KR100219220B1 - Method for processing setup request primitives in layer 3 of isdn uni - Google Patents

Abstract

The present invention relates to a call establishment request primitive processing method in Layer 3 of an ISDN user-network connection, comprising: determining an ID and a link ID of a received primitive; If the received primitive is a call setup request (SETUP_REQ) primitive, checking a minor link ID and determining a state of a corresponding layer 3 entity; If the status of the layer 3 entity is null, sending a SETUP message to layer 2; And starting the timer T303, and bringing the entity into a call initiated state U1. The ISDN terminal is connected to the network according to a layered protocol in the integrated information communication network.

Description

Method of processing setup request primitives in layer 3 of ISDN UNI

The present invention relates to a connection technology between a user (USER) and a network (NETWORK) in an integrated information communication network (ISDN), in particular a call setup request (SETUP_REQ) primitive received from the management (CC) layer in layer 3 (LAYER 3) It is about how to process.

As the information society has progressed, communication demands have diversified, and the media handled by communication networks such as voice, data, and video have also diversified, so that individual networks established by services cannot provide efficient services. Therefore, the ISDN, which can integrate and digitize individual networks established by services and provide comprehensive services, has emerged. These ISDNs are designed to unify various terminals in order to accommodate users and manganese. The interface is standardized by Digital Subscriber Signaling System (DSS1), and the interface between the network and the network is also standardized by No.7 Common Line Signaling (CCS).

DSS1, which is a signaling method of the user-network interface (UNI) of ISDN, is implemented in layers 1 through 3 by an OSI (Open Systems Interconnection) reference model, as shown in FIG. The overview and its relationship with the Recommendations of the ITU-T are shown in Table 1 below.

Digital subscriber line signaling Layer Function Outline Corresponding recommendations Layer 1 Electrical physical conditions 1.430, 1.431 Layer 2 Link setting control and error control for message transmission Q.920, Q.921 Layer 3 Set up, opening Q.930, Q.931

Referring to FIG. 1, a first network terminal device NT1 located in a house (or building) is connected to an ISDN exchange located in a telephone station through a subscriber line, and an ISDN terminal TE1 is connected to an ISDN terminal in a building through an S / T point. Alternatively, the second network terminal device NT2 is connected to the first network terminal device NT1.

Here, 'NT1' (network terminal device 1) is a transceiver in a house for transmitting a digital signal to a subscriber line, and 'NT2' (network terminal device 2) is a device corresponding to a private branch exchange (PBX). The terminal (TE1) can accommodate, 'TE1' is an ISDN standard terminal is directly connected to NT1 and may be connected via NT2, and the existing terminal 'TE2', which does not have an ISDN-compliant function, is not shown. It is connected to the ISDN network through the terminal adapter (TA).

In addition, the interface point between NT1 and NT2 is called 'T' point, and the interface point between NT2 and TE1 is called 'S' point. Since the interface specification of S point is determined to be based on T point, TE1 is The point to be connected is called the 'S / T' point.

In addition, the subscriber terminal, such as the ISDN terminal, is connected according to the above-described protocols of the layers 1 to 3 so as to be connected to the ISDN exchange, and the recommendations for defining such a connection are shown in Table 1 above.

That is, in Table 1, Layer 1 is a user-network interface of the physical layer recommended by ISDN Recommendations I.430 and I431, and includes a basic interface of 2B + D access and a primary group speed interface of 23B + D or 30B + D. In the basic interface, the frame structure consists of 48 bits in 250μs.

Layer 2 is commonly referred to as Link Access Procedure on the D channel (LAPD), which first adopts HDLC's BALANCE mode, which is the standard for the standardized data link layer, and its basic format is Flag. And an address field, a control field, an information field, a frame check sequence (FCS), and a flag.

Layer 3 controls the establishment, maintenance, and release of communication paths required by the network and packet switched services, and various additional service requests, which are received from the other side through layers 1 and 2. The message is analyzed and the call setup related message is formed and sent to the other party through the lower layer. General content relating to Layer 3 is described in Q.930, and call processing procedures for basic calls are recommended by Q.931.

However, in order to implement an ISDN terminal, the functions described above should be implemented. A protocol is defined between appointments in the same layer, and a primitive is defined in logical exchange between upper and lower layers. That is, each layer has entities that implement the functions of the layer, and these entities are configured to exchange information between top and bottom through primitives.

