KR20020004402A - Interworking method between narrow band network and atm network - Google Patents

Abstract

PURPOSE: A method for interworking between a narrow band network and an asynchronous transfer mode network is provided to interwork a narrow band network with an asynchronous transfer mode network. CONSTITUTION: An SSMM of a PIU finds out the ATM address of the PIU, a destination, using a called party number in a SS7 setup message(1). The PIU transmits a call proceeding message to a PBX of a narrow band network in consideration of the time for setting a VCC(2). The PIU sets a signal channel and then sets a VCC for 64Kbps data channel with respect to the corresponding signal by using the set signal channel(3). After setting VCCS for transmitting a call of the PBX in the narrow band network, the PIU transfers a PSTN setup message to the destination PIU through the signal channel(4).

Description

Interworking method between narrowband network and asynchronous transmission mode network {INTERWORKING METHOD BETWEEN NARROW BAND NETWORK AND ATM NETWORK}

The present invention relates to a switching system, and more particularly, to a method for interworking between a narrowband network and an Asynchronous Transfer Mode (ATM) network.

PDH (Pleosychronous Digital Hierarchy) interfaces supported by Asynchronous Transfer Mode (ATM) switches include T1 (1.544 Mbps), E1 (2.048 Mbps), and T3 (44.576 Mbps). The interfaces are used in multiplexed Nx64 Kbps within the digital hierarchy (i.e., channelized), or in an unchannelized way of transmitting framed data occupying all of the bandwidth. The T1 and T3 interfaces use both channelized and unchannelized methods, while E1 uses only unchannelized methods.

1 is an example of a network configuration for transmitting data from the ATM network to the PDH interface. Referring to FIG. 1, in the ATM network 2, network elements (NEs) 4 and 6, which are nodes serving as switching roles, exist. Each of the NEs 4 and 6 of the ATM network 2 is connected to the Public Switched Telephone Network (PSTN) 8 and 12 and the Private Branched eXchange (PBX) 10 and 14 through the T1 interface of the PDH interface. Each of the NEs 4 and 6 of the ATM network 2 is provided with a PIH Interface Unit (PIU) 16 for a PDH interface. As shown in FIG. 1, the protocol stack of the PIU 16 includes a physical layer (PHYsical) PHY, a channel associated signaling (CAS), an ATM adaptation layer 1 (A.1) layer, and a permanent virtual connection module (PVC). ) Contains the hierarchy. The Public Switched Telephone Network (PSTN) 8 and 12 and the Private Branched eXchange (PBX) 10 and 14 of FIG. 1 are physical layer (PHY) PHY, channel associated signaling (CAS) and ATM Adaptation Layer 1 (AAL1). Contains the hierarchy. AAL1 is disclosed in ITU-T (International Telecommunications Union-Telecommunications standardization sector) I.363.1 with the title "B-ISDN ATM Adaptation Layer specification: Type 1 AAL". Services provided by the PIU 16 of FIG. 1 through the PDH interface include voice, voice band, and voice band data (modem and fax). These services are provided using the ABR1 constant bit rate (CBR) method defined by ITU-T.

The PDH data transmission method in the ATM network 2 will be described with reference to FIG. 1 as an example. For example, digital frames from the PSTN 8 (24 channel streams of 64 Kbps in the case of T1), ie PDH frame data, are converted into ATM cells by the NE 4 and the ATM cell data is converted via PVC trunks. The other NE of the ATM network 2 is transmitted to, for example, the NE 6. ATM cell data transmitted through the PVC trunk is converted into frame data channelized by the NE 6 and then transmitted to the PSTN 12. The above transmission method forms ATM PVC (Permanent Virtual Connection) according to the bandwidth pre-allocated for each channel by the subscriber's request within the limits of the bandwidths (T1, E1, T3) allowed by each PDH interface and the virtual accordingly. The PDH data transformed into cells through a virtual path is transmitted on the ATM network 2.

At this time, the NE 4 of the ATM network 2 only plays a role of transparently relaying the received PDH data without any consideration of the PDH data coming from the PSTN 8 (for example, SS7 signal data). . And the PIU 16 of the NE 4 only performs the function of monitoring the A / B signaling bits of the incoming T1 trunk.

However, the PDH transmission method as described above has the following disadvantages.

(1) The existing PIU 16 transmits and receives user data based on AAL1, but this has a disadvantage of occupying more bandwidth than necessary on the backbone trunk.

