KR100295945B1 - D-channel packet service method in isdn exchange system - Google Patents

Abstract

The present invention provides a de-channel packet service method in a network integrated information communication network switching system including a data terminal device and a data line termination device, wherein the logic of the actual data terminal device on the data terminal device and the data line termination device interface is provided. Allocating a logical channel number conversion mapping table to a source and destination processing device of the network for converting a channel into a new data line terminator logical channel in a network including the data line terminator; When de-channel packet data is generated at the source subscriber in the terminal device and applied to the source processing device of the network, the source processing device of the network uses the logical channel conversion mapping table to determine the logical channel of the source subscriber. Change to the data line terminator logical channel And transmitting the de-channel packet data replaced with the converted logical channel to the called party processing device of the network, and the receiving side processing device of the network receives the de-channel packet data with the logical channel replaced. And converts the logical channel of the called party in the actual data terminal device into the logical channel of the called party in the actual data terminal device, and transmits the de-channel packet data replaced by the converted logical channel to the called party in the real data terminal device. The process takes place.

Description

D-channel packet service method in integrated telecommunication network switching system {D-CHANNEL PACKET SERVICE METHOD IN ISDN EXCHANGE SYSTEM}

The present invention relates to a switching system and, more particularly, to a method for D-channel packet service in an integrated services digital network (ISDN) switching system.

Originally, packet communication was a method of providing data communication using software switching in a computer network such as a local area network (LAN), but nowadays, packet communication has evolved from the original packet communication method and has been developed from the network layer (OSI 7 layer). Layer 3) uses the X.25 / X.75 protocol and LAPB (Link Access Procedure Balanced mode) for the data link layer (layer 2 of the OSI 7 layers). And Public Switched Packet Data Networks (PSPDNs).

The introduction of the ISDN concept in the 1980s focused on providing packet-switched services incorporating these protocols (e.g., X.25 / X.75 protocols) into ISDN exchanges, and the International Telecommunications Union-Telecommunications standardization. The sector recommends a method of providing a packet mode bearer service in an ISDN digital exchange, that is, an X.25 packet data service using a B-channel and a D-channel (Recommendation X.31, Recommendation). Q.931).

In Korea, B-channel packet service was first developed by joint development of several exchange manufacturers under the supervision of Korea Telecom and Korea Electronics and Telecommunications Research Institute, and each of the exchange manufacturers independently develops D-channel packet service. . The D-channel packet service provides a function to ensure that the communication between the terminal and the server is always connected like a LAN environment in a general home (always on / dynamic ISDN).

4 is a block diagram of a packet processing system for D-channel packet processing in an exchange system such as an SDX-200. In this exchange system, it consists of ASS (Access Switching Subsystem), INS (Interconnection Network Subsystem), CCS (Central Control Subsystem), ASS performs distributed call processing function, INS performs centralized call processing function, CCS performs centralized operation and maintenance functions.

In FIG. 4, an ASS 40 connected to a data terminal equipment (DTE) 62 is illustrated. The ASS 40 corresponds to a data circuit terminating equipment (DCE). The ASS 40 includes an Access Switching Processor (ASP) 41, an Access Switching Peripheral Processor (ASPP) 42, an ISDN subscriber unit 46, a packet handling unit 46, and a Time Switch Link (TSL). It consists of 48. The ASPP 42 is connected to each of the ISDN subscriber unit 44 and the packet processing unit 46 by a TD (Telephony Device) bus. The ISDN subscriber unit 40 has a Subscriber Call Control Assembly (SCCIA) 50 and a plurality of ISDN Basic Subscriber Interface Assembly (IBSIA) 52, 54, and between the SCCIA 50 and the TSL 48. The D channel packet path is formed. A B channel packet path is formed between each of the plurality of IBSIAs 52 and 54 and the TSL 48. The packet processor 46 includes a packet routing control assembly (PRCA) 56 and a plurality of packet handling control assemblies (PHCA) 58 and 60, and a U link between the PRCA 56 and the TSL 48 is performed. Is formed. A B channel packet path is formed between each of the plurality of PHCAs 58 and 60 and the TSL 48.

Meanwhile, in FIG. 4, the DTE 62 connected to the ASS 40 includes NT (Network Terminal), X.25 TA (X.25 Terminal Adapter), P-DTE (Packet-Data Terminal Equipment), and I-Phone (ISDN Phone). ) Is included.

