JPH05199264A - D-channel control system - Google Patents

Abstract

PURPOSE:To improve the throughput of a line adaptor section with respect to the control system of a layer 2 protocol using a D-channel in relation with the control of a layer 1 protocol in the line adaptor section accommodating a terminal equipment in an ISDN. CONSTITUTION:A layer 2 monitor means 106 in a line adaptor section 104 does not need the termination operation as to frame data including packet data whose transfer number is high but monitoring of the arrival of the data or implementation of the reception operation as to a maintenance frame with a few transfer number. A packet processing means 102 implements termination processing in the lump as to frame data including packet data with lots of transfer number. Thus, it is not required to provide a layer 2 termination section for frame data including packet data with a heavy processing load and many transfer numbers to improve the processing capability of the means.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a D channel control system in an ISDN (Integrated Services Digital Network), and more specifically, in connection with control of a layer 1 protocol in a line interface for accommodating a terminal device. The present invention relates to a control method of a layer 2 protocol using a channel.

[0002]

2. Description of the Related Art In ISDN which can handle various information in an integrated manner, each transmission rate is 64 as a basic interface corresponding to a normal subscriber such as an individual subscriber.
Two information channels B of kbit / s and transmission speed of 16 kbit
An interface having a 2B + D structure consisting of one signal channel D of / s is provided. That is, in the basic interface example, a subscriber can use three information channels and can provide a much larger capacity and variety of interfaces as compared to the traditional analog telephone network.

In this case, the B channel is a channel exclusively used for transmitting information such as telephone and data. Also,
The D channel is a signal channel independent of the information channel B, and is used for transmitting call control signals such as the information channel B, and also for transmitting low speed packet data. In this way, by making the information channel and signal channel independent, it becomes possible to respond to the diversification and sophistication of various services, and to realize unified control of telephones and other data terminals. Various terminals can be connected to one subscriber line.

In order to provide such advanced services, it is necessary to define the communication protocol more strictly than before. Therefore, ISDN adopts a layered protocol based on the OSI (Open System Connection) reference model proposed by ISO (International Organization for Standardization) and agreed by CCITT (International Telegraph and Telephone Consultative Committee).

Among the layered protocols in ISDN, the main protocols of the lower layer (lower layer) are as follows. Layer 1: Rules for electrical and physical conditions of subscriber lines. That is, the rules regarding the speed and bit configuration of the interface such as 2B + D, the home wiring format, and the code format.

Layer 2: A protocol regarding a frame data structure for realizing a transparent transfer function of upper layer information (call control signal or packet data) between a terminal and a network by D channel. Since the D channel is used, LAPD (Link Access Procedure for D-channel)
Called.

Layer 3: establishment and maintenance of communication paths (calls)
Regulations regarding control such as opening. In particular, a protocol that enables requests for both circuit switching using the information channel B and packet switching using the signal channel D, and other additional services.

Here, LA, which is a layer 2 protocol, is used.
In connection with PD, on the D channel, in addition to the link for call control signal transmission as described above, a link for low speed packet data transmission is also established. Therefore, in LAPD, 1
A plurality of independent links can be simultaneously established on one physical interface, and the bus connection wiring of a plurality of terminals in the home can simultaneously establish an independent connection to each of the plurality of terminals on one physical interface. The link can be established. Such a link access protocol is generally called "multiple LAP".

In order to realize the above-mentioned multiple LAP, LA
The PD adopts a frame data structure which is an extension of the HDLC (High Level Data Transmission Procedure) frame format, and each frame has a SAPI for identifying the information transfer function type such as call control signal or packet data. Service access point identifier and a terminal termination point identifier called TEI for identifying a plurality of terminals in the same house, and data following the layer 3 or higher protocol such as call control data and packet data in the information field that follows. Is stored.

