KR0129560B1 - Atm system - Google Patents

Abstract

Disclosed is a switching system of an asynchronous transfer mode type. The switching system comprises a plurality of grouped line portion(1) which supports an user network interface matching protocol recommended at CCITT in order to junction with the user and a network node interface matching protocol for matching with the network and provides a both way ports by embedding a self rooting switch module of NxN, a switch network which is thoroughly manual as an interconnector that exchanges the information between the grouped line portions, and a distribution portion(3) which embeds a processor for managing, maintaining and repairing.

Description

Asynchronous Transfer Mode (ATM) Switching System

1 is a block diagram of an ATM switching system according to the present invention.

2 is a detailed block diagram of the collection end.

3 is a block diagram of a header conversion table and routing information.

4 is a diagram illustrating a basic operation process when setting up a call.

* Explanation of symbols for main parts of the drawings

1: collection group 2: distribution stage

3: maintenance processor 11: subscriber matching unit

12: relay line matching unit 13: switch network

14: internal matching unit 15: signal processor

16: call processing processor

The present invention relates to an asynchronous transfer mode (ATM) switching system that forms a path for transferring user information in a broadband integrated telecommunication network (B-ISDN).

Domestic communication network is divided into general public telephone network (PSTN) for exchanging voice signals and packet switched data network (PSDN) for data information transfer. Recently, however, the N-ISDN, which aggregates and provides various services, has been internationally recommended by the International Telegraph and Telephone Advisory Committee (CCITT) and has been put into practical use. Narrowband Telecommunication Networks provide voice and data services centered around 64Kbps, but as information technology evolves rapidly, dozens faster than 64Kbps such as high-quality voice, high resolution video, large file transfers, and communications between local area networks (LANs). There is a demand for various service communication demanding the bandwidth of Mbps, and therefore, the narrowband integrated telecommunication network must be developed into a broadband integrated telecommunication network.

The International Telegraph and Telephone Advisory Committee (CCITT) adopted the Asynchronous Transfer Mode (ATM) method, which divides and transmits all information into cells of a certain size as the basic method of the transmission system. There are no technologies related to the construction of the exchange system. Accordingly, an object of the present invention is to flexibly provide a high-speed, broadband communication means using the asynchronous transfer mode (ATM) method recommended by the International Telegraph and Telephone Advisory Committee (CCITT), and the user can freely use various services. The present invention aims to provide a large-capacity asynchronous delivery mode switching system that can accommodate thousands of B-ISDN subscribers.

In order to achieve the above object, the present invention, in the asynchronous transfer mode (ATM) switching system, the user network interface (UNI; User Network Interface) recommended by the International Telegraph and Telephone Advisory Committee (CCITT) for matching with the user Supports NNI (Newtork Node Interface) protocol for matching protocol and network, and includes NxN's self-routing switch module to provide multiple (N) bidirectional ports and 1: 1 to maximum ( At least one collection end having a collection ratio in the range N-2): 1; And a pure interconnector without a call processing process for exchanging information between the concentrators, and a general switch network and system for performing self-routing according to routing information and control information in a cell header. Built-in operation maintenance processor to perform a distribution step for distributing the call setup function to the collection end.

Hereinafter, with reference to the accompanying drawings will be described an embodiment according to the present invention;

1 is a configuration diagram of an asynchronous delivery mode switching system according to the present invention, in which 1 represents a collection stage, 2 a distribution stage, and 3 a maintenance processor.

As shown in the figure, the present invention is composed of k collection groups and 1 distribution group, and the collection group 1 includes a UNI protocol and a network recommended by the International Telecommunication Advisory Committee (CCITT) for registration with users. The NNI protocol is supported for matching. In addition, the aggregation stage (1) has a built-in NxN magnetic routing switch module to provide N 155.52Mbps bidirectional ports, of which uses n ports for the user side and m ports for the distribution side. It performs the function of a concentrator having a concentrating ratio of (nm, N = n + m).

Therefore, the collecting ratio of the collecting end 1 can be used in the range of 1: 1 to the maximum (N-2): 1.

