JPH07321794A - Terminal accommodation equipment and its operating method - Google Patents

Abstract

PURPOSE:To process the network service with high performance economically even to a terminal not supporting the protocol of a communication network by converting a user PDU into the form of a cell and implementing PDU capsule processing and de-capsule processing when the user PDU is capsulated into an in-network PDU and transferring it into the network. CONSTITUTION:In an ATM communication network in which a protocol data unit PDU sent by the user is divided into ATM cells and ATM cells are communicated on cell base, each of terminal accommodation equipments 17, 18 is provided with a means identifying the head of a cell sent by the user, a means analyzing the content of a received cell and revising the content of the cell into other content, and a means generating a cell storing an in-network protocol header. That is, terminals 19, 20 are terminals corresponding to ATM connection-less communication CLNAP, since ATM terminals 1, 2 processing the user PDU into a cell to send/receive data have the processing function of CLNAP-PDU, the terminal accommodation equipments 17, 18 arranged in the network are required.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention, in high-speed data communication in which cell transfer processing is performed using ATM technology, efficiently and economically processes network services even for terminals that do not support the protocol of the communication network. The present invention relates to a terminal accommodation device and an operating method thereof.

[0002]

2. Description of the Related Art Since it is necessary to keep the speed of channels constant, channels of different speeds are mixed, and it is difficult to handle image information whose amount of information changes with time. Since the protocol is performed by software, the synchronous transfer mode (STM) and the asynchronous transfer mode (ATM) have been used instead of the packet exchange, which is not good at speeding up. However, the STM is suitable for high-speed wideband communication in which the speed difference between channels is small because the time slots appear periodically and the channel is identified by the time slot position in the frame. Appearance can occur asynchronously based on the request for information transmission, and the channel in the header is used to identify the channel, so various digital information can be centrally transmitted, which is suitable for speeding up the overall processing. . With the introduction of optical fibers, which are communication media with a large capacity and few errors, in ATM communication networks, it is possible to maintain the required quality even if the terminal side is solely responsible for error control and flow control. became. Therefore, in the ATM communication network, it is basically considered to simplify the protocol processing and concentrate on the cell transfer (for example, “Nikkei Communication Separate Volume, ISDN Usage Guide”, Nikkei BP, published 63.12.1). pp.168-177). That is, in the conventional data communication, when a data terminal such as a computer is connected to a wide area, a method of encapsulating and transferring the protocol of the terminal in a wideband protocol has been used. For example, when the IP router is relayed by the ATM connectionless communication network (B-ISDN connectionless data service defined by ITU-T Recommendation F.812), the IP router is the protocol of the accommodated terminal (IP protocol). After receiving a protocol data unit (hereinafter referred to as PDU) composed of, and encapsulating it in an ATM connectionless communication protocol data unit (hereinafter referred to as CLNAP-PDU) handled in the communication network, the cell is divided into cells and the network is cell-by-cell. Had been sent to.
The opposite IP router receives the cell group, and then
Communication is performed by assembling CLNAP-PDU from them, decapsulating them, and reproducing the IP packet transmitted by the calling terminal.

[0003]

By the way, there are the following two methods for accommodating an ATM terminal which does not support the ATM connectionless communication protocol (hereinafter, CLNAP protocol) in the ATM connectionless network. (I) A method of expanding CLNAP encapsulation and decapsulation functions in an ATM terminal. (Ii) A method for realizing independent CLNAP encapsulation and decapsulation functions outside the ATM terminal. However, in the above method (i), it is difficult to economically realize the terminal because the hardware or software of the ATM terminal needs to be significantly modified.
Not a good idea. On the other hand, in the above method (ii), it is not necessary to change the processing of the terminal. However, in the conventional technique, in order to perform encapsulation and decapsulation processing in CLNAP-PDU handled in the network, it is necessary to also mount a cell assembling / disassembling processing function. As a result, since cell assembling and disassembling processing is performed, there is a problem that the cell assembling and disassembling processing causes processing overhead and a delay time and a required buffer capacity increase because one PDU of cell group is accumulated. . An object of the present invention is to solve these conventional problems, and when accommodating an ATM terminal that does not support the CLNAP protocol in an ATM connectionless network, the PD transmitted by the terminal to the PDU handled in the network
An object of the present invention is to provide a terminal accommodating apparatus and method capable of accommodating terminals efficiently by eliminating the overhead associated with cell assembly and disassembly when encapsulating U.