FIG. 10 is a diagram showing a conventional example of the control method of the multiple LAP based on the frame data structure as described above in relation to the control of the layer 1 protocol. CC
A terminal device 1001 (including a local area network, etc.) connected to a point S or a point T which is a defined point of a user / network interface defined based on ITT Recommendation I.411 is terminated by a line interface 1002, It is connected to a call control signal processing unit 1003 which is an exchange switch unit.

In the line interface 1002, the layer 1 terminal 1005 accommodates the subscriber line 1012 and separates the two information channels B1 and B2 from the signal channel D. The B1 and B2 channels separated here are transferred to the call control signal processing unit 1003, and exchange processing is performed on each channel. On the other hand, the D channel frame data demultiplexed by the layer 1 termination unit 1005 is demultiplexed by the demultiplexing unit 1006.
, And the SAPI in the frame data is determined there.

In the demultiplexing unit 1006, SAPI is "0",
That is, when it is determined that the frame data including the data is data for a call control signal, the layer 2 termination unit 1
At 007, the call control data included in the frame data is analyzed and transferred to the call control processor (CC) 1013 via the call control signal processing unit 1003.
Call control processing is performed here.

In the demultiplexing / multiplexing unit 1006, the SAPI is "1".
6 ", that is, when it is determined that the frame data including it is packet data, the layer 2 termination unit 1
At 008, the packet data included in the frame data is analyzed and converted into a frame format inside the exchange. Then, the packet data thus converted is transferred to the Dch packet processing unit 1004 via the call control signal processing unit 1003 (the layer 2 termination unit 1009 will be described later), and the layer 2 termination unit in the processing unit is transferred. It is received at 1011. Dch packet processing unit 100
4 executes an exchange process on the received packet data and transfers it to another exchange or the like.

Up to this point, the structure for transferring data from the terminal device 1001 side to the call control signal processing unit 1003 side has been described, but the reverse case has the same structure. However, the packet data transferred from the Dch packet processing unit 1004 to the line interface unit 1002 via the call control signal processing unit 1003 is terminated by the layer 2 termination unit 1009, and then the demultiplexing unit 1006 and layer 1 termination unit. It is sent to the subscriber line 1012 via 1002.

Here, the starting relation between the layer 1 and the layer 2 in the line interface 1002 will be described. As described above, the communication protocol in ISDN has a hierarchical structure, and the higher layer protocol is defined on the premise of the lower layer protocol. Therefore, when the line is activated and becomes available, the control operation must be started in order from the lower layer, and conversely, when the use of the line is ended, the control operation is started in order from the higher layer. Needs to be terminated.

Therefore, when the line is activated by the line interface unit 1002 itself or the terminal device 1001, the layer 1 terminal unit 1005 is based on the layer 1 for electrically activating the subscriber line 1012. The control operation is started, and thereafter, the control operation based on Layer 2 for establishing the multiplex link of SAPI = 0 or SAPI = 16 is started.

On the other hand, when the use of the line is terminated in the line interface unit 1002, the layer 1 control unit 1010
Monitors the operating states of the layer 2 termination units 1007 and 1008, and detects the disappearance of all the links in the LAPD (Layer 2) via both termination units.
12 is electrically inactivated, and the control operation based on layer 1 is completed.

[0018]

In the conventional example having the structure shown in FIG. 10, a subscriber line 101 facing each subscriber is provided.
In the line corresponding unit 1002 provided for each two, each layer 2 termination unit 1007, 1008, 1009 or the like is generally realized as a function of a microprocessor or DSP. Then, the layer 2 terminating unit 1 for terminating the frame data having SAPI = 0 including the call control data
In No. 007, the number of transfer of call control data is small, so that the load on the microprocessor or the like due to the operation of the termination unit is not so large. On the other hand, the layer 2 termination units 1008 and 1009 for terminating the frame data having SAPI = 16 including the packet data are
Since the number of packet data transfers is large, the load on the microprocessor or the like due to the operation of the terminal end becomes very large.

