JPH04291435A - Computer system - Google Patents

Abstract

PURPOSE:To automatically decide an optimum largest segment size when the communication of date is carried out with use of a local. area network LAN via a gateway. CONSTITUTION:In a computer system where plural host computers 2 are connected to each other via an LAN 3, a fact that the partner computer 2 is connected with the LAN 3 only and with no intervention of a public network when the connection is secured to the partner computer 2 by reference to a host table 4 which contains the names of computers 2 and the largest and largest transfer lengths. Then the partner computer 2 is requested to send the largest segment size. Thus the largest segment size is set at the optimum value for transmission based on the received largest segment size. In such a configuration, the data can be transmitted in a large segment size and with no occurrence of the protocol violation and the communication efficiency is improved.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION The present invention is utilized for setting and managing the maximum segment size for data transmission when establishing a connection. The present invention relates to a computer system that can improve communication efficiency by transmitting data with the maximum segment size without violating protocols.

0002

2. Description of the Related Art Conventionally, the maximum segment size for transmission is set to the maximum segment size notified by the destination host computer.

In particular, in an unreliable network, if the transmission of one of the fragmented packets fails, all the packets before being fragmented must be retransmitted, resulting in data loss. An international standard stipulates that no matter how the sender is implemented, fragmentation will never occur against a host computer with any maximum segment size as long as the protocol rules are followed. It is specified that the data will be sent in the specified packet size.

[0004] However, in the case of communication via a gateway, the maximum segment size sent from the communication partner is not the segment size that the communication partner can actually receive. Packet sizes that would never cause fragmentation were specified and set in international standards, even for host computers with

[0005]

[Problem to be Solved by the Invention] Conventionally, when setting the maximum segment size of this type of communication partner, in the case of communication via a gateway, especially in an unreliable network, it is difficult to set the maximum segment size of fragmented packets. Since all packets before fragmentation must be retransmitted due to a single transmission failure, the maximum segment size sent from the communication partner is set to the maximum segment size notified by the partner host computer in the case of communication that does not go through a gateway. Instead, the packet size was set to a specified packet size that would never cause fragmentation, no matter what the maximum segment size of the host computer.

[0006]Also, in order to speed up communication, it is necessary to send large packets at once, but when establishing a connection, data with a segment length exceeding the maximum segment size sent from the communication partner Because it is a protocol violation to send a large number of packets at once, reliable networks divide the data into small, defined segment sizes that never cause fragmentation, even though large packets can be sent at once. There is a problem in that the transmission efficiency is lowered by transmitting the data.

[0007] The present invention solves this problem by automatically determining the optimum maximum segment size without causing a protocol violation when data communication is performed via a gateway using a LAN. The purpose is to provide a system that can.

[0008]

[Means for Solving the Problems] The present invention provides a system in which a plurality of host computers each having an input device are connected via a network, and each host computer is provided with communication control means for controlling communication with the other host computer. In the computer system, each of the plurality of host computers has a host table that stores the name of the other host computer, the minimum maximum transfer length on the communication path to the other host computer, and the maximum segment size, and a host table that stores the name of the other host computer, the minimum maximum transfer length on the communication path to the other host computer, and the maximum segment size, and a host table that stores commands from the input device. a command analysis means that receives the command and analyzes its contents; and, when the input command is a request to create the host table, creates the name of the other host computer and the minimum maximum transfer length of the communication path to the other host computer. a host table creation means for writing in the host table; and a maximum segment size notification means for reading and notifying the name of the other host computer, the minimum maximum transfer length on the communication path to the other host computer, and the maximum segment size from the host table. , selects the optimum value from the maximum segment size of the destination host computer notified from this maximum segment size notification means and the minimum maximum transfer length on the communication path to the destination host computer, and selects the optimum value for transmission to the destination host computer. maximum segment size determining means for setting a maximum segment size; when the command inputted from the input device to the communication control means is a connection establishment request, the communication control means reads a partner host computer name from the host table, and determines the other party's host computer name. Maximum segment size notification forced notification means for sending a notification of forced maximum segment size notification to the host computer, and maximum segment of the other host computer notified from the other host computer establishing the connection when establishing a connection with the other host computer. and a maximum segment size receiving means for receiving the maximum segment size and transmitting the received maximum segment size and the host computer name of the other host computer, and having each host computer receive the maximum segment size from the maximum segment size receiving means, The present invention is characterized in that it includes a maximum segment size writing means for writing to.