(2) From the service provider's point of view, the PVC trunking method has a limited number of subscribers per hour in a limited backbone band, so that each call can allocate bandwidth through door-to-door signaling and connect or disconnect lines to increase subscriber capacity. There is a need to accommodate scalable SVC services.

(3) The existing call setup method only supports the function of transparently transmitting signals of PSTN and Packet Switched Public Data Network (PSPDN) through PVC trunking through NMS (Network Management System), but with PSTN and PSPDN Switched Virtual Connection (SVC) must be established for interworking. To this end, it is desirable to implement a module capable of interworking with a signaling system number 7 (SS7) signaling network.

Accordingly, an object of the present invention is to provide a method for interworking a narrowband network with an ATM network.

Another object of the present invention is to provide a method for enabling network interworking and service interworking between PSTN, PSPDN and ATM networks.

In accordance with the above object, the present invention provides a method for interworking between a narrowband network and an asynchronous transmission mode network, the function for interworking between the narrowband network signaling protocol stack and the asynchronous transmission mode network signaling protocol stack. And the source narrowband network interface and the destination narrowing by using a function for interworking with the destination information included in the request when configuring the narrowband network and requesting the setup of the narrowband network. Setting a signaling virtual channel between a band network interface, setting a corresponding user data virtual channel using the set signaling channel, and after the virtual channels are formed, the source narrowband network interface and the destination narrowband. Signaling between network interfaces Virtual bandwidth setup mesh through virtual channel It is characterized by consisting of a process for delivering the destination to the destination narrowband network interface.

1 is an example of a network configuration for transmitting data from the ATM network to the PDH interface,

2 is a block diagram illustrating a network interworking communication scenario according to an embodiment of the present invention;

3 is a detailed block diagram illustrating a narrowband network, a PIU, and an ATM network of FIG. 2;

4 is a diagram showing a PIU protocol reference model for SS7 according to an embodiment of the present invention;

5 is a view showing an interworking structure between software of the PIU and AIU according to an embodiment of the present invention;

6 shows a protocol when no VCC is formed;

7 illustrates a protocol in a state where a VCC is formed.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be noted that the same elements in the figures are represented by the same numerals wherever possible. In addition, detailed descriptions of well-known functions and configurations that may unnecessarily obscure the subject matter of the present invention will be omitted.

The existing transmission method simply played a role of transmitting PVC data and signals by configuring PVC trunking in ATM network. Accordingly, in the embodiment of the present invention, by supporting SS7 in an ATM network, various services provided by PSTN and PSPDN can be provided to ATM subscribers for each subscriber. For SVC of PSTN and PSPDN, a software function block capable of interworking with SS7 is required. In the embodiment of the present invention, an SSCM (SS7 Call Control Manager) block to implement an interworking function between the user part of SS7 and ISUP and PNNI is implemented. do. In addition, the present invention implements a more advanced scheme for interworking a narrowband network (voice network) such as a PSTN network with an ATM network. In other words, in the embodiment of the present invention, the ATM network supports SS7 so that the door-to-door signaling transmitted from the narrowband network, that is, the PSTN and PSPDN, can be handled by the ATM network, thereby eventually interworking between the PSTN, PSPDN network and the ATM network. And service interworking. In addition, it improves bandwidth efficiency in ATM network by implementing ATM SVC for each subscriber.

2 is a diagram illustrating a network interworking communication scenario according to an embodiment of the present invention. The ATM-related terminal equipment (TE) 24 is connected to the ATM network 22, and the narrow-band network-related TE 23 is connected to the narrow-band network 20. The narrowband network 20 includes a PSTN, a PSPDN, a PBX, and the like. PIU boards 16 are provided between the ATM network 22 and the narrowband network 20. As shown in FIG. 2, the network interworking communication scenario includes (1) a path, that is, a narrowband network-related TE 23, a narrowband network 20, a PIU (PDH Interface Unit) board 26, and an ATM network 22. ), The network interworking scenarios to and from the ATM network-related TE 24 and vice versa, and (2) the path, i.e., the narrow-band network-related TE 23, the narrow-band network 20, the PIU 26, and the ATM network. (22), there is a linkage scenario to the PIU 26, the narrow-band network TE (23).

In an embodiment of the present invention, the network interworking communication scenario of the path (2) of the network interworking communication scenario is implemented. Each of the PIUs 26 of FIG. 2 may be present in plurality (eg, six) in each of the NEs 4 and 6 of FIG. 1.