[0004]

In order to achieve the above object, the terminal accommodating apparatus of the present invention (a) divides a protocol data unit (PDU) transmitted by a user into ATM cells, and the ATM cells are cell-based. In an ATM communication network for communication, an identification means (32, 72 in FIG. 8) for identifying the beginning of a cell transmitted by a user and a cell for analyzing the content of the received cell and changing the cell to another content analysis·
Conversion means (33, 35, 38, 73, 75, 76),
And a cell generation means (34) for generating a cell storing an in-network protocol header. (B) Identification means (32, 72) for identifying the final portion of the cell transmitted by the user, and cell analysis / conversion means for analyzing the content of the received cell and changing the cell to another content ( 33, 35, 38, 73, 75, 76) and a cell generation means (34) for generating a cell storing an in-network protocol trailer. Further, the operation method of the terminal accommodating device according to the present invention includes (C) the terminal accommodating device (17, 18 in FIG.
The terminal accommodating device (17) arranged at the entrance and the exit of the TM communication network and arranged at the entrance of the ATM communication network is the device (1
A cell (X in FIG. 6) storing an intra-network protocol header generated in the device is inserted in front of the head cell transmitted by the user (1) accommodated by 7), and the cell is placed at the exit of the ATM communication network. The arranged terminal accommodation device (18) is also characterized in that the inserted cell (X in FIG. 7) is deleted. Furthermore, (d) the terminal accommodating device described in (b) above (1 in FIG. 1).
7 and 18) are arranged at the entrance and the exit of the ATM communication network,
Terminal accommodation device (17) located at the entrance of the ATM communication network
Inserts the cell (X) storing the intra-network protocol trailer generated in the device after the final cell transmitted by the user (1) housed in the device, and is arranged at the exit of the ATM communication network. The terminal accommodation device (18) is also characterized in that the inserted cell (X) is deleted.

[0005]

In the present invention, the user PDU is replaced with the intra-network PDU.
User PDU when encapsulating in the network and transferring in the network
Is once converted into a cell form, and then PDU encapsulation and decapsulation processing is performed. As a result, the process of encapsulation and decapsulation in the PDU handled in the network is performed by assembling the cell,
Since processing is performed in the state of the cell as it is without disassembling, processing overhead can be reduced. Further, the required buffer amount can be reduced and the cell accumulation delay time for PDU can be reduced.

[0006]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 is a diagram showing an ATM network configuration to which the present invention is applied. In this embodiment, as a premise of this, the ITU-T recommendation F. ATM in which a connectionless server that provides a B-ISDN connectionless data service defined in 812 is arranged
A connectionless service shall be provided to the terminal. The CLNAP protocol is a protocol that supports connectionless services and is composed of a header and a payload (ITU-T Recommendation I.364). Therefore, in order to encapsulate the user PDU in the CLNAP-PDU, the header of the CLNAP-PDU is set to the user P.
It may be added before the DU. In FIG. 1, reference numerals 1 and 2 denote ATM terminals for converting user PDUs into cells by AAL type 3/4 for data transmission / reception, 3 and 4 denote subscriber lines between the terminals and the network, and 19 and 20 are CLNAP-PDU capsules. Terminals supporting the functionalization function, 5, 6 and 7 are ATM exchanges arranged in the network, 8, 9 and 10 are relay lines between ATM exchanges, and 11, 12 and 13 are ATM exchanges and connectionless servers. ATM lines, 14, 15 and 16 are connectionless servers that perform CLNAP-PDU routing processing, and 17 and 18 are terminal accommodation devices to which the present invention is applied. As shown in FIG. 1, the terminals 19 and 20 are CL
NAP compatible terminals, while terminals 1 and 2 are CLN
Since there is no AP-PDU processing function, the terminal accommodating devices 17 and 18 arranged in the network are required.

