KR980013104A - How ISDN User-Network Connections Handle Primitives at Layer 3 - Google Patents

Abstract

The present invention relates to a primitive processing method at a layer 3 of an ISDN user-network connection, comprising the steps of: determining an ID of a received primitive and a link ID; If the received primitive is a call resume request (RESUME_REQ) primitive, identifying a minor link ID and determining the state of the layer 3 entity; If the state of the layer 3 entity is a null state (U0), designating a minor link ID according to the assigned call reference number, generating a call resume message, and transmitting the message to the layer 2; Activating the corresponding timer T318 and switching the state of the layer 3 entity to the resuming request state, thereby connecting the ISDN terminal to the network according to the layered protocol in the integrated information communication network.

Description

How ISDN User-Network Connections Handle Primitives at Layer 3

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a connection technique between a USER and a NETWORK in an Integrated Services Digital Network (ISDN). More particularly, the present invention relates to a connection method of a call resume request (RESUME_REQ) primitive Quot;

With the advancement of the information society, communication demands are diversified, and media handled by communication networks such as voice, data, and video are diversified. As a result, it is impossible to provide efficient services for individual networks that are constructed for each service. Accordingly, an ISDN (Integrated Services Digital Network) has been introduced, which can provide a comprehensive service by integrating and digitizing individual networks established for each service. In order to uniformly accommodate various terminals, (DSS1: Digital Subscriber Signaling System 1), and the interface between the network and the network is standardized as No. 7 Common Line Signaling System (CCS).

DSS1, which is a signaling scheme of a user-to-network interface (UNI) of the ISDN, is implemented as a layer from Layer 1 to Layer 3 according to the OSI (Open Systems Interconnection) reference model, The relationship between the outline and the recommendations of ITU-T is shown in Table 1 below.

[Table 1]

Configuration of digital subscriber line signal system

Referring to FIG. 1, a first network terminal NT1 located in a house (or a building) is connected to an ISDN exchange located in a domestic telephone, and an ISDN terminal TE1 is connected to the first network terminal NT1 through a S / Or the second network terminal NT2 is connected to the first network terminal NT1.

Herein, 'NT1' (network terminal apparatus 1) is a transmitting / receiving apparatus in a house for transmitting a digital signal to a subscriber line, 'NT2' (network terminal apparatus 2) is a device corresponding to a private branch exchange (PBX) 'TE1' may be directly connected to the NT1 as an ISDN standard terminal and may be connected via the NT2, and 'TE2', which is an existing terminal not having the ISDN corresponding function, may be connected to the terminal And is connected to the ISDN network through the terminal adapter TA.

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

A subscriber terminal such as an ISDN terminal is connected according to the protocols of Layer 1 to Layer 3 described above in order to be connected to an ISDN exchange, and a recommendation for defining such connection is shown in Table 1 above.

In Table 1, layer 1 is a user-network interface of the physical layer recommended in ISDN Recommendations I.430 and I.431, and has a basic interface of 2B + D connection and a primary group interface of 23B + D or 30B + D In the basic interface, the frame structure consists of 48 bits in 250 μs units.

Layer 2 is generally called LAPD (Link Access Procedure on D channel). First, it adopts the BALANCE mode of HDLC which is the standard of the standardized data link layer. The basic format is a flag, An address field, a control field, an information field, a frame check sequence (FCS), and a flag.

Layer 3 controls the circuit-switched services provided by the network and the set up, maintenance, and release of communication paths required for the packet-switched service and requests for various added services. To this end, Layer 3 and Layer 3 receive And transmits a call setup message to the other party through the lower layer. General information related 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 the ISDN terminal, the functions described above must be implemented. It is a "PROTOCOL" in which the appointment is defined between the layers, and a "PRIMITIVE" in which the logical exchange between the upper and lower layers is defined . In other words, there are entities (ENTITY) in each layer that implement the function of the layer, and these entities exchange information between the top and bottom through the primitive.

These primitives are divided into four types such as REQUEST, INDICATE, RESPONSE and CONFIRM. Most of the primitives related to data transmission are REQUEST ) Primitive and an INDICATE primitive that is passed from the lower layer to the upper layer.

The CONFIRM primitive is a primitive informing an upper layer when a lower layer is obliged to respond to a specific request primitive from an upper layer, and a RESPONSE primitive is a primitive indicating a specific indication primitive from a lower layer Is a primitive for informing a lower layer when an upper layer has an obligation to respond to it.

