JPS6029083A - Multi-link packet communication system - Google Patents

Abstract

PURPOSE:To improve packet transmission delay time characteristics, and allow desired setting of buffer, by systematically setting the packet length to be sent out to each link. CONSTITUTION:The device-C forms appropriate size packet for each logical channel according to generated information or information to be handled, and sends out to the device-A by giving order numbers of order control. The multi- link procedure control MLP in the device-A produces frames by giving order numbers and flow control information to the sending-out packet, sends the frames to the signal link LSP-31 in case of the frame length being f>=t1, and sends the frames to SLP-32 in case of the frame length being f<t1. SLP's 31 and 32 have attained a high level transmission control HDLC procedure against SLP's 41 and 42 in the each device-B through the data links 11 and 12; through this procedure the packets are transmitted, which assures a normal action. MLP in the device-B controls the receiving packet order by received packet MLP information.

Description

[Detailed Description of the Invention] (Technical Field) The present invention relates to a packet communication system, and in particular, provides a plurality of data links between devices that perform communication, increases the maximum allowable packet size, and transmits data according to the packet size. The present invention relates to a multi-link packet communication system that can improve overall transfer efficiency by selecting a data link to transfer.

(Background Art) Typical conventional packet communication protocols (communication regulations) include ×, 25, ×, and 75, which are recommended by the GCITT (Global Telegraph and Telephone Consultative Committee).

These are intended for communications where the amount of information generated at one time is relatively small, such as computer TSS terminals.
The maximum allowable size of packets handled is also limited to about 1000 to 2000 bits. In addition, a multi-link procedure is specified for the link level of ×,75, which is a method that is used when multiple data links are physically provided between devices and a failure occurs in some of the data links. This is a procedure that attempts to ensure communication reliability using other links. ×
, 25 basically use predetermined links in a fixed manner.

On the other hand, in recent packet communications, it has become necessary to transfer image information such as facsimile and videotex, that is, a large amount of continuously generated information. For such information transfer, the transfer efficiency can be improved by increasing the maximum allowable packet size.

However, in protocols that do not take into account the length of the packet to be sent, such as ×, 25 and ×, 75 mentioned above,
If the maximum allowable packet size is increased and long and large packets and short and small buckets are mixed, the link will be occupied by the transfer of large packets, and short and small packets such as call setup request packets and confirmation packets for flow control, etc. This method has the disadvantage that the probability that transmission will be blocked increases, and the number of packets waiting to be sent and the waiting time for sending them become large on average.

(Problems to be solved by the invention) The present invention has been made to solve the above-mentioned drawbacks of the prior art, and is characterized in that a plurality of data links are provided between devices, and a data link to be trusted is selectively used depending on the size of a packet to be transferred. This provides a multi-link packet communication system that allows

(Structure and operation of the invention) FIG. 1 is a diagram for explaining the present invention in detail. There is 1. between device A and device B. n books of ~ln (n is the number of squares)
A two-way data link is set up. 2. ~2n,
3. -3n is a link control unit, for example, 21 is a link control unit 3. and realizes data link control procedures.

Here, the link to be used from among the bidirectional data links 11 to 1n is determined according to the length of the packet to be sent. For example, in device A, when the packet length is f, those with II<fi1' are sent out from the link control unit 21, those with 12 x f x 12 are sent out from the link control unit 22, and ln x f < l. 'TI is sent from the link control unit 2n.

Furthermore, in device B, those with r1≦f<r' are sent from link 3, those with r2<f<r'2 are sent from link control unit 22, and those with rn < f <r'n are sent out from link 3. It is sent from the link control unit 2n. Here, the packet length range handled by each link control unit may be continuously divided into packet lengths as shown in (1) of FIG. It may also be divided into two parts. In the case of overlap, for packets that fall within the overlap range, the operating status of the two relevant link control units is checked, and the link control unit that has fewer empty or queued packets for transmission is used to send the packets. do it. Also, with device A and device B.

The keratin length range may be set exactly the same as 1, = parrot + ``l = rI.Furthermore, 11.

"l, '2, ■'2 +lT1, In +"I +
rl'+r2r'2+rn+r'. does not necessarily have to be a fixed value, and may be adaptively changed depending on the nature and amount of traffic.

Next, examples of the present invention will be described. Note that the number of bidirectional data links set between device A and device 8 will be described as two for the sake of simplicity.

FIG. 2 shows an embodiment of the invention. In the figure, A and B are communication devices according to the present invention, which include one multilink procedure controller (NLP) and a plurality of single links (SL
P) A procedure control unit. 1112 is a bidirectional data link established between devices A and B; 1. is V+
(, bps) and 12 is V2 (bT18
) has a speed of C and D are the main devices for packet communication, and perform packet transfer control at the packet level, that is, for each logical channel.Both devices C and D may be user-level terminal devices, or device C may be a computer, the device may be a user terminal or a computer, both devices C and D may be exchanges, or a combination of the above may be used.

Here, 5LP31 faces 5LP41, and 5LP3
2 is a high-level transmission control procedure (
) IDLC: High 1level Data pi
nk Control procedures), and the procedure defined by X,25 or X,75 can be used.

Next, the operation of this embodiment will be explained.