FIG. 2 shows the CL handled in the network in the present invention.
It is a PDU format block diagram of NAP protocol.
In FIG. 2, one horizontal line represents a data structure of 4 octets (32 bits). And Destinati on the first line
CL from on-Address to Header-Extension (HE)
It is a header of NAP. Header-Extension (H
Since the E) field has a variable length of 0 to 20 octets, the HE field length is 16 here.
Octet length (fixed). Therefore, here, the header length is 20 + 16 = 36 octets. After the header portion, there are user information (variable length up to 9188 octet length) and pads (0 to 3 octet length). Figure 3
FIG. 6 is a diagram showing a method of encapsulating a user data unit in a CLNAP frame and transferring data by a cell according to the present invention. User data unit is CLN
A header is added in each of the AP layer, the CPCS sublayer, the SAR sublayer, and the ATM layer, and the cells are finally made into cells. First, FIG. 3A shows a user data unit, in which the user has 8 octets of LLC / SN before the IP packet and ARP packet to be transmitted.
Add AP header. This header indicates the non-OSI protocol with 3 octets of LLC and identifies the IP / ARP protocol with 5 octets of SNAP.

Next, in FIG. 3B, this user information is stored in the User Information field which is the payload of CLNAP. And here, the user data unit (IP packet, ARP packet) is CLNAP.
The trailer CRC field is not used. Next, this information is encapsulated in the CLNAP frame of FIG. 2 and becomes a CLNAP-PDU. Next, in FIG. 3C, the CLNAP frame is an AAL type 3/4 CPC.
It is stored in the payload of the S sublayer. Next, FIG.
As shown in (d), the CPCS-PDU is stored in the payload of the SAR sublayer and made into cells. At this time, the cells generated from the same user data unit are
The same VPI (logical path identifier), VCI (logical channel identifier), and MID (multiplexing identifier) are assigned and used for identification with other data units. Finally, Figure 3
As shown in (e), the ATM header is added to complete the ATM-PDU.

FIG. 4 shows the IP of user information in the present invention.
It is a block diagram of a cell format in the case of encapsulating a packet with a CLNAP frame and transferring the packet in three cells. Each field in FIG. 4 will be briefly described. The 1st to 5th octets of each cell are added in the ATM layer, and are the 6th, 7th octet, 52, 5th.
The 3rd octet is added in the SAR sublayer, and the 8th to 11th octets of the first cell and the 4th of the last cell are added.
The 8th to 51st octets are added by the CPCS sublayer, and the 12th to 47th octets of the first cell are C
It is added in the LNAP layer and is 4 in the first cell.
8 to 51, the 8th to 11th octets of the intermediate cell, and the IP packets of the intermediate cell and the final cell are the user (IP).
It was added in. The fifth octet of the ATM layer header is a pattern common to three cells. S
In the AR sublayer, the first cell is ST (segment type) = 10b, the intermediate cell is ST = 00b, and the last cell is S.
The value of T = 01b is set. SN (sequence number)
Is 16 modulo and is sequentially allocated in the order of the beginning, the middle, and the end. The MID has a common value in all three cells. Also, LI (length indication) indicates the payload length of the SAR sublayer. Also, CRC
Calculates the CRC of the SAR sublayer.

The CPCS sublayer has 8 to 1 of the first cell.
It exists in the 1st octet and the 48th to 51st octets of the final cell. Of the CPCS fields, CPI = 00
0000000b, B-taq = 00000000b,
AL = 00000000b, E-taq = 000000
00b is fixedly set. BA-size, L
Each of ength stores a value indicating the effective length of CPCS. The CLNAP layer header is 12 in the first cell.
It exists in the 36th octet length of the 47th octet. C
As the LNAP payload, an IP packet in which the LLC / SNAP header is prefixed is set. Here, among the 8 octets of the LLC / SNAP header, the first 4 octets are in the 48th to 51st octets of the first cell, the remaining 4 octets are in the 8th to 11th octets of the intermediate cell, and thereafter the IP packet is Is set.
A normal CLNAP-compatible ATM terminal sends an IP
The packet is divided into the ATM cell format shown in FIG. 4 and transmitted / received.