2, the primitives to be processed in the layer 3 (Q.931) include a setting indication (DL_ESTABLISH_IND), a setting confirmation (DL_EST_CFM), a release confirmation (DL_REL_CFM), a data indication (DL_DAT_IND ), A unit data display (DL_UDA_IND), a resume request REST_REQ received from the GCR, a resume confirmation REST_CFM transmitted to the GCR, a timer T316 and a timer T317. The call request ALERT_REQ, the disconnection request DISC_REQ, the information request INFO_REQ, the additional information request MORE_INFO_REQ, the notification request NOTI_REQ, the call progress request PROC_REQ, the call progress request PROG_REQ, T301_EXP, T301_EXP, T301_EXP, T301_EXP, T301_EXP, T301_EXP, and T301_EXP, which are resent to themselves at layer 3, are present in the layer 3, RELE_REQ, RESU_REQ, SETUP_RES, SETUP_REQ and SUSP_REQ, 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, and T322_EXP. In this case, xx_xxxx_REQ indicates the request primitive, xx_xxxx_IND indicates the indication primitive, xx_xxxx_RES indicates the response primitive, and xx_xxxx_CFM indicates the acknowledgment primitive. And 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 M_xxxx_xxx is a primitive between the management layer and the data link layer Lt; / RTI > There is no prefix between Layer 3 and the management layer, and the management (MG) layer is divided into "Call Control" and "Global Call Reference Control (GCR)".

Also, the "state" defined in layer 3 (Q.931) is defined according to the kind of call and whether it is user side or network side.

[Table 2a]

State of layer 3 (circuit switched call / user side)

[Table 2b]

On the other hand, the conventional scheme for handling such primitives in layer 3 has been proposed as SDL in Annex A (ANNEX A) of Recommendation Q.391, which is schematically shown in FIG.

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

That is, when a primitive is received in the past in processing a RESUME_REQ request primitive, first, after determining the current state of the L3 layer (which state is U0 to U25), it goes to the corresponding state processing routine, (RESUME_REQ) primitive by determining what the primitive is.

As described above, since the state of the layer 3 is about 15 to 20 types and the kinds of the primitives to be processed are about 30, it takes much time to determine the state and to determine the primitive. There is a problem that the code length is long in the program.

Therefore, when similar processing is repeated in different states, it is necessary to optimize the processing to shorten the processing time and to reduce the code size. Furthermore, by making it possible to construct multiple lines to widen the channel bandwidth, It is desirable to expand it.

SUMMARY OF THE INVENTION Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and an object of the present invention is to provide a RESUME_REQ primitive processing method that optimizes a processing procedure.

It is another object of the present invention to provide a RESUME_REQ primitive processing method that enables an ISDN terminal to be configured as multiple lines and connected to a network.

According to an aspect of the present invention, there is provided a method for implementing a layer 3 for connecting an ISDN terminal to a network according to a layered protocol in an integrated information communication network, ; If the received primitive is a call resume request (RESUME_REQ) primitive, identifying a minor link ID and determining the state of the layer 3 entity; If the state of the layer 3 entity is a null state (U0), designating a minor link ID according to the assigned call reference number, generating a RESUME message and transmitting the message to the layer 2; And activating the timer T318 and switching the state of the layer 3 entity to the resume request state U17.

1 shows a user-network connection of an ISDN;

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

Figure 3 is a schematic diagram illustrating a conventional method of processing primitives in an ISDN UNI layer 3;

4 is a diagram showing an example of an ISDN communication card to which the present invention is applicable;

5 is a detailed block diagram of the channel connection portion shown in FIG.

6 is a conceptual diagram illustrating processes that are processed in an ISDN communication card in accordance with the present invention.

Figures 7A through 7E show the data formats used in the present invention.

8 is a diagram illustrating a RESUME_REQ primitive processing method according to the present invention.

9 is a flowchart of a procedure for processing a T318 termination primitive that occurs when a timer T318 activated in accordance with the flow shown in Fig. 8 is terminated.

