JP2003333202A - Terminal communication system of isdn - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a system for terminal communication of ISDN. <P>SOLUTION: In communication, using one or more B channels, carried out between ISDN terminal devices having line interfaces of BRI or PRI of ISDN, delay or loss of packets on an ISDN transmission line or an ISDN terminal device is recognized and packets are received in the correct transmission order without spoiling a transmission sequence of sent non-real-time data even when the non-real-time data are divided and transmitted because real-time data are efficiently communicated. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to ISDN (Int
integrated Services Digital
(Network) communication method of a terminal device.

[0002]

2. Description of the Related Art In order to preferentially transmit real-time data when ISDN terminal equipment having a BRI or PRI line interface of ISDN communicates using one or a plurality of B channels,
A packet of non-real time data may be divided and transmitted. In this case, the ISDN transmission line or ISDN
When a packet is delayed or lost in the terminal device, the packet does not arrive in the transmission sequence order. Conventionally, a transmission sequence is monitored by adding a sequence number to a transmission packet, but a packet that does not arrive in the sequence number order is discarded.

Conventionally, if the receiving side does not arrive in sequence number order, the cause is ISDN.
It is difficult to determine whether it is due to a packet delay or a packet loss within the transmission line or the ISDN terminal device.

[0004]

When the receiving side does not arrive in the sequence number order, the cause is IS.
In the case of a packet delay in the DN transmission line or the ISDN terminal device, it is necessary to buffer the packets that have not arrived in the sequence number order, and when the packets with the correct sequence number arrive, take out the buffered packets in the sequence number order. There is. Also, if the receiving side does not arrive in the sequence number order, the cause is the ISDN transmission line or IS.
In the case of packet loss in the DN terminal device, it is necessary to ignore the lost packet and extract the packets received after the lost packet in the sequence number order.

[0005]

In an ISDN communication terminal having a plurality of B channels, a sequence number, a packet length, and a data type are added as a header for each packet, and when the packet is divided, the divided packet is also included. The sequence number and the data type are added, the divided bits are set, and the packet is transmitted to the B channel having the least data to be transmitted among the plurality of B channels.

When the transmission packet is received, it has a reception queue corresponding to the sequence number, and each reception queue has attributes such as a packet length before division, a data length in the reception queue, a packet type, and a reception B channel. With.

The received packet is stored in a receive queue corresponding to the sequence number, and the sequence number of the received packet is compared with the sequence number of the receive queue from which the packet should be taken out next, thereby determining the ISDN transmission line. Alternatively, the packets are extracted in the sequence number order regardless of the packet delay in the ISDN terminal device.

A packet loss is recognized by comparing the sequence number of the received packet with the sequence number of the queue from which the packet should be taken out next, and the packets received after the lost packet are sorted in the sequence number order. Take it out.

By referring to the attribute of the reception queue corresponding to the sequence number of the received packet, the packet loss is recognized, and the packets received after the lost packet are extracted in the sequence number order.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will now be described in detail with reference to the drawings.

(First Embodiment) FIG. 1 shows a block diagram of an ISDN terminal device according to the present invention. CPU1
00 controls the entire apparatus by reading and executing the program stored in the memory 130. HD
LC (Highlevel Data LinkCon)
The controller 110 is a DMAC (Dire).
ct Memory Access Control
er) is built in, and data is DMA-transferred at high speed between 110 and 130, converted into serial data as an HDLC frame and transmitted. In addition, the received HDLC frame is decomposed, and the data is transmitted at high speed between 110 and 130.
MA transfer. ISDN Line Interfac
e120 is a BRI (Basic Rate) of ISDN.
Interface: 2B + D) or PRI (Pr
immediate Rate Interface: 23B +
Implement the user / network interface in D).
In addition, the ITU-T Recommendation I.S. In addition to having the layer 1 control function defined in 430, the Q. 92
0, Q. It supports Layer 2 (LAP-D protocol) defined in 921. Ethernet (R) C
The controller 140 has a plurality of RJ-45 ports and supports the Ethernet (R) protocol. Lin between the ISDN terminal devices (2 units)
e I / F 120 allows multiple Bs through D channel
It is assumed that the channels (B1 to Bn) are call-connected.