Therefore, in the line interface unit 1002 having the configuration as shown in FIG. 10, the ratio of the processing of the two layer 2 termination units 1008 and 1009 in the overall processing of the microprocessor or the like becomes very large, and as a result, The processing capability of the line interface unit 1002 decreases, and the processing capacity of frame data based on LAPD (layer 2) per unit time becomes small, for example, and the terminal device 1001 from the network.
However, there is a problem that the response characteristic to is deteriorated.

An object of the present invention is to realize the control of the layer 1 and layer 2 protocols which can improve the processing capability of the line interface.

[0021]

FIG. 1 is a block diagram of the present invention. The present invention is premised on a digital network (ISDN) having a call control signal processing means 101 for performing circuit switching processing, a packet processing means 102 for performing packet switching processing, and a circuit corresponding means 104. Here, the line corresponding means 104 accommodates the terminal device 103, and separates / multiplexes the B channel (B1, B2) and the D channel by means such as 108 in FIG. Also, the line support means 104
1 separates / multiplexes the frame data storing the call control information and the frame data storing the packet information on the D channel by means such as 109 in FIG.

The following layer 2 terminating means 105 and layer 2 monitoring means 10 are provided in the line corresponding means 104.
6 and layer 1 control means 107. That is, the layer 2 terminating unit 105 monitors and controls the layer 2 link based on the frame data storing the call control information.

The layer 2 monitoring means 106 only monitors the layer 2 link based on the frame data storing the packet information. Therefore, the line corresponding means 104 does not terminate the link. The termination is performed by the packet processing means 102.

The layer 1 control means 107 disconnects the layer 1 link in its own line handling means 104 based on the disappearance of each layer 2 link detected by both the layer 2 termination means 105 and the layer 2 monitoring means 106. .. In this case, the layer 2 monitoring means 106 includes, for example, a timer means that is reset each time either one or both of the frame data storing the packet information directed to the terminal device 103 from the packet processing means 102 or the reverse frame data is received. When the timer means counts a predetermined time, the disappearance of the layer 2 link based on the frame data is detected. Then, the layer 2 monitoring means 106
The timer value notified from the packet processing means 102 using the frame data for maintenance on the D channel is set in the above-mentioned timer means as the predetermined time. Alternatively, the layer 2 monitoring means 106 receives from the packet processing means 102 a layer 2 link disconnection notification based on the frame data storing the packet information notified by using the maintenance frame data on the D channel. , The disappearance of the layer 2 link is detected.

In the above configuration, the line handling means 104
When any one of the terminal termination point identifiers (TEI) added to the frame data storing the call control information is released, the packet processing means using the frame data for maintenance on the D channel indicates that. Can be configured to notify 102. On the other hand, when the packet processing unit 102 detects a possibility of an error in any of the terminal termination point identifiers added to the frame data storing the packet information,
It can be configured to notify the line interface 104 of a request to activate the terminal termination point identifier check procedure using the frame data for maintenance on the D channel.

Further, a local area network (LAN) may be connected between the line corresponding means 104 and the call control signal processing means 101 via another line corresponding means. .. In this case, the line support unit 104 is a LAN node on the terminal side.

[0027]

The layer 2 monitoring means 106 does not need to perform the terminating operation for the frame data of SAPI = 16 including the packet data having a large number of transfers, and the arrival monitoring operation or the transfer of SAPI = 63, for example. It is only necessary to perform the receiving operation for a small number of maintenance frames. Then, an SAP including packet data with a large number of transfers
For the frame data of I = 16, the packet processing means 102 collectively carries out termination processing. Here, the packet processing means 102 does not need to be installed for each subscriber line like the line corresponding means 104, and at least one packet processing means 102 is required, so that the processing can be collectively executed by a processor having a high processing capacity.

As described above, the line interface means 104 does not need to be provided with the layer 2 termination section for the frame data including the packet data having a heavy processing load and a large number of transfers, and the line interface means 104 has a high processing capability. Can be improved.

[0029]

Embodiments of the present invention will now be described in detail with reference to the drawings. Overall Configuration of Embodiment FIG. 2 is a block diagram of an embodiment of the present invention. Portions having the same numbers as in FIG. 10 have the same functions.

