JP3642305B2 - COMMUNICATION SYSTEM, PACKET EXCHANGE METHOD THEREOF, AND RECORDING MEDIUM CONTAINING EXCHANGE PROGRAM - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a communication system using packet switching, and more particularly, to a communication system for efficiently exchanging communication between a server and a client and an exchange method thereof.
[0002]
[Prior art]
In the network protocol of the OSI reference model, the function of the data communication network is roughly divided into seven layers (Layer), and the physical layer, data link layer, network layer, transport layer, session layer, presentation layer, application in order from the lower layer. There are layers. The first layer (Layer 1),
Sometimes called the second layer (Layer 2),...
[0003]
The nodes on the communication network correspond to the layer of data to be referred to in the exchange of the communication, and include a layer 2 switch (Layer 2 Switch), a layer 3 switch (Layer 3 Switch), and a layer 4 switch (Layer 4 Switch). ) And so on. Recently, there is a layer 7 switch (also a 4-7 layer switch) that precisely controls flow and traffic based on information of a higher application layer.
[0004]
FIG. 18 is a block diagram showing a configuration of a conventional communication system including an exchange 100b that is a layer 7 switch.
[0005]
In the conventional communication system of FIG. 18, a server group 71 including a plurality of servers 70 and a client 60 are connected to each other via a network 50 of a packet switching network. Examples of the packet switching network include an IP (Internet Protocol) network.
[0006]
Each client 60 receives a service from the server 70 in the server group 71 via the network 50. In this service, first, the client 60 establishes a transport layer connection capable of bidirectional communication with the server 70 (for example, TCP protocol), and an identifier of data to be acquired is sent from the client 60 to the server 70. The designated data is sent from the server 70 to the client 60. It is also possible to issue a plurality of data acquisition requests with one connection, and the server 70 sequentially sends the received data to the client 60.
[0007]
When the client 60 has obtained all the data desired to be obtained from a certain server 70, the client 60 can send a close request to the server 70 and instruct the server to disconnect the connection.
[0008]
The transport layer connection used for this service for two-way communication includes the sequence number indicating the position of data in the transport layer included in the packet, and the transport of the data in the packet. The data length in the layer and the Ack number indicating the data position in the transport layer that has been reliably received by the communication partner so far are included. Transport layer protocol termination units (termination units) at both ends of the communication control retransmission of packets lost during communication using the sequence number and the Ack number.
[0009]
Further, since flow control is performed at both ends of the communication, a field (window field) for indicating the remaining capacity of the reception buffer may be provided to the communication partner. Hereinafter, this value is referred to as a Win value.
[0010]
At both ends of the communication, the initial value of the sequence number is handshaked and notified to each other. Further, at the end of the connection, the packet is disconnected by exchanging a packet having a flag (end flag) indicating the end of the connection with the packet and a packet including the reception confirmation. An example of such a protocol is the TCP protocol used on the Internet.
[0011]
Next, the role and operation of the conventional exchange 100b of FIG. 18 will be described in more detail.
[0012]
The exchange 100b in FIG. 18 causes the client 60 to virtually recognize the plurality of servers 70 in the server group 71 as one server, and transfers the data acquisition request from the client 60 to the appropriate server 70. It has a function of transferring response data from the server 70 to the client 60.
[0013]
From the client 60, the server group 71 is recognized as one virtual server 70 (virtual server) having the same network 50 address. When the client 60 tries to connect to the virtual server at the address, first, a connection is established between the client 60 and the exchange 100b.
[0014]
The client 60 passes a data acquisition request (identifier of data to be acquired) on this connection. The exchange 100b selects an appropriate connection destination server 70 based on the identifier of the data acquisition request that has flowed through this connection.
[0015]
Next, the exchange 100b opens a connection to the selected server 70 and transfers a data acquisition request over the connection. The server 70 flows the data requested for acquisition onto this connection, and the exchange 100 b transfers this data to the client 60.
[0016]
At this point, there are two connections, that is, a connection between the client 60 and the exchange 100b and a connection between the exchange 100b and the server 70. The exchange 100b connects these connections into one.
[0017]
That is, by connecting two transport layer connections between the client 60 and the exchange 100b and between the exchange 100b and the server 70 into one, the transport layer retransmission and the flow are sent to the server 70 and the client 60, respectively. Since the control is performed, the exchange 100b does not need to perform retransmission control and flow control regarding the connection.
[0018]
This operation is called splicing.
[0019]
Hereinafter, the splicing process of the exchange 100b which is a conventional layer 7 switch will be described in detail with reference to the drawings. FIG. 19 is a block diagram showing a configuration of a conventional exchange 100b.
[0020]
In the exchange 100b of FIG. 19, a client side processing unit 10b that processes communication with the client side, a server side processing unit 20b that processes communication with the server side, an analysis unit 30b that determines a connection destination of each client, A storage unit 40b that stores a forwarding table or the like indicating a connection destination server corresponding to each data acquisition request is provided.
[0021]
The client-side processing unit 10b includes a client-side termination unit 11b that terminates communication on the client side, a client-side switching unit 13b that switches a data communication path, and a client-side communication unit 14b that transmits and receives packets with each client. I have. The server-side processing unit 20b includes a server-side termination unit 21b that terminates communication on the server side, a server-side update unit 22b that rewrites and updates packet header information, a server-side switching unit 23b that switches data communication paths, The server side communication part 14b which transmits / receives the packet with the server 70 is provided.
[0022]
A packet from the client 60 to the exchange 100b arrives at the client side switching unit 13b from the arrow A in FIG. 19, and a packet from the exchange 100b to the client 60 is updated at the client side termination unit 11b or the server side according to the arrows B and C in FIG. It is delivered from the unit 22b to the client 60.
[0023]
Further, a packet from the server side to the exchange 100b arrives at the switching unit 23b from the arrow E in FIG. 19, and a packet from the exchange 100b to the server 70 follows the arrow D in FIG. 22b to the server 70.
[0024]
The client-side switching unit 13b passes the packet arriving from the arrow A to the client-side termination unit 11b or the server-side updating unit 22b according to the instruction from the server-side updating unit 22b. Further, the server-side switching unit 23b passes the packet arriving from the arrow E to the server-side update unit 22b or the server-side termination unit 21b in accordance with the instruction from the server-side termination unit 21b.
[0025]
First, when the client 60 tries to connect to the virtual server, a connection establishment handshake is performed. At this time, the server side update unit 22b instructs the client side switching unit 13b to send the client 60, the client Exchanges are made between the side termination unit 11b, and a connection is established between the client 60 and the client side termination unit 11b. Hereinafter, the initial sequence number of the client 60 of the connection at this time is “SC”, and the initial sequence number of the client side processing unit 10b is “SU”, which are recorded.
[0026]
The client 60 passes a data acquisition request (identifier of data to be acquired) on this connection. The client side termination unit 11b processes the transport layer protocol, extracts the data flowing on this connection, and passes this data acquisition request to the analysis unit 30b.
[0027]
The analysis unit 30b can select an appropriate server 70 by, for example, referring to the forwarding table stored in the storage unit 40b based on the data acquisition request. Then, the analysis unit 30b instructs the server-side termination unit 21b to establish a connection to the selected server 70, and the server-side termination unit 21b establishes a connection to the designated server 70.
[0028]
At this time, a handshake for establishing a connection is performed between the server-side termination unit 21b and the server 70. Here, the server-side termination unit 21b instructs the server-side switching unit 23b on an appropriate communication path so that packets relating to handshaking can be exchanged between the server-side termination unit 21b and the server 70. The initial sequence number of the server 70 of the connection at this time is “SS”, and the initial sequence number of the server side termination unit 21b is “SV”, which are recorded.
[0029]
Next, the analysis unit 30b passes the data acquisition request to the server-side termination unit 21b, and transfers the data acquisition request to the server 70 using the connection in which the data acquisition request is established. Here, the server-side termination unit 21b instructs the switching unit 23b to switch so that subsequent packets sent from the server 70 are passed to the server-side updating unit 22b.
[0030]
Next, a packet carrying data corresponding to the data acquisition request arrives at the exchange 100b from the server 70. The packet sent from the server 70 is transferred to the server side update unit 22b by the switching unit 23b.
[0031]
The server side update unit 22b updates the header information when the packet is relayed. That is, the sequence number and Ack number of the packet are rewritten, and if necessary, the checksum of the transport layer protocol is correctly updated and sent to the client 60.
[0032]
Further, the subsequent update of the sequence number and Ack number of the packet sent from the server 70 is equivalent to the data when the packet is transmitted from the client side processing unit 10 (that is, from the exchange 100b). Rewrite and update as follows.
[0033]
For example, when a packet other than those described above is not transmitted from the client 60, it can be updated as follows.
[0034]
First, for the sequence number, the difference between the initial sequence number “SU” of the client side termination unit 11 b received from the client side termination unit 11 b and the initial sequence number “SS” of the server 70 received from the server side termination unit 21 is added. . That is, “update sequence number = current sequence number + SU−SS”. At this time, the processing when the maximum sequence number is exceeded conforms to the method of adding and subtracting sequence numbers in the transport layer protocol.
[0035]
For the Ack number, the difference between the initial sequence number “SC” of the client 60 received from the client side termination unit 11b and the initial sequence number “SV” of the server side termination unit 21b received from the server side termination unit 21b is added. That is, “Ack number to be updated = current Ack number + SC-SV”.
[0036]
By doing so, the transport layer protocol of the client 60 can process the packet from the server 70 by regarding the packet as coming from the client side processing unit 10b (that is, from the exchange 100b).
[0037]
Similarly, a packet sent from the client 60 to the server 70 thereafter is transferred to the server-side update unit 22 by the client-side switching unit 13b, and the sequence number and Ack number of the packet are displayed, and the packet is transmitted to the server-side processing unit 20b. (Ie, from the exchange 100b) is rewritten to a value equivalent to that of the packet and sent. In other words, “update sequence number = current sequence number + SV−SC” and “update Ack number = current Ack number + SS−SU” are rewritten.
[0038]
In this way, the subsequent exchange of data between the server 70 and the client 60 rewrites the sequence number for each packet without going through the client-side termination unit 11b and the server-side termination unit 21b that terminate the transport layer protocol. Can only communicate in the process.
[0039]
This is the aforementioned connection splicing.
[0040]
Generally, only a small amount of data such as a data acquisition request flows from the client 60 to the server 70, but a large amount of data flows from the server 70 to the client 60. For example, when accessing the web server from a client web browser, a large amount of data such as image data is transmitted from the server 70 to the client 60.
[0041]
By performing this connection splicing, a large amount of data can be relayed without performing complicated transport layer termination processing (retransmission and flow control), and throughput can be improved.
[0042]
[Problems to be solved by the invention]
However, the conventional exchange 100b described above has a problem that the exchange 100b cannot refer to a data acquisition request sent from the client 60 during splicing.
[0043]
Further, in the conventional exchange 100b, since the server 70 corresponding to the request is determined based on only the data acquisition request first sent from the client 60 and the connection is spliced, the data arriving from the client 60 after connection splicing is determined. There has been a problem that an acquisition request cannot be transferred to an appropriate server 70 based on the request.
[0044]
In addition, when the data transfer from the selected server 70 to the client 60 based on the data acquisition request sent first is completed, other data acquisition requests for the same server 70 remain. The close request is sent to the server 70 to disconnect the connection.
[0045]
Since the client 60 is disconnected, the acquisition request that has not been processed by the server 70 needs to be acquired again from the connection establishment (handshake) until the necessary data is acquired. There was a problem that the delay became large.
[0046]
The first object of the present invention is to solve the above-mentioned drawbacks of the prior art, monitor packets such as data acquisition requests transmitted from the client to the server even during splicing, and execute corresponding termination processing. It is to provide a communication system, a packet switching method thereof, and a recording medium recording the switching program.
[0047]
The second object of the present invention is to solve the above-mentioned drawbacks of the prior art and refer to a packet such as a data acquisition request transmitted from the client to the server even during splicing, and always acquire data to the appropriate server 70. For a large amount of data to be transmitted to the client side from the server, the conventional termination processing by splicing that only rewrites the header information such as the sequence number and the Ack number for each packet is realized by conventional termination processing. A communication system that simultaneously realizes a throughput equivalent to that of an exchange, a packet exchange method thereof, and a recording medium on which an exchange program is recorded.
