JPH04223635A - Packet switchboard - Google Patents

Abstract

PURPOSE:To prevent a transfer delay, and to reduce a communication cost by transmitting a short packet after converting it into a long packet. CONSTITUTION:This device is equipped with an extension ISDN basic interface part (BRI) 43 which receives the short packet transmitted from a terminal, packet handle module (PHMB) 44 which converts the short packet into the long packet, and trunk line primary group interface part (PRT) 41 which transmits the converted long packet to a network. Therefore, the short packet transmitted from the terminal is received by the BRI 43, transmitted to the PHMB 44, converted into the long packet by this PHMB 44, and then transmitted to the network by the PRT 41.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a packet switch in a private branch exchange that supports ISDN (Integrated Services Digital Network) packet switching services.

0002

[Prior Art] Packet switching services in ISDN use the B channel (64 km/sec), which is an information channel.
Packet communication is provided not only on the D channel (16 kilobits per second control channel), which is a signal channel, but also on the current Type 1 and Type 2 packet switching services. The usefulness of packet switching services has been proposed.

[0003] D-channel packets in ISDN use LAPD (D-channel link access procedure) as the layer 2 (data link layer) protocol, so the maximum amount of data that can be transmitted is 260 octets.
There are two types of packet sizes in PLP (Packet Layer Protocol): 128 and 256 octets. On the other hand, for B channel packets, the packet size is 1
Not only 28,256 short packets but also 512,
It can handle long packet data such as 1024, 2048, and 4096 octets, and also supports data communications such as file transfer. Furthermore, if this D channel packet is used in the ISDN basic interface, the remaining two B channels can be used for other purposes, leading to improved serviceability for users.

Against this background, recently there has been an increase in the development and commercialization of ISDN terminals and ISDN-TAs (terminal adapters) that support D-channel packet switching services.

[0005]

[Problems to be Solved by the Invention] However, systems in which only the conventional D channel packet switching service can be used are suitable for sending and receiving small amounts of data with a communication partner, but the B channel is not suitable for data such as file transfers. Since the packet size is smaller than long packets in packet switching services, the number of packets to be transmitted and received increases, which increases processing in packet switching during transfer, resulting in transfer delays. In addition, in terms of communication costs, long packets (1024, 2048, 409
6 octets) compared to short packets (128,2 octets).
56 octets) was more expensive.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a packet switch that does not cause transfer delays and can reduce communication costs.

[0007]

[Means for Solving the Problems] In order to achieve the above object, the packet switching device of the present invention comprises: a receiving means for receiving short packets sent from a terminal; a converting means for converting the short packets into long packets; The apparatus is characterized by comprising a sending means for sending the converted long packet to the network.

[0008]

[Operation] A short packet sent from a terminal is received by the receiving means, sent to the converting means, converted into a long packet by the converting means, and then sent to the network by the sending means.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIGS. 1(a) and 1(b) are drawings that best represent the features of the present invention. In FIG. 1(a), reference numeral 11 indicates a short packet of data 1 to data 16 (data 3 to data 15 are not shown) and are layer 3 (network layer) portions of packet data. In FIG. 1(b), 12 is a long packet (256×16=4096
(octet) (data 4 to data 15)
This is the layer 3 part of the packet data (not shown).

FIG. 2 is a diagram showing a table storing the contract status of packet switching services corresponding to each outside line.
In the figure, 20 is the table.