The distribution stage 2 is a purely interconnector without a call processing process exchanging information between the aggregation stages and is a thoroughly passive switch network. Therefore, the distribution stage is a self-routing switch based on routing information in the cell header, and the bandwidth of the internal link between the collection stage and the distribution stage is distributedly managed in each collection stage 1.

Therefore, the connection establishment of the switching network in the distribution stage is made in pure hardware without any separate processing for connection routing establishment control. This means that there is no need for a separate processor for the control of the existing centrally located switching network for all call connection establishment. Therefore, the ATM switching system according to the present invention has no centralized functions for call and connection establishment. It is possible to set up a call and connection in a fully distributed manner (see FIGS. 4 and 7 for a call and connection setup in a fully distributed manner).

The switch network size of the distribution stage 2 is N'xN '(N' = mxk, where k is the total number of aggregation stages) when m ports are connected from the collection stage 1 to the distribution stage 2 side. .

As mentioned above, the path selection of the information delivery is determined by the calling coordinator housed by the originating subscriber and the called coordinator housed by the called party (see step b and step c in FIG. 4), and within the distribution stage 2 Virtual Channel Identifiers (VCIs) are not converted. Further, considering that the distribution stage 2 is a passive switch network, the switching path in the distribution stage 2 is a single path.

Operation and Maintenance Processor (OMP) (OMP) located in the distribution stage 2 is connected to one port of the distribution stage 2 to restart and control the system related to the operation, maintenance and management at the system level. It performs subscriber management function and system resource management function such as function, test, various traffic information, statistics and billing function, subscriber registration, cancellation, and subscriber attribute change.

2 is a detailed block diagram of the converging stage 1, in which 11 is a subscriber matching unit, 12 is a relay line matching unit, 13 is a switching network, 14 is an internal matching unit, 15 is a signal processor, and 16 is a call processing processor. .

The aggregation end 1 largely matches the switching network 13 for providing a route, the controllers 15 and 16 for controlling call processing in the aggregation end 1, and the subscriber line / module and the distribution end 2. It consists of matching parts 11, 12, and 14.

Switching network 13 is a unidirectional NxN magnetic routing switch that switches input cells to corresponding output ports according to routing information in the header of the cell without any control, and provides m multiple paths to improve traffic efficiency of the entire system. It is a single stage structure.

The aggregation switching network 13 has a structure in which the unidirectional N × N magnetic routing switch is folded as shown in FIG. 5 (N × N folded self routing switching network). Allocate n ports to the subscriber and m ports to the distribution. Then, one port is provided to the controller. The total number of ports of the aggregation switching network 13 is n + m + 1 = N. Therefore, it is possible to perform the aggregation function of n: m only by switching network configuration without additional additional concentrator, and can provide up to the maximum aggregation ratio (N-2): 1 when m = 1. In addition, since the aggregation switching network has a folded structure, when an internal call occurs within the assembly, the call and connection processing can be performed directly inside the assembly without passing through the distribution stage.

Communication between the controllers 3, 15 and 16 in the system and the controllers of the devices 11, 12 and 13 is performed through its own switch network without using a separate communication means. Is made in units of cells. The control entity of the system is largely divided into a processor and a controller embedded in hardware, and a communication method between all the processors (3, 15, 6) and the processor and a controller embedded in each hardware device (11, 12, 13). Is made up of routing information 17 consisting of 3 bits and 24 bits representing the type of cell information in the 8-bit control information area of the internal cell format 17. The cell information type bits (3 bits) are set as shown in FIG. 6 according to the type of the incoming control entity of the control and information message, and FIG. 6 is a configuration diagram of the cell information type bits. The third bit (bit 3) is reserved for future system expansion.

If the cell is a user information cell, the cell information type bits are set to 'X00', and all other cases indicate that the cell is a control and information message cell used in the system. First, if the cell information type bit is 'X11', it indicates that the cell destination of the control entity is a processor connected to the link switched by the routing information 17 regardless of the destination. If the cell information type bit is 'X01', it means that the destination of the cell is the aggregation end. In particular, it means that the cell is received by the controller connected to the link to which the cell is routed. If the cell information type bit is 'X10', it means that the destination of the cell is a distribution terminal. In particular, the cell information is transmitted to the controller connected to the route to which the cell is routed.

