KR980013112A - 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 disconnection request (DISCONNECT_REQ) primitive, identifying a minor link ID and determining the status of the layer 3 entity; The state of the layer 3 entity is set to the null state U0, the call initiation U1, the call presence U6, the disconnection request U11, the disconnection indication U12, the pause request U15, the resume request U17, Generating a DISCONNECT message including an information element and transmitting the DISCONNECT message to layer 2 if one of the request (U19) states is satisfied; Activating a corresponding timer T303 if the entity is in a call initiation state (U1); And activating the timer T305 and switching the state of the corresponding entity to a disconnection request U11, 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 (USER) and a network in an Integrated Services Digital Network (ISDN). More particularly, the present invention relates to a technique of transmitting a DISCONNECT_REQ primitive received from a management (CC) layer in Layer 3 Lt; / RTI >

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. 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, Interface is standardized as digital subscriber signaling system 1 (DSS1), and the interface between network and network is standardized as No. 7 common 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.

And a subscriber terminal such as an ISDN terminal are connected according to the protocol of layer 1 to layer 3 described above in order to be connected to an ISDN exchange, and a recommendation stipulating 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 I431, 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 ㎲ units.

Layer 2 is generally called LAPD (Link Access Procedure on the D channel). First, it adopts the BALANCE mode of HDLC which is the standard of the standardized data link layer, 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 that implement the functions of the layer in each layer, and these entities are supposed to exchange information between the top and bottom through primitives.

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, ), A reset request (RELE_REQ), an acknowledgment request (RESU_REQ), a call setup response (SETUP_RES), a call setup request (SETUP_REQ), a call pause request (SUSP_REQ), and timers T301_EXP, 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_xxx_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 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" 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.931, 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 the DISCONNECT_REQ primitive, the primitive is discriminated from the current state of the L3 layer (which state is U0 to U25) And processed the DISCONNECT_REQ primitive.

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 to solve the above-mentioned problems, and it is an object of the present invention to provide a method of processing a discontinuity request (DISCONNECT_REQ).

It is another object of the present invention to provide a disconnection request (DISCONNECT_REQ) primitive processing method that enables an ISDN terminal to be connected to a network by configuring multiple lines.

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 disconnection request (DISCONNECT_REQ) primitive, identifying a minor link ID and determining the status of the layer 3 entity; The state of the layer 3 entity is set to the null state U0, the call initiation U1, the call presence U6, the disconnection request U11, the disconnection indication U12, the pause request U15, the resume request U17, Generating a DISCONNECT message including an information element and transmitting the DISCONNECT message to layer 2 if one of the request (U19) states is satisfied; Activating a corresponding timer T303 if the entity is in a call initiation state (U1); And switching the state of the corresponding entity to the disconnection request U11 after activating the timer T305.

1 is a diagram illustrating a user-network connection of an ISDN,

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

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 applied,

5 is a detailed block diagram of the channel connection portion shown in FIG. 4,

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

Figures 7A through 7E are diagrams illustrating the data formats used in the present invention,

8 is a diagram illustrating a method of processing a DISCONNECT_REQ primitive according to the present invention;

9 is a flow chart of a procedure for processing the T305 termination primitive that occurs when the timer T305 activated according to the flow shown in Fig. 8 is terminated.

DESCRIPTION OF THE REFERENCE NUMERALS

1: ISDN terminals 3-1 to 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 to n: CODECs 25-1 to 25-n: Channel connection units (ISAC)

26: Socket 27: S bus

28: Subscriber Line

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 an ISDN communication card 12 through a slot 12, The ISDN communication card 20 is connected to the network terminal apparatuses NT1: 5-1 to 5-n through the S bus 27, and the network terminal apparatuses 5-1 to 5-n And 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 ISDNs 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 connection unit 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 commercially . 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 .

6, the entities of the respective layers are divided into a LAPD process 61, an L3 common process 62 and an 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 the primitives DL_EST_IND, DL_EST_CFM, DL_RELE_IND, DL_RELE_CFM, DL_DATA_IND and DL_UDATA_IND transmitted from the layer 2 process 61 to the layer 3 and primitives related to 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) (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 installed on the ISDN communication card to form multiple lines, the link ID (ID) is set to 1 to n (or 0 (MID) is an identification number of 0 or 1 for identifying the B channel on each line (there are two B channels in the 2B + D basic connection), and the minor link ID .