These primitives are divided into four types: REQUEST, INDICATE, RESPONSE, and CONFIRM. Most of the primitives related to data transfer are REQUEST passed from the upper layer to the lower layer. ) Primitives, and INDICATE primitives passed from the lower layer to the upper layer.

The CONFIRM primitive is a primitive that notifies the upper layer when the lower layer is obliged to respond to the specific request primitive from the upper layer, and the RESPONSE primitive is applied to a specific indication primitive from the lower layer. This is a primitive to inform the lower layer when the upper layer is obliged to respond.

On the other hand, primitives to be processed in layer 3 (Q.931) are as shown in Figure 2, the setting indication (DL_ESTABLISH_IND), the setting confirmation (DL_EST_CFM), the release confirmation (DL_REL_CFM), the data confirmation (DL_DAT_IND) transmitted from the layer 2 ), Unit data display (DL_UDA_IND), resume request (REST_REQ) received from GCR, resume confirmation (REST_CFM) delivered to GCR, timer (T316), timer (T317), and transfer from MG (CC) layer. Call request (ALERT_REQ), disconnect request (DISC_REQ), information request (INFO_REQ), additional information request (MORE_INFO_REQ), notification request (NOTI_REQ), call progress request (PROC_REQ), call progress request (PROG_REQ), reject request (REJ_REQ) ), Release request (RELE_REQ), call resumption request (RESU_REQ), call setup response (SETUP_RES), call setup request (SETUP_REQ), foil stop request (SUSP_REQ), and timers T301_EXP sent back to themselves in layer 3, T302_EXP, T303_EXP, T304_EXP, T305_EXP, T306_EXP, T307_EXP, T308_EXP, T309_EXP, T310_EXP, T313 _EXP, T314_EXP, T318_EXP, T319_EXP, T321_EXP, T322_EXP, and the like. In this case, xx_xxxx_REQ represents a request primitive, xx_xxxx_IND represents an indication primitive, xx_xxxx_RES represents a response primitive, and xx_xxxx_CFM represents an confirm primitive. PH_xxxx_xxx is a primitive between the data link layer and the physical layer, DL_xxxx_xxx is a primitive between the layer 3 and the data link layer, MPH_xxxx_xxx is a primitive between the management layer and the physical layer, and MDL_xxxx_xxx is a primitive between the management layer and the data link layer. . There is no prefix between layer 3 and the management layer, and the management (MG) layer is divided into call control (CC) and global call reference control (GCR).

In addition, the state defined in Layer 3 (Q.931) is defined according to the type of call and whether it is user side or network side.

State of Layer 3 (line switched / user side) Status Name Mark Contents Null state U0 No call exists Call initiation U1 User requested call setting in call Sending nested U2 Received confirmation of call setup request so that user can send additional information in overlapping mode at originating signal. Signaling progress U3 Received confirmation that the network has received all the information needed to set up a call from an outgoing call Call forwarding U4 In the outgoing call, the calling user receives an indication that the calling of the other user has been initiated. Arc existence U6 On incoming call, user is requested to set up call but not answered Receive call U7 On an incoming call, the user marked the call but did not answer Connection request U8 Wait for user to answer on incoming call and receive call Incoming call U9 The user sends a confirmation that an incoming call has received all the information necessary to set up a call. Active U10 The user has received a confirmation that the call has been placed on an incoming call, or the user has received an indication that the other party has answered the call. Cutting requirements U11 The user requests the recovery of an end-to-end connection and waits for a response Cutting marks U12 User received a cut request because the network cut the end-to-end connection Pause request U15 User requests pause of call and waits for response Resumption request U17 The user has requested to resume a previously paused call and is waiting for a response Release requirement U19 The user requests a release and waits for a response Overlapping U25 In the incoming call, the user acknowledges the call setup request and prepares to receive additional call information in the overlapping mode.

On the other hand, the conventional method of processing such primitives in layer 3 was proposed as SDL in Appendix A (ANNEX A) of Recommendation Q.931, which is roughly summarized as shown in FIG.