Device C forms a packet of an appropriate size for each logical channel depending on the information generated or handled, or attaches a sequence number for order control, and sends the packet to device MA. Device A's [, P is the NLP for the packet to be sent.
Information for sequence number Yahoo flow control (r ML
After making the frame into a frame, if the frame length f is fat, it is sent to 5LP31, and if f<t, it is sent to 5LP32 (including putting it in a queue).
, 5LP31 is data link 1. 5LP41 of device B via
2) opposite 5LP42 of device B via IDLC
A procedure is implemented, and packet transmission is performed according to this procedure. Here, the flow control phase frames etc. generated by the SLP itself are directly sent to the opposing SLP regardless of their length, so normal operation is guaranteed.

In the NLP of device B, the order of received packets is controlled by the NLP information of the packets received by the 5LP 41 or 42. In other words, packets continuously generated from one logical channel do not necessarily all have the same S.
Although LP is not necessarily used, NLP on the receiving side performs order control and sends packets to the devices in the correct order, ensuring communication between devices C and D.

The transmission from the device MD to the device C is completely opposite to that described above.

In this embodiment, the speeds V, V2 of the bidirectional data links 11 and 12 may be equal, but the speed V1 of the bidirectional data link it that transmits a long frame is set more appropriately than the speed ■2 of the bidirectional data link 12. By increasing the number of frames, the transfer time and waiting time per frame on both links 11 and 12 can be averaged, and the order of frames arriving at the NLP can be improved.

As described above, in order to selectively use a data link according to the frame length to be sent, fat is used.

Only short and short frames that satisfy the above conditions will be sent out from the 5LP 32, and the sending of short and short frames will not be delayed due to long and large frames, and will be transmitted to device B relatively quickly.

Note that it is also possible to control the transmission waiting time by adaptively changing the values of tl of device A and t2 of device B depending on the nature or amount of traffic. Further, in the NLP, the SLP used at one point 11 or t2 was selected, but the SLP used may be determined by taking into account 2 in FIG. 1(b).

Next, another embodiment of the present invention shown in FIG. 3 will be described.

This embodiment attempts to equalize the loads on St and P by having each SLP handle long and large frames in one direction (for example, transmission) and handle short and small frames in the other direction (for example, reception). In other words, since the load on the SLP largely depends on its processing amount, that is, the number of frames handled, it is taken into consideration that it is larger when handling short and small frames than when handling long and large frames.

Therefore, in this embodiment, in the NLP of device A, a frame with a frame length f≧t1 is sent from 5LP31, a frame of f×t2 is sent from 5LP32, and device B
In NLP, the fat2 frame is 5LP41
Therefore, frames with f>t2 are transmitted from the 5LPE 12, and long and large frames are transmitted through the bidirectional data link 11 with a speed of Vl, and short and small frames are transmitted through the bidirectional data link 12 with a speed of V2. Furthermore, in each SLP, those that transmit long and large frames are wired so that they receive short and small frames, and those that transmit short and small frames are wired so that they receive long and large frames. Other operations are similar to those in FIGS. 1 and 2. In addition, in SLP, even if the sending speed and receiving speed are different, this does not impair the function;
It should be exactly the same as the one in the picture.

In this embodiment, even if the speeds v1 and V2 of the bidirectional data links l and 12 are equal, the effect of equalizing the load on the SLP is produced, but as described in FIG. The speed V of the link 11 is the speed V2 of the bidirectional data link 12 that transmits short and small frames.
By increasing the number of transmission frames, the number of transmission frames can be averaged, and the load on the SLP can be evened out.

Furthermore, according to this embodiment, the buffer memory size of each SLP is made uniform. In other words, when looking at 5LP3.1, a confirmation frame is promptly returned in response to a sent long frame, so there is no need to wait for a long frame, and the buffer memory size for this is small. I'll try it. Also, if you pay attention to 5LP41,
The confirmation frame for the received short frame is 5LP31.
The transmission will be performed after the transmission of the long frame from 1 is completed, and a large number of confirmation frames to be transmitted will accumulate due to this waiting period. However, since the size of the confirmation frame is very small, the buffer memory size can be small.

According to the tree embodiment as shown in 2 below, the processing amount of each SLP (
Since the load (load) and required buffer memory can be equalized, it is possible to standardize the specifications of all SLPs, and the SLP
This is a great advantage when converting LP into LSI.

(Effects of the Invention) As described above, according to the present invention, in a multi-link packet communication system, by systematically setting the packet length to be sent to each link, it is possible to set the length of the packet to a desired amount. , its industrial value is great.

BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1(a) and (b) are diagrams for explaining the present invention in detail, and FIGS. 2 and 3 are configuration diagrams of an embodiment of the present invention. 11 to 1n; Two-way data link 21 to 2n; Link control unit 3, to 3n; Link control unit Patent applicant International Telegraph and Telephone Co., Ltd. #1 Patent attorney Megumi Yamamoto -

Claims (1)

[Claims] In a packet communication system that communicates via multiple bidirectional data links, each data link is assigned a range of frame lengths and communication speeds to be transferred, and the transmitting side selects a data link according to the frame length to be sent. A multi-link packet communication system characterized in that a frame containing 7 data links is sent out, and the receiving side extracts the received frames from each data link in the same order as the sending side according to the sequence number.