signalling protocol, a network management protocol, a method for signalling protocol emulation on a management protocol using a secure signalling protocol emulator, characterised in that said method includes the step of transforming signalling frames, generated by a customer premises equipment, into management protocol operations using said protocol emulator.

The signal frame transformation step of the present invention may be effected by a protocol emulator interposed between said signalling protocol and said management protocol . The management protocol may be SNMP, and the signalling protocol may be a Q931/Q2931 protocol.

The signal frame transformation step of the present invention may be used to transform UNI signalling frames, such as, UNI Q931/Q2931 signalling frames, into SNMP operations .

Also, the signal frame transformation step of the present invention may be used to transform NNI signalling frames into SNMP operations.

In accordance with the method of the present invention, the management protocol may be SNMP, and the signal frame transformation may effect the transformation of UNI signalling into SNMP operations, said transformation yielding at least one table for each type of signalling message frame and at least one table for IEs. The said at least one frame-table may be for a connect message, or an alert message, or any other message. The said at least one IE-table and the said at least one frame-table may be related by means of internal indexes.

The method may include the steps of indexing each element of said at least one IE-table using an index number identical to a call reference value of a frame, and assigning the same index value to frames relating to the same call.

The method may include the step of indexing said at least one frame-table by means of at least a call reference value .

The method may include the step of indexing said at least one frame-table by means of a call reference, a protocol discriminator, and an index to IE-tables. The index to IE-tables may be used to index individual rows of said IE-tables that pertain to the message type of a particular call.

The method may nclude the step of indexing said at least one frame-table to include a further field to enable explicit commitment of a signalling message so that individual fields of the message can be written asynchronously.

When the signalling message frame is a CONNECT Message Frame (CMF) including a Bearer Capability IE, the method of the present invention may include the steps of:

making an entry m an IE-table;

converting the CMF into a set of objective identifiers (OJds) and values;

- sending the entire set of Olds and values, in the form of a list, in an SNMP SetRequest;

a network SNMP sending, in response to said SNMP SetRequest, a confirmation, after which, a user signalling protocol emulator issues a commit request by setting a variable in a frame-table.

The foregoing and other features of the present invention will be better understood from the following description with reference to the accompanying drawings, in which :

Figure 1 illustrates a secure signalling protocol emulator for SNMP (Simple Network Management Protocol), according to the present invention; and Figure 2 illustrates mapping between ISDN/BISDN frames to SNMP SMI.

To facilitate an understanding of the present invention, a glossary of the abbreviations used in this patent specification are set out below:

ATM: Asynchronous Transfer Mode

BISDN: Broadband ISDN

CCS: Common Channel Signalling

CORBA: Common Object Request Broker Architecture

CPE: Customer Premises Equipment

DAVIC:

DCE: Data Circuit Terminating Equipment

DSM-CC:

HUB:

IE: Information Elements

ILMI: Interim Local Management Interface

IP: Internet Protocol

ISDN: Integrated Services Digital Network

LAN: Local Area Network

MIB: Management Information Base MTP3: Message Transfer Part 3 of CCS

NICs: Network Interface Cards

NNI: Network Node Interface

OAM: Operations, Administration and Maintenance

Olds: Object Identifiers

PDU: Protocol Data Unit

Q931/

Q2931: A signalling p otocol

SCCP: Signalling Connection and Control Part

SNMP: Simple Networi: Management Protocol (Internet)

SNMPv2: SNMP version 2

SMI:

SPES: Signalling Protocol Emulator System

SS7: ITU Signalling System No. 7

SSCOP: Service Specific Connection Oriented Protocol

SSPES: Secure Signalling Protocol Emulator System

TCS: Telia City Service

TINA: Telecommunication Information Network Architecture T INA-C :

TLV :

UDP: User Datagram Protocol (Internet)

UNI: User Networi: Interface

It will be seen from subsequent description that the secure signalling protocol emulator system, of the present invention, can be stacked as follows:

use of management protocols and an overlaying emulator to transform signalling frames into SNMP operations.

use of SNMP and an overlaying emulator to transform UNI signalling frames into SNMP operations .

use of management protocols and an overlaying emulator to transform UNI Q2931/931 signalling frames into SNMP operations.

use of SNMP and an overlaying emulator to transform NNI signalling frames into SNMP operations .

- use of SNMP and an overlaying emulator to transform UNI signalling frames into SNMP operations - this transformation yields one, or several, tables per signalling frame and one, or several, tables for lEs; the IE-tables and frame- tables being related by means of internal indexes.

use of SNMP and an overlaying emulator to transform UNI signalling frames into SNMP operations - this transformation yields one, or several, tables per signalling frame and one, or several, tables for IEs; the IE-tables and frame- tables being related by means of internal indexes

- the frame-tables being indexed by means of the call reference value and possibly other sub- indexes .

Thus, it will be seen from subsequent description, and the accompanying drawings, that a SSPES, according to the present invention, for ISDN/BISDN, includes a plurality of CPEs for ISDN/BISDN users, a user network interface, a user- to-network-interface signalling protocol, a network management protocol, and a protocol emulator overlaying the management protocol, which is adapted to transform signalling frames generated by a CPE into management protocol operations. It will also be seen that the signalling protocol emulator is, in practice, interposed between a signalling protocol, i.e. a Q931/Q2931 protocol, and said management protocol, i.e. SNMP. The manner in which SNMP secure table manipulation is effected is also outlined .

The system solution, of the present invention, for SPES signalling across ISDN/BISDN UNI, is illustrated in Figure 1 of the accompanying drawings. It should, however, be noted that the same principles can be applied for signalling across NNI.

As illustrated in Figure 1, the system is in two parts, namely, a user domain and an operator domain. Thus, a Q931/Q2931 protocol entity is provided on each side of the ISDN/BISDN User Network Interface (UNI), i.e. the Q931/Q2931 protocol entity 1 is provided on the user side, and the Q931/Q2931 protocol entity 2 is provided on the operator side. An NNI-signalling unit 3 is associated with the Q931/Q2931 protocol entity 2.

The SPES systems solution allows the protocol entity to either work as before, i.e. the SPES is totally transparent to Q931/Q2931, or directly against SNMP. It should be noted that the first alternative enables SPES to interwork with a traditional Q2931 solution, i.e. an operator, such as Telia, could use SPES on its side of the UNI and still inter- operate with an AT&T UNI.

In operation, whenever a signalling message frame, for example, a CONNECT Message Frame, is generated, it is normally passed to a transport/network mechanism specifically designed for signalling, for example, SSCOP (Service Specific Connection Orientated Protocol), or SCCP (Signalling Connection and Control Part)/MTP3 (Message Transfer Part 3 of Common Channel Signalling (CCS)). The signalling message frame consists of a static part oi various fields and a dynamic part which is referred to as IEs (Information Elements).

With the SPES system solution, a signalling message frame is sent, as illustrated in Figure 1, on the user side, from Q931/Q2931 protocol entity 1 to SPES 4 and, on the operator side, from Q931/Q2931 protocol entity 2 to SPES 5.

The SPESs 4 and 5 respectively convert respective signalling message frames into a SNMP table manipulation command for the SNMPs 6 and 7 which are respectively connected to UDP

(User datagram Protocol ( Internet )) /IP (Internet Protocol)

8 and 9. The conversion requires a mapping from ISDN/BISDN frames to SNMP tables and vice-versa. A technique for such a mapping is illustrated in Figure 2 of the accompanying drawings.

It will be seen from Figure 2 of the drawings that a Q2931 signalling message frame 10 is connected to a SPES 11. There is one type of table for each type of signalling message frame, for example, one table for connect messages and one table for alert messages.

Alternatively, a more flexible method can be applied for emulation of signalling message frames in one single table for IEs (Information Elements). With this arrangement, elements of the table are indexed by means of an index number which is identical to the call reference value of the frame. In other words, signalling message frames belonging to the same call will be indexed by the same index value. As illustrated in Figure 2, each frame table 12 will contain an index (= Call reference) , a protocol discriminator, an index to IE-tables, i.e. a nested index that will be used to link the related frame with further information found in IE-tables, and an optional field to enable explicit commitment of a signalling message so that its individual fields can be written asynchronously.

In essence, the index to IE-tables is used to index individual rows of IE-tables pertaining to the message type of a particular call.

For instance, if a CONNECT Frame consists of, among other things, a Bearer Capability IE, then an entry will be created in the IE-table. It is not material to the present invention whether there is one single IE-table, with a different structure according to the TLV-method of specifying entries in a SNMP-table, or one table per IE- type .

When a signalling message frame has been converted to a set of object identifiers (Olds) and values, the entire list of Olds/Values is sent in one SNMP SetRequest. The opposite SNMP entity will later respond with a confirmation after which the initiating SPES may issue a commit request by setting a variable in the frame table 12.

It will be seen from the foregoing that, when the signalling message frame is a CONNECT Message Frame (CMF) including a Bearer Capability IE, the method of the present invention includes the steps of making an entry in an IE- table; converting the CMF into a set of objective identifiers (Olds) and values; sending the entire set of Olds and values, in the form of a list, in an SNMP SetRequest; a networi: SNMP sending, in response to said SNMP SetRequest, a confirmation, after which, a user signalling protocol emulator issues a commit request by setting a variable in a frame-table.

It should be noted that since the SPES interaction is transformed into a traditional NNI signalling message exchange. NNI exchanges will eventually lead to UNI signalling between a local exchange and the called CPE. Thus, the use of SNMP on a UNI will be transparent to those operators that operate their UNI according to a standardised method.

Most signalling protocols are supplied as software modules, i.e. as part of NIC (Network Interface Cards) drivers, over various physical media. It would, therefore, be possible for an operator to license SPES and cooperate with a software developer to port the software modules to the SPES interface instead of the NICs UNI signalling protocols. Operations, administration and maintenance (OAM) will be greatly simplified for UNI CPE and local exchanges employing the present invention.

It will be directly evident to persons skilled in the art that the secure signalling protocol emulator system

(SSPES) of the present invention, which utilises signalling message exchanges by means of SNMP, is a unique and novel arrangement. In particular, SSPES eliminates the need to use an entire protocol stack which has traditionally been regarded as absolutely necessary for signalling netwuil.s. In addition, the present invention reuses network management protocols to implement the communication facilities for signalling message exchanges.

The SNMP-based solution is also new in its approach to offer an asynchronous object-oriented interface to UNI- signalling applications. For example, a Q2931 entity on one side of the UNI may issue incomplete signalling messages to the other side and later complement those messages with additional IE before committing the entire message to the peer SPES entity.

Claims

1. A secure signalling protocol emulator system for an integrated services digital network, including a plurality of customer premises equipments for users of the network, a user network interface, a user-to-network-interface signalling protocol, and a network management protocol, characterised in that said system includes a protocol emulator overlaying said management protocol, said emulator being adapted to transform signalling frames generated by a customer premises equipment into management protocol operations .

2. A system as claimed in claim 1, characterised in that said protocol emulator is interposed between said signalling protocol and said management protocol.

3. A system as claimed in claim 1, or claim 2, characterised in that said management protocol is SNMP.

4. A system as claimed in claim 2, or claim 3, characterised in that said signalling protocol is a Q931/Q2931 protocol.

5. A system as claimed in claim 3, or claim 4, characterised in that said protocol emulator is adapted to transform UNI signalling frames into SNMP operations.

6. A system as claimed in any one of the preceding claims, characterised in that said protocol emulator is adapted to transform UNI Q931/Q2931 signalling frames into SNMP operations .

7. A system as claimed in claim 3, characterised in that said protocol emulator is adapted to transform NNI signalling frames into SNMP operations.

8. A system as claimed in any of claims 3 to 6, characterised in that said management protocol is SNMP, and in that said protocol emulator is adapted to transform UNI signalling into SNMP operations, said transformation yielding at least one frame-table for each type of signalling message frame and at least one IE-table for IEs.

9. A system as claimed in claim 8, characterised in that said at least one frame-table is for a connect message, or an alert message.

10. A system as claimed in claim 8, or claim 9, characterised in that said at least one IE-table and said at least one frame-table are related by means of internal indexes .

11. A system as claimed in any of claims 8 to 10, characterised in that each element of said at least one IE- table is indexed using an index number identical to a call reference value of a frame, frames relating to the same call being indexed by the same index value.

12. A system as claimed in any one of claims 8 to 11, characterised in that said at least one frame-table is indexed by means of at least a call reference value.

13. A system as claimed in claims 12, characterised in that said at least one frame-table is indexed by means of a call reference, a protocol discriminator, and an index to IE- tables.

14. A system as claimed in claims 13, characterised in that said index to IE-tables indexes individual rows of said IE- tables pertaining to the message type of a particular call.

15. A system as claimed in any of claims 12 to 14, characterised in that said at least one frame-table includes a further field to enable explicit commitment of a signalling message so that individual fields of the message can be written asynchronously.

16. An integrated services digital network including a plurality of customer premises equipments for users of the network, a user network interface, a user-to-network- interface signalling protocol, a network management protocol, and a secure signalling protocol emulator system as claimed in any one of the preceding claims.

17. A network as claimed in claim 16, characterised in that said network is a broadband network.

18. In an integrated services digital network including a plurality of customer premises equipments for users of the network, a user network interface, a user-to-network- interface signalling protocol, a network management protocol, a method for signalling protocol emulation on a management protocol using a secure signalling protocol emulator, characterised in that said method includes the step of transforming signalling frames, generated by a customer premises equipment, into management protocol operations using said protocol emulator.

19. A method as claimed in claim 18, characterised in that- said signal frame transformation is effected by a protocol emulator interposed between said signalling protocol and said management protocol.

20. A method as claimed in claim 18, or claim 19, characterised in that said management protocol is SNMP.

21. A method as claimed in claim 19, or claim 20, characterised in that said signalling protocol is a

- 1! Q931/Q2931 protocol.

22. A method as claimed in claim 20, or claim 21, characterised in that said signal frame transformation transforms UNI signalling frames into SNMP operations.

23. A method as claimed in claim 18, or claim 19, characterised in that said signal frame transformation transforms UNI Q931/Q2931 signalling frames into SNMP operations .

24. A method as claimed in claim 20, characterised in that said signal frame transformation transforms NNI signalling frames into SNMP operations.

25. A method as claimed in any of claims 20 to 23, characterised in that said managernent protocol is SNMP, and in that said signal frame transformation transforms UNI signalling into SNMP operations, said transformation yielding at least one frame-table for each type of signalling message frame and at least one IE-table for IEs.

26. A method as claimed in claim 25, characterised in that said at least one frame-table is for a connect message, or an alert message.

27. A method as claimed in claim 25, or claim 26, characterised in that said at least one IE-table and said at least one frame-table are related by means of internal indexes .

28. A method as claimed in any of claims 25 to 27, characterised by the steps of:

indexing each element of said at least one IE- table using an index number identical to a call reference value of a frame; and

assigning the same index value to frames relating to the same call.

29. A method as claimed in any one of claims 25 to 28, characterised by the step of indexing said at least one frame-table by means of at least a call reference value.

30. A method as claimed in claims 29, characterised by the step of indexing said at least one frame-table by means of a call reference, a protocol discriminator, and an index to IE-tables.

31. A method as claimed in claims 30, characterised in that said index to IE-tables indexes individual rows of said IE- tables pertaining to the message type of a particular call.

32. A method as claimed in any of claims 28 to 30, characterised by the step of indexing said at least one frame-table to include a further field to enable explicit commitment of a signalling message so that individual fields of the message can be written asynchronously.

33. A method as claimed in any of claims 27 to 32, characterised in that, when the signalling message frame is a CONNECT Message Frame (CMF) including a Bearer Capability IE, said method includes the steps of:

making an entry in an IE-table;

converting the CMF into a set of objective identifiers (Olds) and values;

sending the entire set of Olds and values, in the form of a list, in an SNMP SetRequest; a network SNMP sending, in response to said SNMP SetRequest, a confirmation, after which, a user signalling protocol emulator issues a commit request by setting a variable in a frame-table.

34. A secure signalling protocol emulator system for ISDN/BISDN, including a plurality of CPEs for users of the network, a user network interface, a Q931/Q2931 signalling protocol for user-to-network-interface signalling, and SNMP, characterised in that said system includes a protocol emulator overlaying SNMP, said emulator being interposed between said Q931/Q2931 signalling protocol and SNMP, and adapted to transform signalling frames generated by a CPE into SNMP operations.

35. A system as claimed in claim 34, characterised in that said protocol emulator is adapted to transform UNI

Q931/Q2931 signalling frames, or NNI signalling frames, into SNMP operations.

36. A system as claimed in claim 35, characterised in that said protocol emulator is adapted to transform UNI Q931/Q2931 signalling frames into SNMP operations, in that said transformation yields at least one frame-table for each type of signalling message frame and at least one IE-table for IEs, in that said at least one frame-table is for a connect message, or an alert message, in that said at least one IE-table and said at least one frame-table are related by means of internal indexes, in that each element of said at least one IE-table is indexed using an index number identical to a call reference value of a frame, frames relating to the same call being indexed by the same index value, and in that said at least one frame-table is indexed by means of at least a call reference, a protocol discriminator, and an index to IE-tables.

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