Referring to FIG. 3, the conventional method determines a current state of layer 3 after receiving a primitive (S1) (S2), and then drives a primitive processing routine according to the determined current state (S3). The primitive processing routine then determines the received primitive (S4), and processes the received primitive according to the determined state and primitive (S5).

That is, in the case of processing a call setup request (SETUP_REQ) primitive, if any primitive is conventionally received, first determine the current state of the L3 layer (which is U0 to U25), and then go to the corresponding state processing routine and receive the received primitive. The call setup request (SETUP_REQ) primitive was processed by determining what the primitive was.

As described above, since the state of layer 3 is about 15 to 20 types and about 30 types of primitives to be processed, it takes a long time to determine the state and the primitive, and when processing each primitive after state determination There was a problem in that the code lengthened during programming because of a large number of duplicate processing procedures.

Therefore, when similar processing is repeated in different states, it is necessary to reduce the processing time and optimize the code size by optimizing this, and furthermore, it is possible to configure multiple lines to widen the channel bandwidth. It is desirable to expand it.

Accordingly, an object of the present invention is to provide a call setup request (SETUP_REQ) primitive processing method for optimizing a processing procedure in order to solve the above problems.

Another object of the present invention is to provide a method for processing a call setup request (SETUP_REQ) primitive, which allows an ISDN terminal to be connected to a network by configuring multiple lines.

In order to achieve the above objects, the present invention provides a method for implementing layer 3 to connect an ISDN terminal to a network according to a layered protocol in an integrated information communication network. Determining; If the received primitive is a call setup request (SETUP_REQ) primitive, checking a minor link ID and determining a state of a corresponding layer 3 entity; If the status of the layer 3 entity is null, sending a SETUP message to layer 2; And starting the corresponding timer T303 and bringing the corresponding entity into a call initiated state U1.

1 shows a user-network connection of an ISDN;

FIG. 2 shows the relationship of primitives processed in ISDN UNI layer 3; FIG.

3 is a schematic diagram illustrating a conventional method for processing primitives in ISDN UNI layer 3;

4 is a diagram showing an example of an ISDN communication card suitable for application of the present invention;

FIG. 5 is a detailed block diagram of the channel connection unit shown in FIG. 4; FIG.

6 is a conceptual diagram illustrating processes processed in an ISDN communication card according to the present invention;

7A to 7E show a data format used in the present invention;

8 is a diagram illustrating a call setup request (SETUP_REQ) primitive processing method according to the present invention;

FIG. 9 is a flowchart of a procedure for processing a T303 end primitive generated when the timer T303 started in the flowchart shown in FIG. 8 ends.

* Explanation of symbols for main parts of the drawings

1: ISDN terminal 3-1 ~ n: handset

5-1 to n: Network terminal device (NT1) 7: ISDN network

10: PC 12: Slot

20: ISDN communication card 21: DP RAM

22: memory 23: CPU

24-1 ~ n: Codec 25-1 ~ n: Channel connection (ISAC)

26: socket 27: S bus

28: subscriber line

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

First, when implementing the ISDN terminal according to the present invention, looking at the schematic configuration of the hardware, as shown in Figure 4, the ISDN terminal 1 is ISDN communication card through the slot 12 in the personal computer (PC: 10) 20 is connected, the ISDN communication card 20 is connected to the network terminal device (NT1: 5-1 ~ n) via the S bus 27, the network terminal device (5-1 ~ n) is The subscriber line 28 is connected to the ISDN network 7.

At this time, the ISDN communication card 20 to which the present invention is applied is provided with n channel connection parts (ISAC: (25-1 to n) so as to connect 2B + D basic interfaces to n ISDN networks 7, respectively. The n channel connections are connected to the network terminal devices 5-1 to 5-n through the S bus 27, respectively.

In this way, the host interface can be extended up to n so that the host system has a large amount of data to be transmitted (for example, in a video conferencing system). In addition, by adding several (n) basic interfaces, the host system can transfer data by appropriately extending the channel capacity.

Here, the ISDN communication card 20 is a dual port RAM (DP RAM: 21), memory 22, CPU 23, codec (CODEC: 24-1 ~ n), channel connection unit (ISAC) as shown in FIG. : 25-1 to n), and implements the functions of Layer 1 to Layer 3 so that the ISDN terminal 1 can be connected to the ISDN network 7 as described above. It is built in the memory 22.