FIG. 5 is a format configuration diagram of a cell transmitted / received by an ATM terminal not compatible with CLNAP in the present invention. Here, the IP packet is AAL as it is.
It shall be stored in the 3/4 CPCS payload and cellized by the SAR. That is, 1st to 5th octets are added in the ATM layer and 6th in the SAR sublayer.
~ 7th octet, 52, 53th octet are added, and the 8th to 11th octet of the first cell and the 48th to 51st octet of the last cell are added in the CPCS sublayer,
The user sets the IP packet. FIG. 6 is an image diagram in which a certain terminal transfers data cell-by-cell to an ATM exchange in the present invention. Here, the case where the terminal 1 transfers data to the ATM exchange 5 via the terminal accommodation device 17 is shown. Here, the terminal 1 transmits the two cells (first cell A and last cell B) shown in FIG. In addition, the terminal accommodation device 17 transmits the newly generated cell X before the received cell A, and then transfers the data in the order of cell A ′ cell B ′ in which cells A and B are modified.
In the present embodiment, when the terminal 1 of FIG. 1 transmits the IP packet divided into the cells of FIG. 5 to the terminal accommodating device 17, the device 17 does not perform the cell assembling and disassembling processes to perform the LL.
A method of adding a C / SNAP header and encapsulating a CLNAP frame will be described.

(Processing 1) FIG. 10 is an operation flowchart for adding an LLC / SNAP header and encapsulating a CLNAP frame in a terminal accommodating apparatus according to an embodiment of the present invention. The process 1 is a process in which, when the terminal accommodation device 17 receives a head cell (head cell A in FIG. 6), a new head cell X is generated based on the cell. Note that among these processes, steps 101 to 105, 110 to 114
Is a fixed process. First, the cell header of the cell is set (step 101), and 10b is set in the ST field (step 102). Next, a value obtained by subtracting 1 (modulo 16) from the SN of the cell is set in the SN field (step 103). Next, the value of the MID field of the cell is set as it is in the MID field (step 104). All 0s are set in the CPI and Btag fields (step 105). Then B
The SIZE field is 4 in the BAsize of the cell.
A value obtained by adding 4 is set (step 106). CLNA
The DA and SA fields of the P header correspond to the E.D.SA corresponding to the DA and SA of the IP address described in the cell. 16
4 addresses are retrieved and set (step 107).

The 000001b value is fixedly set in the HLPI field (step 108). PADlength
In the h field, the value to be newly set in the BAsize field is divided by 4, and when the remainder is 0, 1, 2, 3 respectively, 0, 3, 2, 1 are set (step 109). The QOS, CIB, and RES fields are fixedly set to 0 (step 110). The HEL field is fixedly set to 4 (this causes the HE field length to be 16 octets) (step 111).
The HE field is fixedly set to 0 (step 1
12). The LLC / SNAP header sets a value having a length of 8 octets (step 113). Here, I
Since the P-type protocol is assumed, 16
Code in hex. In the case of IP packet: AA-AA-03-00-00
-00-08-00 For ARP packet: AA-AA-03-00-00
-00-08-06 When generating a new head cell, the upper 4 octets of these values are set. The LI field is
It is fixed at 44 octets (step 114). CRC
The field stores the result calculated for the newly created SAR-PDU (step 115).

(Process 2) Process 2 is a process for transmitting the newly generated head cell X to the network. In this process, as shown in FIG. 6, the leading cell X is transferred from the terminal accommodation device 17 to the ATM.
Transfer to the exchange 5. (Processing 3) FIG. 11 is an operation flow chart of transmitting the cell A as a new head cell A ′ after the cell A is modified. In the process 3, as shown in FIG. 6, the received head cell A is treated as a cell A'after the new head cell X and the exchange 5
It is a process of transmitting to. First, set the ST field to 10b
The type is changed from (top cell) to 00b (intermediate cell) (step 201). Next, the latter 4 octets of the LLC / SNAP header are set in the CPCS header portion (step 202). Next, the CRC of the SAR sublayer
Is recalculated and the result is stored (step 20).
3). Next, the cell A'is transmitted (step 204). (Processing 4) FIG. 12 is an operation flowchart for correcting the received final cell B and then transmitting it to the network as the final cell B ′. First, CPCS trailer Lengt
A value obtained by adding 44 octets to the value of the h field is set (step 301). Next, C of the SAR sublayer
Recalculate RC and store the result (step 3
02). Next, the cell B'is transmitted (step 30).
3). As described above, if the CLNAP header length is set to 36 octets, the LLC / SNAP header is set to CLN.
4 octets at the end of the AP header and CPC of the next cell
Since the previous 4 octets can be stored in the S field storage portion, encapsulation is possible without assembling and disassembling cells.