The difference between FIG. 2 and FIG. 10 is that in the line interface 201 corresponding to the line interface 1002 of FIG.
The point is that the layer 2 termination units 1008 and 1009 in FIG. 10 are replaced by the frame monitoring unit 202.

In the frame monitoring unit 202, it is not necessary to perform the terminating operation for the frame data of SAPI = 16 including the packet data with a large number of transfers, and the specific monitoring operation described below or SAPI = 63. It is only necessary to perform the receiving operation for the maintenance frame with a small number of transfers. Then, S including packet data with a large number of transfers
The layer 2 termination unit 204 of the Dch packet processing unit 203 collectively terminates the frame data of API = 16. Here, the Dch packet processing unit 203 does not need to be installed for each subscriber line 1012 like the line corresponding unit 201, and at least one Dch packet processing unit 203 is sufficient. Therefore, a processor with high processing capability can collectively execute the processing.

As described above, the line interface unit 201 does not need to be provided with the layer 2 terminal unit having a heavy processing load such as 1008 and 1009 in FIG.
The processing capacity of 01 can be improved. Explanation of LAPD Frame Format Before explaining the specific operation of this embodiment, first,
The frame format of LAPD transferred by the D channel in the ISDN exchange network of FIG. 2 will be described with reference to FIG.

In FIG. 3, a flag F having a length of 1 octet is used.
Is bit pattern data of "01111110", for example, D
It is a flag for identifying the frame data of LAPD on the channel. As can be seen from the above, in the data portion other than the flag F, the bit "1" is controlled so as not to be consecutive 6 or more.

Next, the 2-octet long address field contains both SAPI and TEI identifiers. These data realize the multiple LAP described above. Subsequently, the control field having a length of 2 octets is used to transfer various control data.

In the information field having a maximum length of 260 octets, data based on a protocol of layer 3 or higher is stored, and as described above, the SAP of the address field is stored.
If I is "0", call control data is stored, and if it is "16", pattern data is stored. Thus, the LAPD frame data is variable length data. When the LAPD frame data is maintenance frame data with SAPI = 63, as will be described later, various maintenance data described later are stored in this information field.

Five examples of the operation of the line interface unit 201 of FIG. 2 based on the LAPD frame format as described above will be sequentially described below. First Embodiment of Operation of Line Corresponding Section In this operation example, the LAP is provided in the frame monitoring section 202.
A timer for measuring the passing interval of the D frame data is provided. This timer is not particularly shown in FIG. 2, but may be a hardware timer or a software-controlled timer.

When a packet data link is established on the D channel, the LAPD always uses the LAPD frame data (RR) at regular time intervals (for example, every 10 seconds).
(Called a frame) is a rule that is transferred on the D channel.

Therefore, the frame monitoring unit 202 monitors the LAPD frame data either on the transmission line from the Dch packet processing unit 203 to the demultiplexing unit 1006 or on the reverse transmission line, and each time it detects the frame data. Reset the internal timer. The operation of detecting the LAPD frame data is realized as an operation of detecting six consecutive "1" s of the flag F in FIG. Therefore, the frame monitoring unit 202 is realized by a simple circuit configuration including a circuit including a comparator and a counter and the above timer.

Then, when the timer measures the above-mentioned fixed time and times out, the frame monitoring section 202 notifies the layer 1 control section 1010 to that effect. The layer 1 control unit 1010 generates the notification of the above-mentioned timeout, and SAPI = via the layer 2 termination unit 1007.
When the disappearance of the 0 link is detected, the subscriber line 1012
Are electrically inactivated, and the control operation based on layer 1 is completed.

By the above operation, it is not necessary to provide a layer 2 termination unit for terminating frame data of SAPI = 16, which has a large number of transfers, in the line interface unit 201, and the processing capability of the line interface unit 201 can be improved. You can Second Embodiment of Operation of Line Corresponding Section In the above-mentioned first embodiment, the fixed time interval at which frame data is forcibly transmitted when the packet data is linked on the D channel is 2 terminal devices 1
It may change depending on the type of 001 and the like.