In FIG. 4, the DP RAM 21 provides a physical path for transferring data with the PC 10, which is the host system, through the slot 12, and the memory 22 operates various kinds of cards for operating the communication card 20. Programs and system data are stored, and the CPU 23 starts various processes in accordance with software stored in the memory 22 to control the operation of the entire communication card. In the embodiment of the present invention, IDT71321 is used as the dual port RAM 21, and 80C188 of Intel Corporation is used as the CPU 23.

The codecs 24-1 to n are for connecting a voice to a basic interface. The codec 24-1 to n encodes and decodes a voice signal input and output through the handsets 3-1 to n, and the channel connection units 25-1 to n. And the channel connection units 25-1 to n are configured as shown in Fig. 5 to connect a data terminal or a voice terminal to the network terminal apparatuses 5-1 to n.

In Fig. 5, the channel connection units 25-1 to n include the SSI 51, the SDL 52, the B channel switching unit 53, the D channel processing unit 54, the FIFO 55, and the processor connection unit 56. In addition, the IOM connection unit 57, the buffer 58, the buffer control unit 59, and the ISDN basic access layer 1 unit 60 may be configured. The channel connection unit of such a configuration may be implemented as a single semiconductor chip and can be purchased commercially. . In the embodiment of the present invention, the channel access units 25-1 to n are implemented by SIEMENS's ISDN Subscriber Access Controller model name: PEB2085, and the operation of the ISAC is described in detail in the corresponding Technical Manual. It is.

In order to process primitives in the ISDN communication card 20, entities of each layer are divided into a LAPD process 61, an L3 common process 62, and an L3 local process 63 as shown in FIG. 6. It works by referring to the variable table.

Herein, the L3 common process 62 may include entities for processing primitives DL_EST_IND, DL_EST_CFM, DL_RELE_IND, DL_RELE_CFM, DL_DATA_IND, and DL_UDATA_IND that are transferred from the layer 2 process 61 to layer 3, and the primitives related to the GCR (RESTART_REQ). , RESTART_CFM, T316_OUT, T317_OUT), and the L3 local process 63 consists of entities for processing the remaining primitives recommended in Q.931.

At this time, the LAPD process (layer 2) refers to the layer 2 environment variable table (L2env_tab [x]), which is identified by a link ID (Link ID or id), and exists in a plurality of layer 3 common processes. Reference numeral 62 refers to the layer 3 common environment variable table (L3coord_tab [x]), which is also identified according to the link ID. The layer 3 local process 63 references the layer 3 local environment variable table (L3env_tab [x]), which contains two link IDs per link ID and a link ID (ID) and a minor link ID (mID). Are identified according to. In FIG. 6, the illustrated processes show the case of three link IDs and six minor link IDs (ie, a communication card having three channel connections (ISAC)).

Here, the link ID (ID) is as shown in Figure 4, when configuring multiple lines by installing a plurality of ISAC on the ISDN communication card, from 1 to n times (or 0 times) to distinguish these lines To n-1) n identification numbers, and the minor link ID (mID) is a 0 or 1 identification number for identifying B channels on each line (there are two B channels in the 2B + D basic connection). .

As described above, since the present invention can provide a plurality of lines, a link ID (ID) and a minor link ID (mID) are used to identify them.

7 is a data format of a message or primitives processed on an ISDN communication card, where 7a represents a messageless primitive, 7b and 7c are an unnumbered format, and 7d and 7e are a numbered format, respectively.

In FIG. 7, the Q.931 message field is a part processed by layer 3, the Q.291 non-numbered and numbered fields are a part (header) processed in layer 2, and the primitive header part transfers information between layers. This is the part used for primitive processing in each layer.

That is, in 7a to 7e, the primitive header consists of a 'primitive id' for identifying a primitive, a link ID (link_id = ID), a minor link ID (mlink_id = mID), and a size indicating a message size. The unnumbered field of .921 consists of add1, add2, mm (3 bytes), and the non-numbered field of Q921 consists of add1, add2, n_r, n_s (4 bytes). This Q.921 field and the message field of Q.931 are described in detail in the Recommendations, so further explanation is omitted.

8 is a flowchart illustrating a method of processing a call setup request (SETUP_REQ) primitive according to the present invention.

