KR100233909B1 - Method for switching frame relay module in isdn switch - Google Patents

Abstract

The present invention provides a primary rate subscriber block (PSI), a match exchange processor (ASP), a frame relay module (FRM), a time switch module (TSW) in a match exchange subsystem; A method for exchanging frame relay data in an ISDN switching system having a telephony processor (TP), the method comprising: requesting a B, D, and H channel for the delivery of frame data; And an ASP assigns a link to the FRM, determines a channel of the TSW, notifies the TP, and the TP sets a link level according to the LAPF protocol to the FRM. Steps; The TP assigns the frame relay link of the called party by the called address, sets up a channel of the called TSW and notifies the called party TP, and the called party TP causes the called party FRM to link level by the LAPF protocol. An incoming frame link assignment and switch connection step having a step of establishing a; The originating and terminating subscriber has a data transmission step of processing frame data of Layer 2 by LAPF protocol through B, D and H channels connected between respective PSI and FRM.

Therefore, the present invention has an effect of transmitting frame relay data more efficiently by using a frame relay module.

Description

Frame Relay Exchange Method in ISDN Switching System

The present invention relates to a switch, and more particularly, to a frame relay exchange method in an ISDN switching system capable of frame relay service.

Currently, most data networks operate based on packet transmission technology. Especially in public data networks, packet transmission technology based on the X.25 standard is responsible for network layers 1, 2, and 3 as a natural international standard both at home and abroad. .

Packet services within an ISDN exchange can be provided in two ways: Case A and Case B of the X.31 Recommendations. In the TDX-10 ISDN exchange, there is packet processing within the ISDN exchange, allowing subscribers to access B and D channels. The case B method can be used by using both services.

The TDX-10 packet switched service is provided through the structure as shown in FIG. 1, which does not distribute the packet handling subsystem, the packet handling subsystem, to each subscriber interface module, and all packet traffic is stored in the TDX-10. A centralized structure that is centralized and processed by an Access Switching Subsysem for Packet Switching (ASS-P) 1 through a TST switching network is achieved.

Related to processing packet traffic involves ISDN Access Switching Subsysem for Packet Switching (ASS-I) (2), Interconnection Network Subsystem (INS) (3) and trunk line matching sub-not shown. System (Access Switching Subsysem for Trunk (ASS-T)), dual ASS-I (2) provides the interface with subscribers, I.430 I.441 (Q.921), I.451 (Q.931) Process the protocol.

This ASS-I 2 is a Basic Subscriber Interface Block (BSI) and a Primary Rate Subscriber Block (PSI) 22 and a BAMI 23, as shown. In addition to these, a Time Switch (TS) 24, an ISDN Subscriber Access Processor (ISAP) 25, 26, a Time Switch Processor (TSP) 27, A Control Interworking Block (CI) 28 and an ISND Access Switching Processor-ISDN 29 are provided.

On the other hand, ASS-T (not shown) provides a relay line and an interface, and supports T1 and CEPT signaling methods.

In this case, the INS 3 has a Space Switch Block (SSW) 31 therein so as to connect the ASS between the TDX-10 or between the ASS and the Central Control Subsystem (CCS) 4. In addition, the CCS 4 performs system-wide maintenance, testing, measurement, statistical functions, and registration with the operator.

The packet switching device applies the concept of a distributed control structure to the ASS-P, Packet Layyer Control Processor (PLCP) (PL1-PLn), Packet Handling Module (PHM) (PH1-PHn). The three hardware blocks are connected through IPS (Inter Processor Communication) and P-BUS (Packet BUS) 11. The ASS-P 1 also includes a TSP 17, a CI 18, and an ASP-I 19 in addition to these configurations.

Each function of this distributed control structure is as follows. ASP-P (1) is responsible for the connection and disconnection of the physical matching path with the subscriber matching module (BSI, PSI, BAMI) (21, 22, 23), the packet processing period, PLCP (PL1-PLn) is a packet call control and It is in charge of routing information processing function. PHM (PH1-PHn) is a PHM-P that performs B-channel packet service based on X.25 protocol and PHM-P which performs packet service between ISDN and PSPDN interworking interfaces based on X.75 protocol. Various kinds are classified according to the exchange service characteristics.

However, under the TDX-10 ISDN packet-switched architecture, the X.25 protocol is used to perform end-to-end transmission quality, which leads to complex processing such as error detection and recovery. Therefore, in order to satisfy service needs of users in the future, a better way of technology is required. (1) Since the flow control and error control are performed at the link layer of the packet protocol layer 2 and the layer 2 of the packet layer layer, there is a large transmission overhead in the network because the protocol overhead is too large.