FIG. 3 is a block diagram of a packet switch according to the present invention, in which 40 is a packet switch;
Reference numerals 1 and 42 are a station line primary group interface unit (hereinafter referred to as PRT) and a station line basic interface unit (hereinafter referred to as PRT), which are connected to the ISDN and are sending means for sending converted long packets to the network. , BRT), and 43 is an extension ISDN basic interface unit (hereinafter referred to as BRI) to which the ISDN terminal and ISDN-TA are connected, and which is a receiving means for receiving short packets sent from the terminal. , 44 is a packet handler module (hereinafter referred to as PHMB) which is a B channel packet converting means that stores packets and converts short packets into long packets, 45 stores packets and converts long packets into short packets. A packet handler module (hereinafter referred to as PHMD), which is a D channel packet conversion means for converting into
Communication path switch for exchanging BRT42, BRI43, PHMB44, 47 is PRT41, BRT42, BR
A central control unit (hereinafter referred to as CC) that controls I43, PHMB44, PHMD45, and communication path switch 46, 48 is a transmission line for transmitting B channel packets, 49 is a transmission line for transmitting D channel packets,
In addition, the CC 47 is also a control bus that controls the PRT 41, BRT 42, and BRI 43. The CC 47 is a first storage means that stores the initial request packet size when receiving call request packet data, and a PHMB 44 that is a conversion means.
, a second storage means for storing the packet size finally determined through negotiation between the PHMD 45 and the first storage means, and a second storage means for storing the packet size finally determined by negotiation between the PHMD 45 and the first storage means; A third storage means is provided for storing an optimal packet size determined by negotiation between a requesting means for making a request, a party with whom the packet communication is to be performed, and the converting means 44, 45, respectively. 50 is PHMD45 to PHM
It is a transmission line that can directly transfer "X.25" PLP, which is the layer 3 information of the packet, to the B44.
is a control bus by which CC47 controls PHMB44 and PHMD45.

Next, the control operation of the packet switch having the above configuration will be explained with reference to the flowcharts shown in FIGS. 4 to 9.

First, in FIG. 4, when the control operation starts, the CC 47 establishes a layer 2 packet link (SAP
Determine whether the setting (I=16) is established (
Step 1). If not established, perform step 1 until established; if established, CC47:
It is determined whether the BRI 43 has received a CR (call request) packet on the D channel (step 2). If it is not received, the CC 47 determines whether it is another command (step 3), and if it is not another command, it returns to step 2, and if it is another command, it processes this other command ( Step 4). On the other hand, in step 2,
If BRI43 receives the CR packet, CC47
Under the communication control of the PHMD 45, the BRI determines whether or not the CR packet has been transmitted to the PHMD 45 using the transmission path 49 in FIG. 3 (step 5). If you don't send it,
This step 5 is executed until the CR packet is sent, and if it is sent, the CC 47 determines whether or not the PHMD 45 has received the CR packet (step 6). If it is not received, the CC 47 executes step 6 until the CR packet is received. If so, proceeding to step 7, the CC 47 determines whether the PHMD 45 has transmitted a CR packet for controlling call setup and call disconnection using the transmission path 51 in FIG. If it is not transmitted, step 7 is executed until it is transmitted, and if it is transmitted, the CC 47 receives the CR packet (step 8). And C.C.
47 analyzes the facility and user data in the CR packet, and stores the requested packet size (short packet packet size) in the CR packet in the first storage means (step 9). At this time, CC4
7 is, for example, a coding indicating a request from the user to change a short packet to a long packet (i.e., conversion from a D channel to a B channel) in the calling address extension (facility code 11001011) part, which is one of the DTE facilities. It is determined whether or not this has been done (step 10). Once the coding has been completed, the CC 47 checks the contract status of the B channel packet switching service of the external line to be used with reference to the table 20 of FIG. 2, which is the fourth storage means, and determines the external line to be used ( Step 11). Next, the CC 47 connects the packet link (SAPI=
16) is established (step 12). If not established, CC47
The B channel packet link of T42 (or PRT41) is set up (step 13). Next, it is determined whether or not a contract for flow control parameter negotiation has been made in the contract for the external line used that was checked in step 11 (step 14). Further, if the B channel packet link is established in step 12, the process proceeds to step 14 without executing step 13.

Next, the control procedure when a negotiation contract has been made will be explained.