1 is a functional block diagram illustrating the provision of a D-channel packet service in an ISDN switching system as shown in FIG. 4, and includes a plurality of data terminal equipment (DTE) 10 and 20 and an ISDN subscriber unit. (12, 18), packet handlers (14, 16) are included. In Fig. 1, the packet processing units 14 and 16 are network side using X.25 / X.75 layer 3 (packet layer protocol).

In general, packet communication uses Layer 2 X.25 / X.75 protocol based on LAPB. The provision of packet services over the B-channel to ISDN subscribers is likewise based on LAPB. Of course, because of the special environment called ISDN, the B-channel is selected using D-channel signaling of the ISDN protocol LAPD (Link Access Procedure on D-channel) protocol. It is only a procedure for forming a physical path between packet handlers, and a packet call setup procedure for actual data transmission and reception between DTE-DCE follows the X.25 protocol based on LAPB. That is, in the ISDN environment, the physical path setup and packet call setup procedures, that is, two call setup procedures, are performed as described above.

Unlike the D-channel packet service of ISDN, the service must always be kept on (always on service). Therefore, in hardware, the packet processing unit (14, 16 in FIG. 1 and 46 in FIG. 4) and subscriber processing must be performed in hardware. Between the ISDN subscriber unit (12, 18 in FIG. 1 and 44 in FIG. 4), a fixed-up path (NUP in FIG. 1, D-channel packet path in FIG. 4) for transmitting and receiving D-channel packet data is provided. The software uses LAPD, a D-channel protocol, as Layer 2, and uses X.25 Layer 3 (PLP; Packet Layer Protocol) as Layer 3.

Since LAPD is a logical multi-link protocol concept, LAPB is logically a single-link protocol, and since X.25 Layer 3 protocol is logically a single-link concept, applying it as a D-channel packet service has many problems. Will occur.

In terms of software, the biggest difference between B-channel packet service and D-channel packet service is that in case of B-channel, Q.931 signaling procedure is used to switch a single link physically and logically between subscriber and packet processing part. However, in the case of the D-channel, a plurality of subscribers can simultaneously use one channel of the packet processor (14 and 16 in FIG. 1) through a fixed physical path (a logical multilink concept on a single physical link). In addition, in the case of the D-channel, a service access point identifier (SAPI) and a subscriber that distinguish service types (packet service and line service) on one physical line (subscriber line) up to the DTE (10 in FIG. 1) and the subscriber end. It should be considered that logical terminal multiplexing (maximum of 8 TEIs per subscriber line can be allocated on a D-channel) by a terminal equipment identifier (TEI) for identifying a terminal.

The X.25 protocol stack controls virtual lines using logical channels for individual logical links. In the case of D-channel packet service, the concept of subscriber lines and multiple logical links by TEI is applied to a single physical link. The logical channel must be managed. In other words, if the X.25 protocol stack does not manage this multiplexed logical link, the logical channel number (hereinafter referred to as “LCN”) applied from the DTE side is determined for the subscriber line and TEI. If the same value is introduced into the X.25 protocol stack of the packet processing unit (14, 16 of FIG. 1, 46 of FIG. 4), it will cause great confusion.

However, there are many problems in managing logical channels using the multilink concept. For example, in the case of an electronic switch such as the current TDX-10A, a 128 kilobit per second (Kbps) timeslot is allocated to 128 basic interface subscribers and connected to the packet processing unit (after TDX-10A). In the case of a new exchange made by the exchange's manufacturers, for example, one 64Kbps timeslot per 256 or 512 subscribers is connected to the packet processor). In this case, the logical channel management table for the multiple logical links has a burden of managing a huge database with all subscriber lines (eg, 128), TEI 128, and LCN 4096 as indexes. More specifically, since there are 128 subscriber lines, 128 TEIs are allocated to each subscriber line, and 4095 LCNs are allocated to each TEI, the packet processing unit may use 128 * 128 * 4096 blocks for one 64Kbps time slot. You have to manage a huge database with indexes. In FIG. 1, a packet processing unit 14 or 16 manages a database using a subscriber line (LINE), a TEI, and an LCN. If the packet processing unit has a centralized structure in the switching system, the access switching subsystem (ASS) number to which the subscriber belongs should be managed as an additional index.

If the network side manages such a burden, even if it is a low-speed D-channel packet service of 16 Kbps, the logical channel management table must be searched for every packet data transmitted and received in the data transmission state. Will be caused.

One way to reduce the database is to allocate more packet processing for D-channels to current subscribers, but this can be a waste of system resources.

Accordingly, an object of the present invention is to prevent a large size database management problem caused by managing a logical channel with multiple logical links for a physical link when providing a D-channel packet service in a switching system, and to prevent a decrease in packet data transmission performance. To provide a method for this.