3 is a detailed block diagram of the narrowband network 30, the PIU 26, and the ATM network 22 of FIG. In FIG. 3, the PIU 26 is connected to the ATM network 22 through an ATM Interface Unit (AIU) 30. The ATM Interface Unit (AIU) 30 is a device that is responsible for signaling and routing to the ATM network 22, and various processes including a Private Network (Node) to Network Interface (PNNI) are driven. The virtual channel connection (VCC) manager 32 in the AIU 30 manages the ATM VCC. A switching system unit (SSU) 40 is provided between the PIU 26 and the AIU 30 to perform switching.

The PIU 40 of FIG. 3 performs the following functions.

Signaling termination: SS7 signaling termination for interworking SS7 with ATM PNNI protocols.

Call processing function: A function for translating and routing a call by translating messages such as call setup / disconnection from NE connected to narrowband network 20, for example, PBXs 50A and B.

Multiplexing: multiplex multiple channels from narrowband network 20 to transmit to ATM network 22 or vice versa.

Channel Mapping: Ability to map 64Kbps channels to ATM Virtual Channel Connection (VCC).

In order to perform this function, the PIU 26 has an SS7 Call Control Manager (SSCM) 42, a framer (FR) 44A, B, an AAL1, 5 / SAR function 46A, B, and a routing tag attached. Routing tag attach unit (RT) 48A, 48B is included. SSCM 42 performs operations related to signaling termination function and call processing function, and related to FR (44A, B), AAL1, 2, 5 / SAR function (46A, B), and RT (48A, 48B). ). The FRs 44A and B perform a function of extracting data for each channel from the corresponding PDH interface. The data output from the FRs 44A and B are divided into signal messages and user data and are applied to the AAL1, 5 / SAR function units 46A and B. The AAL1, 5 / SAR function units 46A, B perform the AAL1, AAL2, and AAL5 functions, the segmentation and reassembly (SAR) function, the channel mapping, and the multiplexing function. The AAL5 function is provided for ATM signaling. The RTs 48A and 48B perform a function of tagging the cell data so that the cell data output from the AAL1, 5 / SAR function units 46A and B can be routed through the SSU 34.

The PIU 26 of FIG. 3 supports several signaling functions according to an embodiment of the present invention, which includes signaling for a narrowband interface, signaling between two PIUs 26 (FIG. 3). PIU-PIU SS7 signaling), signaling between PIU 26 and ATM network 22 (network management (NM) signaling for ATM signaling / provisioning, as shown in FIG. 3). There is a function.

Among these signaling functions, signaling for narrowband interface includes SS7 and channel association signaling (CAS). In the present invention, SS7 signaling uses an integrated service digital network user part (ISP) defined in ITU-T Q.762,764. ITU-T G.704, on the other hand, defines the frame structure including CAS signal bits in the T1 and E1 interfaces. Since the PIU 26 does not define the translation of the CAS signal bits in the standard, in the embodiment of the present invention, the PIU 26 does not terminate the ATM network when a frame including the CAS signal bits is received in the CAS mode. Make it transparent.

In addition, signaling between two PIUs 26 (PIU-PIU SS7 signaling) among the signaling functions will be described in detail below, and protocols used include SS7 (Q.762, Q764) and PNNI signaling (ATM Forum). af-pnni-0055.000). In addition, among the signaling functions, protocols used for signaling between PIU 26 and ATM network 22, that is, ATM signaling, SS7 (Q.762, Q764) and PNNI signaling (ATM Forum af-pnni-0055.000) are also used. have.

The PIU 26 according to an embodiment of the present invention supports an SS7 signaling function for interworking with a narrowband network 20 such as a PSTN network, and provides an interworking function with a PNNI for signal processing to an ATM network 22. Perform.

4 is a diagram illustrating a protocol reference model of the PIU 26 to support the SS7 signaling function according to an embodiment of the present invention, and FIG. 5 is a diagram illustrating a connection between the PIU 26 and the AIU 30 according to an embodiment of the present invention. It is a diagram showing an interworking structure between softwares.