A case in which the ISDN terminal device transmits data with the above configuration will be described with reference to the flowchart of FIG. The memory 130 is provided with a real-time data queue and a non-real-time data queue corresponding to each B channel. When waiting for the transmission request in step S500,
When there is a transmission request to the HDLC controller 110, the packet header shown in FIG. 2 is added to the transmission data. The fragmented bit 200 is the first packet (divided bit = 0) of the transmission packet or the fragmented packet (divided bit =
1) or not. The data type 210 indicates real-time data (data type = 0) or non-real-time data (data type = 1). A 5-bit field 220 represents a sequence number in the range of 0-30. The sequence number is incremented and added for each transmission data, and the same sequence number is added to the first packet (divided bit = 0) and the divided packet (divided bit = 1). The following 230 length field is for the first packet (fragment bit = 0)
Indicates the transmission data length. Packet after fragmentation (fragment bit =
In the case of 1), the 230 length field is not added. The transmission packet added with the packet header is
In the case of real-time data, in step S502, the B channel with the least untransmitted real-time data is selected, and in step S503, the real-time data with the packet header added is inserted (Pop) into the B-channel real-time data queue. Then, in step S504, when real-time data is being transmitted, the process returns to step S500. When real-time data is not being transmitted, the process proceeds to step S505, and when non-real-time data is being interrupted, step S505 is performed.
Return to 500. If the non-real-time data is not being interrupted, the process proceeds to step S521. If the non-real-time data is being transmitted, in step S523, an interrupt request is made to the non-real-time data being transmitted. At this time, the non-real-time data being transmitted is interrupted, and the divided bit 2 of the packet header of the remaining non-real-time data is divided.
Set 00. At this time, the data type of 210 and the sequence number of 220 are the same as the header of the non-real time data being transmitted. The 230 length field is not added. After that, the process returns to the transmission request waiting state of step S500. In step S521,
When non-real time data is not being transmitted, step S
Proceeding to 522, real-time data is fetched from the real-time data queue inserted in step S503 (Push), and a DMA request is made for that data. After that, the process returns to the transmission request waiting state of step S500. If the transmission request is non-real-time data in step S501, the flow advances to step S506 to select the B channel having the least untransmitted data, and then step S5.
At 07, the non-real-time data added with the packet header is inserted (Pop) into the non-real-time data queue for the B channel. Then, step S50
If the real-time data is being transmitted in step 8, the process returns to step S500. When real-time data is not being transmitted, the procedure proceeds to step S509, and when non-real-time data is being transmitted, the procedure returns to step S500. When non-real time data is not being transmitted, the process proceeds to step S510, the non-real time data is fetched from the non-real time data queue inserted in step S507 (Push), and a DMA request is made for the data.
After that, the process returns to the transmission request waiting state of step S500.

Next, when the transmission is completed in step S530, the process proceeds to step S531. Step S531
In step S533, if there is data that has not been pushed in the real-time data queue of the transmission completed B channel, the flow advances to step S533 to push real-time data from the real-time data queue, and D
Make an MA request. After that, the process returns to the transmission completion waiting state in step S530. In step S531, if there is no unpushed data in the real-time data queue of the transmission completed B channel, the process proceeds to step S532.
In step S532, if there is unpushed data in the non-real-time data queue of the transmission completed B channel, the flow advances to step S534 to push real-time data from the real-time data queue and make a DMA request for the data. After that, the process returns to the transmission completion waiting state in step S530. Step S532
If there is no data that has not been pushed in the non-real-time data queue of the transmission completed B channel, the process returns to the transmission completion waiting state of step S530.

The transmission data of 1024 bytes is 512B.
Consider a case in which the packet is divided into three packets of 256 bytes, 256 bytes, and 256 bytes and transmitted. Assuming that the sequence number of this transmission data is 3, as shown in FIG. 3300, the first packet of 512 bytes has a transmission header with sequence number = 3, divided bits = 0, and length field = 1024, and is added to the transmission queue. Store. As shown in FIG.
The divided packet of te has a sequence number of 3, a divided bit of 1, and has a length header without a transmission header and is stored in a transmission queue. As shown in 320 in FIG. 3, the remaining 256-byte fragmented packets are added with a transmission header with sequence number = 3, fragmented bits = 1, and no length length field, and stored in the transmission queue. After that, when all the previously stored transmission packets have been transmitted, the packets are transmitted in the order of 300, 310 and 320.