[0009]

[Operation] Between host computers that are connected to each other without going through a public communication network, it is possible to transmit and receive long segment sizes that are outside the standards of the public communication network.

[0010] When setting the maximum segment size for transmission, especially when communicating via a gateway, the LA
Among communication partners connected only by N, fragmentation should not occur for those whose addresses exist in the host table, no matter what the maximum segment size notified to the host computer. Sends a notification that sets the packet size to a specified value and stops processing at the other host computer.

Furthermore, in the case of communication not via a gateway, the maximum segment size notified by the partner host computer is transmitted to determine the maximum segment size for transmission.

[0012] This makes it possible to set the maximum segment size that allows optimal and fast transmission without violating the protocol.

[0013]

Embodiments Next, embodiments of the present invention will be explained based on the drawings. FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention.

In the embodiment of the present invention, a plurality of host computers 2 each having an input device 1 are connected via a network 3, and each host computer is provided with communication control means 7 for controlling communication with the other host computer. moreover,
As a feature of the present invention, each of the plurality of host computers 2 is provided with a host table 4 that stores the name of the other host computer, the minimum maximum transfer length on the communication path to the other host computer, and the maximum segment size; A command analysis means 5 receives a command from the device 1 and analyzes its contents, and when the input command is a request to create a host table 4, the name of the other host computer and the minimum communication path to the other host computer are provided. A host table creation means 6 creates a maximum transfer length of and writes it into the host table 4, and reads out the destination host computer name, the minimum maximum transfer length on the communication path to the destination host computer, and the maximum segment size from the host table 4. The optimum value is selected from the maximum segment size notification means 8 to be notified, the maximum segment size of the other host computer notified from the maximum segment size notification means 8, and the minimum maximum transfer length on the communication path to the other host computer. , maximum segment size determining means 9 for setting the maximum segment size for transmission to the other host computer, and when the command inputted from the input device 1 to the communication control means 7 is a connection establishment request, the host table maximum segment size notification forced notification means 11 for reading out the name of the other host computer from 4 and sending a notification of forced maximum segment size notification to the other host computer;
When establishing a connection with the other host computer, receive the maximum segment size of the other host computer notified from the other host computer establishing the connection, and send the received maximum segment size and host computer name of the other host computer.Maximum segment size reception means 12, and each host computer is provided with maximum segment size writing means 10 for receiving the maximum segment size from the maximum segment size receiving means 12 and writing it into the host table 4.

FIG. 2 is a diagram showing the contents of the host table in the embodiment of the present invention.

The host table 4 contains the address of the other host computer, the minimum maximum transfer length on the communication path from the own host computer to the other host computer at that address, and the maximum segment notified from the host computer at that address. The size is stored.

FIG. 3 is a block diagram showing an example of the overall configuration according to an embodiment of the present invention.

In this example, the host computer 2 and
The host computer 2 has a counterpart host computer 21 connected to the own host computer 2 without a gateway 31, and a counterpart host computer 22 connected via the gateway 31.

Next, the maximum segment size setting operation for transmission in the embodiment of the present invention configured as described above will be explained.

When communicating with the other host computer 21 and the other host computer 22, a command for creating the host table 4 from the input device 1, the name of the other host computer, and the minimum maximum transfer length on the communication path to the other host computer. Insert.

The command analysis means 5 analyzes the command input from the input device 1 and delivers the analysis result to the host table creation means 6. The host table creation means 6 is
The destination host computer name passed as a result of the analysis by the command analysis means 5 and the minimum maximum transfer length on the communication path to the destination host computer are written in the host table 4, and the creation of the host table 4 is completed.

Next, the operation of setting the maximum segment size for transmission when the own host computer 2 communicates with the other host computer 22 will be explained.

When establishing a connection when the own host computer 2 communicates with the other host computer 22 through the communication control means 7, the maximum segment size notification means 8 reads the name of the communication destination host computer connected only by LAN, The other host computer is LAN
Refer to the host table 4 to confirm that the host computer is connected to the own host computer.