[0015] If it is determined in step 14 of FIG. 4 that a negotiation contract has been made, the process proceeds to step 15 of FIG. CR packet with packet size coded as PH
Send to MB44. CC47 then PHMB4
4 determines whether or not the CR packet coded with the packet size of the long packet has been transmitted to the BRT 42 (step 16). If not, this step 16 is executed until it is transmitted; if it is transmitted, the next Proceeding to step 17, the CC 47 determines whether the BRT 42 has transmitted the CR packet to the ISDN. If it is not transmitted, this step 17 is executed until it is transmitted, and if it is transmitted, the CC 47 determines whether or not the BRT 42 has received a CC (call setup complete) packet from the ISDN (step 18). If it is not received, this step 18 is executed until it is received, and if it is received, the CC47
44 receives a CC packet from the BRT 42 (step 19). If not received, execute step 19 until received; if received, CC
47 determines whether the PHMB 44 has stored in the third storage means the packet size coded in the CC packet determined through negotiation with the communication partner (step 20). If it is not memorized, execute this step 20 until it is memorized, and if it is memorized, CC47
receives a CC packet from the PHMB 44 (step 21). Next, the CC 47 determines the packet size handled by the PHMD 45, taking into consideration the traffic volume on the D channel, the number of packet links, etc., and the short packet size desired by the terminal, which is stored in the first storage means in step 9. , change the packet size of the long packet (handled by PHMB44) in the CC packet to the packet size of the short packet, and
(step 22). Next, proceeding to step 23 in FIG. 6, the CC 47 determines whether the PHMD 45 has stored the packet size (short packet) coded in the CC packet in the second storage means (step 23). If it is not stored, execute this step 23 until it is stored, and if it is stored, CC47
determines whether the PHMD 45 has transmitted the CC packet to the BRI 43 (step 24). If not, this step 24 is executed until it is sent, and if it is sent, the CC 47 determines whether the BRI 43 has sent the CC packet to the extension terminal side (step 25). If the data is not transmitted, this step 25 is executed until it is transmitted, and if it is transmitted, the CC 47 establishes the data transmission phase (step 26) and ends this control.

Next, a control procedure when a negotiation contract has not been made will be explained. If it is determined in step 14 of FIG. 4 that no negotiation contract has been made, the process proceeds to step 27 of FIG. Send. Next, the CC 47 determines whether the PHMB 44 has stored the packet size in the CR packet in the third storage means (step 28). If it is not stored, this step 28 is executed until it is stored, and if it is stored, the CC47
It is determined whether the MB 44 has transmitted the CR packet to the BRT 42 (step 29). If it is not sent, execute this step 29 until it is sent, and if it is sent, CC4
7 determines whether the BRT 42 has transmitted the CR packet to the ISDN (step 30). If you don't send it,
Perform this step 30 until you send it, and once it is sent,
The CC 47 determines whether the BRT 42 has received a CC packet from the ISDN (step 31). If it is not received, this step 31 is executed until it is received, and if it is received, the CC 47 transmits the CC packet to the PHMB 44 (step 32). Then CC47 is PHM
It is determined whether the B 44 has transmitted the CC packet to the CC 47 (step 33). If it is not transmitted, this step 33 is executed until it is transmitted, and if it is transmitted, the CC 47 receives the CC packet from the PHMB 44 and sends it to the PHMD.
45 (step 34). Next, steps 23 to 26 in FIG. 6 described above are sequentially executed, and this control is completed.

[0017] Next, a control procedure in the case where the user has not encoded a request to change a short packet to a long packet will be described. If it is determined in step 10 of FIG. 4 that no coding indicating a request to change the short packet to a long packet is made, the process proceeds to step 34 of FIG. 8, and the CC 47 transmits the CR packet to the PHMD 45. Next, CC47 connects the D channel (Dch), which is the external line used by PHMD45.
It is determined whether or not it has been investigated (step 35). If the CC 47 does not check, this step 35 is executed until the check is made, and if the check is done, the CC 47 determines whether the setting of the packet link of the D channel to be used has been established (step 36). If not established, CC47
42 (or PRT 41), sets up the D channel packet link (step 37), and then performs the next step 38.
Proceed to. Further, if the packet link is established in step 36, the process proceeds to step 38 without executing step 37. Then, in this step 38, the CC 47 determines that the PHMD 45 receives the CR packet from the B
It is determined whether or not it has been transmitted to RT41. If it is not transmitted, this step 38 is executed until it is transmitted, and if it is transmitted, the CC 47 determines whether the BRT 41 has transmitted the CR packet to the ISDN (step 39). If not transmitting, this step 39 is executed until transmitting, and if transmitting, CC47 is
Determine whether a packet has been received (step 40)
. If it is not received, this step 40 is executed until it is received, and if it is received, the CC 47 receives the X. 25 After confirming that the packet layer is established, convert the CC packet to PHM.
D45 (step 41). Then CC47
determines whether the PHMD 45 has transmitted the CC packet to the CC 47 (step 42). If you don't send it,
Execute this step 42 until sending, and once it is sent,
The CC 47 transmits the CC packet to the PHMD 45 (step 43), and then steps 23 to 2 of FIG. 6 described above
6 is executed sequentially to end this control.