Therefore, in the second embodiment, first, the LAPD is set by the timer provided in the frame monitoring unit 202.
The operation of measuring the passing interval of the frame data is the same as that of the first embodiment. In addition to this, in the second embodiment, the Dch packet processing unit 203 notifies the line corresponding unit 201 provided corresponding to each subscriber line 1012 in FIG. 2 of the timer value which is the above-mentioned fixed time interval. Has a configuration.

The notification of the timer value from the Dch packet processing unit 203 to each line interface unit 201 is performed by using the maintenance frame. The maintenance frame is LAPD frame data transmitted on the D channel. As shown in FIG. 4 (a), the configuration is such that SAPI = 63 and the timer value for each line corresponding unit 201 is stored in the information field. Have.

The layer 2 terminating unit 204 of the Dch packet processing unit 203 of FIG. 2 has the terminal device 100 as shown in FIG.
The data of the maintenance frame as described above is sent to the highway connected to each line corresponding unit 201 while the frame data including the packet data of SAPI = 16 is communicated to and from No. 1.

In each line corresponding unit 201, the frame monitoring unit 202 of FIG. 2 monitors the arrival of the above-mentioned maintenance frame, and when the frame is received, the timer value contained therein is preset in the internal timer. ..

In this way, each line corresponding unit 201
According to the type of the terminal 1001 or the like connected to it, a fine-grained monitoring operation based on the operation of the first embodiment described above can be realized.

Since the number of maintenance frames transferred is small, the load on the line interface 201 of the frame monitoring unit 202 does not become heavy. Third Embodiment of Operation of Line Corresponding Section In this operation example, the frame monitoring section 202 uses the LAP
Two operations are performed: monitoring whether the D frame data passes and receiving a maintenance frame. Then, the detection of disappearance of the layer 2 link with SAPI = 16 in each line corresponding unit 201 is performed by the Dch packet processing unit 203 notifying each line corresponding unit 201 of “link disconnection”.

The notification of "link break" from the Dch packet processing unit 203 to each line corresponding unit 201 uses the maintenance frame of SAPI = 63 as shown in FIG. 5 similar to the second embodiment. Done. The information of "broken link" is stored in the information field. Then, the layer 2 termination unit 204 of the Dch packet processing unit 203 of FIG.
As shown in (b), SAPI = 1 with the terminal device 1001.
While the frame data including the packet data of No. 6 is being communicated, the above-mentioned maintenance frame data is sent to the highway connected to each line corresponding unit 201.

The operation of the third operation example realized by using such a maintenance frame will be described with reference to the state transition diagram of FIG. <State 1> First, in the state 1 in which both the layer 2 links of SAPI = 0 and SAPI = 16 are also stopped, and the layer 1 is also stopped, the line is activated by the line corresponding unit 1002 itself or the terminal device 1001. If
The layer 1 termination unit 1005 first starts a control operation based on layer 1 for electrically activating the subscriber line 1012.

Then, the layer 2 termination unit 1007 is
The arrival of the frame data of I = 0 is monitored, and the frame monitoring unit 202 monitors the arrival of the frame data of SAPI = 16.

In this state 1, when the layer 2 terminating unit 1007 receives the frame data of SAPI = 0, the layer 2 terminating unit 1007 terminates the frame data of SAPI = 0 and performs the link setting operation. Move to 2.

On the other hand, in the state 1, when the frame monitoring unit 202 receives the frame data of SAPI = 16,
Transition to state 3. <State 2> State 2 is a state in which there is a layer 2 link for SAPI = 0 call control and there is no SAPI = 16 layer 2 link for packet data transfer. This state 2
Then, the layer 2 termination unit 1007 is terminating the frame data of SAPI = 0, and the frame monitoring unit 20
2 performs only the arrival monitoring operation of the frame data of SAPI = 16.