Another object of the present invention is to provide a method for simply operating a logical channel management table in a packet processing unit in an ISDN exchange system.

In accordance with the above object, the present invention provides a de-channel packet service method in a network integrated information communication network switching system including a data terminal device and a data line termination device, wherein the data terminal device and the data line termination device are on an interface. A logical channel number translation mapping table for converting a logical channel of an actual data terminal device into a new logical channel number of the data line termination device in a network including the data line termination device is allocated to the source and destination processing devices of the network. And when the D-channel packet data is generated at the originating subscriber in the data terminal device and applied to the originating processor of the network, the originating processor of the network uses the logical channel conversion mapping table. The data channel of the logical channel of the subscriber Converting a device logical channel, and transmitting the de-channel packet data replaced with the converted logical channel to a called party processing device of the network; Upon receiving the channel packet data, the logical channel conversion mapping table is used to convert the channel packet data into the logical channel of the called party subscriber in the actual data terminal device, and the de-channel packet data replaced by the converted logical channel is received in the actual data terminal device. Characterized in that the process to send to the subscriber.

1 is a functional block diagram illustrating a D-channel packet service provision in a conventional ISDN switching system.

2 is a functional block diagram illustrating the provision of a D-channel packet service in an ISDN switching system according to an embodiment of the present invention.

3 is a flowchart illustrating D-channel packet service performing communication in an ISDN switching system according to an exemplary embodiment of the present invention.

4 is an exemplary configuration of a packet processing system for D-channel packet processing in a switching system;

5 is a view for explaining a data conversion process using the LCN conversion mapping table according to an embodiment of the present invention.

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 denoted 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.

In the embodiment of the present invention, reference will be made to an example configuration of a packet processing system for D-channel packet processing in the switching system shown in FIG.

2 is a functional block diagram for providing a D-channel packet service in an ISDN switching system according to an exemplary embodiment of the present invention, and includes a plurality of data terminal equipment (DTE) 100, 110, ISDN subscriber units 102, 108, and packets. Processing units 104 and 106 are included. In Fig. 2, the packet processing units 104 and 106 are network side using X.25 layer 3 (packet layer protocol).

In the case of a D-channel packet, a plurality of subscribers may be connected to one physical link of the packet processing unit 104, 106, and multiplexed by the TEI. Therefore, in the embodiment of the present invention, the logical channel number (LINE, user channel number assigned to the TEI base) flowing from the DTE side (100, 110 of FIG. 2) to the network side: hereinafter referred to as 'U_LCN' ) Is converted into a network logical channel number (called 'N_LCN') inside the network, and N_LCN is used for a packet going from the network side to the DTE side (100, 110 in FIG. 2). To convert to U_LCN to manage logical channel mapping table. The logical channel mapping table is implemented in the packet processing units 104 and 106 included in the network side according to an embodiment of the present invention.

In fact, in view of the time slot (64Kbps) as the physical link from the perspective of the packet processing unit 104,106 in the network, considering the throughput class and the size of the packet buffer, it may exist in the physical link. The number of virtual lines present is a system dependency. For example, in case of B-channel packet of an electronic switchboard such as TDX-10A, the number of virtual circuits that can exist simultaneously on a link of 64 Kbps is limited to 10.

Even in the case of D-channel packet service, designing to handle all TEIs of all subscribers at the same time is a very unreasonable implementation without any system efficiency, and is limited by network resources (particularly packet memory). Depending on the system, the number of virtual lines that can be provided simultaneously through a physical link (one time slot) from the standpoint of the packet processing units 104 and 106 is, for example, about 128 to 255, so that packet size and window size (data loss prevention It means that the size of the data can be stored as a purpose for the purpose of the data transmission), but the packet processing unit 104, 106 has a quite large packet memory.

In the case of D-channel packets, because of the hardware characteristics of the system, the ISDN subscriber units 102 and 108 and the packet processing units 104 and 106 provide a D-channel fixed-up path (NUP). One frame is introduced into the same time slot from the packet processing unit 104 and 106, and the outgoing frame also uses a predetermined time slot.