Next, the control procedure in the data transfer phase will be explained with reference to FIG. In FIG. 9, when the control operation starts, the CC 47 determines whether a long-sized data packet transmitted from the extension terminal side has arrived at the BRI 43 (step 44). If the call does not arrive, the CC 47 determines whether the PHMB 44 has divided the long packet into short packets stored in the second storage means and transmitted them to the PHMD 45 (step 45). If it is not sent, this step 45 is executed until it is sent, and if it is sent, the CC 47
BRI the short packet received from PHMB44.
43 (step 46). If not, this step 46 is executed until it is sent, and if it is sent, the CC 47 determines whether the BRI 43 has sent the short packet to the extension terminal (step 47). If the data is not transmitted, this step 47 is executed until it is transmitted, and if it is transmitted, the CC 47 determines whether or not the data has ended (step 48). If not completed, the process returns to the first step 44, and if completed, this control is ended. On the other hand, in step 44, BRI43
When a long packet arrives at PH
It is determined whether the MD 45 has transmitted the short packet to the PHMB 44 (step 49). If you don't send it,
This step 49 is executed until the packet is transmitted, and once the packet is transmitted, the CC 47 determines whether the PHMB 44 has converted the short packet into a long packet and transmitted it to the BRT 42 (step 50). If it is not sent, this step 50 is executed until it is sent, and if it is sent, the CC
47 determines whether the BRT 42 has transmitted the long packet to the ISDN (step 51). If not, this step 51 is executed until it is sent, and if it is sent, step 48 is executed.

In the above embodiment, the part for storing and converting packets in FIG. 3 is separated into the PHMB 44 and the PHMD 45, but the invention is not limited to this. The present invention can also be implemented. Further, in step 32 of FIG. 4, coding indicating a user's request to change the packet size is made to the DTE facility, which is the facility of the CR packet. The present invention can be implemented even if coding is performed to indicate the following.

[0020]

As explained above, the packet switching device of the present invention includes a receiving means for receiving short packets sent from a terminal, a converting means for converting the short packets into long packets, and a converting means for converting the short packets into long packets. and sending means for sending packets to the network.

[0021] Therefore, the number of packets to be processed within the network is reduced, problems such as transfer delays are eliminated, and communication costs are reduced because relatively expensive short packets are transmitted and received as relatively inexpensive long packets.

[0022] In this way, even from a terminal that can only use the D channel packet switching service, the B channel packet switching service can be used, which is effective as an additional service in packet switching.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the relationship between short packets and long packets whose packet sizes are changed in a packet converter according to the present invention.

FIG. 2 is a diagram of a table storing the contract status of an outside line in a packet switching service.

FIG. 3 is a block diagram of a packet switch according to the present invention.

4 to 9 are flowcharts showing the control operation procedure of the packet switch of the present invention.

[Explanation of symbols]

41 Office line primary group interface section (sending means) 42
Office line basic interface section (sending means) 43 Extension ISDN basic interface section (receiving means) 44
Packet handler module (exchange means) 45 Packet handler module (exchange means) 47 Central control unit

Claims (1)

[Claims] 1. A packet switching device that stores and exchanges packet data between a terminal and a network, comprising receiving means for receiving short packets sent from the terminal;
A packet switching device characterized by comprising a converting means for converting the short packet into a long packet, and a sending means for sending the converted long packet to the network.