FIG. 7 is a diagram showing an image in which the exchange 7 transfers data to the terminal 2 by the cell bus cell via the terminal accommodation device 18 in the present invention. Here, the exchange 7 is
Cells X, A ', B'transmitted to the terminal accommodation device 17 on the originating side
And is received by the terminal accommodation device 18 on the receiving side. At this time, the head cell X is discarded. After the intermediate cell A ′ and the final cell B ′ are converted into the first cell A and the last cell B, the terminal 2
Sent to. The processing of the terminal accommodating device described in FIG. 7 will be described below. (Process 5) Process 5 is a process of discarding the received first cell X. Save the information of the receiving cell. Discard the first cell. (Processing 6) FIG. 13 is an operation flowchart for converting the intermediate cell A ′ into the leading cell A and transferring it to the terminal 2. Process 6 is a process of converting the intermediate cell A ′ to the head cell A and then transferring the converted cell to the terminal. First, S of the received cell A '
Convert T from middle cell to first cell (step 40
1). Next, among the values of the CPCS header of cell X, BA
The size obtained by subtracting 44 octets from the size is set to the 8th to 11th octets of the cell A '(step 402).
Next, CRC calculation of the SAR sublayer is performed and the result is stored (step 403). Then, the modified cell A'is transmitted as the cell A (step 404).

(Processing 7) FIG. 14 is an operation flowchart for converting the final cell B'to the final cell B and transferring it to the terminal 2. Process 7 is a process of converting the final cell B ′ into a cell B and a process of transmitting this to the terminal 2. First, the value of the Length field of the received CPCS trailer is subtracted by 44 octets (step 501). Then S
The CRC calculation of the AR sublayer is performed and the result is stored (step 502). Next, the modified cell B'is transmitted as cell B (step 503). Through the above processing, the communication between the terminals 1 and 2 that are not CLNAP-compatible has been described as an example. In addition, these terminals 1, 2 and CL
It is possible to connect to the NAP-compatible terminals 19 and 20. In this case, the terminal accommodation device functions only on the originating side or the terminating side.

FIG. 8 is a block diagram of an apparatus portion for performing processing in the CLNAP encapsulation direction in the terminal accommodating apparatus showing the embodiment of the present invention. In FIG. 8, 30 is a receiving circuit that terminates the physical layer from the data received from the terminal, extracts the cell format and stores the cells in the buffer 31, 31 is a cell buffer, and 32 is a process based on the cell segment type ST. A cell branching circuit for distribution, 33 is a cell analysis circuit for analyzing BOM and SSM cell data among received cells, 34 is cell header information from the cell analysis circuit, ST, SN, MID, protocol type of IPARP packet and DA, SA It receives the IP address and the E. By converting 164 addresses, a 36-octet-long CLNAP header and LL
New B containing the upper 4 octets of the C / SNAP header
B to generate an OM cell and store it at the beginning of the buffer 36
OM cell generation circuit, 35 is the BOM received from the calling terminal,
For the SSM cell, the BOM cell converts the type into a COM cell, the SSM cell converts the type into an EOM cell, and the lower 4 octets of the LLC / SNAP header are set in the CPCS area. BOM / SSM cell conversion circuit to store in, 36 is 2
When the control line 43 indicates that the BOM cell generation circuit has stored cells in the buffer 36, the cell buffer for cells 37 reads out two cells from the head of the buffer 36 and transfers them to the CRC circuit via the cell multiplexing circuit. The driver circuit for transmitting the cell, when the 38 receives the EOM cell, the CP
EOM that adds 44 to the Length field of the CS trailer and transmits the cell to the cell multiplexing circuit and CRC circuit
Cell conversion circuit, 39 cell multiplexing circuit, 40 SAR-P
The reference numeral 41 is a CRC circuit for performing the CRC calculation of the DU and storing the result in the CRC field, 41 is a shaver circuit, and 42 is a transmission circuit for transmitting as a payload of the cell physical layer. Further, 43 indicates a control line and 51 to 67 indicate data lines. Of these, among the received cells, BOM,
In the SSM cell, the cell branch circuit 32 includes a data line 54 and an EOM.
The cells are transferred via the data line 61, and the COM cells are transferred via the data line 63.