Therefore, a packet logically multiplexed frame of a link logically multiplexed with respect to a TEI coming from the DDN 100, 110 via the ISDN subscribers 102, 108 is virtually connected to all subscriber lines (LINE), TEIs, and LCNs. Since it is not supported at the same time and is limited below the maximum number of system-dependent virtual lines (128 described below as an example), an algorithm that logically unifies and manages only the virtual lines can be used. That is, in the embodiment of the present invention, the packet processing unit 104, 106 does not actually have a virtual line management table in which subscriber lines (e.g., 256 subscribers), TEI (128), and LCN (4096) are indexed. By operating the logical channel mapping table (hereinafter referred to as 'LCN transformation mapping table') according to the logical channel conversion and having only the system-dependent maximum number of virtual lines (128), the problems caused by the large database size ( In order to reduce the database, it is possible to solve the problem of allocating more packet processing units to the D-channel for the subscriber, and degrading the packet data transmission performance due to extensive database search.

Hereinafter, the operation of the data conversion process using the LCN conversion mapping table according to an embodiment of the present invention will be described in detail with reference to FIG. 5. The data conversion process according to an embodiment of the present invention performs data conversion for processing multiple subscribers of the D-channel as if one subscriber requires packet call establishment.

For data conversion, the packet processing unit (104, 106 in FIG. 2, 44, 46 in FIG. 4) includes an X.25 layer 3 protocol stack 200, a D-channel packet control module 202, as shown in FIG. The LCN conversion mapping table 204 is included. The X.25 Layer 3 protocol stack 200 performs packet call processing, and the D-channel packet control module 202 uses the information in the LCN transformation mapping table 204 to perform LCN transformation on the input D-channel packet. Perform. In the LCN transformation mapping table 204, as many transformation U_LCNs as the maximum number of virtual lines are provided, subscriber line information LINE #, TEI information TEI #, and LCN information LCN # are indexed in each U_LCN.

As an example, as shown in FIG. 5, A packets of LINE # = 100, TEI # = 11, and LCN # = 15 among D-channel packets are converted into U_LCN = 100 by the D-channel packet control module 202. This is output to the subscriber. In this way, B packets of LINE # = 101, TEI # = 11, LCN # = 16 are U_LCN = 101, and C packets of LINE # = 102, TEI # = 12, LCN # = 15 are U_LCN. = 102, D packet with LINE # = 103, TEI # = 11, LCN # = 15 is converted to U_LCN = 103, E packet with LINE # = 104, TEI # = 11, LCN # = 16 is converted to U_LCN = 104 This is output to the subscriber.

On the other hand, the D-channel packet coming from the subscriber is subjected to LCN conversion in the reverse process as described above (U_LCN → N_LCN).

3 is a flowchart illustrating a de-channel packet service performing communication in an ISDN switching system according to an embodiment of the present invention.

2 and 3 will be described in detail the operation according to the embodiment of the present invention.

In the embodiment of the present invention, as described above, in the case of the D-channel packet, the logical channel number U_LCN (LINE, user logical channel number assigned to the TEI base) flowing into the network from the DTE side (100, 110 of FIG. LCN which converts N_LCN into a network logical channel number N_LCN in the network, that is, the packet processing unit 104 and 106, and converts N_LCN into LINE, TEI, and U_LCN for packets going to the DTE side (100 and 110 in FIG. 2). Manage the conversion mapping table. Therefore, only N_LCN is used in the call processing block (layer 3 based) in the network.

In the embodiment of the present invention, in the case of the B-channel packet using the LAPB, since the U_LCN and the N_LCN are the same, the X.25 protocol stack of the packet processing unit 104, 106 uses the LCN in use only as the meaning of N_LCN.

Referring to Figure 3 D-channel packet processing flow according to an embodiment of the present invention in more detail as follows. The calling party and the called party subscriber in FIG. 3 may be subscribers in the DTE 100, 110 of FIG. 2, and the calling party and destination packet processing part in FIG. 3 may be the packet processing part 104, 106 of FIG. 2. have. The call processing block of FIG. 3 is not shown in FIG. However, the call processing block corresponds to the ASP 41 in the ASS 40 illustrated in FIG. 4, and plays a role of layer 3 (call processing related functions).

Referring to FIG. 3, when a D-channel packet is to be transmitted from a calling party to a called party, the calling party and the calling packet processor perform a restart packet processing procedure. That is, when the D-channel packet is to be transmitted, the calling party transmits a restart packet RST Packet to the calling packet processor (①), and the calling packet processor sends a restart acknowledgment signal (restart) in response thereto. confirm signal) RST Conf is transmitted to the calling subscriber (2).