A case where the ISDN terminal device receives data will be described. A reception data queue corresponding to each sequence number (0 to 30) is provided in the memory 130.
Q for the receive data queue corresponding to the sequence number I
i. Qi has attributes such as a data type corresponding to FIG. 2 210, a packet length (packet length before division) corresponding to FIG. 2 230, a reception B channel, and a data length stored in Qi. The sequence number of the packet to be assembled next is the integer variable RxSeqNo, and the sequence number of the received packet is the integer variable NowSeq.
No, the number of sequence numbers is an integer constant MaxSeqN
o. In this embodiment, the number is 31 from the 5-bit field in FIG. The integer variable RxSeqN
o, NowSeqNo and the integer constant MaxSeqN
o and the attributes of the reception queue Qi,
FIG. 4 shows a flowchart in which the SDN terminal device receives data. Step S400 in FIG. 4A is in a reception waiting state. When the data is received, it looks at the sequence number of the packet. Here, the sequence number is Now
SeqNo. In step S401, it is checked whether the divided bits 200 of the packet header shown in FIG. 2 are 0 or 1.
If the divided bit is 0, it is determined that the received packet is the first packet, and in step S402, NowSe
Check if there is data in the receive queue of qNo. If data exists in the reception queue of NowSeqNo in step S402, all data in the reception queue is discarded and all attributes of the reception queue are initialized in step S404. Furthermore, No in RxSeqNo
Substitute wSeqNo. If the divided bit is 1 in step S401, it is determined that the received packet is a divided packet, and in step S403, NowSe
Check if there is data in the receive queue of qNo. If no data exists in the reception queue of NowSeqNo in step S403, it is determined that the first packet of NowSeqNo is lost, the reception packet is discarded, and the process returns to step S400. After clearing the reception queue at step S404, or Now at step S403.
If there is data in the reception queue of SeqNo, in step S405, the reception data is written in the reception queue of NowSeqNo, the reception data type, the reception packet length,
Now such as receive B channel and data length in receive queue
The reception queue attribute of SeqNo is updated. Then, in step S406, NowSeqNo and RxSeqNo
If the difference between is larger than (MaxSeqNo-2), then R
It is determined that the packet of xSeqNo is lost, and in step S407, the reception queue is cleared as in step S404. Furthermore, increment RxSeqNo,
Substituting it into NowSeqNo, B step S41
Go to 0. If the difference between NowSeqNo and RxSeqNo is (MaxSeqNo-2) or less in step S406, the process proceeds to step B410 without doing anything. In step B410, the loop variable I = 0 is set. I <MaxS
eqNo (step S411), RxSeqNo and NowSeqNo are equal (step S412), and the data length of the reception queue of RxSeqNo (NowSeqNo)> 0 (step S413), and RxSeqNo.
(= NowSeqNo) receive queue data length and Rx
If the packet lengths of the reception queues of SeqNo (= NowSeqNo) are equal (step S414), step S
Proceed to 415. If not, the process returns to the reception waiting state in step A400. In step S415, RxSe
The assembled reception data is extracted from the reception queue of qNo (= NowSeqNo). Then, step S4
In step 16, the reception queue is cleared as in step S404, RxSeqNo, NowSeqNo, and i are both incremented, and the process returns to step B410.

According to the above reception sequence, even if the transmission data is divided, the reception data is assembled and received in the sequence number order.

[0017]

As described above, according to the present invention,
When transmitting data using a plurality of B channels between ISDN terminal devices having an ISDN BRI or PRI line interface, the transmission rate is increased by selecting the B channel with the least amount of data waiting to be transmitted. You can

According to the present invention, the BRI of ISDN is also included.
Or ISD with PRI line interface
When non-real-time data is divided and transmitted between N terminal devices by using one or more B channels for the purpose of efficiently communicating real-time data,
Even if a packet delay occurs in the ISDN transmission line or the ISDN terminal device, the packets can be correctly received in the transmission order without damaging the sequence of the transmitted non-real time data. At that time, the reception attributes such as the reception data length, reception B channel, and reception type can be known.

According to the present invention, the BRI of ISDN is also provided.
Or ISD with PRI line interface
When non-real-time data is divided and transmitted between N terminal devices by using one or more B channels for the purpose of efficiently communicating real-time data,
When a packet loss occurs in the ISDN transmission line or the ISDN terminal device, the receiving side can recognize the packet loss and correctly extract the packets received after the lost packet in the transmission order.

[Brief description of drawings]

FIG. 1 is a block configuration diagram of an ISDN terminal device according to an embodiment of the present invention.

FIG. 2 shows an example of a packet header format of the present invention.

FIG. 3 shows an example of packet division according to the present invention.

FIG. 4 is an operation flowchart of the receiving side of the present invention.

FIG. 5 is an operation flowchart of the transmitting side of the present invention.

Claims (3)

[Claims] 1. An ISD for accommodating an ISDN line having a plurality of B channels and performing real-time data communication and non-real-time data communication using the plurality of B channels.
In the N communication terminal, a means for detecting a real-time data communication request, a means for detecting a real-time data communication request when detecting a real-time data communication request, and a means for respectively checking the transmission waiting data amount of each of the B channels, Means for determining a B channel used for communication; means for dividing a packet of non-real time data being transmitted in the B channel used for communication into a plurality of elements; and, after transmitting the real time data, the divided non real time data Means for transmitting the elements of, and an ISDN communication terminal. 2. The ISDN communication terminal according to claim 1, wherein information indicating that the packet has been divided is added to the plurality of divided non-real-time data packets. 3. An ISD for accommodating an ISDN line having a plurality of B channels and performing real-time data communication and non-real-time data communication using the plurality of B channels.
In the N communication terminal, means for detecting that the received non-real time data packet is divided into a plurality of elements, means for assembling the plurality of elements of the divided non-real time data packet into one, An ISDN communication terminal comprising: means for detecting a change in the order of real-time data packets; and means for correcting the order when the change is detected.