In state 2, the layer 2 terminating unit 1007 outputs SA
When the layer 2 link with PI = 0 is terminated, the layer 1 control unit 1010 determines SAPI = 0 and SAPI = from the states of the layer 2 termination unit 1007 and the frame monitoring unit 202.
It is identified that both layer 2 links of 16 are lost. As a result, the layer 1 control unit 1010 electrically inactivates the subscriber line 1012, ends the control operation based on layer 1, and returns to the state 1 described above.

On the other hand, in the state 2, when the frame monitoring unit 202 receives the frame data of SAPI = 16,
Transition to state 4. <State 3> State 3 is a state in which there is no layer 2 link for call control with SAPI = 0 and there is a layer 2 link for packet data transfer with SAPI = 16. This state 3
Then, the layer 2 terminating unit 1007 monitors the arrival of the frame data of SAPI = 0, and the frame monitoring unit 202 monitors the arrival of the "link break" maintenance frame from the Dch packet processing unit 203. ing.

In the state 3, the layer 2 terminating unit 1007 is SA
When the frame data of PI = 0 is received, the layer 2 termination unit 1007 terminates the frame data of SAPI = 0, performs the link setting operation, and shifts to state 4.

On the other hand, in the state 3, when the frame monitoring unit 202 receives a maintenance link of "link broken", the layer 1 control unit 1010 determines the SAPI from the respective states of the layer 2 termination unit 1007 and the frame monitoring unit 202. = 0 and SA
It is identified that both layer 2 links of PI = 16 are lost. Thereby, the layer 1 control unit 1010
The subscriber line 1012 is electrically inactivated, the control operation based on layer 1 is terminated, and the state 1 is returned to. <State 4> State 4 is a state in which there are both a layer 2 link for SAPI = 0 call control and a layer 2 link for SAPI = 16 packet data transfer. In this state 4, the layer 2 terminating unit 1007 is terminating the frame data with SAPI = 0, and the frame monitoring unit 202 receives a “link break” from the Dch packet processing unit 203.
Monitoring operation of the arrival of the maintenance frame.

In state 4, the layer 2 terminating unit 1007 is SA
When the layer 2 link with PI = 0 is completed, the state returns to the state 3 described above. On the other hand, in the state 4, when the frame monitoring unit 202 receives the maintenance frame of "link broken", the state returns to the state 2 described above.

According to the third operation example as described above, the frame monitoring unit 202 only performs the operation of monitoring the arrival of the maintenance frame of "link break" from the Dch packet processing unit 203, and the layer 1 and layer 2 The cooperative control of can be realized. Fourth Embodiment of Operation of Line Corresponding Section As described above, one subscriber line 1 in FIG.
It is possible to connect a plurality of terminal devices (corresponding to 1001 in FIG. 2) to 012. In the control of LAPD, each terminal device is identified by the terminal termination point identifier TEI added to the frame data. It for that reason,
In the line interface 201, for example, the terminal device number and TEI
Corresponding table is provided.

Here, for example, one terminal device 1001
Is performing packet communication using the frame data of SAPI = 16 of the D channel, and the terminal device further uses the frame data of SAPI = 0 to make a call operation for line communication. , SAPI = 0
When an erroneous TEI that overlaps with another terminal device is added to the frame data of 1, the line interface unit 201 performs control to forcibly cancel the allocation of the TEI to the terminal device 1001.

In such a case, it is necessary to notify the Dch packet processing unit 203 of this. This is because, in the configuration of FIG. 2, the termination operation of the frame data of SAPI = 16 is not performed by the line corresponding unit 201 but is collectively performed by the Dch packet processing unit 203, so that the above notification is performed. If not, the Dch packet processing unit 203
Even after the above TEI is released, the released TE
This is because communication control is performed in association with the terminal device whose I has been canceled, and link consistency cannot be maintained.

Therefore, in the line interface 201, the TEI
When the TEI cancellation is canceled, the Dch packet processing unit 203 is notified of the TEI cancellation by the control operation as described below.