When the calling party receives the restart acknowledgment signal RST Conf, the calling party sends a call request packet Call Req to the calling packet processing unit (③), and the calling packet processing unit calls the call request packet message. When a Req is received, the call setup procedure is performed. At this time, the source packet processor analyzes the subscriber line number (LINE), the TEI, and the header of the packet message of the call to know the U_LCN, and searches the LCN conversion mapping table previously assigned to the source packet processor to find the U_LCN. The N_LCN corresponding to the M_LCN is allocated and the subscriber line number (LINE), TEI, U_LCN, and N_LCN information of the corresponding call are registered in the LCN conversion mapping table. Subsequently, the U_LCN information of the header of the packet message is replaced with the allocated N_LCN information, and then the network connection indication packet message Net Conn Ind including the replaced N_LCN information is transmitted to the upper call processing block (④). ). The originating occupancy request packet message Net Conn Ind also includes the calling party throughput and the called party number.

Accordingly, the upper call processing block obtains the TEI of the terminal responding through the Q.931 / Q.921 signaling procedure (X.25 packet data service) to the called subscriber line using the called subscriber number, and then If there is no call in progress by checking the TEI state, the LAPD setup procedure for packet service (Q.931 / Q.921 specifies SAPI = 16) is performed. The call processing block manages allocation of N_LCN and U_LCN allocation for TEI of the corresponding subscriber line.

Thereafter, when the call processing block transmits an incoming packet call establishment request message (Net Conn Req) including subscriber line number (LINE), TEI, N_LCN, and U_LCN information to the called party packet processing unit (⑤), the called party packet processing unit is The N_LCN found in the incoming packet call establishment request message ((Net Conn Req)) is searched, the U_LCN is found from the LCN conversion mapping table, and the found U_LCN information is applied to the incoming call packet (Incoming Call) and transmitted to the called party. ). Then, when the called party transmits a call accept packet in response to the incoming call packet (⑦), the called party packet processing unit U_LCN in the field of the call accept packet. N_LCN is found from the LCN transformation mapping table, and the found N_LCN information is included in the call occupancy response message (Net Conn Resp) and transmitted to the upper call processing block (⑧). Accordingly, the call processing block transmits an originating occupation confirmation signal (Net Conn Conf) to the originating packet processing unit using N_LCN (⑨). Accordingly, the originating packet processing unit also transmits an originating occupation confirmation signal (Net Conn Conf) ()).

In this way, the packet data transmission process is performed after the call is established. In the case of the D-channel data processing packet applied from the calling party to the calling packet processing unit via the ISDN subscriber unit (102 or 108 in FIG. 2), the LCN information contained in the data packet field is U_LCN information. Search the LCN conversion mapping table to find N_LCN information corresponding to the subscriber line (LINE), TEI, U_LCN information, and transmit the data packet replacing U_LCN information with the found N_LCN information to the destination packet processing unit through communication between packet processing units. do. Accordingly, the called party processor retrieves U_LCN information corresponding to the N_LCN information of the data packet using an internal LCN conversion mapping table, and transmits the data packet to the called party subscriber based on the retrieved U_LCN information.

In the above description of the present invention, specific embodiments have been described, but various modifications can 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 defined by the equivalent of claims and claims.

As described above, the present invention provides a D-channel packet service in an ISDN environment, in which a logical channel is managed by multiple logical links for a physical link, and a logical channel (subscriber line, Applying an algorithm that converts the TEI base logical channel number) into a new virtual DCE logical channel on the network side and enables software switching inside the network, it solves a huge database management problem and efficiently uses the database. This can prevent performance degradation of packet data transmission.

Claims (3)

A de-channel packet service method in a network integrated information communication network switching system having a data terminal device and a data line termination device, A logical channel number conversion mapping table for converting a logical channel of an actual data terminal device on the interface between the data terminal device and the data line termination device into a new logical line of the data line termination device in a network including the data line termination device; Assigning to the originating and called party processing devices of the network; When de-channel packet data is generated at the calling party subscriber in the data terminal device and applied to the calling party processing device of the network, the calling party processing device of the network uses the logical channel conversion mapping table to determine the logic of the calling party subscriber. Converting a channel into a logical channel of the data line termination device and transmitting the de-channel packet data replaced with the converted logical channel to a called party processing device of the network; When the called party processing device of the network receives the de-channel packet data in which the logical channel is replaced, it converts the logical channel of the called party subscriber in the actual data terminal device using the logical channel conversion mapping table, and converts the converted logic. And transmitting the de-channel packet data replaced with the channel to the called party subscriber in the actual data terminal apparatus. The method of claim 1, wherein the logical channel of the actual data terminal device is a logical channel number based on a subscriber line and a terminal device identifier base. The method of claim 1 or 2, wherein the logical channel conversion mapping table is assigned logical channel numbers corresponding to the maximum number of virtual lines.