[0048]
A third object of the present invention is to solve the above-mentioned drawbacks of the prior art and establish a connection established between the client and the exchange until the client receives all data transmitted in response to a data acquisition request from the client. The communication system, the packet switching method thereof, and the recording medium recording the switching program can be provided in which the delay until the necessary data is acquired can be kept small.
[0049]
[Means for Solving the Problems]
In order to achieve the above object, the communication system of the present invention is a packet exchange communication system in which packet communication is performed between a server and a client via an exchange, and the exchange is transmitted from the server to the client. When the packet is relayed, the header information of the packet is rewritten to the contents set when the packet is transmitted from the switch, the packet is transmitted to the client, and the data acquisition request from the client is transmitted. From the time of relay until the end of transmission of the response packet transmitted from the server to the client, one-way splicing processing is performed in the direction from the server to the client, and from the client For communication in the direction to the server Retransmission control And flow control.
[0050]
In the communication system of the present invention according to claim 2, the exchange receives a connection from each of the clients, manages a connection with the client and transmits / receives a packet, and accesses each of the servers. A server-side processing unit that manages a connection with the server and transmits / receives a packet, and rewrites the header information of the packet when relaying a packet transmitted from the server to the client, Means for transmitting packets to the client; and one-way splicing processing in the direction from the server to the client; and communication in the direction from the client to the client-side processing unit and the server-side processing unit Established for communication in the direction from the server to the server To cut the connection Retransmission control without And means for performing flow control.
[0051]
In the communication system according to the third aspect of the present invention, the client-side processing unit controls a connection with each of the clients, and receives a connection or request from each of the clients. A client-side update unit that rewrites and relays packets sent to the client by rewriting header information, and the server-side processing unit manages a connection with each of the servers and is sent from the client-side termination unit A server-side termination unit that relays instructions and data for each server, and a server-side update unit that receives a packet transmitted from each server to each client and sends the packet to the client-side update unit. To do.
[0052]
In the communication system of the present invention according to claim 4, the header information of the packet includes, in transmission data divided into individual packets, a sequence number indicating the order of data in the packet, a data length of the packet, It includes an Ack number indicating a sequence number of data that has already been received by the communication partner.
[0053]
The communication system of the present invention according to claim 5 is characterized in that the header information of the packet includes a Win value indicating a remaining capacity of a reception buffer that has not yet been received by a communication partner.
[0054]
6. The communication system according to claim 6, wherein the client-side termination unit includes means for notifying the client-side update unit and the server-side termination unit of header information of a packet received from each of the clients. The side update unit includes means for notifying the server side termination unit of header information of a packet transmitted from each server to each client, and the client side update unit and the server side termination unit are notified. The header information of the packet is appropriately rewritten by referring to the recorded header information.
[0055]
In the communication system according to the seventh aspect of the present invention, in the state where the one-way splicing process is set, the client-side termination unit instructs the client-side update unit to perform a response process for a packet received from each of the clients. The client-side update unit includes means for receiving an instruction for the response process, generating a response packet for the client, and transmitting the response packet.
[0056]
In the communication system of the present invention according to claim 8, the server-side update unit relays transmission of packets from a plurality of the servers to one client, and the packet information in each server is determined from the header information of the relayed packets. Means for removing a flag indicating the end of transmission of the packet, and relaying a packet transmitted by switching the plurality of servers to the client without disconnecting the connection with the client. To do.
[0057]
In the communication system according to the ninth aspect of the present invention, the client-side termination unit and the server-side termination unit divide transmission data that is divided into individual packets and transmitted from the client to the server. It is characterized by comprising means for restoring to the previous state and selecting each packet by selecting a server.
[0058]
The communication system of the present invention according to claim 10 includes an analysis unit that determines a connection destination server to which each of the clients is connected, and the analysis unit transmits the client to each of the servers from the client-side termination unit. Means for obtaining information of a request to be made, means for determining a connection destination server to which the client is to be connected based on the request, and the determined connection destination of the client with respect to the server-side termination unit Means for instructing connection to the server.
[0059]
In the communication system of the present invention according to claim 11, the client-side termination unit and the server-side termination unit divide transmission data that is divided into individual packets and transmitted from the client to the server. Means for transmitting to the server after restoring to the previous state, wherein the analysis unit determines the connection destination server based on the transmission data restored to the original state before the division It is characterized by providing.
[0060]
The communication system of the present invention according to claim 12 is characterized in that the analysis unit sequentially classifies unprocessed data acquisition requests transmitted by the client into groups for each connection destination server, and the server-side termination unit. On the other hand, each classified group includes means for instructing connection to a corresponding server and execution of the data acquisition request classified into the group.
[0061]
The exchange according to the thirteenth aspect of the present invention is an exchange that relays packet communication between a plurality of servers and clients via a communication network, and when a packet transmitted from the server to the client is relayed, a header of the packet The information is rewritten to the contents set when the packet is transmitted from the exchange, the packet is transmitted to the client, and from the relay of the data acquisition request from the client, the server to the client Until the transmission of the response packet to be transmitted is completed, splicing processing is performed in one direction in the direction from the server to the client, and communication in the direction from the client to the server is performed. Retransmission control And flow control.
[0062]
The exchange of the present invention according to claim 14 receives a connection from each of the clients, manages a connection with the client and transmits / receives a packet, accesses each of the servers, A server-side processing unit that manages connections between the server and a packet, and rewrites the header information of the packet when relaying a packet transmitted from the server to the client, and sends the packet to the client. A means for sending to the server, and a one-way splicing process for the direction from the server to the client, and communication in the direction from the client to the client side processing unit and from the server side processing unit to the server. For direction communication, disconnect the established connection. Make Retransmission control without And means for performing flow control.
[0063]
In the exchange of the present invention according to claim 15, the client side processing unit manages a connection with each of the clients, and receives a connection or request from each of the clients; A client-side update unit that rewrites and relays a packet transmitted to the server, and the server-side processing unit manages a connection with each server, and is sent from the client-side termination unit. A server-side termination unit that relays instructions and data to the server, and a server-side update unit that receives a packet transmitted from each server to each client and sends the packet to the client-side update unit. .
[0064]
In the exchange of the present invention according to claim 16, the header information of the packet includes, in the transmission data divided into individual packets, a sequence number indicating the order of data in the packet, a data length of the packet, a communication It includes an Ack number indicating a sequence number of data already received by the other party.
[0065]
The exchange of the present invention according to claim 17 is characterized in that the header information of the packet includes a Win value indicating a remaining capacity of a reception buffer that has not yet been received by a communication partner.
[0066]
The exchange of the present invention according to claim 18, wherein the client-side termination unit includes means for notifying the client-side update unit and the server-side termination unit of header information of a packet received from each of the clients. The update unit includes means for notifying the server side termination unit of header information of a packet transmitted from each server to each of the clients, and the client side update unit and the server side termination unit are notified The header information is recorded and referred to, and the header information of the packet is appropriately rewritten.
[0067]
In the exchange of the present invention according to claim 19, in the state where the one-way splicing process is set, the client-side termination unit instructs the client-side update unit to perform a response process for a packet received from each of the clients, The client-side updating unit includes means for receiving a response processing instruction, generating a response packet for the client, and transmitting the response packet.
[0068]
In the exchange according to the twentieth aspect of the present invention, the server-side updating unit relays transmission of packets from the plurality of servers to one client, and from the header information of the packets to be relayed, A means for removing a flag indicating the end of transmission is provided, and packets transmitted by switching the plurality of servers are relayed to the client without disconnecting the connection with the client. .
[0069]
The exchange of the present invention according to claim 21, wherein the client-side termination unit and the server-side termination unit are configured to divide transmission data transmitted from the client into the individual packets to the server before dividing the original transmission data. And a means for selecting each server and transmitting each packet.
[0070]
The exchange according to the twenty-second aspect of the present invention includes an analysis unit that determines a connection destination server to which each client is connected, and the analysis unit transmits the client to each server from the client-side termination unit. Means for obtaining request information; means for determining a server to which the client is to be connected based on the request; and determining the connection destination of the client to the server-side termination unit. A means for instructing connection to the server is provided.
[0071]
In the exchange of the present invention according to claim 23, the client-side termination unit and the server-side termination unit are configured to divide transmission data transmitted from the client to the server in an individual packet before the original division. Means for transmitting to the server after being restored to the state, and the analysis unit comprises means for determining the connection destination server based on the transmission data restored to the original state before the division. It is characterized by providing.
[0072]
In the exchange of the present invention according to claim 24, the analysis unit includes means for sequentially classifying unprocessed data acquisition requests transmitted by the client into groups for each server to which the connection is made, and the server-side termination unit. On the other hand, each classified group includes means for instructing connection to a corresponding server and execution of the data acquisition request classified into the group.
[0073]
The packet switching method of the present invention according to claim 25 is a packet switching method of an exchange that relays packet communication between a plurality of servers and clients via a communication network, and is transmitted from the server to the client. When the packet is relayed, the header information of the packet is rewritten to the contents set when the packet is transmitted from the exchange, the packet is transmitted to the client, and the data acquisition request from the client is relayed. From the time until the transmission of the response packet transmitted from the server to the client is completed, the one-way splicing processing is performed in the direction from the server to the client, and the client performs the server processing. In the direction of communication Retransmission control And flow control.
[0074]
The packet switching method of the present invention of claim 26 manages a connection between each of the clients, accepts a connection or request from each of the clients, and transmits a packet transmitted from the server to the client. A step of rewriting and relaying the header information, and a step of managing a connection between each of the servers and relaying a command and data to each of the servers sent from the client. Sequence number indicating the order of data in the packet, the data length below the transport layer of the packet, and the Ack indicating the sequence number of the data already received by the communication partner Number and the rest of the receive buffer that the communication partner has not yet received Characterized in that it comprises a Win value indicating the amount.
[0075]
The packet switching method of the present invention according to claim 27 relays packet transmission from a plurality of servers to one client, and indicates the end of packet transmission at each server from the header information of the relayed packets. And a packet transmitted by switching the plurality of servers is relayed to the client without disconnecting the connection with the client.
[0076]
The packet switching method of the present invention according to claim 28, wherein transmission data divided into individual packets and transmitted from the client to the server is restored to the original state before division, and each packet is restored to the server The step of selecting and transmitting is provided.
[0077]
The packet switching method of the present invention according to claim 29 is a step of acquiring information of a request that the client sends to each of the servers, and determining a connection destination server to which the client should connect based on the request. And a step of instructing connection of the client to the determined connection destination server to determine a connection destination server to which each of the clients is connected.
[0078]
The packet switching method of the present invention according to claim 30 is the step of sequentially classifying the unprocessed data acquisition request transmitted by the client into groups for each server to which it is connected, and for each of the classified groups, A step of instructing connection to a corresponding server and execution of the data acquisition request classified into the group is provided.
[0079]
The recording medium on which the exchange program of the present invention according to claim 31 is recorded allows the computer to read the exchange program for relaying packet communication between a plurality of servers and clients via a communication network by controlling the computer. In the recording medium recorded in the above, the exchange program sets the header information of the packet when the packet transmitted from the server is relayed to the client, and the contents set when the packet is transmitted from the exchange The packet is transmitted to the client, and from when the data acquisition request from the client is relayed until the transmission of the response packet transmitted from the server to the client ends. One direction from server to client Performs processing for splicing, and the direction of communication from the client to the server Retransmission control And flow control.
[0080]
The server of the present invention according to claim 37 is a server in a communication system that performs packet communication between a server and a client via an exchange, and the client from the time of relaying a data acquisition request from the client in the exchange The packet is transmitted to the client by one-way splicing until the transmission of the response packet transmitted to the client is completed.
[0081]
The client of the present invention according to claim 45 is a client in a communication system that performs packet communication between a server and a client via an exchange, and the server from the time of relaying a data acquisition request to the server in the exchange The packet is received from the server by one-way splicing until the transmission of the response packet received from the server is completed.