(2) In-band signaling, which processes user information and control information in a layer 3 packet layer, is inflexible in adding a new service.

(3) During packet call processing, the virtual call is set up by a two-step procedure. That is, after performing channel allocation process by out-of-band control using D channel. A call for establishing a virtual circuit is required according to an in-band procedure on an allocated B or D channel. In this way, there is no flexibility to add new services.

(4) There is a limitation in speeding up the network because it is not suitable for high-speed data transmission service of 64 Kbps or more.

On the other hand, in recent information society, there is a demand for a protocol that can replace the existing X.25, which can transmit more information at high speed. Frame relay is proposed as an alternative. The existing packet protocol is designed to guarantee the end-to-end transmission quality due to the lack of the development of the initial communication path. Therefore, error detection, error recovery, flow control, etc. are performed in the data link layer. DTP (Data Transfer Protocol) of X.25 PLP (Packet Layer Protocol) was implemented.

However, due to the development of current transmission technology, the error occurrence rate is considerably lowered, thus minimizing various control functions in the data link layer. In the network, only the core functions of Layer 2 required for data transmission are implemented, and functions such as error recovery and flow control are performed. The frame relay enables short delay time and high speed transmission by allowing the user device to perform it when necessary. In fact, frame relay was proposed in 1986 as the evolutionary step of packet communication in ISDN, and is currently being spread worldwide for use in high-speed data communication.

In response to this trend, the inventors distributed the frame relay handler module to each subscriber access subsystem and use a message switch, which is a separate IPC network, without passing through the existing TST switch network as a path for exchanging frame relay between these subsystems. The "Matched Exchange Subsystem in ISDN Switching System" (Application No.) is filed on the same day as this application.

The present inventors studied an exchange process that can exchange frame relays more efficiently in the above-described ISDN exchange system.

According to the present invention, an object of the present invention is to provide a frame relay exchange method of an ISDN exchange system capable of efficiently exchanging frame relay data in an ISDN exchange system using a frame relay handler module.

The frame relay exchange method of the ISDN switching system according to the present invention includes a primary rate subscriber block (Pimary Rate nterface Block), a match exchange processor (ASP), a frame relay module (FRM), and a time switch module in a match exchange subsystem. and; A method for exchanging frame relay data in an ISDN switching system having a telephony processor (TP), the method comprising: requesting a B, D, and H channel for the delivery of frame data; The matching exchange processor assigns a link to the frame relay module, determines a channel of a time switch module and notifies the telephony processor, and the telephony processor sets a link level according to the LAPF protocol to the frame relay module. Outgoing frame handler assignment and switch connection step; The telephony processor assigns a frame relay link of the called subscriber by the called address, sets a channel of the called time switch module, and notifies the called telephony processor, and the called telephony processor is connected to the called frame relay module. An incoming frame link assignment and switch connection step having a step of setting a link level by the LAPF protocol; The originating and terminating subscribers have a data transfer step of processing the frame data of Layer 2 by the LAPF protocol via the B, D, and H channels connected between each primary speed subscriber matching block and frame relay module.

1 is a diagram illustrating a packet exchange structure in a conventional TDX-10 ISDN;

2 is a block diagram of a match exchange subsystem in an ISDN switch system implementing the present invention;

3 illustrates a standard of a frame relay user-to-network interface in a matched switching subsystem of an ISDN switching system for implementing the present invention;

4 illustrates a frame structure of a link layer defined in a frame relay protocol in a matching exchange subsystem in an ISDN switching system for implementing the present invention;

5 is a diagram illustrating a frame relay switching path in a matched switching subsystem in an ISDN switching system embodying the present invention;

6 is a diagram illustrating a frame relay exchange exchange procedure in the ISDN exchange system according to the present invention.

<Description of the code | symbol about the principal part of drawing>

ASS-1 ~ ASS-n: Match Exchange Subsystem

101: basic subscriber matching block

102: primary speed subscriber matching block

103: relay line connection module 104: frame relay module

105: time switch 106: registration exchange processor

107,108: Telephony Processor

The above and other objects and various advantages of the present invention will become more apparent from the preferred embodiments of the invention described below with reference to the accompanying drawings by those skilled in the art.

Hereinafter, with reference to the accompanying drawings will be described in detail a preferred embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail.

2 shows an exchange structure for performing the frame relay exchange method according to the present invention.