First, the layer 2 termination unit 1007 of FIG.
As shown in FIG. 7B, when the TEI cancellation factor as described above is detected during the termination operation of the frame data of SAPI = 0, the TEI is canceled according to a predetermined procedure.

After that, a maintenance frame sending unit (not shown) in the line interface unit 201 of FIG. 2 sends a maintenance frame of SAPI = 63 as shown in FIG. 7A similar to the second embodiment. Use the Dch packet processing unit 203 to send T
Make an EI cancellation notification.

As a result, the Dch packet processing unit 203
Performs control such as disconnecting the layer 2 link of SAPI = 16 related to the TEI. Fifth Embodiment of Operation of Line Corresponding Section In the above-described fourth embodiment, the case where the line corresponding section 201 detects the TEI cancellation factor, the Dch packet processing section 203 side may have an error in TEI. In some cases, sex can be detected. That is, in the state where one terminal device 1001 is performing packet communication using frame data of SAPI = 16 of the D channel, SAPI = 16 from which the terminal device has an inconsistent TEI added thereto.
This is the case when the frame data of is transmitted.

In such a case as well, it is necessary to check the contents of the TEI and release the allocation of the TEI to the terminal device if necessary, but the TEI is normally managed by the line interface unit 201.

Therefore, when the Dch packet processing unit 203 detects the possibility of TEI error, the TEI is detected.
Of the check request is notified to the corresponding line corresponding unit 201, and the control operation as described below is executed in the line corresponding unit 201.

First, the layer 2 termination unit 204 of the Dch packet processing unit 203 shown in FIG.
When the above TEI check request factor is detected during the termination operation of the frame data of SAPI = 16, S as shown in FIG. 8A similar to the second embodiment is detected.
Using the maintenance frame of API = 63, the Dch packet processing unit 203 is notified of the TEI check request.

On the other hand, when the not-shown maintenance frame receiver in the line interface 201 receives the above-mentioned maintenance frame, the layer 2 termination unit 1007 in the line interface 201 follows the TEI according to a predetermined procedure. And TEI is released if necessary.

When the TEI is released, the maintenance frame sending unit (not shown) in the line corresponding unit 201 of FIG.
SAP similar to that of the fourth embodiment, as shown in FIG.
Using the maintenance frame of I = 63, as shown in FIG. 8B, the Dch packet processing unit 203 is notified of the TEI cancellation.

As a result, the Dch packet processing unit 203
Performs control such as disconnecting the layer 2 link of SAPI = 16 related to the TEI. Embodiment in which a local area network is accommodated Here, as shown in FIG. 9, a call control signal processing unit 10
The local area network (LAN) 903 is connected to the network connection unit 901 and the network side LAN node 902, and the terminal device 905 is connected to the LAN 903 via the terminal side LAN node 904. May have different configurations.

In the case of such an embodiment, normally, the layer 1 is always activated between the line interface 901 and the network side LAN node 902. And FIG.
In FIG. 9, the same configuration as that of the line corresponding unit 201 is configured not on the line corresponding unit 901 side but on the terminal side LAN node 904 side. Thereby, the cooperative operation of the layer 1 and the layer 2 in the same node can be efficiently performed.

[0071]

According to the present invention, the layer 2 monitoring means is
It is not necessary to perform the terminating operation for frame data including packet data with a large number of transfers, but it is possible to start and stop layer 1 and Two
Management of TEI is possible. Therefore, it becomes possible to simplify the control processing in the line corresponding means and improve the processing capacity of frame data.

[Brief description of drawings]

FIG. 1 is a block diagram of the present invention.

FIG. 2 is a block diagram of an embodiment of the present invention.

FIG. 3 is a diagram showing a frame format of LAPD.

FIG. 4 is an explanatory diagram of a second embodiment of the operation of the line interface.

FIG. 5 is an explanatory diagram of a third embodiment of the operation of the line interface.

FIG. 6 is a state transition diagram of the third embodiment of the operation of the line interface.