[0082]
55. The communication system of the present invention according to claim 55, wherein the analysis unit sequentially classifies unprocessed data acquisition requests transmitted by the client into groups for each connection destination server, and the server-side termination unit. For each of the classified groups, means for instructing to disconnect the connection to the server after connection to the corresponding server, execution of the data acquisition request classified into the group, and transmission of the acquisition request It is characterized by providing.
[0083]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0084]
First, the concept of a communication system according to the present embodiment that performs packet communication between a server and a client via a communication network will be described with reference to FIG. In FIG. 1, 100 is a one-way terminal switch according to the present invention that relays connections of a plurality of servers to a communication network, 60 is a client, and 70 is a server.
[0085]
In the present invention, splicing is performed only for communication in the direction from the server 70 to the client 60 where a large amount of data is often transferred, and at the same time, retransmission is performed for communication in the direction from the client 60 to the server 70. Termination processing such as control and flow control is executed.
[0086]
Conventionally, the connection between the client 60 and the exchange 100b and the connection between the exchange 100b and the server 70 are spliced into one connection between the client 60 and the server 70. In the exchange 100b, termination processing such as retransmission and flow control is performed. On the other hand, in the one-way terminal switch 100 of the present invention, the client 60 and the server 70 are not connected to each other in a single TCP connection in both directions, but from the server 70 to the client 60. Only the packet sequence number and the Ack number by the splicing process are rewritten only for the data that flows to the server 70, and the server 70 and the client 60 themselves perform the retransmission control and the flow control.
[0087]
Here, in the transport layer connection from the client 60 to the one-way terminal switch 100, the one-way terminal switch 100 controls the retransmission of data flowing from the client 60 to the one-way terminal switch 100 and the client 60. Terminate with flow control. Further, the connection between the exchange 100 and the server 70 also terminates the one-way termination exchange 100 by performing retransmission control and flow control of data flowing from the one-way termination exchange 100 toward the server 70 with respect to the server 70.
[0088]
FIG. 2 is a block diagram illustrating an example of a network configuration using the one-way terminal switch 100 according to the first embodiment of this invention.
[0089]
Compared with the conventional technique shown in the example of FIG. 18, the present embodiment is characterized in that it includes a one-way terminal switch 100 that performs splicing in only one direction instead of the conventional switch 100b.
[0090]
In the conventional exchange 100b, in both directions of communication between the client 60 and the server 70, it is only possible to set the same state for the communication termination and the splicing state at the same time. In the one-way terminal switch 100 of the configuration, splicing is performed only for the communication in the direction from the server 70 to the client 60 where a large amount of data is often transferred, and at the same time the communication in the direction from the client 60 to the server 70 is performed. Thus, termination processing such as retransmission control and flow control is executed.
[0091]
The roles of each server 70 and client 60 in the server group 71 of FIG. 2 are the same as those of the prior art described with reference to FIG. The same is true in that they are connected to each other by a network 50 of a packet switching network. Further, the service provided by each server 70 of the server group 71 of FIG. 2 is also connected using the connection of the transport layer protocol as in the prior art, and in the packet, in the transport layer included in the packet The sequence number indicating the data position, the data length in the transport layer of the data in the packet, and the data position in the transport layer that has been reliably received so far for the communication partner It is assumed that the Ack number shown is included as header information. The connection establishment and termination methods are exactly the same.
[0092]
The function of the one-way terminal switch 100 of the present embodiment is different from the conventional switch 100b in the splicing method.
[0093]
Conventionally, two connections of the connection between the client 60 and the exchange 100b and the connection between the exchange 100b and the server 70 are spliced into one connection between the client 60 and the server 70. In this case, the exchange 100b performs retransmission, flow control, etc. Cannot be terminated.
[0094]
However, in the one-way terminal switch 100 according to the present embodiment, a single TCP connection is not made between the client 60 and the server 70 in both directions, but only for data flowing from the server 70 in the client 60 direction. As in conventional splicing, only rewriting of the packet sequence number and Ack number is performed, and the server 70 and the client 60 themselves perform retransmission control and flow control.
[0095]
Here, in the transport layer connection from the client 60 to the one-way terminal switch 100, the one-way terminal switch 100 controls the retransmission of data flowing from the client 60 to the one-way terminal switch 100 and the client 60. Terminate with flow control. Further, the connection between the exchange 100 and the server 70 can be terminated by the retransmission control and flow control of data flowing from the one-way termination exchange 100 to the server 70. Different from conventional ones.
[0096]
Hereinafter, this splicing method of the present invention is referred to as one-way splicing.
[0097]
FIG. 3 is a block diagram illustrating a configuration of the one-way terminal switch 100 according to the first embodiment of this invention.
[0098]
Referring to FIG. 3, a one-way terminal switch 100 according to the present embodiment includes a client-side processing unit 10 that processes communication with a client side, a server-side processing unit 20 that processes communication with a server side, and communication in an application layer. An analysis unit 30 that analyzes data and determines a connection destination of each client, and a storage unit 40 that records a forwarding table indicating a connection destination server corresponding to each data acquisition request from the client are provided.
[0099]
The client-side processing unit 10 includes a termination unit 11 that terminates communication on the client side, an update unit 12 that rewrites and updates packet header information, and a communication unit 14 that transmits and receives packets with each client. . The server-side processing unit 20 also includes a termination unit 21 that terminates communication on the server side, an update unit 22 that rewrites and updates packet header information, a switching unit 23 that switches a data communication path, and packet packets with each server 70. A communication unit 24 for sending and receiving is provided.
[0100]
First, the function of each component of the exchange 100 according to the present embodiment will be outlined.
[0101]
Client end unit 11
The client-side terminal unit 11 establishes a connection with the client 60 in the transport layer, and receives data including retransmission control and flow control with the client 60 from the transport layer.
[0102]
When the connection is established, the Win value (remaining capacity of the reception buffer) of the client 60 is notified to the server side termination unit 21.
[0103]
In the one-way splicing state, the client side termination unit 11 does not perform a packet reception confirmation response (acknowledgment, Acknowledge: Ack) from the client 60, but the client side update unit 12 receives the Ack number and A flow control Win value is notified and a response is requested to be transmitted. In the one-way splicing state, when data is received from the client 60, the Ack number and Win value of the packet from the client 60 are transferred to the server-side termination unit 21, and a response (Ack) transmission request to the server 70 is made. The client side update unit 12 also answers the inquiry about the current Ack number and Win value.
[0104]
The server side update unit 22 is notified of the transition to the one-way splicing state.
[0105]
Further, when a packet with an end flag indicating a connection disconnection request arrives from the client 60, the side heading from the client 60 to the client side processing unit 10 in the bidirectional connection between the client 60 and the client side processing unit 10 Disconnect the transport layer for the connection. Further, in this case, the server-side termination unit 21 is notified that the connection on the side from the client 60 toward the client-side processing unit 10 has been disconnected.
[0106]
For the connection in the direction from the client side processing unit 10 to the client 60, the server side update unit 22 notifies the final sequence number of the data in the packet with the end flag arriving from the server 70. "Is updated to" Update F = F-SS + SU ". When the same Ack number arrives thereafter, it is recognized that the connection has been disconnected (that is, the transmission of a packet with an end flag and the arrival of a positive response packet), and the client side A disconnection process of the transport layer of the connection from the processing unit 10 to the client 60 is performed. Here, “SS” is an initial sequence number of the server 70, and “SU” is an initial sequence number of the client side processing unit 10, and details will be described later.
[0107]
Client side update unit 12
A packet transmitted from the server 70 to the client 60 is received from the server-side update unit 22, header information such as the sequence number, Ack number, and Win value of the packet is rewritten, and the updated packet is transmitted to the client 60.
[0108]
The sequence number can be rewritten by “sequence number: = sequence number of packet−SS + SU”. Here, “SS” is an initial sequence number (of the server 70) of the connection between the server side processing unit 20 and the server 70. “SU” is an initial sequence number (of the client side processing unit 10) of the connection between the client side processing unit 10 and the client 60. These values are obtained from the client-side terminal unit 11 and the server-side terminal unit 21, respectively.
[0109]
As for addition / subtraction of sequence numbers, processing when the maximum value of sequence numbers is exceeded or below the minimum value shall conform to the handling of addition / subtraction of sequence numbers in the transport protocol.
[0110]
The Ack number and Win value are rewritten to the latest Ack number and Win value returned when a new packet is currently transmitted from the client side processing unit 10 to the client 60, respectively. These latest Ack numbers and Win values can be acquired from the client-side terminal unit 11.
[0111]
If necessary, the transport layer protocol checksum is also updated correctly.
[0112]
Also, when a response (Ack) transmission request to the client 60 is received from the client-side terminal unit 11, the Ack number and the Win value are as described above, and the sequence number used most recently is the same as the sequence number. To generate and send a response packet.
[0113]
Packets sent from the server 70 to the client 60 are sequentially sent from the server-side update unit 22 to the client-side update unit 12, and the rewritten values of the sequence numbers of the sent packets are sequentially recorded. The most recently used sequence number refers to the latest sequence number after rewriting. The initial value of the sequence number is that the packet arrives from the server-side update unit 22 at the same time as the one-way splicing state is entered, and the rewritten sequence number for this packet is used as the initial value.
[0114]
A response (Ack) packet to the client 60 requested to be transmitted from the client-side termination unit 11 may be transmitted as a single packet together with the packet from the server-side update unit 22 after a little waiting for transmission. Is possible.
[0115]
Analysis unit 30
Information on a data acquisition request (or a plurality of data) transmitted from the client 60 is acquired from the client-side terminal unit 11, the application layer is terminated, the information is analyzed, and an appropriate connection destination server 70 is determined. As a method of determining the connection destination, for example, a table in which the name of the server 70 that provides the data corresponding to each data requested from the client 60 is recorded (hereinafter, this table is referred to as a forwarding table). ) In advance, and can be determined by a method such as searching this forwarding table.
[0116]
When the connection destination server 70 is determined, the data acquisition request and the connection destination server 70 name are transferred to the server-side terminal unit 21 to instruct connection.
[0117]
Storage unit 40
Information for the analysis unit 30 to select an appropriate server 70 is stored. For example, by recording the above forwarding table in the storage unit 40, an appropriate server 70 name can be returned in response to a search request from the analysis unit 30.
[0118]
Server-side termination 21
In accordance with the name of the connection destination server 70 instructed from the analysis unit 30, a transport layer connection is established with the connection destination server 70.
[0119]
When this connection is established, the Win value (remaining reception buffer) notified from the client-side termination unit 11 is registered and used as the initial value of the Win value of the server-side processing unit 20.
[0120]
When establishing a connection with the server 70, the switching unit 23 is instructed in advance so that the server-side terminal unit 21 receives a packet sent from the server 70.
[0121]
When this connection is established, the server-side termination unit 21 sends the data acquisition request to the server 70 using the established transport layer connection. Subsequently, the switching unit 23 is instructed to perform switching so that the server-side updating unit 22 subsequently receives a packet related to this connection sent from the server 70. Thereafter, the unidirectional splicing state is established.
[0122]
Thereafter, the Ack number and Win value of the packet sent from the server 70 are sequentially notified from the server-side update unit 22, and using these values, transport layer data ( Retransmission control and flow control for data acquisition requests and the like.
[0123]
From this point onward, the client 60 sequentially transmits a packet (Ack) for confirming the receipt of the packet, and the client-side termination unit 11 receives the packet, and the Ack number and Win value of each packet are sequentially transmitted to the server-side termination. The unit 21 is notified. The server-side terminal unit 21 updates the notified Ack number as “Ack number: = Ack number notified from the client-side terminal unit 11−SU + SS”, and the Win value is used as it is. A packet (Ack) for confirming reception of the packet with respect to 70 is generated and transmitted to the server 70.
[0124]
Here, “SU” is an initial sequence number of the client-side processing unit 10 of the connection between the client 60 and the client-side processing unit 10, and “SS” is a connection of the server-side processing unit 20 and the server 70. , The initial sequence number on the server 70 side. The value of “SU” is notified from the client end unit 11.