As shown, a Basic Subscriber Interface Block (BSI) as a subscriber access module that performs ISDN subscriber access in an Access Switching Subsystem (ASS) (ASS-1 to ASS-N). 101 and the Primary Rate Nterface Block (PSI) 102, a relay line connection module (DTI) 103 for frame relay service between other nodes, and a subscriber access module (BSI, PSI, (101), (102) and the time switch module (TSW) 105, which provides a data connection path between the DTI 103 and the frame relay module (FRM) 104, and is responsible for the higher functions of the frame relay call processing. Telephony Processor (ASP) 106 to control devices such as TSW 105, Subscriber Access Module (BSI, PSI,) 101, 102, DTI 103, FRM 104, etc. (TP) ((107,108), inter-processor communication path and other subsystems between ASP 106 and TP (107,108) Communication path between the inter-processor is configured together with the IPC network (MSCI) (109), frame relay protocol processing and FRM (109) for performing data exchange functions that make the data communication path between the FRM (104) in the other subsystems.

The function of each module in such a configuration will be described in more detail as follows.

Subscriber access module (BSI, PSI)

The frame relay service in the ISDN system uses the existing BSI block 101 in the case of a 64Kbps subscriber and uses the PSI access module 02 in the case of a subscriber requesting a high speed service of 64Kbps or more.

In the case of the PSI block 102, in order to efficiently use the NS 64 Kbps (1 &lt; N &lt; 30) band in the same manner as a 64 Kbps circuit-switched call in real time, the TSW 105 preserves the time slot order to transparently transmit the 64 Kbps channel. Allocate circuits by maintaining Time Slot Sequence Integrity. Therefore, service is available to users who require high-speed data service. The service channel types and information transmission rates are 384 Kbps for the HO channel, 1.536 Mbps for the H11 channel, and 1.920 Mbps for the H12 channel.

Subscriber access module performs control functions such as call setup, monitoring, and release through D channel control channel.

3 shows a frame relay user-to-network connection standard, the processing procedure is as follows.

The channel setting for accommodating such H channel service to the FRM 104 uses the Q.933 procedure, which is an ISND D-channel layer 3 protocol, and uses an out-of-band method that delivers only the link layer frame in the network for data transmission. Send user information quickly.

The subscriber access module goes through the following discussion on the quality of service between the user and the network through Q.933 processing.The network can determine the level of service that the network can provide to the user in the current state of the network. The network can regulate traffic to avoid congestion.

Time Switch Module (TSW)

In order to support H channel service in an ISDN exchange, a switch network that satisfies a Time Slot Sequence Integrity (TSSI) requirement must be implemented. In the time switch module of this exchange, the voice memory is configured as a double buffer to realize the time slot order preservation for the multi time slots in the exchange.

TSW 105 is subscriber module (PSI) 102. In the conventional packet service method, the service is available only through the TST interval between the packet handler and the subscriber access module as a connection path connecting the DTI 103 and the FRM 104. However, in the present invention, frame relay between other subsystems is provided. In order to exchange data, the service could be provided via a message switch (MSCI-SPCI-MSCI) through a separate IPC network without passing through the existing switch section. This method eliminates the disadvantage of occupying multiple channels of an existing switch by occupying multiple channels of an existing switch for one packet call service, and eliminating a separate processing procedure for occupying such switch channels. Simplified.

Frame Relay Module (FRM)

FRM (104) performs core functions of link layer of frame relay service and applies multiplexing concept that can fully utilize bandwidth from 64Kbps service to 1.192Mbps service and according to transmission rate HO, H11, H12 service is available. 4 shows the frame structure of the link layer defined in the frame relay protocol, and the FRM 104 processes the frame received from the subscriber. The frame consists of 2-4 octet address fields, a variable information area, an FCS, and a flag field.

In addition, a user with frequent line usage may be assigned a fixed path between the network and the user terminal at the time of subscription, and may use a permanent virtual line that does not perform a route setting and release procedure for data transmission.

Matched Switch Processor (ASP)

The ASP 106 is responsible for the high level of all call processing in the subsystem, and performs the connection, release and call processing higher functions of the physical path between the subscriber and the FRM 104 for the frame relay service. It also manages the shape of the frame relay handler and negotiates information transfer rates, DLCI (Data Link Connection Identifier) negotiations, and quality of service (QoS).

Telephony Processor (TP)

The TPs 107 and 108 perform functions for controlling each device module in the subsystem. The TPs 107 and 108 perform frame routing call control and link layer control functions as well as error recovery and flow control functions for frame relay call processing. It also performs frame relay related operation, maintenance and statistics processing.