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 the portion processed by Layer 3, the Q.291 Unnumbered and Numbered fields are the portion (header) processed in Layer 2, the primitive header portion is for information transfer between layers, It is the part used for primitive processing in each 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 The non-number field of Q921 is composed of "add1", "add2", "n_r", "n_s" ( 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 handling a DISCONNECT_REQ primitive in accordance with the present invention. The DISCONNECT_REQ primitive is a primitive that is passed from the call control processor (CC) of the management layer to the layer 3 entity when the user wishes to clear the call, Clearing initiated by the user.

The state of layer 3 that can handle the disconnection request primitive is a null state U0, a call initiated U1, a call present U6, a disconnect request U11, (Disconnect indication U12), a Suspend request (U15), a Resume request (U17), and a Release request (U19) state. When a disconnect request primitive is received in one of these states A DISCONNECT message is generated and transmitted to the other party to start the call release procedure, and timer T305 is started. At this time, the disconnect message may include a CAUSE information element, and in the call initiation state (U1), the active timer T303 must be stopped.

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 an information request (INFORMATION_REQ) 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 call progress request primitive is processed 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 .

Then, the current state of the L3 entity identified is a null state U0, a call initiated U1, a call present U6, a disconnection request U11, a disconnection indication (U12), a suspend request (U15), a resume request (U17), and a release request (U19), a DISCONNECT message including an information element is generated, 2 (104, 105, 106). At this time, the size of the primitive header includes the length of the information element included in the DISCONNECT message (e.g., cause information element).

If the entity is in a call initiated state (U1), the corresponding timer T303 is stopped (107, 108).

When the operation is completed, the timer T305 is activated, and the state of the corresponding entity is switched to a disconnection request (U11) (109, 110).

If the DISCONNECT_REQ primitive is received, the null state U0, Call initiated U1, Call present U6, Disconnect request U11, It is possible to display an error by driving an exception handling routine if the status is not one of a status (Disconnect indication U12), a suspend request (U15), a resume request (U17), and a release request (U19) And provides information for debugging (111).

9 is a flow chart of a procedure for processing the T305 termination primitive that occurs when the timer T305 activated according to the flow shown in Fig. 8 is terminated.

Timer T305 is a timer that operates in the DISCONNECT_REQ state and is activated after sending a DISCONNECT message from the user side to the network side until a response is received. The time of timer T305 is set to 30 seconds in Table 9-2 of Q.931 and is normally stopped by a RELEASE message or a DISCONNECT message.

The processing procedure of the T305 termination primitive generated by terminating the timer T305 determines whether the corresponding entity is in a cutoff request (U11) state after the primitive ID and the link ID are identified as in the other primitives, if the T305 is the termination primitive (200 to 204) .

As a result of the determination, if the disconnection request state (U11), the RELEASE message including the CAUSE information element causing the cause number to be 102 (Recovery on timer expiry) is transmitted to the layer 2 and the timer T308 is started (205,206 ). Subsequently, the state of the corresponding entity is switched to the release request state U19 (207). If the entity is not in a disconnection request state, the exception processing routine is driven (208).

As described above, according to the present invention, in processing the DISCONNECT_REQ primitive, the primitives are first identified, and then the appropriate processing procedure is performed according to the state to optimize the processing procedure, thereby shortening the processing time and reducing 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 disconnection request (DISCONNECT_REQ) primitive, identifying a minor link ID and determining the status of the layer 3 entity; The state of the layer 3 entity is set to the null state U0, the call initiation U1, the call presence U6, the disconnection request U11, the disconnection indication U12, the pause request U15, the resume request U17, Generating a DISCONNECT message including an information element and transmitting the DISCONNECT message to layer 2 if one of the request (U19) states is satisfied; Activating a corresponding timer T303 if the entity is in a call initiation state (U1); And switching the state of the entity to a truncation request (U11) after activating the timer (T305) in the layer (3) of the ISDN user-network connection. 2. The method of claim 1, wherein, when the activated timer T305 has elapsed after a predetermined time elapses, a release message having a predetermined cause number is generated and transmitted to the layer 2, the timer T308 is activated, In a layer 3 of an ISDN user-network connection. ※ Note: It is disclosed by the contents of the first application.