First, referring to the reference model of the PIU 26 of FIG. 4, it may be easier to understand the interworking relationship between the ATM network 22 and the narrowband network 20. In FIG. 4, a stack connected to a narrowband interface includes a physical layer (PHY) 60, a message transfer part level 2 layer (MTP2) 62, a message transfer part level 3 layer (MTP3) 64, and an integrated service (ISP). Digital Network User Part layer (66), and SSCM (SS7 Call Control Manager) 42. On the PHY 60, MTP2 62, MTP3 64, and ISUP 66 are layered in this order. In FIG. 4, a stack connected to an ATM interface includes a PHY 68, an ATM layer 70, an ATM adaptation layer 1 (AAL1) 72, an ATMAdaptation Layer 5 (AAL5) 74, and a mapping function. ) Layer 76, and Inter Process Communication layer (IPC) 78. ATM 70 on PHY 68, AAL1 72 and AAL5 74 on ATM 70, mapping function layer 76 on AAL1 72, IPC 78 on AAL5 74 Is stratified. PHY (60), MPT2 (62), MTP3 (64), ISUP (66), SSCM (42), Mapping Function Layer (76), IPC (78), AAL1 (72), AAL5 (74), ATM (70) ), The function of the layer of the PHY 68 is preferably implemented in the AAL1,5 / SAR function 46A, B of FIG. The AAL5 74 is provided for ATM signaling. AAL1 72 of FIG. 4 will be replaceable with AAL2 later. AAL2 delivers a service data unit (SDU) at a variable bit rate, and transfers time information between an information source and a destination. It also displays error recovery and unrecovered errors. The basic function of the AAL2 protocol is consistent with AAL, and improved services provided by the ATM layer to support the functions required by the upper layer. However, AAL2 includes features to support higher layer requirements that were not possible or considered in AAL1. That is, AAL2 can support both Variable Bit Rate (VBR) and Constant Bit Rate (CBR) in ATM networks.

In FIG. 4, the paths of the PHY 60, the mapping function layer 76, the AAL1 72, the AAL5 74, the ATM 70, and the PHY 68 are set to Nx64Kpbs user data according to an embodiment of the present invention. It is the path forwarded, and is based on PHY 60, MPT2 62, MTP3 64, ISUP 66, SSCM 42, IPC 78, AAL5 74, ATM 70, PHY 68 The path is a path for transmitting an SS7 signaling message of 64 Kbps according to an embodiment of the present invention.

Next, the interworking structure between the software between the PIU 26 and the AIU 30 according to an embodiment of the present invention will be described with reference to FIG. 5. FIG. 5 is a diagram for explaining an interworking function of a PIU 26 having a reference model as shown in FIG. 4 with a PNNI for signal processing to an ATM network 22.

In FIG. 5, the specific configuration in the PIU 26 is the same as that shown in FIG. 4. In addition, the configuration of the AIU 30 in charge of signaling and routing to the ATM network 22 in FIG. 5 includes a PNNI call control block 80, a Q.93b layer 82, a Q.SAAL 84, and a common part. (common part) AAL5 (86), ATM (88), PHY (90), PNNI route manager (92), IPC channel (94). The software configuration of the AIU 30 is a known technique except for the PNNI call control block 80, and thus detailed descriptions of the specific configurations of the AIU 30 are omitted.

As shown in FIG. 5, in the embodiment of the present invention, the ISUP to Q.93b interworking is performed between the SSCM 42 of the PIU 26 and the PNNI call control block 80 of the AIU 30. ). In an embodiment of the present invention, the ISUP to Q.93b interworking between the SSCM 42 and the PNNI call control block 80 is responsible for the basic call processing function. In more detail, basic signal messages related to call establishment and release through the interworking are transferred from SSCM 42 of PIU 26 to PNNI call control block 80 of AIU 30, and AIU 30. The PNNI call control block 80 of the PNNI signal is reconstructed into a PNNI signal and transmitted to the ATM network 22. At present, there is no standard specification for interworking between ISUP and PNNI. However, the PNNI Generic Application Transport ver 1.0 standard (ATM Forum af-cs-0126.00), which can send ISUP information elements to PNNI basic messages, is defined. It provides some extensibility, although it supports only a few messages and information arguments related to the establishment and termination of calls among ISUP's 49 messages. Therefore, in the present invention, ISUP to Q.93b interworking between the SSCM 42 and the PNNI call control block 80 is made possible using the provisions of the PNNI Generic Application Transport version 1.0 standard (ATM Forum af-cs-0126.00). Enable call processing.

The basic signal messages related to the establishment and release of the call include a request for forming a separate signal channel of the ATM network 22 between two PIUs according to an embodiment of the present invention. A separate virtual channel is formed between the two PIUs through the PNNI signal. The channel of the PIU-PIU SS7 signaling shown in FIG. 3 is the separate virtual channel. The separate virtual channel is a PHY (60), MPT2 (62), MTP3 (64), ISUP (66), SSCM (42), IPC (78), AAL5 in the PIU (26) of FIGS. 74, the ATM 70, and the PHY 68 are routed. The separate virtual channel may be formed of one of a permanent virtual channel (PVC) and a switch virtual channel (SVC). A signaling channel for transmitting a signaling message of Nx64kbps channels, that is, a PIU-PIU SS7 signaling channel, between two PIUs is sufficient with one ATM virtual channel connection (VCC) between the corresponding PIUs.