[0125]
In addition, in addition / subtraction of sequence numbers, processing when the maximum value of sequence numbers is exceeded or below the minimum value shall conform to the handling of addition / subtraction of sequence numbers of the transport protocol.
[0126]
Further, when a connection disconnection request is transmitted from the client 60, the client side termination unit 11 receives this and notifies the server side termination unit 21. The server-side terminal unit 21 sends a packet with an end flag to the server 70 on the assumption that the connection from the server-side processing unit 20 to the server 70 is disconnected in the bidirectional connection between the client 60 and the server 70. Cutting). In this case, the connection disconnection process from the client 60 to the client-side processing unit 10 is performed by the client-side termination unit 11.
[0127]
Further, for the connection from the server 70 to the client 60, the server-side termination unit 21 receives a notification of the final sequence number of the data in the packet with the end flag arriving from the server 70 from the server-side update unit 22, This final sequence number “F” is updated and recorded as “update F = F−SS + SU”. If the same Ack number as the updated last sequence number arrives, it is assumed that the connection is disconnected (a packet with an end flag and an Ack packet corresponding thereto have arrived) from the server 70 to the exchange 100. Disconnect the transport layer of the connection going to the client 60 via
[0128]
Server side update unit 22
The server side update unit 22 receives a packet transmitted from the server 70 to the client 60 from the server 70 and sends the packet to the client side update unit 12. Each time the server side update unit 22 receives a packet from the server 70, the server side update unit 22 notifies the server side termination unit 21 of the Ack number and Win value of the packet.
[0129]
If the length of the transport layer data of the received packet is “0”, the packet is discarded without being sent to the client side update unit 12. If it is not “0”, the packet is transferred to the client side update unit 12.
[0130]
Further, when a packet that is not “0” is received for the first time after the connection is established, the packet is transferred to the client side update unit 12 and at the same time, an instruction to start unidirectional splicing is issued to the client side termination unit 11. .
[0131]
Further, when a packet with an end flag is received from the server 70, the final sequence number “F” of the data in the packet is passed to the server-side terminal unit 21 and the client-side terminal unit 11.
[0132]
Next, the operation of each component of the exchange 100 according to the present embodiment will be described.
[0133]
FIG. 4 is a flowchart for explaining the operation of the client side termination unit 11 of the present embodiment.
[0134]
Referring to FIG. 4, the client-side termination unit 11 of the present embodiment first receives a packet from the client 60 (step 301). If it is a series of packets related to connection establishment (step 302), the client-side termination unit 11 60 establishes a connection in the transport layer (step 303), and stores the initial sequence number “SC” of the client 60 and the initial sequence number “SU” of the client side processing unit 10 (step 304). A response (Ack) is returned to 60, and data including retransmission control and flow control in the transport layer is received with the client 60 (step 305).
[0135]
After the connection is established, until a one-way splicing state described later (step 306), a response (Ack) is returned to the client 60 and data including retransmission control and flow control at the transport layer with the client 60 is returned. Is received (step 307). Further, the Win value on the client 60 side at this time is passed to the server-side termination unit 21.
[0136]
If the one-way splicing state is reached (step 306), the data reception confirmation response (Ack) is not sent by the client side termination unit 11, but the client side update unit 12 receives the Ack number and the flow control Win value. To request transmission of a response (step 308). In the one-way splicing state, when data is received from the client 60, the Ack number and the Win value of the packet from the client 60 are transferred to the server-side terminal unit 21, and a response transmission request to the server 70 is made (step 309). . It also answers an inquiry about the current Ack number and Win value from the client side update unit 12. The server side update unit 22 is notified of the transition to the one-way splicing state.
[0137]
When a packet with an end flag indicating a connection disconnection request has arrived from the client 60 (step 310), the side from the client 60 toward the client-side processing unit 10 in the bidirectional connection between the client 60 and the client-side processing unit 10 As a result, the transport layer is disconnected (step 311). Further, it notifies the server-side termination unit 21 that the connection on the side from the client 60 toward the client-side processing unit 10 has been disconnected (step 312).
[0138]
For the connection from the client side processing unit 10 to the client 60, the final sequence number of the data in the packet with the end flag arriving from the server 70 is notified from the server side update unit 22. Is updated and recorded as “update F = F−SS + SU”.
[0139]
If the same Ack number as the final sequence number arrives, the connection is disconnected (assuming that a packet with an end flag is transmitted and an Ack packet corresponding thereto arrives), and the transport layer is disconnected. (Steps 313 and 314).
[0140]
FIG. 5 is a flowchart for explaining the operation of the client side updating unit 12 of the present embodiment.
[0141]
Referring to FIG. 5, the client side update unit 12 of the present embodiment first receives a command from the client side termination unit 11 and a packet from the server side update unit (step 401). If a packet to be transmitted to the client 60 is received from the server side update unit 22 (step 402), the sequence number, Ack number, Win value, etc. of the packet are rewritten (step 403), and the packet updated to the client 60 is sent. Transmit (step 404). The method for rewriting the sequence number, Ack number, and Win value here is as described above.
[0142]
When the client side termination unit 11 receives a response (Ack) transmission request to the client (step 405), the Ack number and Win value are as described above, and the sequence number is the most recently used sequence. A response (Ack) packet is generated using the number (step 406) and transmitted to the client 60 (step 404). The method of generating the response packet is also as described above.
[0143]
Further, the transmission of the acknowledgment (Ack) to the client 60 requested from the client side termination unit 11 is a little waited, and the server 70 receives the packet sent from the server 60 to the client 60 from the server side update unit 22. It is also possible to transmit as a single packet.
[0144]
FIG. 6 is a flowchart for explaining the operation of the server-side termination unit 21 of the present embodiment.
[0145]
Referring to FIG. 6, the server-side termination unit 21 according to the present embodiment first receives an instruction from the analysis unit 30, and transmission of an Ack number and a Win value from the server-side update unit 22 and the client-side termination unit 11 ( Step 501).
[0146]
If there is a connection establishment request from the analysis unit 30 (step 502), a transport layer connection is established to the connection destination server 70 designated by the analysis unit 30 (step 503), and an initial sequence is established. The numbers SV and SS are recorded (step 504). When this connection is established, the switching unit 23 is instructed in advance so that the server-side termination unit 21 receives a packet arriving from the server 70.
[0147]
If the packet sent from the client 60 is a data acquisition request to be sent to the server 70 when the connection has been established (step 505), the data acquisition request is sent to the server 70 using the established transport layer connection. If this is the first data acquisition request to be sent to the server 70 after the connection is established (step 506), the switching unit 23 is instructed to send a packet related to the corresponding connection from the server 70 thereafter. The server side update unit 22 is instructed to receive (step 507). Then, a data acquisition request is sent to the server 70 using the established transport layer connection (step 508).
[0148]
In step 501, when the server side update unit 22 notifies the Ack number and the Win value of the packet received from the server 70 (step 509), the transport layer data is registered and sent to the server 70. This is used for retransmission control, flow control, etc. (step 510).
[0149]
In step 501, if the Ack number and the Win value are notified from the client end unit 11 (step 511), the values are updated as described above, and the transport layer data to be sent to the server 70 is updated. Ack number and Win value are determined to generate a packet (step 512), and a response (Ack) packet is transmitted to the server 70 (step 513). Also, the transport layer data to be sent to the server 70 The Ack number and Win value are also updated to this value.
[0150]
Further, when the client-side termination unit 11 notifies that the connection has been disconnected (step 514), the server-side processing unit 20 to the server 70 in the bidirectional connection between the server-side processing unit 20 and the server 70. Assuming that the incoming connection has been disconnected (assuming that a packet with an end flag has been sent to the server 70), the transport layer is disconnected (step 515).
[0151]
For the connection from the server side processing unit 20 to the client 60, the server side update unit 22 notifies the final sequence number of the data in the packet with the end flag arriving from the server 70. If the same Ack number as the updated last sequence number arrives (step 516), it is assumed that the connection is disconnected (the packet with the end flag and the Ack packet corresponding thereto are updated). Assuming that it has arrived, disconnection processing of the transport layer of the connection from the server side processing unit 20 to the client 60 is performed (step 517). In addition, the switching unit 23 is instructed to send the packet of the subsequent connection to the server-side termination unit 21 (step 514).
[0152]
FIG. 7 is a flowchart for explaining the operation of the server-side update unit 22 of the present embodiment.
[0153]
First, the server side update unit 22 sequentially receives packets sent from the server 70 to the client 60 from the server 70 (step 601), and sends the Ack number and Win value written in the packet to the server side termination unit 21. Notification is made (step 602).
[0154]
When a packet with an end flag arrives from the server 70 (step 603), the final sequence number “F” of the data in the packet is transferred to the server-side terminal unit 21 and the client-side terminal unit 11 (step 604). The packet is transferred to the client side update unit 12 as it is (step 609).
[0155]
In step 603, when a packet without an end flag is received, if the length of the transport layer data of the packet is “0” (step 605), the packet is discarded (step 606).
[0156]
If the data length is not "0" (step 605), the packet is transferred to the client side update unit 12 (step 609). However, the first packet that is not "0" of the connection is sent to the client. In the case of delivery to the side updating unit 12 (step 607), an instruction to start one-way splicing is simultaneously issued to the client side termination unit 11 (step 608).
[0157]
FIG. 8 is a diagram for explaining the flow of data in the one-way terminal switch 100 according to the present embodiment. When a one-way splicing operation is performed, the sequence number, Ack number, Win value, and transmission data are shown. Etc. show how data are exchanged by the client 60, the server 70, the client side termination unit 11, the server side termination unit 21, the client side update unit 12, the server side update unit 22, and the like.
[0158]
Data transmission from the client 60 to the client-side terminal unit 11 and its response, data transmission from the server-side terminal unit 21 to the server 70 and its response, data transmission from the server 70 to the client 60 and its response flow, and reception The Win values indicating the rest of the buffer are correctly processed in the following order.
[0159]
From the client 60 to the client end unit 11
The sequence number of the data from the client 60 is subjected to the transport layer protocol processing in the client side termination unit 11, and as shown in step 308 in FIG. 4 of the flowchart (corresponding to Y001 in FIG. 8), the client side update unit 12 is reflected as the Ack number of the response packet transmitted from the client 12 to the client 60.
[0160]
Similarly, the rest of the reception buffer of the client-side termination unit 11 is a packet transmitted from the client-side update unit 12 to the client 60 as shown in step 309 in FIG. 4 of the flowchart (corresponding to Y004 in FIG. 8). And is used for appropriate retransmission control and flow control.
[0161]
Server-side terminal unit 21 to server 70
For the data from the server-side termination unit 21 to the server 70, the sequence number is processed by the transport layer protocol termination unit in the server 70, and as an Ack number of the packet to the server-side update unit 22 as Y008. Reflected. This is reflected as the Ack number of the packet transmitted from the client side update unit 12 to the client 60 as shown in step 602 of the flowchart in FIG. 7 and step 510 in the flowchart of FIG. 6 (corresponding to Y005 in FIG. 8). Is done.
[0162]
Similarly, the rest of the reception buffer of the server 70 should be reflected as the Ack number of the packet to the server side update unit 22 as indicated by Y009 of FIG. 8, and this is reflected in the step of FIG. 7 of the flowchart. As indicated by 602 (corresponding to Y006 in FIG. 8), it is reflected as the Win value of the packet transmitted from the client side update unit 12 to the client 60. In this way, correct retransmission control and flow control are performed.
[0163]
Server 70 to client 60
As for data from the server 70 to the client 60, the sequence number received from the server 70 is indicated to the client side as shown in step 403 of FIG. 5 in the operation flowchart of the client side update unit 12 (corresponding to Y007 in FIG. 8). ) The sequence number is rewritten and passed as if it were data transmitted from the client-side terminal unit 11.
[0164]
On the other hand, the Ack number and the Win value returned from the client 60 (corresponding to Y010 and Y011 in FIG. 8), the Ack number is as if the end on the server side as shown in step 512 in FIG. The number is updated and returned to the server 70 as if it were the Ack number generated by the unit 21 (corresponding to Y002 in FIG. 8), and the Win value is also indicated by step 512 in FIG. As described above, since it is returned to the server 70 (corresponding to Y003 in FIG. 8), the retransmission control and the flow control are correctly performed between the server 70 and the client 60.