The call setup request (SETUP_REQ) primitive is a primitive required by the management layer to send a SETUP message, which is the first message that a user uses to set up a call, to the network side. Therefore, since it is a primitive generated to set up the first call, it is valid only in the null state U0, and processing of this primitive is rejected in other states.

Immediately after the SETUP message is transmitted, the timer T303 is started to set the maximum waiting time for the response, and the state of the layer 3 is brought into the call initiated state U1.

In this case, when a user designates a call reference number and a B channel, the information element field of this primitive should be included in the information element, which is performed by the management layer to enable various ISDN services. The handling of such call establishment request primitives is well described in Section 5.1.1 (Call request) of Q.931.

Referring to FIG. 8, when an arbitrary primitive is received in the primitive receiving step, the primitive ID and the link ID are determined (100, 101). Here, the primitive id is an identifier defined to identify the type of the primitive, and is recorded in the header of the primitive along with the link ID. The link id is used to identify the base interface on multiple lines. For example, if the link ID is 0, the link id is related to the base interface provided through ISAC1 (25-1 of FIG. 4). Notice that it is related to the process on (Link 0).

If the received primitive is a call setup request (SETUP_REQ) primitive, the minor link ID mid is checked and the current state of the layer 3 entity is determined (102, 103). That is, since the call setup request primitive is handled by the entity of the L3 local process 63 shown in Fig. 6, the L3 local environment variable table L3env_tab [] specified by the link ID id and the minor link ID mid. It is processed with reference to.

Subsequently, if the current state of the determined L3 entity is null (U0) state, it generates and sends a SETUP message to layer 2, and the L3 local environment variable table (L3env_tab) specified by the determined link ID and the minor link ID. The timer T303 on []) is started, and the state of the entity is set to call initiated U1 (104, 105, 106, 107).

At this time, the setup message includes at least bearer capability information elements (IEs) and may include other information elements (eg, address and facility related information elements) required for call setup.

The timer T303 is for setting the maximum response time until the first response arrives after the user sends the call setup message to the network. The default value is 4 in Table 9-2 (Timers in the user side) of Q.931. It is in seconds. Therefore, after the timer T303 has been started 4 seconds after the start (time oout), the end of the T303 must be generated and processed accordingly.

If a call setup request (SETUP_REQ) primitive is received and is not null (U0), an exception handling routine is driven to indicate an error or provide information for debugging (108).

FIG. 9 is a flowchart of a procedure for processing a T303 end primitive generated when the timer T303 started in the flowchart shown in FIG. 8 ends.

In general, a timer end primitive is a primitive that is generated at layer 3 and received / processed again at layer 3 when the started timer expires. The sequence of discriminating primitives is similar to other message processing primitives.

When the T303 end (T303_EXP) primitive is received, it is determined whether the state of the layer 3 entity is a call initiated state (U1), and if it is a call initiation state (U1), it is determined whether it is the first end again (200 to 205). ). That is, even after T303 is terminated, one retry is enabled to prevent delay of call setting due to an instantaneous error. Therefore, retry is performed at the first end and error processing is performed at the second or more time.

Subsequently, if it is the first end, a SETUP message is generated again and retransmitted to layer 2, and the timer T303 is started again (206, 207). If it is the second or more end, the call setup confirmation (SETUP_CFM) primitive with error information is sent to the management (CC) layer, the call reference number (CR) is released, and the corresponding layer 3 entity is null. state: U0) (208, 209, 210).

As described above, in processing the call setup request (SETUP_REQ) primitive according to the present invention, the primitive is first identified, and then the appropriate processing procedure is performed according to the state, thereby optimizing the processing procedure to reduce the processing time and reduce the code amount. It can work. In addition, by enabling a multi-line configuration, the channel capacity can be expanded as needed.

Claims (1)

A method for implementing layer 3 to connect an ISDN terminal to a network according to a layered protocol in an integrated information communication network, the method comprising: determining an ID and a link ID of a received primitive; If the received primitive is a call setup request (SETUP_REQ) primitive, checking a minor link ID and determining a state of a corresponding layer 3 entity; If the status of the layer 3 entity is null, sending a SETUP message to layer 2; And initiating the timer T303 and placing the entity in a call initiated state U1. The method for processing a call establishment request primitive at Layer 3 of an ISDN user-network connection.