The frame relay exchange path in the above configuration is shown in FIG.

As shown, the configuration of the exchange path is as follows. First of all, the exchange path in the case where the called party exists in the same service system is TE1-NT1-PSI-TSW-FRM-TSW-PSI-NT2-TE2.

The TSW 105 is used as a connection path between the subscriber access module (PSI) 102 and the FRM 104, and performs exchange between the FRM 104.

The call processing process when the called party is distributed in a separate subsystem is as follows.

TE1-NT1-PSI-TSW-FRM-MSCI-SPCI-MSCI-FRM-TSW-PSI-NT2-TE2 When exchanging frames between other subsystems, the frame relay module communicates with the FRM of another sub system through the message switch (MSCI.SPCI) through the U-link.

Here, NT means network termination and TE means terminal.

The frame relay exchange procedure in the exchange structure having the above-described configuration will be described in detail with reference to FIG.

First, the allocation and switch connection steps of the outgoing frame handler are as follows.

The frame handler subscription group is physically connected to NT or TE, and when a call request is made, the calling party TE uses the D. Q.933 protocol procedure, which is a user-to-network connection protocol, through the D-channel. Requires a connection.

That is, NT and TE apply Set Ansynchronous Balanced Mode to the exchange side, and output a SET UP message when Unnumbered Acknowledgement is applied from the exchange.

That is, for frame transfer, the user requests the B, D, and H channels using NT or TE. At this time, the ASP 106 in the subscriber access module communicates with the processor through a call setup message (SET UP) to allocate a link in one FRM 104. After determining the TSW 105 channel for connection with the subscriber during the frame processing period, a physical path is established and notified to the TPs 107 and 108. At this time, the TPs 107 and 108 cause the FRM 104 to set the link level by the LAPF protocol.

Next, incoming and frame link allocation and switch connection steps are as follows.

The calling TPs 107 and 108 request number translation of the called address and assign the called frame relay link when the recipient of the number translation determines the called subscriber. At this time, the destination side time switch channel is determined, and then a physical path is formed and the destination side TPs 107 and 108 are notified. Likewise, at this time, the TPs 107 and 108 cause the frame handler to set the link level by the LAPF protocol.

That is, when the calling party TPs 107, 108 apply the asynchronous balanced mode setting signal SABME to the called party corresponding to the call setup message SET UP, and the non-numbering confirmation signal UA is applied from the called party. The call setup message (SET UP) is applied to the called party.

The called party applies the call setup reception message (CALL PROC) and response message (CONN) for this call setup message (SET UP) to the calling party TPs (107, 108). While acknowledging the response message (CONN) to the TE) and sending a response confirmation message (CONN ACK) to the called party.

After receiving the response message CONN, the terminal NT or TE transmits frame data FR DATA after transmitting the response confirmation message CONN ACK to the above-described source TPs 107 and 108.

That is, the originating and terminating subscriber transmits layer 2 frame data by the LAPF protocol through the B, D, and H channels connected between the PSI 102 and the FRM 104.

At this time, in the case of the H channel, since the time slot order is maintained for the path in the exchange, the FRM 14 processes the data of the subscriber in units of frames. In the case of the H channel that can be provided at the exchange, the HO channel has a bandwidth of 384 Kbps, the H11 channel is 1.536 Kbps, and the H12 channel is 1.920 Mbps.

As described above, the present invention has an effect of more efficiently transmitting frame relay data using the frame relay module.

Claims (1)

A Primary Rate Subscriber Block (PSI), a Match Switch Processor (ASP), a Frame Relay Module (FRM), and a Time Switch Module (TSW) in a Match Switch Subsystem; A method of exchanging frame relay data in an ISDN exchange system having a telephony processor (TP), The user requests the B, D, and H channels for the delivery of frame data, the ASP allocates a link to the FRM according to the user's request, determines the channel of the TSW, and informs the TP. And the TP is configured to assign an outgoing frame handler and switch connection to the FRM, setting a link level according to a LAPF protocol; The TP assigns a frame relay link of a called subscriber by a called address, sets a channel of the called TSW and notifies the called TP, and the called TP causes the called FRM to the LAPF protocol. An incoming frame link assignment and switch connection step having a step of setting a link level by means of; And transmitting and processing the source and destination subscribers to process layer 2 frame data by the LAPF protocol through B, D, and H channels connected between respective PSIs and FRMs.

Images