[0165]
Further, in the client-side termination unit 11 and the server-side termination unit 21 of the present embodiment, the transmission data that is divided and transmitted from the client 60 to the server 70 is sent to the state before the original division. A method of transmitting to the server after restoration is also possible.
[0166]
As described above, the exchange 100 according to the present embodiment is configured so that the client 60 and the server respectively handle the transport layer data flowing from the client 60 in the direction of the unidirectional termination exchange 100 and from the unidirectional termination exchange 100 to the server 70. 70, the retransmission layer and the flow control can be performed to terminate the transport layer, and at the same time, the data flowing from the server 70 toward the client 60 is not subjected to the retransmission control and the flow control. The packet can be relayed at high speed only by rewriting the packet sequence number or Ack number as in the case of splicing. In this one-way splicing state, data in the direction from the server 70 to the client 60 is subjected to retransmission control, flow control, and the like by the server 70 and the client 60 themselves.
[0167]
Exchange 100 according to the present embodiment can realize one-way splicing communication as described above.
[0168]
Next, a specific operation example of the communication system according to the first embodiment configured as described above will be described with reference to the timing chart of FIG. FIG. 9 shows a time sequence of the sequence number and the Ack number in the first embodiment.
[0169]
A handshake is performed between the client 60 and the client side processing unit 10. Here, the initial sequence number of the data on the client 60 side is “1000”, and the initial sequence of the client side processing unit 10 is “2000” (901).
[0170]
Data with a data acquisition request is transmitted from the client 60 to the client side processing unit 10. At this time, it is assumed that the data acquisition request is from the sequence number “1001” to “1100” (902).
[0171]
The client-side processing unit 10 returns “1101”, which is the Ack number for this data acquisition request, to the client 60 (903).
[0172]
The analysis unit 30 determines that the first several of the received data acquisition requests (including a plurality of acquisition requests) are correct to be transmitted to the server 70 and establishes a connection with the server 70. Assume that the initial sequence number of the server-side processing unit 20 is “3000” and the initial sequence number of the server 70 is “4000” (904).
[0173]
A data acquisition request to be transmitted is sent to the server 70 (905).
[0174]
A part of data corresponding to the request (sequence numbers “4001” to “4200”) is returned to the client 60 (906).
[0175]
The sequence number and Ack number are rewritten, and the requested data is delivered to the client 60. By the number conversion, the sequence numbers become “2001” to “2200”, and the Ack number is also rewritten to “1101” (907).
[0176]
A packet with an Ack number indicating that data up to sequence number “2200” has been received is sent from the client 60 (908).
[0177]
The Ack number information is number-converted and delivered to the server side processing unit 20 (909).
[0178]
The server-side processing unit 20 transmits a packet with the number-converted Ack number to the server 70 (910).
[0179]
The last data (sequence number “4201” to “4500”) for the request is sent from the server 70 to the client 60. The FIN flag is set in this packet (911).
[0180]
The server side processing unit 20 stores the Ack number “4501” for the last sequence number of this packet (912).
[0181]
The client-side processing unit 10 stores a number “2501” obtained by converting the Ack number for the last sequence number of this packet (913).
[0182]
The sequence number and Ack number are rewritten, and the requested data is delivered to the client 60. By the number conversion, the sequence numbers are changed from “2201” to “2500”, and the Ack number is also rewritten to “1101”. Upon receiving this packet, the client 60 starts the end process (914).
[0183]
The Ack number “2501” is returned from the client 60 (915).
[0184]
The client-side processing unit 10 confirms this Ack number and matches the stored number “2501”. Therefore, the client-side processing unit 10 knows that the client 60 has received the last data for the request from the server 70, and performs the end processing. Perform (916).
[0185]
On the server 70 side, the number “4501” obtained by converting the Ack number of this packet matches the stored number. Therefore, the server 60 knows that the last data for the request from the server 70 has been received, and terminates the processing. Perform (917).
[0186]
A packet with the Ack number converted in number is returned to the server 70 (918).
[0187]
Next, a second embodiment of the present invention will be described.
[0188]
FIG. 10 is a block diagram showing an example of a network configuration using the one-way terminal switch 100a according to the second embodiment of the present invention, and FIG. 11 shows the configuration of the one-way terminal switch 100a according to the present embodiment. FIG.
[0189]
These are the same as those of the first embodiment shown in FIGS. 2 and 3, but the client side termination unit 11a, the client side update unit 12a, the analysis unit 30a, the server side termination unit 21a, and the server side update. Each operation of the unit 22a is different from that of the first embodiment.
[0190]
First, these components will be described.
[0191]
Client end unit 11a
The difference from the client-side terminal unit 11 of the first embodiment is that the transport layer connection between the client 60 and the client-side terminal unit 11a is disconnected (a packet with an end flag is sent) according to an instruction from the analyzing unit 30. And the point that the value of the final sequence number “F” is not received from the server side update unit 22a. Other operations are the same as those in the first embodiment.
[0192]
That is, the client-side termination unit 11a of the present embodiment establishes a connection with the client 60 at the transport layer, and receives data including retransmission control and flow control with the client 60 at the transport layer. To do.
[0193]
In the one-way splicing state, which will be described later, the data reception confirmation response is not performed by the client side termination unit 11a, but the Ack number and the flow control Win value are notified to the client side update unit 12a. ).
[0194]
In the one-way splicing state, when data is received from the client 60, the Ack number and Win value of the packet from the client 60 are transferred to the server-side terminal unit 21 and a response transmission request to the server 70 is made. The client side update unit 12a also answers an inquiry about the current Ack number and Win value. The server side update unit 22a is notified of the transition to the one-way splicing state.
[0195]
Further, when a packet with an end flag indicating a connection disconnection request arrives from the client 60, a transport layer disconnection process is performed for the connection from the client 60 toward the client-side processing unit 10a. In addition, the server-side termination unit 21a is notified that the connection from the client 60 toward the client-side processing unit 10a has been disconnected.
[0196]
For the connection from the client side processing unit 10a to the client 60, the transport layer of the connection is disconnected in accordance with an instruction from the analysis unit 30a.
[0197]
Client side update unit 12a
The difference from the operation of the client-side update unit 12 in the one-way terminal switch 100 of the first embodiment is that the server-side terminal unit 21 targets the initial sequence number of the connection of the server 70 used for rewriting the sequence number. Therefore, the sequence number is rewritten as “sequence number: = sequence number of packet−SS + SU” using the value of the current connection.
[0198]
Here, “SS” is the initial sequence number of the current connection with the server 70 of the server side termination unit 21, and the value is obtained from the server side termination unit 21.
[0199]
“SU” in the present embodiment is the initial sequence number of the connection with the client 60 of the client side processing unit 10a or the final sequence number of the packet including the end flag from the immediately preceding server 70 + 1. The value of “SU” is from the client-side terminal unit 11a when SU is the initial sequence number, or the server-side update unit 22a when the last sequence number of the packet including the end flag from the immediately preceding server 70 is +1. Receive from.
[0200]
In addition, in addition / subtraction of sequence numbers, processing when the maximum value of sequence numbers is exceeded or below the minimum value shall conform to the handling of addition / subtraction of sequence numbers of the transport protocol.
[0201]
Analysis unit 30a
The analysis unit 30a acquires data from the client-side terminal unit 11a, terminates the application layer, analyzes a data acquisition request from the client 60 (a plurality of requests can be performed at once), and generates an appropriate server 70. To decide.
[0202]
When the servers 70 corresponding to a plurality of data acquisition requests are different, the plurality of data acquisition requests are grouped in order for the corresponding servers 70 from the front.
[0203]
For example, when there are ten acquisition requests R1 to R10, R1 to R2 are the first server, R3 to R5 are the second server, and R6 to R10 are the first server. The first group, R3 to R5 as the second group, and R6 to R10 as the third group can be grouped.
[0204]
In this example of grouping, the servers 70 corresponding to the first group and the third group are the same first server, but here, the acquisition requests are grouped in order from the front to divide them into different groups. .
[0205]
The analysis unit 30a passes the server 70 name and the acquisition request to the server-side termination unit 21 for each group.
[0206]
In addition, for the last acquisition request of one group, the analysis unit 30a gives the server 70 a close request for disconnecting the connection when the transmission of the data is completed. However, if the group is the last one (no other unprocessed group remains), there may be an additional data acquisition request from the client 60 during the processing, so the close request is added. It is also effective to use a method that does not.
[0207]
Further, when it becomes necessary to switch the server 70 by responding to an additional data acquisition request from the client 60, a close request is given to the data acquisition request and passed to the server-side termination unit 21a, or the data is left as it is. The acquisition request is passed to the server-side termination unit 21a. Further, here, when switching the server 70 with the first addition request, a connection disconnection request is made to the server-side termination unit 21a. When processing for one group is completed, the server-side termination unit 21a notifies the group, and the analysis unit 30a instructs the next group to perform processing.
[0208]
The analysis unit 30a repeats this process every time data is acquired from the client side termination unit 11a.
[0209]
The data acquisition request received from the client 60 by the analysis unit 30a may be given a close request last. In this case, the group of the data acquisition request is stored as a group to be disconnected, and the group After the above process is completed, the client side termination unit 11a is instructed to disconnect the connection to the client 60.
[0210]
Server-side termination 21a
The difference from the server-side termination unit 21 of the first embodiment is that, in this embodiment, the data acquisition requests delivered from the analysis unit 30a are divided for each group, so that each group is processed in turn, The point of disconnecting the connection with the server 70 for each group (this is the case where a close request is added to the last acquisition request of each group delivered simultaneously with the connection disconnection request from the analysis unit 30a. Is transmitted to the server 70 by the server-side terminal unit 21a, and if the close request is not added, the server-side terminal unit 21a transmits the last acquisition request for each group to the server 70. This is achieved by explicitly issuing a connection disconnection request) or for a new group, the server indicated for that group The server side that is different each time it is reestablished to reestablish the connection to the server 70 and transfer the data acquisition request group to the server 70 or to determine the Ack number of the transport layer data to be sent to the server 70 The initial sequence number is different. Another difference is that when the Ack packet corresponding to the updated final sequence number “F” is received, the analysis unit 30a is notified. Other processes are the same as those in the first embodiment.
[0211]
That is, it is as follows.
[0212]
The server-side termination unit 21a receives one group of data acquisition requests and the name of the server 70 from the analysis unit 30a. Then, a transport layer connection is established with the server 70 in accordance with the name of the server 70.
[0213]
As the initial value of the Win value, the Win value notified from the client-side terminal unit 11a is used when the connection is established for the first time, and after that, when the previous connection ends (the same as the updated final sequence number “F” described below) The Win value stored when the response packet having the Ack number is received is used as the initial value.
[0214]
When this connection is established, the switching unit 23 is instructed so that the server-side termination unit 21 can receive a packet transmitted from the server 70 in response to the data acquisition request.
[0215]
When the connection is established, a group of data acquisition requests is sent to the server 70 using the established transport layer connection. A close request is given to the last acquisition request.
[0216]
At the same time, the switching unit 23 is instructed to instruct the server side updating unit 22a to receive packets related to the corresponding connection from the server 70 thereafter.
[0217]
Thereafter, the server side updating unit 22a notifies the Ack number and Win value of the packet received from the server 70, and transport layer data (data acquisition request) to be sent to the server 70 using this value. Etc.), retransmission control and flow control are performed.
[0218]
Thereafter, the Ack number and the Win value are communicated from the client-side terminal unit 11a, and the Ack number is rewritten and updated as “Ack number: = Ack number notified from the client-side terminal unit 11a−SU + SS”. As the value, the notified value is used as it is, and a response packet is generated and transmitted to the server 70.
[0219]
Here, “SU” is an initial sequence number of the client side processing unit 10a of the connection between the client 60 and the client side processing unit 10a, and “SS” is the server side processing unit 20a and the current server 70. It is the initial sequence number on the server side of the connection or the last sequence number +1 of the packet with the end flag from the immediately preceding server 70. The initial sequence number of the client-side termination unit 11a of “SU” is notified from the client-side termination unit 11a.