The operation of FIG. 8 can correspond to the above-mentioned processing 1 to processing 4. Steps 101 to 11 of processing 1
4 (B cell generation process) is a BOM cell generation circuit 34.
Information of the cell header, ST, SN, MID value, IP address and protocol identifier extracted from the cell analysis circuit 33, and the LLC / SN held internally.
AP header value, IP-E. A new BOM is created based on the H.164 address conversion table, the CLNAP protocol initial setting value, and the like. The process 2 (process of transmitting the head cell X) is executed by the BOM cell generation circuit 34 loading the head of the buffer 36. Further, the process 3 (process of transmitting as the cell A ′) is executed by the BOM / SSM cell conversion circuit 35 and loaded in the last of the buffer 36. Process 4 (process for transmitting as final cell B ')
Is executed by the EOM cell conversion circuit 38. Also,
CRC processing common to processing 1, 3 and 4 is collectively CR.
This is performed by the C circuit 40.

FIG. 9 is a block diagram of an apparatus portion for performing processing in the CLNAP decapsulation direction in the terminal accommodating apparatus showing the embodiment of the present invention. In FIG. 9, 70 is a receiving circuit that terminates the physical layer from the data received from the terminal, extracts the cell format and stores the cells in the buffer 71, 71 is a cell buffer, and 72 is based on the segment type (ST) of the cell. Cell branch circuit that distributes processing, 7
3 is a cell analysis circuit that analyzes the BOM cell data of the received cells, writes the cell data and the initial value (= 1) of the number of arriving cells in the table 74, and discards the cell, 74 is a cell analysis V of BOM cell processed by circuit 73
PI, VCI, MID, SN values, CPCS BAsi
A state management table that holds the ze value and the number of arriving cells from the BOM, and 75 is the Le of the EOM when the EOM is received.
When 44 is subtracted from the ngth field and the number of arriving cells in the state management table 74 is 1,
Type to SSM, otherwise type to EO
When the EOM cell conversion circuit 76 which changes to M and deletes the registration data related to the PDU receives COM,
When the number of arriving cells is 1, the type is changed to BOM, the number of arriving cells is incremented by 1, and the value of BAsize in the state management table 74 is decremented by 44.
When the CS header is created, and when the number of arriving cells is other than 1, the COM cell conversion circuit which counts up the number of arriving cells and then transmits as it is, 77 is a cell multiplexing circuit,
78 is the C stored in the CRC field of the SAR-PDU
RC circuit, 79 is a shaver circuit, and 80 is a transmission circuit for transmitting cells as a payload of the physical layer. Also,
81 to 95 are data lines.

The operation of the apparatus portion shown in FIG.
It can be explained in correspondence with the process 7. That is,
The operation of discarding the received head cell X in the process 5 is performed by the cell analysis circuit 73, and the intermediate cell A ′ in the process 6 is set to the head cell A.
The COM cell converting circuit 76 performs the operation of converting the data to the terminal and transferring the data to the terminal.
The EOM cell conversion circuit 75 performs the operation of converting the data to the terminal and transferring it to the terminal. Further, the CRC calculation operation common to each processing is performed by the CRC circuit 78. As described above, in this embodiment, an ATM terminal that does not support CLNAP is set to CLNA.
In the case of a P-compatible terminal, the function can be changed without changing the terminal function. Although the terminal accommodating devices 17 and 18 are arranged in the network in the present embodiment, the positions to be arranged are not limited to this. For example, if they are the entrance and the exit of the network, they are arranged in the user's home. May be. Further, in the embodiment, as shown in FIG. 5, the terminal accommodating apparatus generates cells in which ATM headers are stored as shown in FIG. 4 for the first cell and the last cell sent from the user. This is used as the head cell, the received head cell is modified to be an intermediate cell, and the head cell generated above in the terminal accommodation device of the other party is deleted, but the present invention is not limited to such an operation method. For example, the final cell sent from the user is identified, a cell storing the ATM trailer is generated, and this is used as the final cell, and the final cell is transferred after the received first cell and intermediate cell to accommodate the terminal of the other party. The device may delete the generated final cell.

[0021]

As described above, according to the present invention,
When accommodating an ATM terminal that does not support the protocol of the communication network in the communication network, it can be accommodated without changing the function of the terminal, and user information is encapsulated or decapsulated by the protocol of the communication network. At this time, since cell assembling and disassembling processing is not involved, the processing is not delayed and the buffer capacity is not increased. Also,
Since there is no need to assemble or disassemble the cells, the throughput is not reduced, and therefore the terminal can be accommodated in the communication network in a small size, economically, and with high performance.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a communication network to which the present invention is applied.