Description of the Related Art

1: ISDN terminal 3-1 to n: handset 5-1 to N: network terminal device 7: ISDN network 10: PC 12: slot 20: ISDN communication card 21: DP RAM 22: memory 23: 1 to n: CODEC 25-1 to n: Channel connection unit (ISAC) 26: Socket 27: S-bus 28:

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

4, an ISDN terminal 1 is connected to a personal computer (PC) 10 through a slot 12 and an ISDN terminal 1, Card 20. The ISDN communication card 20 is connected to the network terminal apparatuses NT1: 5-1 to 5-n through the S bus 27, Is connected to the ISDN network 7 via the subscriber line 28. [

The ISDN communication card 20 to which the present invention is applied includes n channel connection units (ISAC: 25-1 to n) for connecting 2B + D basic interfaces to n ISDN networks 7, respectively. And these n channel connection units are connected to the network terminal devices 5-1 to 5-n via the S bus 27, respectively.

If the host system can not transmit data to one basic interface (2B + D) because the amount of data to be transmitted by the host system is large (for example, application to the video conferencing system or the like) , And the host system can transmit data by appropriately expanding the channel capacity by adding several (n) basic interfaces.

4, the ISDN communication card 20 includes a dual port RAM (DP RAM) 21, a memory 22, a CPU 23, CODECs 24-1 to n, : 25-1 to n), and functions of layers 1 to 3 are implemented so that the ISDN terminal 1 can be connected to the ISDN network 7 as described above. And is built in the memory 22.

4, the DP RAM 21 provides a physical pathway for transferring data with the PC 10, which is a host system, through the slot 12, and the memory 22 stores various kinds of information for operating the communication card 20 Programs and system data are stored and the CPU 23 activates various processes according to the software stored in the memory 22 to control the operation of the entire communication card.

In the embodiment of the present invention, the IDT 71321 is used as the dual port RAM 21 and the 80C188 of Intel Corporation is used as the CPU 23. [

The codecs 24-1 to 24-n are used for connecting a voice to the basic interface. The codecs 24-1 to n encode and decode voice signals input / output through the handsets 3-1 to 3-n, And the channel connection units 25-1 to 25-n are configured as shown in FIG. 5 to connect the data terminal and the voice terminal to the network terminal devices 5-1 to 5-n.

5, the channel connection units 25-1 to 25-n include an SSI 51, an SDL 52, a B channel switching unit 53, a D channel processing unit 54, a FIFO 55, a processor connection unit 56, An IOM 57, a buffer 58, a buffer control unit 59 and an ISDN basic access layer 1 unit 60. The channel connection unit having such a configuration can be realized as a single semiconductor chip and can be purchased on the market.

In the embodiment of the present invention, the channel connection units 25-1 to 25-n are implemented as an ISAC (ISDN Subscriber Access Controller Model name: PEB2085) of SIEMENS, and the operation of the ISAC is described in detail in the Technical Manual .

Entities in the respective layers are divided into LAPD process 61, L3 common process 62 and L3 local process 63 in order to process the primitives in the ISDN communication card 20, And operates with reference to the variable table.

Here, the L3 common process 62 includes entities for processing primitives (DL_EST_IND, DL_EST_CFM, DL_RELE_IND, DL_RELE_CFM, DL_DATA_IND, L_UDATA_IND) transmitted from the layer 2 process 61 to the layer 3 and primitives related to the GCR , 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) (L3coord_tab [x]), and the environment variable table is also identified by a link ID. The layer 3 local process 63 refers to the layer 3 local environment variable table L3env_tab [x], which includes two link IDs per link ID, and stores the link ID and the minor link ID (mID) ≪ / RTI >

In Fig. 6, the depicted processes illustrate the case where there are three link identities id and six minor link identities (mid) (i.e., for communication cards with three channel interfaces (ISAC)).

4, when a plurality of ISACs are provided on the ISDN communication card to form multiple lines, the link IDs (IDs) are assigned from 1 to a (or 0 to n is an identification number of 0 or 1 for identifying a B channel on each line (there are two B channels in a 2B + D basic connection), and a minor link ID (mID)

As described above, since a plurality of lines can be provided in the present invention, a link ID (ID) and a minor link ID (mID) are used so that they can be identified.

On the other hand, FIG. 7 shows a data format of messages or primitives processed on the ISDN communication card, in which 7a is a primitive without a message, 7b and 7c are non-numbered formats, and 7d and 7e are numbered formats, respectively.

7, the Q.931 message field is a portion processed by layer 3, the Q.291 non-recipient and number field is a part (header) processed in layer 2, and the primitive header part is a part processed by layer 3, It is the part used for primitive processing in the layer.

In other words, in 7a to 7e, the primitive header is composed of a primitive id, a link id (ID), a minor link ID (mlink_id = mID) for identifying a primitive, and a size Addr "," addr "," n_r ", and" n_s "in the non-number field of Q.921 are composed of" add1 " Quot; (4 bytes). These Q.921 fields and Q.931's message fields are described in detail in the Recommendations and will not be described further.