[0220]
In addition, in addition / subtraction of sequence numbers, processing when the maximum value of sequence numbers is exceeded or below the minimum value shall conform to the handling of addition / subtraction of sequence numbers of the transport protocol.
[0221]
Furthermore, if the client-side termination unit 11a notifies that the connection has been disconnected, the connection from the server-side processing unit 20a to the server 70 is a bidirectional connection between the server-side processing unit 20a and the server 70. As a result of disconnection (assuming that a packet with an end flag has been sent to the server 70), disconnection processing is performed.
[0222]
For the connection from the server side processing unit 20a to the client 60, the server side update unit 22a notifies the final sequence number of the data in the packet with the end flag arriving from the server 70. Update as “Update F = F−SS + SU”. If the same Ack number as the updated last sequence number arrives, it is assumed that the connection is disconnected (the packet with the end flag and the Ack packet corresponding thereto arrives) As a result, the transport layer of the connection from the server 70 to the client 60 via the exchange 100a is disconnected. Then, the analysis unit 30 is notified that the processing of the group has been completed. In addition, the Win value at this time is stored.
[0223]
When a connection disconnection request is received from the analysis unit 30a, the switching unit 23 is instructed to transmit a packet of the subsequent connection to the server-side termination unit 21, and the connection is disconnected. 30 is notified.
[0224]
Server side update unit 22a
The difference from the server side update unit 22a of the first embodiment is that a process for defeating the end flag when the end flag is set in the packet coming from the server 70 side is included, and the value of the final sequence number “F” is set. The process of passing to the client side termination | terminus part 11a becomes unnecessary.
[0225]
That is, it is as follows.
[0226]
For the packet received from the server 70, the server-side update unit 22a notifies the server-side termination unit 21a of the Ack number and Win value written in the packet. When the length of the transport layer data of the packet is “0”, the packet is discarded.
[0227]
If the data length is not “0”, the packet is transferred to the client side update unit 12a. In addition, when this is the first packet that is not “0” of the connection to be transferred to the client-side updating unit 12a, an instruction to start one-way splicing is simultaneously issued to the client-side termination unit 11a.
[0228]
When a packet with an end flag arrives from the server 70, the end flag is cleared and the final sequence number “F” of the data in the packet is transferred to the server-side terminal unit 21.
[0229]
Next, the process of each part of this Embodiment is demonstrated.
[0230]
FIG. 12 is a flowchart for explaining the operation of the client side termination unit 11a of the present embodiment.
[0231]
The operation of the client-side termination unit 11a in the present embodiment is the same as in steps 301 to 312 in the first embodiment shown in FIG.
[0232]
The difference between the operation of the client-side termination unit 11a of the present embodiment and the first embodiment is that a connection disconnection request from the analysis unit 30a can be received, and a connection disconnection request is received from the analysis unit 30a. (Step 1001), the client-side termination unit 11a disconnects the connection from the client-side processing unit 10a to the client 60 (Step 1002).
[0233]
The flowchart of the operation of the client side updating unit 12a of this embodiment is the same as that of the first embodiment of FIG.
[0234]
FIG. 13 is a flowchart for explaining the operation of the analysis unit 30a of the present embodiment.
[0235]
Referring to FIG. 13, the analysis unit 30a according to the present embodiment first receives an instruction or the like from each of the client-side termination unit 11a and the server-side termination unit 21a.
[0236]
When a data acquisition request is received from the client-side terminal unit 11a (step 1102), the application layer is terminated, and the data acquisition request (a plurality of data) from the client 60 is analyzed, and an appropriate connection destination server 70 is determined (step 1103). Then, the data acquisition request and the name of the server 70 are delivered to the server-side termination unit 21.
[0237]
If the corresponding server 70 is different for each of the plurality of data acquisition requests, the data acquisition requests are grouped for each server (step 1104). As a grouping method, a method of dividing a plurality of data acquisition requests for each corresponding server 70 in order from the front is possible.
[0238]
That is, in this method, for example, when there are ten acquisition requests R1 to R10, R1 to R2 are the first server, R3 to R5 are the second server, and R6 to R10 are the first server, R1 to R2 can be grouped in order with the first group, R3 to R5 can be grouped with the second group, and R6 to R10 can be grouped with the third group. In this example, the servers 70 for the first group and the third group are the same first server, but are grouped as different groups by grouping the acquisition requests in order from the front.
[0239]
If the data acquisition request arrived from the client 60 has a close request (step 1105), the group with the close request is stored as a group to be disconnected (step 1106).
[0240]
If the processing of the group currently being processed has been completed (step 1107), the first group is extracted (step 1108). If it is not the last group (step 1109), the last group acquisition request is made. A close request is given (step 1110). As a result, when the reception of the data is completed, the server 70 disconnects the connection from the server 70 side. Then, an appropriate server name and an acquisition request are transferred to the server-side terminal unit 21 (step 1111).
[0241]
In the case of the last group, since there may be additional data acquisition requests, an appropriate server 70 name and acquisition request are transferred to the server-side terminal unit 21 without adding a close request (step 1111). ).
[0242]
If it is determined in step 1107 that the group currently being processed has not been completed, if the group currently being processed is not the final group, the classified group and the name of the server 70 are stored and the process ends (steps 1112 and 1113). ).
[0243]
If it is the last group (step 1112), if there is a group other than the first group of the newly arrived acquisition request, it is stored together with the corresponding server 70 name (step 1114), and the currently processed group and the newly arrived acquisition request If the first group is for the same server 70 (step 1115), the first group of the newly arrived acquisition request is added to the server side processing unit (step 1116).
[0244]
In the case of going to a different server 70, a connection disconnection request is issued to the server-side termination unit 21, and the first group of acquisition requests newly arrived at the server-side termination unit 21 after the disconnection is completed is delivered (step 1117).
[0245]
In step 1101, if the server 70 receives a processing completion notification for the group currently being processed (step 1118), if the group is a group to be disconnected, the client-side termination unit 11a disconnects the connection with the client 60. (Steps 1119 and 1120).
[0246]
Otherwise, if an unprocessed group remains, the same processing as in step 1108 and subsequent steps is performed for that group (steps 1119 and 1121).
[0247]
FIG. 14 is a flowchart for explaining the operation of the server-side termination unit 21a of the present embodiment.
[0248]
Referring to FIG. 14, the difference between the operation of the server-side termination unit 21 a of the present embodiment and the operation of the first embodiment of FIG. 6 is the operation when the instruction from the analysis unit 30 a is received (step 1201 to step 1210) and between step 517 and step 518 includes a process of notifying the analysis unit 30a of the completion of disconnection of the connection.
[0249]
For this reason, the operation (step 1201 to step 1210) when receiving a command from the analysis unit 30a will be described here.
[0250]
First, when a new data acquisition request group is received from the analysis unit 30a (step 1201), a transport layer connection is established to the server 70 in accordance with the designation of the connection destination server 70 received at the same time (step 1201). Step 1202). When this connection is established, the switching unit 23 is instructed in advance so that the server-side termination unit 21 receives a packet arriving from the server 70.
[0251]
When the connection is established, a group of data acquisition requests is sent to the server 70 using the established transport layer connection. At the same time, the switching unit 23 is instructed to send a packet related to the corresponding connection from the server 70 thereafter. Instructs to arrive at the server-side update unit 22a. Then, a data acquisition request is sent to the server 70 using the established transport layer connection (steps 1203 to 1205).
[0252]
If it is not a new group designation in step 1201, if it is a connection disconnection request (step 1206), the switching unit 23a is instructed to transmit a packet to the server termination unit (step 1207). The connection is disconnected (step 1208), and the analysis unit 30a is notified of the completion of the disconnection (step 1209). If it is not a connection disconnection request in step 1206, the received data acquisition request is transmitted to the corresponding server 70 (step 1210).
[0253]
FIG. 15 is a flowchart for explaining the operation of the server side update unit 22a of the present embodiment.
[0254]
Referring to FIG. 15, the operation of the server-side update unit 22 a of this embodiment is different from the first embodiment shown in FIG. 7 in that a packet with an end flag is received from the server 70 in step 603. (Steps 1301 and 1302).
[0255]
When a packet with an end flag arrives from the server 70, the server-side update unit 22a of the present embodiment sends the final sequence number “F” of the data in the packet to the server-side termination unit 21 and the client-side termination unit 11a. The packet is transferred (step 1301), the end flag of the packet is changed to “ON” (turned down) and changed (step 1302), and the changed packet is transferred to the client side update unit 12a (step 609).
[0256]
FIG. 16 is a diagram for explaining the flow of data in the one-way terminal switch according to the present embodiment. When the one-way splicing operation is performed, how the sequence number, Ack number, and Win value are determined. It shows whether data is exchanged among the client 60, the server 70, the client-side termination unit 11a, the server-side termination unit 21, the client-side update unit 12a, the server-side update unit 22a, and the like.
[0257]
Also in the present embodiment, data from the client 60 to the client-side terminal unit 11a and its response, data from the server-side terminal unit 21 to the server 70 and its response, and data from the server 70 to the client 60 and its response flow And the Win value indicating the rest of the reception buffer is correctly processed in the same manner as described in FIG. 8 of the first embodiment of the present invention.
[0258]
Similarly to the description in the first embodiment, the client-side termination unit 11a and the server-side termination unit 21a of the present embodiment are divided into individual packets from the client 60 and transmitted to the server 70. It is also possible to transmit the transmission data to the server after restoring to the original state before dividing, and when adopting a single method, the analysis unit 30a of the present embodiment With reference to the transmission data restored to the state before the division, it is also possible to perform processing such as determination of the connection destination server.
[0259]
In the exchange 100a of the present embodiment described above, in addition to the effects of the first embodiment, the data acquisition requests from the clients 60 are grouped and distributed to the appropriate server 70 by the analysis unit 30a. Can do.
[0260]
In addition, the end of the sequence number of the packet that has arrived from the server 70 and that has an end flag set is sent to the server 70 indicating that the data transfer from the server 70 to the client 60 for each data acquisition request group has been completed. The server 70 can be switched at the correct timing.
[0261]
Further, by defeating the end flag of the packet transmitted from the server 70 to the client 60, the connection between the client 60 and the one-way terminal switch 100 is disconnected until the client 60 finishes receiving data for all data acquisition requests. Can be maintained without.
[0262]
Next, a specific operation example in the communication system according to the second embodiment configured as described above will be described with reference to the timing chart of FIG. FIG. 17 shows a time series of the sequence number and the Ack number in the second embodiment. Here, the first server 70 (1) and the second server 70 (2) will be described as being grouped.
[0263]
A handshake is performed between the client 60 and the client side processing unit 10. Here, the initial sequence number of the data on the client 60 side is “1000”, and the initial sequence number of the client side processing unit 10 is “2000” (1701).
[0264]
Data with a data acquisition request is transmitted from the client 60 to the client side processing unit 10. At this time, it is assumed that the data acquisition request is from the sequence number “1001” to “1100” (1702).
[0265]
The client-side processing unit 10 returns “1101”, which is the Ack number for this data acquisition request, to the client 60 (1703).
[0266]
The analysis unit 30 determines that the first few of the received data acquisition requests (including a plurality of acquisition requests) are correct to be transmitted to the server 70 (1), and the server 70 (1) Establish a connection. It is assumed that the initial sequence number of the server-side processing unit 20 is “3000” and the initial sequence number of the server 70 (1) is “4000” (1704).
[0267]
A data acquisition request to be transmitted is sent to the server 70 (1) (1705).
[0268]
A part of the data corresponding to the request (sequence numbers “4001” to “4200”) is returned to the client 60 (1706).
[0269]
The sequence number and Ack number are rewritten, and the requested data is delivered to the client 60. By the number conversion, the sequence numbers become “2001” to “2200”, and the Ack number is also rewritten to “1101” (1707).
[0270]
A packet with an Ack number indicating that data up to sequence number “2200” has been received is sent from the client 60 (1708).
[0271]
The Ack number information is number-converted and delivered to the server-side processing unit 20 (1709).
[0272]
The server-side processing unit 20 transmits a packet with the number-converted Ack number to the server 70 (1) (1710).