Meanwhile, in order to distinguish the call for the circuit connection on the narrowband network 20 side, the SSCM 42 or the network management device (not shown) of the PIU 26 is referred to as a Virtual Circuit Connection Identifier. VCCI ", which is included in basic signal messages related to the establishment and release of the call together with the CID (Circuit Identifier) of the narrowband network 20. Is passed to.

In FIG. 5, the SSCM 42 receives a basic call related message from the ISUP 66, converts it into a PNNI signaling message, and delivers the message to the AIU 30. In addition, the PNNI signaling message transmitted by the AIU 30 is converted into a narrowband ISUP signal message and serves to deliver to the narrowband network 20. For ISUP to Q.93b interworking between SSCM 42 and PNNI call control block 80, SSCM 42 performs functions such as ISUP message mapping and information factor conversion, routing information request, storage, and trunking management. The call related message is converted into a PNNI signaling message and transmitted to the AIU 30.

6 is a diagram illustrating a protocol when no VCC is formed. Referring to FIG. 6, when the VCC is not formed, an operation of transmitting the PSTN setup message by the PIU 26 according to an embodiment of the present invention will be described below.

The SSCM 42 of the PIU 26 finds the ATM address of the destination PIU using the Called Party number in the SS7 ISUP setup message. If there is no VCC configured for signaling between the PIU and the PIU, the PIU 26 sets up the VCC for ATM PNNI signaling. At this time, SSCM 42 terminates the setup message of ISUP and transmits the message mapping to setup message of PNNI to AIU 30, and PNNI call control block 80 of AIU 30 sends a separate signal channel with this message. Set it.

② Meanwhile, the PIU 26 transmits a call proceeding message to the PBX side of the narrowband network 20 in consideration of the time for setting the VCC.

③ The PIU 26 sets the separate signal channel and then sets the VCC for the 64 Kbps data channel for the corresponding signal using the set signal channel. At this time, the signal-to-data channel is recognized by information such as a circuit identifier (CID), VPI / VCI, calling party number (Calling Party Number, Called Party Number) and ATM number of each PIU in the PSTN.

(4) After the VCCs for delivering the call of the PBX in the narrowband network 20 are established, the PIU 26 delivers the PSTN setup message to the destination PIU through separate signal channels set between the PIUs.

Next, an operation of transmitting a PSTN setup message in a state where VCCs are formed will be described with reference to FIG. 7. 7 is a diagram illustrating a protocol in a state where a VCC is formed.

① With the called party number in ISUP setting message of SS7, PIU finds the destination PIU address through AIN's PNNI routing block and delivers messages through separate signal channels formed between PIUs.

In the above description of the present invention, specific embodiments have been described, but various modifications may be made without departing from the scope of the present invention. Therefore, the scope of the present invention should not be defined by the described embodiments, but should be determined by the equivalent of claims and claims.

As described above, the present invention implements the SS7 function for interworking with the existing PSTN network in the PDH interface board, and implements the interworking function with the PNNI for signal processing to the ATM network. Through this, the present invention can not only transmit voice calls of existing PSTN subscribers at high speed through ATM network but also use SVC, and thus can accommodate more circuits by reducing bandwidth. In addition, by using PNNI's soft PVC instead of the fixed path PVC method, the replacement capacity of the line error can be improved. In other words, different paths can be selected in case of line failure and error, thereby ensuring stability.

Claims (2)

In the method for interworking between a narrowband network and an asynchronous transmission mode network, Configuring a function for interworking between the narrowband network signaling protocol stack and the asynchronous transmission mode network signaling protocol stack corresponding to each of the narrowband network interface and the asynchronous transmission mode interface; Setting a signaling virtual channel between a source narrowband network interface and a destination narrowband network interface by using the destination information included in the request and a function for interworking when a narrowband network setup request is made; Setting a corresponding user data virtual channel using the set signaling channel; And after the virtual channels are formed, transmitting a narrowband network setup message to the destination narrowband network interface through a virtual channel between virtual channels between the source narrowband network interface and the destination narrowband network interface. Way. The narrowband network signaling interface of claim 1, wherein the narrowband network signaling interface requires narrowband network message mapping, information factor conversion, and routing information request for interworking between the narrowband network signaling protocol stack and the asynchronous transmission mode network signaling protocol stack. Method for performing a function including, storage, trunking management.