Figure 8 is a flow chart illustrating a method for processing a RESUME_REQ request primitive in accordance with the present invention.

The RESUME_REQ primitive is a primitive that sends a Suspended call from the Management (CC) layer to the Layer 3 entity to resume a call on another terminal of the same type, ) It is a primitive that is valid only in state (U0).

In this case, a situation in which a pause is required is a state in which the user physically disconnects for a while while maintaining a call to move the terminal to another location, or a situation where a plurality of terminals of the same type exist in one ISDN line, , Or a situation where the user temporarily truncates the call of the current B channel to respond to a call received on another B channel, or the like.

And if this primitive is received in a null state U0, it sends a RESUME message with a new call reference number (CR) to the network side, activates the corresponding timer T318, Resume request: U17).

Referring to FIG. 8, when an arbitrary primitive is received in the primitive receiving step, a primitive id and a link id are discriminated (100, 101). Here, a primitive ID is recorded in a "header of a primitive" together with a link ID as an identifier defined to identify the type of a primitive.

The link ID is for identifying a basic interface on multiple lines. For example, if the link ID is "0 ", it refers to a basic interface provided through ISAC1 (25-1 in FIG. 4) It can be seen that it is related to the process on Link 0.

Next, if the received primitive is a RESUME_REQ request primitive, a minor link ID (mid) is checked and the current state of the layer 3 entity is determined (102, 103). That is, since the RESUME_REQ primitive is processed by the entity of the L3 local process 63 shown in FIG. 6, the L3 local environment variable table (L3) specified by the link ID (id) and the minor link ID L3env_tab_ []).

Then, if the current state of the L3 entity identified is a null state (U0), a new call reference is assigned to the minor link ID, a RESUME message is generated and transmitted to the layer 2 (105, 106 ).

Then, the timer T318 is activated, and the state of the layer 3 entity is changed to a resume request (U17) (107, 108).

If the RESUME_REQ primitive is received but not null state U0, an exception handling routine is driven to indicate an error or provide information for debugging (109).

9 is a flowchart of a procedure for processing a T318 termination primitive that occurs when a timer T318 activated in accordance with the flow shown in Fig. 8 is terminated.

Timer T318 is a timer that operates while waiting for a response from the user after sending a RESUME message to the network for the acknowledgment and in Table 9-2 of Q.931 the default value is 4 seconds. Therefore, if a RESUME ACK or a RESUME REJECT message is not received within 4 seconds after transmitting the acknowledgment message, the T318 termination primitive is generated due to timeout.

The T318 termination primitive processing procedure checks the ID of the received primitive and the link ID, as in the other general primitives, and then determines whether the state of the corresponding entity is a resume request (17) if the T318 termination primitive is set (200 to 204).

(RESUME_CFM) primitive including the error information is generated and transmitted to the management (CC) layer, and a RELEASE message is generated and transmitted to the layer 2 (205, 206).

Then, the timer T318 is activated, and the state of the corresponding entity is switched to the release request state U19 (207, 208). If it is not the resume request state U17, the error processing routine is driven (209).

As described above, according to the present invention, primitives are first identified in the RESUME_REQ primitive processing, and then the appropriate processing procedure is performed according to the state, thereby optimizing the processing procedure to shorten the processing time and reduce the code amount There is an effect that can be. In addition, by enabling multi-line configuration, the channel capacity can be expanded as needed.

Claims (2)

A method for implementing layer 3 for connecting an ISDN terminal to a network according to a layered protocol in an integrated information communication network, the method comprising: identifying an ID of a received primitive and a link ID; If the received primitive is a call resume request (RESUME_REQ) primitive, identifying a minor link ID and determining the state of the layer 3 entity; If the state of the layer 3 entity is a null state, designating a minor link ID according to the assigned call reference number (CR), generating a RESUME message and transmitting the message to the layer 2; And activating a corresponding timer T318 and transitioning the state of the layer 3 entity to a resume request state U17. 2. The method of claim 1, wherein when the activated timer (T318) has elapsed after a predetermined time elapses, a RESUME_CFM primitive containing error information is transmitted to the management layer, a RELEASE message is generated, And initiates T308. The method of claim 1, wherein the T308 initiates the T308. ※ Note: It is disclosed by the contents of the first application.