[0273]
The server 70 (1) sends the last data (sequence number “4201” to “4500”) for the request to the client 60. The FIN flag is set in this packet (1711).
[0274]
The server side processing unit 20 stores the Ack number “4501” corresponding to the last sequence number of this packet. Further, the FIN flag is defeated (1712).
[0275]
The client-side processing unit 10 stores a number “2501” obtained by converting the Ack number for the last sequence number of this packet (1713).
[0276]
The sequence number and Ack number are rewritten, and the requested data is delivered to the client 60. By the number conversion, the sequence numbers are changed from “2201” to “2500”, and the Ack number is also rewritten to “1101”. Here, since the client 60 is a packet in which the FIN flag has fallen, connection termination processing is not performed (1714).
[0277]
The Ack number “2501” is returned from the client 60 (1715).
[0278]
The client-side processing unit 10 looks at this Ack number and matches the stored number “2501”, so it knows that the client 60 has received the last data for the request from the server 70 (1) (1716). ).
[0279]
On the server 70 (1) side, the number “4501” obtained by converting the Ack number of this packet matches the stored number, so that the client 60 has received the last data for the request from the server 70 (1). The process is terminated (1717).
[0280]
A packet with the Ack number converted in number is returned to the server 70 (1) (1718).
[0281]
The analysis unit 30 transmits some of the data acquisition requests received from the client 60 (sequence numbers “1051” to “1100” in the client-side processing unit 10) to the server 70 (2). It determines that it is appropriate, and establishes a connection with the server 70 (2). Here, it is assumed that the initial sequence number of the server-side processing unit 20 is “5000” and the initial sequence number of the server 70 (2) is “6000” (1719).
[0282]
A data acquisition request to be transmitted is sent to the server 70 (2) (1720).
[0283]
A part of data corresponding to the request (sequence numbers “6001” to “6200”) is transmitted to the client 60 (1721).
[0284]
The sequence number and Ack number are rewritten, and the requested data is delivered to the client 60. By the number conversion, the sequence numbers become “2501” to “2700”, and the Ack number is also rewritten to “1101” (1722).
[0285]
A packet with an Ack number indicating that data up to sequence number “2700” has been received is sent from the client 60 (1723).
[0286]
The Ack number information is number-converted and delivered to the server-side processing unit 20 (1724).
[0287]
The server-side processing unit 20 transmits a packet with the number-converted Ack number to the server 70 (2) (1725).
[0288]
As described above, by defeating the end flag of the packet transmitted from the server 70 (1) to the client 60, the client 60 and the one-way terminal switch 100 until the client 60 finishes receiving data for all data acquisition requests. Maintain the connection between them without breaking.
[0289]
It should be noted that the exchanges 100 and 100a according to each of the above embodiments realize the functions of the client side processing unit 10, the server side processing unit 20, the analysis unit 30, and the like as well as other functions in hardware. The computer program having each function can be realized by being loaded into the memory of the computer processing apparatus. This computer program is stored in a magnetic disk, semiconductor memory, or other recording medium 90, 90a. Each function described above is realized by being loaded from the recording medium into the computer processing apparatus and controlling the operation of the computer processing apparatus.
[0290]
Further, by controlling the computer on the server 70 and operating an exchange program on the server 70 for performing packet communication between the server and the client via the exchange, the present invention can be realized. is there. This exchange program is stored in the recording medium of the server 70 in the same manner as described above. In other words, the exchange program sends the response packet sent to the client 60 to the client 60 by one-way splicing from when the data acquisition request is relayed from the client 60 to the client 60 in the exchange 100. It operates to send packets to it.
[0291]
Further, by controlling a computer on the client 60, an exchange program for performing packet communication between the server 70 and the client 60 via the exchange 100 is operated on the client 60, thereby realizing the present invention. Is also possible. This exchange program is stored in the recording medium of the client 60 in the same manner as described above. That is, the exchange program sends a packet from the server 70 by one-way splicing from the time of relaying the data acquisition request to the server 70 in the exchange 100 until the transmission of the response packet received from the server 70 is completed. Operates to receive.
[0292]
Although the present invention has been described with reference to the preferred embodiments and examples, the present invention is not necessarily limited to the above-described embodiments and examples, and various modifications can be made within the scope of the technical idea. Can be implemented.
[0293]
【The invention's effect】
As described above, according to the one-way terminal switch of the present invention, the following effects are achieved.
[0294]
First, in the one-way termination switch according to the present invention, during one-way splicing, the data from the server to the client is simply rewritten for each packet without terminating the transport layer. High-speed packet transfer can be realized by transferring the packet to the server, and at the same time, one-way splicing can be realized that refers to and terminates a data acquisition request sent from the client to the server.
[0295]
With one-way splicing, it is possible to always forward the data acquisition request to the appropriate server by referring to the data acquisition request sent from the client to the server, and at the same time, a large amount of data arriving from the server to the client side. With respect to data, a throughput equivalent to that of the conventional exchange 100 is realized by a simplified termination process in which only the sequence number and the Ack number are rewritten for each packet.
[0296]
Furthermore, until the client receives all data in response to a data acquisition request from the client, the connection established between the client and the one-way terminal switch can be maintained without disconnection. It is not necessary to set up the connection with the server again, and the delay until the necessary data is acquired can be kept small.
[Brief description of the drawings]
FIG. 1 is a diagram for explaining the concept of a communication system using a one-way terminal switch according to the present invention.
FIG. 2 is a block diagram illustrating an example of a network configuration using the one-way terminal switch according to the first embodiment of this invention.
FIG. 3 is a block diagram showing a configuration of a one-way terminal switch according to the first embodiment of this invention.
FIG. 4 is a flowchart for explaining an operation of a client side termination unit according to the first embodiment of this invention;
FIG. 5 is a flowchart for explaining the operation of the client side update unit according to the first embodiment of this invention;
FIG. 6 is a flowchart for explaining the operation of the server side termination unit according to the first embodiment of this invention;
FIG. 7 is a flowchart for explaining the operation of the server side update unit according to the first embodiment of this invention;
FIG. 8 is a diagram for explaining a data flow in the one-way terminal switch according to the first embodiment of this invention;
FIG. 9 is a timing chart illustrating a specific operation example of the first exemplary embodiment of the present invention.
FIG. 10 is a block diagram illustrating an example of a network configuration using a one-way terminal switch according to a second embodiment of this invention.
FIG. 11 is a block diagram showing a configuration of a one-way terminal switch according to a second embodiment of this invention.
FIG. 12 is a flowchart for explaining an operation of a client side termination unit according to the second embodiment of this invention;
FIG. 13 is a flowchart for explaining an operation of an analysis unit according to the second embodiment of this invention;
FIG. 14 is a flowchart for explaining the operation of the server-side termination unit according to the second embodiment of this invention;
FIG. 15 is a flowchart for explaining the operation of the server side update unit according to the second embodiment of this invention;
FIG. 16 is a diagram for explaining a data flow in the one-way terminal switch according to the second embodiment of this invention;
FIG. 17 is a timing chart illustrating a specific operation example of the second exemplary embodiment of the present invention.
FIG. 18 is a block diagram showing a configuration of a conventional communication network.
FIG. 19 is a block diagram showing a configuration of a conventional layer 7 switch.
[Explanation of symbols]
100, 100a One-way terminal switch
100b Conventional switch
10, 10a Client side processing unit
11, 11a Client side termination
12, 12a Client-side update unit
13b switching part
20, 20a Server side processing unit
21, 21a Server side termination
22, 22a Server side update unit
23, 23a switching unit
30, 30a Analysis unit
40, 40a storage unit
50 network
60 clients
70 servers
71 servers
90, 90a recording medium

Claims (55)

In a communication system using packet switching for performing packet communication between a server and a client via an exchange,
The exchange is
When a packet transmitted from the server to the client is relayed, the header information of the packet is rewritten to the contents set when the packet is transmitted from the exchange, and the packet is transmitted to the client. Outgoing,
One-way splicing processing from the server to the client from the time when the data acquisition request from the client is relayed until the transmission of the response packet transmitted from the server to the client is completed the performed, and a communication system, characterized by performing the retransmission control and flow control for the direction of communication to the server from the client. The exchange is
A client-side processing unit that accepts a connection from each of the clients, manages a connection with the client, and transmits and receives packets;
A server-side processing unit that accesses each of the servers, manages a connection with the server, and transmits and receives packets;
Means for rewriting the header information of the packet at the time of relaying the packet transmitted from the server to the client, and transmitting the packet to the client;
One-way splicing processing is performed in the direction from the server to the client, and communication in the direction from the client to the client side processing unit and communication in the direction from the server side processing unit to the server are performed. The communication system according to claim 1, further comprising means for performing retransmission control and flow control without disconnecting the established connection. The client side processing unit
A client-side terminator that controls connections between the clients and accepts connections and requests from the clients;
A client side update unit that relays a packet transmitted from the server to the client by rewriting header information,
The server side processing unit
A server-side termination unit that manages a connection between each of the servers and relays instructions and data for each of the servers sent from the client-side termination unit;
The communication system according to claim 2, further comprising a server-side update unit that receives a packet transmitted from each server to each client and sends the packet to the client-side update unit. In the header information of the packet,
In the transmission data divided into individual packets, a sequence number indicating the order of data in the packet,
The data length of the packet,
The communication system according to claim 3, further comprising an Ack number indicating a sequence number of data that has already been received by the communication partner. In the header information of the packet,
The communication system according to claim 4, further comprising a Win value indicating a remaining capacity of a reception buffer that has not yet been received by the communication partner. The client side termination is
Means for notifying the header information of the packet received from each of the clients to the client side update unit and the server side termination unit;
The server side update unit
Means for notifying the server-side termination unit of header information of a packet transmitted from each server to each client;
The client side update unit and the server side termination unit are:
The communication system according to claim 2 or 3, wherein the notified header information is recorded and referred to, and the header information of the packet is appropriately rewritten. In the state where the one-way splicing process is set, the client-side termination unit is
Instructing the client side update unit to perform response processing for packets received from each of the clients,
The client-side update unit
The communication system according to claim 6, further comprising means for receiving a response processing instruction and generating and transmitting a response packet to the client. The server side update unit
Relay transmission of packets from a plurality of the servers to one client;
Means for removing from the header information of the packet to be relayed a flag indicating the end of packet transmission in each of the servers,
8. The packet transmitted by switching the plurality of servers is relayed to the client without disconnecting the connection with the client. 8. Communications system. The client side termination unit and the server side termination unit are:
It comprises means for restoring transmission data divided and transmitted to individual packets from the client to the server to a state before the original division, and transmitting each packet by selecting a server. The communication system according to any one of claims 2 to 8. An analysis unit for determining a connection destination server to which each of the clients connects;
The analysis unit
Means for acquiring information of a request that the client sends to each of the servers from the client-side termination unit;
Means for determining a connection destination server to which the client should connect based on the request;
The communication according to any one of claims 2 to 8, further comprising means for instructing the server-side termination unit to connect the client to the determined connection destination server. system. The client side termination unit and the server side termination unit are:
A means for transmitting to the server after restoring the transmission data divided into individual packets and transmitted to the server from the client to the original state before the division,
The analysis unit
11. The communication system according to claim 10, further comprising means for determining the connection destination server based on the transmission data restored to the original state before the division. The analysis unit
Means for sequentially classifying unprocessed data acquisition requests sent by the client into groups for each server to which the connection is made;
The server-side termination unit is provided with means for instructing connection to a corresponding server and execution of the data acquisition request classified into the group for each of the classified groups. The communication system according to claim 10 or claim 11. In an exchange that relays packet communication via a communication network between multiple servers and clients,
When the packet transmitted from the server to the client is relayed, the header information of the packet is rewritten to the contents set when the packet is transmitted from the exchange, and the packet is transmitted to the client. And
One-way splicing processing from the server to the client from the time when the data acquisition request from the client is relayed until the transmission of the response packet transmitted from the server to the client is completed the performed, and exchange and performing retransmission control and flow control for from the client in the direction of communication to the server. A client-side processing unit that accepts a connection from each of the clients, manages a connection with the client, and transmits and receives packets;
A server-side processing unit that accesses each of the servers, manages a connection with the server, and transmits and receives packets;
Means for rewriting the header information of the packet at the time of relaying the packet transmitted from the server to the client, and transmitting the packet to the client;
One-way splicing processing is performed in the direction from the server to the client, and communication in the direction from the client to the client side processing unit and communication in the direction from the server side processing unit to the server are performed. 14. The exchange according to claim 13, further comprising means for performing retransmission control and flow control without disconnecting the established connection. The client side processing unit
Managing a connection between each of the clients, and a client-side termination unit that accepts connections and requests from each of the clients;