FIG. 2 is a PDU format diagram of a CLNAP protocol showing an embodiment of the present invention.

FIG. 3 shows an embodiment of the present invention and is an explanatory diagram of encapsulation of a user data unit by a CLNAP frame and data transfer by a cell format.

FIG. 4 shows an embodiment of the present invention, and is a cell format diagram in the case of encapsulating an IP packet, which is user information, in a CLNAP frame and transferring it in a network with three cells.

FIG. 5 shows an embodiment of the present invention and is a format diagram of a cell transmitted and received by an ATM terminal not compatible with CLNAP.

FIG. 6 is a sequence chart showing data transfer from a terminal to an ATM exchange via a terminal accommodation device according to an embodiment of the present invention.

FIG. 7 is a sequence chart showing data transfer from an ATM exchange to a terminal via a terminal accommodation device according to an embodiment of the present invention.

FIG. 8 is a block diagram of the terminal accommodating device C according to the embodiment of the present invention.
It is a block diagram of the apparatus part which processes LNAP encapsulation direction.

FIG. 9 is a block diagram of a terminal accommodating device C according to an embodiment of the present invention.
It is a block diagram of the apparatus part which processes the LNAP decapsulation direction.

FIG. 10 shows an embodiment of the present invention and is a flowchart of a process (process 1) for generating a new head cell X based on the head cell.

FIG. 11 shows an embodiment of the present invention and is a flowchart of a process (process 3) of correcting a received head cell and transmitting a new head cell A ′.

FIG. 12 is a flowchart of a process (process 4) of modifying the received final cell and transmitting a new final cell B ′ according to the embodiment of the present invention.

FIG. 13 shows an embodiment of the present invention and is a flowchart of a process (process 6) of converting the intermediate cell A ′ to the head cell A and transferring the converted cell to the terminal.

FIG. 14 shows an embodiment of the present invention and is a flowchart of a process (process 7) of converting the final cell B ′ into the final cell B and transferring the final cell B to the terminal.

[Explanation of symbols]

1, A User PDU is converted into cells and data is transmitted / received
TM terminal, 3,4 Subscriber line between terminal and network, 5, 6,
7 ATM exchanges, 8, 9, 10 Relay lines between ATM exchanges, 11, 12, 13 ATM lines connecting ATM exchanges and connectionless servers, 14, 15, 16
Connectionless server that performs CLNAP-PDU routing processing, 17, 18 Terminal accommodation device, 19, 2
0 A terminal that supports the encapsulation function of CLNAP-PDU.

Claims (4)

[Claims] 1. An identification means for dividing a protocol data unit (PDU) transmitted by a user into ATM cells, and for identifying the head portion of the cell transmitted by the user in an ATM communication network for communicating the ATM cells on a cell basis. , A terminal having a cell analysis / conversion means for analyzing the content of the received cell and changing the cell to another content, and a cell generation means for generating a cell storing an in-network protocol header Containment device. 2. An identification means for identifying a final portion of a cell transmitted by a user in an ATM communication network in which a protocol data unit (PDU) transmitted by the user is divided into ATM cells and the ATM cells are communicated on a cell basis. A terminal having a cell analysis / conversion means for analyzing the content of the received cell and changing the cell to another content, and a cell generation means for generating a cell storing an intra-network protocol trailer Containment device. 3. An ATM communication network in which a protocol data unit (PDU) transmitted by a user is divided into ATM cells, and the ATM cells are communicated on a cell basis. Terminal accommodating devices arranged at the entrance and the exit and arranged at the entrance of the ATM communication network are
The terminal accommodating device arranged at the exit of the ATM communication network inserts a cell storing the in-network protocol header generated in the device before the first cell transmitted by the user accommodated in the device. ,
A method of operating a terminal accommodating device, characterized in that the inserted cell is deleted. 4. An ATM communication network in which a protocol data unit (PDU) transmitted by a user is divided into ATM cells, and the ATM cells are communicated on a cell basis, wherein the terminal accommodating device according to claim 2 is used as an ATM communication network. Terminal accommodating devices arranged at the entrance and the exit and arranged at the entrance of the ATM communication network are
After the last cell transmitted by the user accommodated in the device, a cell storing the intra-network protocol trailer generated in the device is inserted, and the terminal accommodation device arranged at the exit of the ATM communication network is
A method of operating a terminal accommodating device, characterized in that the inserted cell is deleted.