The address for internal message cell transmission between control entities consists of routing information and cell information type bits for a link of a switch network to which the control entity is physically connected. Some examples of path and address configurations for internal message transfer between control entities are:

Case 1) The control unit 15, 16 of the collecting end delivers an internal message to the maintenance processor of the distribution end.

Address for cell transmission: Calling group routing information + Distribution routing information + 'X11' (cell information type bit)

Case 2) The control unit (15, 16) of the aggregation end transfers the internal message to the switch network controller of the distribution end

Address for cell transmission: Calling group routing information + distribution routing information + 'X10' (cell information type bit)

Case 3) The control unit 15, 16 of the aggregation end transmits an internal message to the controller of the hardware devices 11, 12, 13 belonging to it.

Address for cell transmission: Calling group routing information + distribution routing information + 'X01' (cell information type bit)

Case 4) The switch network controller of the distribution stage delivers the internal message to the controller of the aggregation stage.

Address for cell transmission: distribution route routing information + destination cluster routing information + 'X11' (cell information type bit)

The main function of the control unit, which consists of the signal processor 15 and the call processing processor 16, performs call processing of subscribers accommodated to the other party through the switching network 13 without the use of a separate internal control bus. do. The main function of the call processing processor 16, together with the signal processor 15 which terminates the signal cell received from the subscriber or the network, extracts the signal information, is the control function for the call requested by the subscriber and the virtualization of the accepted call. Head transformation that assigns path identifier / virtual channel identifier (VPI / VCI) and adds routing information to input cell and changes new VPI / VCI value to send cell inputted to corresponding VPI / VCI to corresponding output port. Perform an update of the table.

In addition, the call processing processor 16 performs a traffic control function for the multiple paths in the collection stage, collects error information and billing information in the collection stage, and sends the same to the maintenance processor 3 located in the distribution stage 2. .

The call processing processor 16 communicates with the call processing processor of the called party's aggregation group where the called party is accommodated as well as the subscriber / relay line matching units 11 and 12 and the switching network 13 to set up the call / connection requested by the user. shall. In the present invention, the path for the internal communication uses its own ATM switch network as shown in FIGS. 2 and 3 as the internal communication network between each controller without using a communication network.

The main function of the matching unit of the aggregation stage 1 is to support UNI / NNI of the Synchronous Digital Hierarchy (SDH) frame structure and terminate the physical layer. According to the matching position, the matching unit may include a subscriber matching unit 11, which is an end device having a UNI protocol to perform subscriber matching with a STM-1 (Synchronous Transport Module-1) (155.52 Mbps) SDH transmission structure; There is a trunk line matching section 12, which is an end device having an NNI protocol to perform STM-4 (622.08 Mbps) matching with subscriber modules or trunk lines.

In addition, there is an internal matching unit 14 that performs matching between the aggregation end 1 and the distribution end 2, and all functions except for the cell header conversion-related functions are the same as the subscriber matching unit or the relay line matching unit. The main function performed by the matching unit is divided into a function of receiving a cell and a function of transmitting a cell.

The cell reception function converts the cell of the optical transmission signal input from the user into an electrical signal and extracts information data contained in the VC-4 (Virtural Container-4) of the STM-1 frame by a SIM-1 disassembler. A HEC (Header Error Control) procedure is used to perform cell synchronization and HEC algorithm error detection and correction, which determines a cell start point in a bit string. In addition, header conversion table for the addition of routing information and the conversion of a new virtual path identifier / virtual channel identifier (VPI / VCI) to allow the cell inputted from the user to self route to the corresponding output port through the magnetic routing switch. Update the information.

Other functions of the cell receiver of the matching unit include UPS (Usage Parameter Control), which monitors whether all established connections normally perform a predetermined protocol, and counts the number of transmitted cells to the distribution unit 2. It provides to the maintenance processor (OMP) 3 which processes the charging information located, and performs the cell alignment function in front of the magnetic routing switch, which is the switching network 13.

On the other hand, as a function of the matching unit in cell transmission, first change the internal cell structure to the external cell structure recommended by the International Telegraph and Telephone Advisory Committee (CCITT), and update the HEC area of the cell header according to the cell header change (new VPI / VCI). Do this.