FIG. 7 is an explanatory diagram of a fourth embodiment of the operation of the line interface.

FIG. 8 is an explanatory diagram of a fifth embodiment of the operation of the line interface.

FIG. 9 is a block diagram of an embodiment in which a local area network is accommodated.

FIG. 10 is a diagram showing a conventional example of a control method of a layer 2 protocol using a D channel in relation to control of a layer 1 protocol.

[Explanation of symbols]

 101 Call Control Signal Processing Means 102 Packet Processing Means 103 Terminal Equipment 104 Line Corresponding Means 105 Layer 2 Termination Means 106 Layer 2 Monitoring Means 107 Layer 1 Control Means

Continuation of the front page (51) Int.Cl. ⁵ Identification number Office reference number FI Technical indication location H04L 29/10 8529-5K H04L 11/20 102 Z 8020-5K 13/00 309 Z (72) Inventor Takeshi Uehara 1015 Kamiodanaka, Nakahara-ku, Kawasaki City, Kanagawa Prefecture, Fujitsu Limited (72) Inventor Shigehiko Yazawa 1015, Kamiodanaka, Nakahara-ku, Kawasaki City, Kanagawa Prefecture Fujitsu Limited (72) Inventor, Shoji Daikichi, Nakahara-ku, Kawasaki City, Kanagawa Prefecture 1015 Odanaka, Fujitsu Limited (72) Inventor, Masaaki Kato 1-19-24, Watanabe, Naka-ku, Nagoya-shi, Aichi Fujitsu Nagoya Communication Systems Ltd. (72) Inventor Ken Iwasa Shin-Yokohama, Kohoku-ku, Yokohama-shi, Kanagawa 3-9-18 Fujitsu Communication Systems Limited

Claims (7)

[Claims] 1. A call control signal processing means (101) for performing a circuit switching process, a packet processing means (102) for performing a packet switching process, and a terminal device (103) are accommodated to separate a B channel and a D channel. In a digital network having a line-corresponding means (104) for multiplexing / demultiplexing frame data storing call control information and frame data storing packet information on a D channel, in the line-corresponding means (104) And a layer 2 termination means (1) for monitoring and controlling the layer 2 link based on the frame data storing the call control information.
05) and a layer 2 monitoring means (106) for monitoring the layer 2 link based on the frame data storing the packet information.
And a layer 1 that disconnects the layer 1 link in the own line handling means (104) based on the disappearance of each layer 2 link detected by both the layer 2 termination means (105) and the layer 2 monitoring means (106). Control means (10
7) and a D channel control method characterized by including: 2. The layer 2 monitoring means stores frame data storing the packet information going from the packet processing means to the terminal device, or frame data storing the packet information going from the terminal device to the packet processing means. Of the layer 2 link based on the frame data storing the packet information is detected when the timer means counts a predetermined time. The D channel control system according to claim 1, wherein 3. The layer 2 monitoring means sets a timer value notified from the packet processing means using maintenance frame data on the D channel as the predetermined time in the timer means. The D channel control system according to claim 2, characterized in that 4. The layer 2 monitoring means sends a layer 2 link disconnection notification based on the frame data storing the packet information notified from the packet processing means by using the maintenance frame data on the D channel. The D channel control method according to claim 1, wherein the disappearance of the layer 2 link is detected by receiving the layer 2. 5. The line correspondence means, when any of the terminal termination point identifiers added to the frame data storing the call control information is released, the fact is indicated by the frame data for maintenance on the D channel. 5. The D channel control method according to claim 1, 2, 3 or 4, wherein the packet processing means is notified using. 6. The packet processing means, when detecting a possibility of an error in any of the terminal termination point identifiers added to the frame data storing the packet information,
6. The D channel control method according to claim 5, wherein the activation request for the procedure for checking the terminal termination point identifier is notified to the line corresponding unit by using frame data for maintenance on the D channel. 7. The local area network is connected between the line support unit and the call control signal processing unit via another line support unit. The D channel control method described in 2, 3, 4, 5 or 6.