The notification means 11 for forcing notification of maximum segment size forces the maximum segment size to the other host computer 22 so that fragmentation will never occur to the host computer having any maximum segment size. The host computer 2 is notified of the maximum segment size before the packet size is set to the specified packet size.

The maximum segment size receiving means 12 receives the maximum segment size of the other host computer 22, and writes the maximum segment size writing means 1 together with the host computer name of the other host computer 22.
Pass to 0.

The maximum segment size writing means 10 searches the host table 4 for the host computer name of the other host computer, writes the maximum segment size in the host table 4, and then notifies the maximum segment size notification means 8.

The maximum segment size notifying means 8 reads the maximum segment size and the minimum maximum transfer length on the communication path to the other host computer from the host table 4, and passes it to the maximum segment size determining means 9.

The maximum segment size determining means 9 is shown in FIG.
Processing is performed according to the flow shown in .

First, it is checked whether the address of the communication partner is in the host table 4, and if it is not, the communication partner is not notified of the maximum segment size.
You will be notified of the maximum segment size as usual. Therefore, that value is used as is as the optimal maximum segment size. If the address of the communication partner is in the host table 4, the process advances to the next step.

If the maximum segment size received from the maximum segment size receiving means 12 and the minimum maximum transfer length on the communication path to the other host computer are smaller, the optimum maximum segment is selected. Let size be the largest segment size received.

If the maximum segment size received from the maximum segment size receiving means 12 and the minimum maximum transfer length on the communication path to the other host computer are larger, the optimum maximum segment is selected. The size is determined between the maximum segment size received and the minimum maximum transfer length on the communication path to the destination host computer. In this embodiment, the minimum maximum transfer length is set as the optimal maximum segment size.

As described above, the maximum segment size for transmission can be set to an optimal value without violating protocol rules.

[0033]

As described above, according to the present invention, it is possible to automatically determine the maximum segment size for faster data transmission in communication from a host computer to a partner host computer. Also,
For systems that have been unable to fully utilize their communication performance due to a WAN environment (wide area network), it is now possible to set the maximum segment size for transmission to match the destination host computer, resulting in improved performance in a LAN environment. This has the effect of allowing high data transmission.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention.

FIG. 2 is a diagram showing the configuration of a host table in the embodiment of the present invention.

FIG. 3 is a diagram showing an example of the overall configuration according to the embodiment of the present invention.

FIG. 4 is a flowchart showing the processing flow of the maximum segment size determining means in the embodiment of the present invention.

[Explanation of symbols]

1 Input device 2 Host computer 3 Network 4 Host table 5 Command analysis means 6 Host table creation means 7 Communication control device 8 Maximum segment size notification means 9 Maximum segment size determination means 10 Maximum segment size writing means 11 Maximum segment size notification forced notification Means 12 Maximum segment size receiving means 21, 22 Other host computer 31 Gateway

Claims (1)

[Claims] 1. A computer system in which a plurality of host computers each having an input device are connected via a network, and each host computer is provided with communication control means for controlling communication with a partner host computer. Each computer has a host table that stores the name of the other host computer, the minimum maximum transfer length on the communication path to the other host computer, and the maximum segment size, and a command that receives commands from the input device and analyzes the contents thereof. an analysis means, and host table creation for creating the name of the other host computer and the minimum maximum transfer length on the communication path to the other host computer and writing it in the host table when the input command is a request for creating the host table. means, maximum segment size notification means for reading and notifying the destination host computer name, the minimum maximum transfer length on the communication path to the destination host computer, and the maximum segment size from the host table; and from the maximum segment size notification device. The maximum segment to be set as the maximum segment size for transmission to the other host computer by selecting the optimal value from the notified maximum segment size of the other host computer and the minimum maximum transfer length on the communication path to the other host computer. size determining means, when the command input from the input device to the communication control means is a connection establishment request, reads the name of the other host computer from the host table, and notifies the other host computer of a maximum segment size. Maximum segment size notification that sends a forced notification A forced notification means, and when establishing a connection with the other host computer, receives the maximum segment size of the other host computer notified from the other host computer establishing the connection, and receives the maximum segment size received. maximum segment size receiving means for transmitting the size and the host computer name of the other host computer; maximum segment size writing means for each host computer to receive the maximum segment size from the maximum segment size receiving means and write it to the host table; A computer system characterized by comprising: