EP1730988A1

EP1730988A1 - Method for providing functionality of an exchange termination unit and a line termination unit in a communication network

Info

Publication number: EP1730988A1
Application number: EP05707647A
Authority: EP
Inventors: Wieland Roeser
Original assignee: Siemens AG; Nokia Siemens Networks GmbH and Co KG
Current assignee: Nokia Solutions and Networks GmbH and Co KG
Priority date: 2004-03-27
Filing date: 2005-02-26
Publication date: 2006-12-13
Also published as: WO2005096662A1; CN1939084A; US20070223485A1; DE102004015157A1

Abstract

The invention relates to a method and communication network enabling a primary rate access digital section (DS), e.g. ISDN PRI's, to be monitored while maintaining existing OAM mechanisms in an NGN environment. According to the invention, a communication network and a method for the provision of functionality of an exchange termination unit (ET) and a line termination unit (LT) in a communication network (NW) are provided, comprising at least one time-multiplex oriented partial network (ISDN) on the subscriber side and at least one packet-oriented partial network (NGN) on the transport side, wherein a gateway (AGW) and a media gateway controller (GWC) or an SIP server are arranged at the transport-side end of the time-multiplex oriented partial network (ISDN), and the functionalities of the exchange termination unit (ET) and the line termination unit (LT) are implemented in the gateway (AGW) and/or media gateway controller (GWC) or SIP server. .

Description

description

Method for providing the functionality of an exchange termination unit and a line termination unit in a communication network

The invention relates to a method for providing the functionality of an exchange termination unit and a line termination unit in a communication network. The invention further relates to a communication network for exchanging information, which transmits the information on the subscriber side via at least one time-division-oriented subnetwork and on the transport side via at least one packet-oriented subnetwork.

The information includes, for example, numerical data or voice data. The time division multiplex-oriented communication network is, for example, an ISDN data transmission network (Integrated Services Digital Network). In the time-multiplex-oriented communication network, the data are transmitted in different time slots according to a time-division multiplex method. A packet-oriented communication network is a network in which the information or data is transmitted in data packets. The packet-oriented communication network is, for example, a communication network that works according to the Internet protocol. Another example of a packet-oriented communication network is an ATM network (Asynchronous Transfer Mode), in which the data packets are referred to as cells.

Functions for the operation, administration and maintenance in the time-multiplex-oriented communication network have been specified, for example, in the following standards of the ETSI (European Telecommunications Standards Institute) and ITU-T (International Telecommunication Union - Telecommunications Standardization Sector): ETSI ETS 300 233, Integrated Services Digital Network (ISDN); Access Digital Section for ISDN Primary Rate, May 1994, ITU T G.962, Digital Sections and Digital Line Systems; Access Digital Section for ISDN Primary Rate at 2048 kbit / s, 03/93, ETSI ETS 300 011, Integrated Services Digital Network (ISDN); Primary Rate User-Network Interface Layer 1 Specification and Test Principles, April 1992.

For example, the functions for operation, administration and maintenance relate to switching test loops or error monitoring. These functionalities can generally be summarized under the term OAM mechanisms. OAM stands for the organization, administration and management of the communication network with a so-called Telecommunications Management Network (TMN), which includes, for example for ISDN, an Operations System (OS) that accesses the Q3 interface according to CCITT recommendation M.30 ,

In the time-multiplex-oriented network, these functions are used for the ISDN primary rate access digital section (DS), i.e. for the digital message transmission link between a reference point T and a primary rate connection V3 (T) designed as a reference point. Between the subscriber terminal and the subscriber-side network termination unit ( NT: Network Termination Unit) and V3 lies between the physical line termination (LT: Line Termination unit) and the logical switching termination (ET: Exchange Termination unit), through the Exchange Termination Unit in an interplay of participants Network termination unit and transport-side line termination unit monitored (see also CCITT recommendation Q.542 and "Peter Bocker: ISDN - The integrated service digital communications network, 3rd edition, 1990, Springer-Verlag, Heidelberg, page 149 to 151 ^w with references to CCITT-E recommendations Q.511 and Q.512).

The interaction of time-multiplex-oriented communication networks and packet-oriented communication networks creates new problems, however, because such OAM tasks (organization, administration and management) have to be distributed between the two types of communication networks depending on the arrangement of the interface.

For a case in which the digital ISDN connection section DS is replaced by an ATM network and the advantages of the AAL2 (ATM Forum) are used, a simple method for transmitting information within at least one is known from the European patent application EP 1 374 629 AI time-multiplex-oriented communication network via at least one packet-oriented communication network, wherein functions for the operation, administration or maintenance of the time-multiplex-oriented communication network in the time-multiplexing-oriented communication network can still be used by emulating these functions in the packet-oriented network. With this method, at least part of the information is transmitted via the packet-oriented communication network. At least some of the functions for operation, administration and maintenance are emulated by the packet-oriented communication network, i.e. simulated. In this way, the functions defined for the time-multiplex-oriented communication network can continue to be used essentially without restrictions.

Conversely, in VoIP networks or in general the so-called new generation networks (NGN with convergence of voice and data), so-called ISDN PRI interfaces (interfaces with ISDN rimary rate interface) are required for which the OAM mechanisms from the time-division-oriented techno logic should also be provided in such a package-oriented technology. In this way, the OAM mechanisms, as described in the corresponding standards (G.962, ETS 300 233, ITU-T 1.411, 1.412, Q.152), could be adopted, which has an advantageous effect on the reusability of already used equipment and the reusability of known OAM processes would impact.

The present invention is therefore based on the object of specifying a method and a communication network with which a “primary rate access. Digital Section "(DS), such as the ISDN PRI's, can be monitored in an NGN environment while maintaining the existing OAM mechanisms.

With regard to the method according to the invention, this above object is achieved by a method for providing the functionality of an exchange termination unit and a line termination unit in a communication network, which comprises at least one time-multiplex-oriented subnetwork on the subscriber side and at least one packet-oriented subnetwork on the transport side a gateway and a media gateway controller or a SIP server is arranged at the transport end of the time-division-oriented subnetwork, the functionality of the exchange termination unit and the line termination unit being arranged in the gateway and / or in the media gateway controller or in the SIP server can be implemented.

With regard to the communication network, the object mentioned above is achieved according to the invention in that a communication network is provided for exchanging information, which transmits the information on the subscriber side via at least one time-division-oriented subnetwork and on the transport side via at least one packet-oriented sub-network, with a gateway at the end of the time-division multiplex-oriented subnetwork on the transport side and a media Gateway controller or a SIP server are arranged, the functionality of an exchange termination unit and a line termination unit being implemented in the gateway and / or em media gateway controller or in the SIP server.

In this way, the functionality of the logical switching termination (Exchange Termination Unit) and this physical line termination (Line Termination-Ein? Fceit) is implemented in the gateway and / or the Media Gateway Controller or the SIP server, whereby Despite the existing packet-oriented network with regard to the OAM mechanisms, there are no changes compared to the OAM mechanisms used in previous time-division-oriented networks.

The gateway and / or the media gateway controller or the SIP server is thus equipped with the corresponding time-multiplex-oriented functional logic units (OAM funct ion and corresponding state machine), so that in the implemented exchange termination unit and the implemented line termination unit Functions for c Betrieben operation and / or for administration and / or for maintenance in the time-division-oriented subnetwork for the transmission of information within the entire, ie time-division-oriented subnetwork and packet-oriented subnetwork are realized.

In an advantageous embodiment of the invention, the functionality of the exchange termination unit in the media gateway controller (a so-called soft switch) and the functionality of the line termination unit in the gateway can be implemented, so that the exchange of signals between the gate-way and media gateway controller according to the gateway control protocol. Corresponding extensions for H.248

(MEGACO), MGCP by defining new packages are possible. For SIP-controlled gateways (SIP: Session Initiated Proto— koll), implementation is also possible by expanding the SIP standard by specifying a new standardization proposal (RFC: Reguest for Comments). For SIP this means that on the one hand the functionalities of the line termination and the exchange termination can be arranged in the gateway or on the other hand the functionality of the line termination in the gateway and the functionality of the exchange termination can be arranged in the SIP server.

In a further development of the present invention, the packet-oriented communication network can be implemented in accordance with the Internet protocol or in accordance with ATM or in accordance with the SIP specification.

An ISDN network can be used for the time-multiplex-oriented communication network, which is still very important in terms of its distribution. Accordingly, the functions for operation, administration and maintenance can essentially be provided in accordance with the ETSI ETS 300 011 standard and / or the ITU-T G.962 standard and / or the ETSI ETS 300 233 standard, so that a comparatively simple and rapid implementation is made possible because the implementation uses known and already established mechanisms.

Further advantageous embodiments of the invention can be found in the remaining subclaims.

Exemplary embodiments of the invention are explained below with reference to the accompanying drawings. In it show:

1 shows an ISDN primary multiplex interface model with a processing of a time slot TS0 according to the standard ETSI ETS 300 233 according to the prior art, FIG. 2 shows a schematic illustration of a first packet-oriented communication network with ISDN primary rate access connections,

FIG. 3 shows a schematic illustration of a second packet-oriented communication network with ISDN primary rate access connections, and

Figure 4 is a schematic representation of a pronounced ATM-heavy communication network.

In the following, an overview of the application of the ISDN primary multiplex interface in the world of classic time division multiplex (TDM - Time Division Multiplex) is given. It also specifies requirements that must be met when parts of the digital access section (DS) of the primary multiplex connection are replaced by an ATM network. Procedures are also specified that meet these requirements. SDN primary multiplex interface model (PRI) with operation and maintenance functions (for a 2048 kbps signal / El)

FIG. 1 shows a digital connection section DS (access digital section) with its limitations and the processing of the time slot TS0.

The operating and maintenance functions support methods and information elements which are required for controlling the digital connection section by a logical switching center ET or a service network server (service node).

A Sa5, a Saβ, an E and an A bit of a time slot TS0 are relevant for display and control. The bit structure of the time slot TSO and the multi-time frame structure are defined in accordance with the ITU-T G.704 standard. The A bit becomes the alarm status information between the service node and a customer telephone device TE (customer telephony end equipment) used. Only the A bit needs to be monitored and is transmitted transparently. All other control bits of the time slot TSO are to be transmitted transparently. In addition, FIG. 1 shows the elements of the digital connection section DS that use CRC methods 4, 6 (Cyclic Redundancy Check). The CRC-4 methods 4, 6 are implemented and used between the switching center ET and a network termination unit NT1 and between the network termination unit NTl and the customer telephone device TE. This is also known as option two according to the ITU-T G.962 standard.

Figure 1 also shows a line termination unit LT. There is a V3 reference point (the so-called primary rate connection) between the line termination unit LT and the exchange ET. There is a T reference point between the customer telephone device TE and the network termination unit NT1. The following table shows the signals that are exchanged between the T reference point and the digital connection section DS under the normal operating conditions and faults specified in the ETS 300 011 standard:

The signals exchanged between the digital connection section DS and the switching center ET are defined in the following table:

(only for a 2048 kbps system)

The following additional signals are required to indicate fault conditions that occur with respect to the digital connection section DS:

Name List of signals

Normal time frames These are time frames without error displays or test loop requests generated by the switching center ET or the customer telephone device TE, an A bit with the value one or zero not being relevant for the digital connection section DS.

Time frames These are time frames which, in addition to the normal time frames in the Sa6 bits, contain error display signals which have been generated in the network termination unit NT1 and have been transmitted to the switching center ET. Alternatively, the Sa6 bits can contain test loop requests that have been transmitted from the switching center ET to the digital connection section DS. In this case, the Sa5 bit is also used to indicate the direction and to display the test loop. The Sa5 bit in the transmission direction from the digital connection section DS to the exchange ET is set in the network termination unit NT1 or in the line termination unit LT and transmitted to the exchange ET according to the following rules: - Sa5 = 1 test loop 2 not activated, - Sa5 = 0 test loop 2 activated.

CRC-4 process The CRC procedure is used to protect against defective frames (framing) and error performance monitoring. This includes the multi-time frame procedures that are defined in the ITU-T G.704 standard.

Operation and maintenance of the digital connection section

The digital connection section DS provides the means for transmitting display elements and. for recording fault cases at the T reference point intersections and at the V3 reference point interface and to support test procedures. According to the ETSI ETS 300 233 standard, the following functions are supported by the exchange ET in the interaction of network termination NT1 and line termination LT:

Test loops Test loop 1 (loopback), transparent test loop in the line termination device LT or in the exchange-side network gateway unit CO-IWF, test loop 2, transparent test loop in the network termination unit NT1 or in the customer-side network gateway unit CP-IWF, - errors within the digital Connection section DS Loss of the signal (LOS) or loss of frame alignment (LFA) on the line side of the network termination unit NTl or the customer-side gateway function CP-IWF (in the to the network termination unit NTl or the customer-side network transition unit CP-IWF from the line termination unit LT or yours exchange-side network gateway unit CO-IWF incoming signal, also called downstream signal), Loss of signal (LOS) on the line side of the line termination unit LT or the exchange-side network transition unit CO-IWF, operating voltage failure in the network termination unit NT1 or in the customer's network transition unit CP-IWF, AIS (alarm indication signal) on the line side of the network termination unit NTl or the customer's network transition unit CP-IWF, the AIS being generated in the network and forwarded transparently by the line termination unit LT or the switching center-side network transition unit CO-IWF, at the V3 reference point - signal loss (LOS), at the T reference point Signal loss (LOS) or loss of frame alignment (LFA), operating voltage failure (if relevant) - Error performance monitoring (fault performance monitoring) detected faulty CRC blocks on the line side of the network termination unit NT1 or the customer's network transition unit CP-IWF, - faulty CRC blocks at the T reference point of the Net z-termination unit NTl or the customer's network transition unit CP-IWF detected, CRC error message received from the customer telephone device TE in the E-bit, - faulty CRC blocks recorded at the T reference point of the network termination unit NTl or the customer's network transition unit CP-IWF and simultaneously Receiving CRC error information from the customer telephone device TE.

These entire OAM mechanisms are initially no longer available if the transport-side (switching center-side ge) transmission is replaced by a packet-oriented communication network, eg H.248 or Ethernet GigE or 2xFE or ATM. However, they are again available in a first arrangement according to FIG. 2, in which the line termination LT and the exchange termination ET are implemented in an access gateway AGW. In this way, the functions of line termination LT and. of the transaction conclusion ET in the Access Gateway AGW. In detail, these are exactly the test loops, error cases and error performance monitoring specified in the previous section. This means that the functional elements of the contractor (the digital access link) can also be monitored, for example to provide throughput information (transmission performance accor- ding to G.821). Furthermore, the maintenance communication devices can be integrated as a telecommunications management network (T-MN) via relevant interfaces, such as the Q3 interface or an interface that supports S? NMP (Simple Network Management Protocol) (TCP / IP), so that the Control and monitoring mechanisms to control the data received from the. Grinding, evaluating performance, error messages and initiating appropriate measures. For this, the implementation of the state machine of the exchange conclusion ET according to table A.1 / G.962 is necessary.

A second inventive arrangement is shown in Figure 3 schematically ^', which differs from the first arrangement is that the functionality of the exchange termination ET in the media gateway controller is implemented GWC advantage. In this way, the Media Gateway Controller GWC, equipped with the functionality of the Exchange Termination ET, can control all the Access Gateways AGW it controls with the full OAM functionality of the time-division-oriented network used, which is therefore also necessary for the time-division-oriented subnetwork to achieve the above monitor the benefits mentioned. So here is the SLDM (Subscriber Line Management Digital) in the media gateway Controller GWC relocated. In the case of the SIP network, the Media Gateway Controller GWC would be replaced by a SIP server and the functionality of the exchange termination would be implemented accordingly in the SIP server.

FIG. 4 shows a schematic overview of a possible embodiment for a communication network NW, which comprises a time-oriented subnetwork ISDN, which uses ISDN access interfaces ISDN-PRI (primary rate interface) at a gateway AGW for a packet-oriented subnetwork NGN are coupled. The packet-oriented subnetwork includes transmission methods according to ITU-T standard H.248 (Media Gateway Control Protocol), Ethernet (GigE or 2xFE) and ATM (STM-l / OC-3: 155 Mbps; STM-4 / OC- 12622 Mbps, E3 / DS-3: European Signal Level 3 / Digital Signal Level 3). In addition to the ISDN access interface parts ISDN-PRI, the actual intended access interfaces for broadband access (BB access) and the packet-oriented through-signaling of the information to a packet-oriented subscriber-side network termination device IAD (IAD: Integrated Access Device) are provided at the gateway AGW. In addition, a management system EMK is provided which, due to the implementation of the LT and ET functionality in the access gateway AGW described above, carries out the conventional OAM mechanisms customary for the time-division-oriented subnetwork ISDN.

Claims

claims

1. Method for providing the functionality of an exchange termination unit (ET) and a line termination unit (LT) in a communication network (2Sf), which comprises at least one time-division-oriented subnetwork (ISDN) on the subscriber side and at least one packet-oriented subnetwork (NGN) on the transport side , with a gateway (AGW) and a media gateway controller at the transport-side end of the time-division-oriented subnetwork (ISDN)

(GWC) is arranged, the functionality of the Exchange Termination Unit (ET) and the Line Termination Unit (LT) being implemented in the Gateway (AGW) and / or in the Media Gateway Controller (GWC).

2. Method for providing the functionality of an exchange termination unit (ET) and a line termination unit (LT) in a communication network (NW), which comprises at least one time-division-oriented subnetwork (ISDN) on the subscriber side and at least one packet-oriented subnetwork (NGN) on the transport side , a gateway (AGW) and a SIP server being arranged at the transport-side end of the time-division-oriented subnetwork (ISDN), the functionality of the Exchange Termination Unit (ET) and the Line Termination Unit (LT) in the gateway ( AGW) and / or implemented in the SIP server

3. The method according to claim 1 or 2, characterized in that in the exchange termination unit (ET) and the line termination unit (LT) functions (OAM) for operation and / or for administration and / or for maintenance in the time-multiplex-oriented communication network (ISDN) for the transmission of information within the time-multiplex-oriented communication network (ISDN).

4. The method according to claim 1, characterized in that the functionality of the Exchange Termination Unit (ET) is implemented in the Media Gateway Controller (GWC) and the functionality of the Line Termination Unit (LT) in the Access Gateway (AGW).

5. The method according to any one of the preceding claims, characterized in that the packet-oriented communication network (NGN) is implemented in accordance with the Internet Protocol (IP) and / or SIP and / or ATM.

6. The method according to any one of the preceding claims, characterized in that the time-division-oriented subnetwork (ISDN) is an ISDN network or a number of ISDN SS.

7. The method according to any one of the preceding claims, characterized in that the functions (OAM) for the operation, administration and maintenance essentially according to the standard ETSI ETS 300 011 and / or according to the standard ITU-T G.962 and / or according to Standard ETSI ETS 300 233 can be provided.

8. Communication network (NW) for exchanging information, which transmits the information on the subscriber side via at least one time-division-oriented subnetwork (ISDN) and on the transport side via at least one packet-oriented subnetwork (NGN), with a gateway (AGW) at the end of the time-division multiplex-oriented subnetwork (ISDN) on the transport side. and a media gateway controller (GWC) are arranged, the functionality of an exchange termination unit (ET) and a line termination unit (LT) being implemented in the gateway (AGW) and / or the media gateway controller (GWC) is.

9. Communication network (? NW) for exchanging information, which transmits the information on the subscriber side via at least one time-division-oriented subnetwork (ISDN) and on the transport side via at least one packet-oriented subnetwork (NGN), with a gateway at the end of the time-division multiplex-oriented subnetwork (ISDN) on the transport side (AGW) and a SIP server are arranged, the functionality of an exchange termination unit (ET) and a line termination unit (LT) being implemented in the gateway (AGW) and / or the SIP server.