In addition, the matching unit performs an STM-1 assembly function of filling an ATM cell in the VC-4 by an STM-1 assembler, and finally has a function of converting a cell of an electrical signal into an optical transmission signal. .

FIG. 3 adds routing information to the cell header so that the input cell can self-route to the output port of the magnetic routing switch by the routing information without additional control, and output virtual path identifier / virtual channel identifier when the input cell is output. Fig. 1 shows a procedure of converting an incoming / outgoing header to a VPI / VCI) and a cell header.

The internal cell format 17 converted by the subscriber matching unit 11 or 12 is composed of a basic 53 octet ATM cell of CCITT and additional information for routing and control in the system.

Additional information added to the input cell is obtained from the input header conversion table 18 of the calling party as a total of 32 bits (4 bytes). The configuration of the input header conversion table includes 8 bits of control information, 24 bits of routing information meaning switching information of each stage allocated to the originating / receiving aggregation end and the distribution end, respectively, and virtualization of the input cell header. It consists of 16 bits of Internal Virtual Channel Identifier (IVCI) information for converting the Path Identifier / Virtual Channel Identifier (VPI / VCI) into an internal virtual channel identifier within the exchange system. The control information of 8 bits of the cell additional information added by the input header conversion table includes 3 bits indicating the type of information contained in the cell, 1 bit for tagging indicating the cell violated by the UPC, and 1 bit indicating whether the cell is broadcast. It consists of the broadcast flag of the remaining three bits are used as spare bits. When the cell arrives at the destination aggregation terminal by the routing information, it is output from the output header conversion table 19 having its own internal virtual address (IVCI) to the virtual path identifier / virtual channel identifier (VPI / VCI) and the virtual path. After conversion into identifiers / virtual channel identifiers (VPIo, VCIo), cell additional information is removed and user information is transmitted in the cell format recommended by the International Telegraph and Telephone Advisory Committee (CCITT).

4 and 7 illustrate a call setup process and an internal control message flow in five steps on the layer structure of the ATM switching system having the configuration of FIG. 1 and the cell header conversion function of FIG. The operation at each stage is as follows.

Step a: Signaling virtual signal identifier (Signalling VCI) is allocated by meta signaling, the signal cell is separated from the matching unit, and the signal information of the subscriber is transmitted to the call processor 16 through the semi-permanent internal signal channel. do.

Step b: The call processor 16 of the originating aggregation group allocates an input virtual path identifier / virtual channel identifier (VPII / VCII) from the user and performs translation of the aggregation group (1) number from the called subscriber number contained in the subscriber signal information. Thereafter, among the m distribution terminal 2 access links accommodated by the user, the called party number is transmitted to the called party collecting group for link number and the called party number translation to satisfy the call requested by the user.

Step c: The call processor 16 and the signal processor 15 of the destination side aggregation end allocate the virtual path identifiers / virtual channel identifiers (VPIo, VCIo) output from the power station through the virtual channel identifier (SVCIN) for signaling in the network. Selects an optimal information transmission path (physical address of the switch) from among the accessible link numbers received from the originating aggregation end, and considers the status of the links accommodated at the destination side aggregation end, and the internal virtual identifier (IVCI) for the path. Set.

Step d: The call processor 16 of the called side aggregation end sends the physical address of the switch and the internal virtual channel identifier (IVPI) to the call processor 16 of the originating side aggregation.

Step e: The call processor 16 of the originating party inputs the physical address of the switch, the new internal virtual channel identifier (IVPI), and the control information for the cell provided from the called party to the input header conversion table 18. Let's do it. The call processing processor 16 of the called party's aggregation end inputs the output virtual path identifier / virtual channel identifiers (VPIo, VCIo) to the output header conversion table 19 addressing the internal virtual channel identifier (IVPI). Call setup is made between called subscribers.

After the call setup is made through the above five steps, when the user information cell having the input virtual path identifier / virtual channel identifiers (VPII, VCII) enters the calling matching unit, the input header conversion table 18 performs self routing. The physical address of the switch is added to the cell header and changed from the called party header translation table to the new output virtual path identifier / virtual channel identifier (VPIo, VCIo) and sent to the called party.