A client side update unit that relays a packet transmitted from the server to the client by rewriting header information,
The server side processing unit
A server-side termination unit that manages a connection between each of the servers and relays instructions and data for each of the servers sent from the client-side termination unit;
15. The exchange according to claim 14, further comprising a server-side update unit that receives a packet transmitted from each server to each client and sends the packet to the client-side update unit. In the header information of the packet,
In the transmission data divided into individual packets, a sequence number indicating the order of data in the packet,
The data length of the packet,
The exchange according to claim 15, further comprising an Ack number indicating a sequence number of data that has already been received by a communication partner. In the header information of the packet,
The exchange according to claim 16, further comprising a Win value indicating a remaining capacity of a reception buffer that has not yet been received by a communication partner. The client side termination is
Means for notifying the header information of the packet received from each of the clients to the client side update unit and the server side termination unit;
The server side update unit
Means for notifying the server-side termination unit of header information of a packet transmitted from each server to each client;
The client side update unit and the server side termination unit are:
16. The exchange according to claim 14 or 15, wherein the header information of the packet is appropriately rewritten by recording and referring to the notified header information. In the state where the one-way splicing process is set, the client-side termination unit is
Instructing the client side update unit to perform response processing for packets received from each of the clients,
The client-side update unit
19. The exchange according to claim 18, further comprising means for receiving a response processing instruction and generating and transmitting a response packet to the client. The server side update unit
Relay transmission of packets from a plurality of the servers to one client;
Means for removing from the header information of the packet to be relayed a flag indicating the end of packet transmission in each of the servers,
20. The packet transmitted by switching the plurality of servers is relayed to the client without disconnecting the connection with the client. 20. switch. The client side termination unit and the server side termination unit are:
It comprises means for restoring transmission data divided into individual packets to be transmitted from the client to the server to the state before the original division, and transmitting each packet by selecting the server. The exchange according to any one of claims 14 to 20. An analysis unit for determining a connection destination server to which each of the clients connects;
The analysis unit
Means for acquiring information of a request that the client sends to each of the servers from the client-side termination unit;
Means for determining a connection destination server to which the client should connect based on the request;
The exchange according to any one of claims 14 to 21, further comprising means for instructing the server-side termination unit to connect to the determined connection destination server of the client. . The client side termination unit and the server side termination unit are:
A means for transmitting to the server after restoring the transmission data divided into individual packets and transmitted to the server from the client to the original state before the division,
The analysis unit
23. The exchange according to claim 22, further comprising means for determining the connection destination server based on the transmission data restored to the original state before the division. The analysis unit
Means for sequentially classifying unprocessed data acquisition requests sent by the client into groups for each server to which the connection is made;
The server-side termination unit is provided with means for instructing connection to a corresponding server and execution of the data acquisition request classified into the group for each of the classified groups. The switch according to claim 22 or 23. In a packet switching method of an exchange that relays packet communication between a plurality of servers and clients via a communication network,
When the packet transmitted from the server to the client is relayed, the header information of the packet is rewritten to the contents set when the packet is transmitted from the exchange, and the packet is transmitted to the client. And
One-way splicing processing from the server to the client from when the data acquisition request from the client is relayed until the response packet transmitted from the server to the client is completed the performed, and packet switching method, wherein from said client to perform the direction of retransmission control and flow control for the communication to the server. Managing a connection between each of the clients and receiving a connection or request from each of the clients;
A packet transmitted from the server to the client, rewriting the header information, and relaying;
Managing a connection with each of the servers, and comprising relaying instructions and data for each of the servers sent from the client;
In the header information of the packet,
In the transmission data divided into individual packets, a sequence number indicating the order of data in the packet,
The data length below the transport layer of the packet,
26. The packet exchange according to claim 25, comprising an Ack number indicating a sequence number of data that has already been received by a communication partner, and a Win value indicating a remaining capacity of a reception buffer that has not yet been received by the communication partner. Method. Relay transmission of packets from a plurality of the servers to one client;
A step of removing a flag indicating the end of packet transmission in each of the servers from the header information of the packet to be relayed,
27. The packet switching method according to claim 26, wherein a packet transmitted by switching the plurality of servers is relayed to the client without disconnecting a connection with the client. The transmission data divided into individual packets sent from the client to the server is restored to the state before the original division, and each packet is selected and transmitted to the server. The packet switching method according to claim 26 or 27. Obtaining information of a request that the client sends to each of the servers;
Determining a connection destination server to which the client should connect based on the request;
29. The server according to claim 26, further comprising a step of instructing connection of the client to the determined connection destination server, thereby determining a connection destination server to which each of the clients is connected. Or the packet switching method according to claim 1. Sequentially classifying the raw data acquisition requests sent by the client into groups for each server to which it is connected;
30. The packet switching method according to claim 29, further comprising a step of instructing, for each of the classified groups, connection to a corresponding server and execution of the data acquisition request classified into the group. In a recording medium in which an exchange program that relays packet communication between a plurality of servers and clients via a communication network by controlling the computer is recorded so as to be readable by the computer,
The exchange program is
When a packet transmitted from the server to the client is relayed, the header information of the packet is rewritten to the contents set when the packet is transmitted from the exchange, and the packet is transmitted to the client. Outgoing,
One-way splicing processing from the server to the client from the time when the data acquisition request from the client is relayed until the transmission of the response packet transmitted from the server to the client is completed the conducted, and a recording medium recording a replacement program and performs retransmission control and flow control for the direction of communication to the server from the client. The exchange program is
Managing a connection between each of the clients and receiving a connection or request from each of the clients;
A packet transmitted from the server to the client, rewriting the header information, and relaying;
Managing a connection with each of the servers, and comprising relaying instructions and data for each of the servers sent from the client;
In the header information of the packet,
In the transmission data divided into individual packets, a sequence number indicating the order of data in the packet,
The data length below the transport layer of the packet,
An Ack number indicating the sequence number of data that the communication partner has already received;
32. The recording medium on which the exchange program according to claim 31 is recorded, comprising a Win value indicating a remaining capacity of a reception buffer that has not yet been received by a communication partner. The exchange program is
Relay transmission of packets from a plurality of the servers to one client;
A step of removing a flag indicating the end of packet transmission in each of the servers from the header information of the packet to be relayed,
The recording medium recording the exchange program according to claim 32, wherein a packet transmitted by switching the plurality of servers is relayed to the client without disconnecting the connection with the client. The exchange program is
The transmission data divided into individual packets transmitted from the client to the server is restored to the state before the original division, and each packet is selected and transmitted to the server. A recording medium on which the exchange program according to claim 32 or 33 is recorded. The exchange program is
Obtaining information of a request that the client sends to each of the servers;
Determining a connection destination server to which the client should connect based on the request;
35. The server according to claim 32, further comprising a step of instructing connection of the client to the determined connection destination server to determine a connection destination server to which each of the clients is connected. A recording medium on which the exchange program according to claim 1 is recorded. The exchange program is
Sequentially classifying the raw data acquisition requests sent by the client into groups for each server to which it is connected;
36. The exchange program according to claim 35, further comprising a step of instructing, for each of the classified groups, connection to a corresponding server and execution of the data acquisition request classified into the group. recoding media. In a recording medium in which an exchange program operating on a server in a communication system that performs packet communication between a server and a client via an exchange is recorded by controlling the computer on the server so that the computer can read it,
The exchange program is
Transmitting the packet to the client by one-way splicing from the time of relaying the data acquisition request from the client in the exchange until the end of transmission of the response packet transmitted to the client The recording medium which recorded the exchange program which operate | moves on the server characterized by these so that reading by a computer was possible. In a recording medium in which an exchange program that operates on a client in a communication system that performs packet communication between a server and a client via a switch by controlling the computer on the client is readable by the computer,
From the time of relaying a data acquisition request to the server in the exchange until the end of transmission of a response packet received from the server, the packet is received from the server by one-way splicing. The recording medium which recorded the exchange program which operate | moves on the client to be readable by a computer. A server in a communication system that performs packet communication between a server and a client via an exchange,
Transmitting the packet to the client by one-way splicing from the time of relaying the data acquisition request from the client in the exchange until the end of transmission of the response packet transmitted to the client Server characterized by. 40. The server according to claim 39, wherein the packet is transmitted to the client in which the header information of the packet is rewritten to the contents set when the packet is transmitted from the exchange. In the header information of the packet,
In the transmission data divided into individual packets, a sequence number indicating the order of data in the packet,
The data length of the packet,
41. The server according to claim 40, further comprising an Ack number indicating a sequence number of data that has already been received by a communication partner. In the header information of the packet,
42. The server according to claim 41, comprising a Win value indicating a remaining capacity of a reception buffer that has not yet been received by a communication partner. The switch relays transmission of packets from the plurality of servers to one client;
A flag indicating the end of packet transmission in each of the servers is removed from the header information of the packet to be relayed,
43. The packet transmitted by switching the plurality of servers is relayed to the client without disconnecting the connection with the client, according to any one of claims 40 to 42. server. 41. The transmission data transmitted by being divided into individual packets from the client is restored to the original state before the division, and each packet is received by the selected server. 44. The server according to any one of 43. A server to which each client connects is determined by the exchange,
Obtain information of the request that the client sends to each of the servers with the exchange,
Based on the request, a connection destination server to which the client should connect is determined,
45. The server according to claim 40, wherein the client is instructed to connect to the determined connection destination server. Unprocessed data acquisition requests sent by the client are sequentially grouped into groups for each connected server,
46. The server according to claim 45, wherein each of the classified groups is instructed to connect to a corresponding server and execute the data acquisition request classified into the group. A client in a communication system that performs packet communication between a server and a client via an exchange,
From the time of relaying a data acquisition request to the server in the exchange until the end of transmission of a response packet received from the server, the packet is received from the server by one-way splicing. Client. 48. The client according to claim 47, wherein the packet is received from the server in which the header information of the packet is rewritten to the contents set when the packet is transmitted from the exchange. In the header information of the packet,
In the transmission data divided into individual packets, a sequence number indicating the order of data in the packet,
The data length of the packet,
49. The client according to claim 48, further comprising an Ack number indicating a sequence number of data that has already been received by a communication partner. In the header information of the packet,
The client according to claim 49, further comprising a Win value indicating a remaining capacity of a reception buffer that has not yet been received by a communication partner. The switch relays transmission of packets from the plurality of servers to one client;
A flag indicating the end of packet transmission in each of the servers is removed from the header information of the packet to be relayed,
51. The packet transmitted by switching the plurality of servers is relayed to the client without disconnecting the connection with the client, according to any one of claims 48 to 50. client. 49. The transmission data transmitted by being divided into individual packets from the client is restored to the state before the original division, and each packet is transmitted to a selected server. 51. The client according to any one of 51. A server to which each client connects is determined by the exchange,
Obtain information of the request that the client sends to each of the servers with the exchange,
Based on the request, a connection destination server to which the client should connect is determined,
53. The client according to claim 48, wherein the client is instructed to connect to the determined connection destination server. Unprocessed data acquisition requests sent by the client are sequentially grouped into groups for each server to which they are connected,
The client according to claim 53, wherein for each of the classified groups, connection to a corresponding server and execution of the data acquisition request classified into the group are instructed. In Claim 12, the analysis unit comprises:
Means for sequentially classifying unprocessed data acquisition requests sent by the client into groups for each server to which the connection is made;
For each group that has been classified to the server-side termination unit, connection to the corresponding server, execution of the data acquisition request classified into the group, and disconnection of the server after transmission of the acquisition request are disconnected 12. The communication system according to claim 10, further comprising means for instructing a thing.

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