A comparison of the hardware scale of a typical conventional large switching system and the system of the present invention is shown in FIG. As shown in FIG. 8, the ATM switching system according to the present invention does not require a separate concentrator or a separate control system communication network, and has a fully distributed structure that does not require a centralized centralized processor for call and connection establishment at a distribution end. It is simpler, more economical in terms of system structure, and does not cause bottlenecks fundamentally, resulting in system reliability and performance improvement.

Accordingly, the present invention configured and operated as described above enables cell switching of a high-speed asynchronous delivery mode method recommended by the International Telegraph and Telephone Advisory Committee (CCITT), thus integrating various services requiring a rental bandwidth of several tens of Mbps. The system can be economically and efficiently provided to the user, and the entire configuration of the system is completely distributed, so it is excellent in scalability and reliability when increasing the capacity of the system. In addition, it can process functions such as link status and resource management for devices in module unit. Also, all processors can communicate with each other through the high-speed switching network in the system. By not using the bus, the reliability of control information transmission can be improved, and the processor There is an effect capable of reducing the amount of hardware for communication.

Claims (4)

In the Asynchronous Transfer Mode (ATM) switching system, the Network Node Interface (UNI) protocol recommended by the International Telegraph and Telephone Advisory Committee (CCITT) for matching with the user and the network node for matching with the network. Network Node Interface (NNI) protocol support, built-in NxN self-routing switch module provides multiple (N) bidirectional ports, ranging from 1: 1 to up to (N-2): 1 At least one collection end 1 having an anterior ratio; And a pure interconnector without a call processing process for exchanging information between the aggregation stages 1, which maintains a passive switch network and a system that perform self-routing according to control information and routing information in a cell header. And a distribution stage (2) for distributing call setting functions to the collection stage (1) by incorporating an operation maintenance parameter processor (3) for performing a maintenance function. The method of claim 1, wherein the aggregation end 2 is configured to use a network node aggregation (NNI) protocol for matching a user network matching (UNI) protocol of a Synchronous Digital Hierarchy (SDH) frame structure with a subscriber and a relay line and a network. Matching means (11, 12, 14) for supporting, terminating a physical layer and performing a matching function with the distributing end (2); The matching means (11, 12, 14) is connected, as a one-way NxN magnetic routing switch, switching the input cell to the corresponding output port according to the routing information in the cell header without additional control, and improves the traffic efficiency of the whole system An exchange network 13 having a single-end structure that provides multiple paths for improvement; And control means (15, 16) connected to the switching network (13) for carrying out call processing of a subscriber housed therein under the cooperation of the other control group control unit through the switching network (13) without using a separate internal control bus. An asynchronous delivery mode switching system, characterized in that. 3. The matching means (11, 12, 14) is connected to the subscriber side and the switching network 13 inside the collecting end 1, Synchronous Transport Module-1 (STM-1) (155.52 Mbps) A subscriber matching unit (11), which is an end device having a user network matching protocol for performing broadband general information communication network subscriber matching with the SDH transmission structure; A relay line junction unit 12 which connects a remote subscriber module and a relay line with the internal switching network 13 and is an end device having a network node matching protocol to perform STM-4 (622.08 Mbps) matching; And an internal matching unit (14) for connecting the distribution end (2) side and the switching network (13) and performing matching with the distribution end (2). The signal processing means according to claim 2, wherein the control means (15, 16) are connected to the switching network (13) to terminate signal cells received from subscribers and networks via the switching network (13) and extract signal information. (15); And connected to the signal processing means 15, the lock control for the call requested by the subscriber and the allocation of the virtual path identifier / virtual channel identifier (VPI / VCI) for the accepted call, and input to the corresponding VPI / VCI. Update the head conversion table which adds routing information to the input cell and changes the new VPI / VCI value to send the cell to the corresponding output port, and controls the traffic for the multiple paths in the aggregation stage 1 An asynchronous delivery mode, characterized in that it comprises a call processing processor (16) which performs the processing and collects error information and billing information in the collection stage and sends the same to the maintenance processor (3) located in the distribution stage (2). Method of exchange system