KR100333730B1 - Method for Requesting Data Retransmission between Network Access Systems over Ethernet - Google Patents

Abstract

1. TECHNICAL FIELD OF THE INVENTION

The present invention relates to a data retransmission request method between network matching devices distributed in Ethernet, and to a computer readable recording medium storing a program for realizing the method.

2. The technical problem to be solved by the invention

The present invention stores a previously received data PDU (Protocol Data Unit), and when retransmission is requested, all data PDUs having a transmission error within the window size are found and retransmitted at the same time so that the network is distributed over Ethernet for efficient retransmission. It is an object of the present invention to provide a method for requesting data retransmission between devices and a computer-readable recording medium having recorded thereon a program for realizing the method.

3. Summary of the Solution of the Invention

The present invention provides a method of requesting data retransmission between network matching devices distributed in Ethernet, the method comprising: receiving a data PDU (Protocol Data Unit) from a sender and comparing a sequence number of the received data PDU with a reception state variable; ; A second step of storing the received data PDU in a storage means if the sequence number of the received data PDU is greater than the reception state variable according to the comparison result of the first step; A third step of retrieving data PDUs requiring retransmission within a predetermined window size in said storage means; And generating a retransmission request data PDU using the retrieved data PDU, and then requesting the sender to retransmit.

4. Important uses of the invention

The present invention is used for data retransmission.

Description

Method for Requesting Data Retransmission between Network Access Systems over Ethernet}

The present invention relates to a retransmission method between heterogeneous network matching devices distributed in Ethernet. In particular, when a previously received data PDU is stored and a retransmission is requested, all data PDUs having a transmission error within the window size are found and retransmitted at once. The present invention relates to a data retransmission request method between network matching devices distributed over a required Ethernet, and a computer-readable recording medium storing a program for realizing the method.

In the conventional error recovery through retransmission, there is a problem that the sequence error recovery is inefficient because the sequence number of the currently received data PDU requires the retransmission of the data PDU immediately if it is not the expected sequence number.

The present invention has been proposed in order to solve the above problems, and when the previously received data PDUs are stored, when retransmission is requested, all data PDUs having a transmission error are found within a window size range, and then retransmission is requested at once. It is an object of the present invention to provide a method for requesting data retransmission between network matching devices distributed over Ethernet for efficient retransmission, and a computer-readable recording medium having recorded thereon a program for realizing the method.

Figure 1 is an embodiment network configuration for the interworking of various network matching devices having an Ethernet backbone to which the present invention is applied.

2 is a state variable table of a receiving side.

FIG. 3 is a diagram illustrating an embodiment of a protocol data unit (PDU) format for delivering retransmission information used in connected communication according to the present invention. FIG.

4 is a flowchart illustrating a method for requesting data retransmission between network matching devices distributed in Ethernet according to the present invention.

5 is a diagram illustrating an embodiment of a receive buffer.

6 is a flow diagram of an embodiment of a receive buffer search and retransmission request PDU generation for a retransmission request in accordance with the present invention.

In order to achieve the above object, the present invention provides a method for requesting data retransmission between network matching devices distributed in Ethernet, the method comprising: receiving a protocol data unit (PDU) from a sender, and then receiving the order of the received data PDUs; A first step of comparing the number and the received state variable; A second step of storing the received data PDU in a storage means if the sequence number of the received data PDU is greater than the reception state variable according to the comparison result of the first step; A third step of retrieving data PDUs requiring retransmission within a predetermined window size in said storage means; And generating a retransmission request data PDU using the retrieved data PDU, and then requesting retransmission from the sender.

In addition, the present invention, in order to request data retransmission between the network matching devices distributed in Ethernet, to receive a protocol data unit (PDU: Protocol Data Unit) from the sender to the communication system having a processor, the received data A first function of comparing a sequence number of the PDU and a reception state variable; A second function of storing the received data PDU in a storage means if the sequence number of the received data PDU is greater than the reception state variable according to a comparison result of the first function; A third function of retrieving data PDUs requiring retransmission within a predetermined window size in said storage means; And generating a retransmission request data PDU using the retrieved data PDU and then recording a program for realizing a fourth function for requesting the retransmission to the sender. The present invention provides an Ethernet network. By using the backbone to provide reliable communication between distributed network matching devices. When network matching devices for accessing various networks are connected with an Ethernet network as a backbone, a communication path should be established between the subscriber network matching device and the information provider network matching device. The subscriber and the information provider transmit and receive signal information and data. Therefore, the link between network matching devices formed on Ethernet is capable of point-to-point communication and ensures reliable information transmission. Accordingly, an object of the present invention is to provide an efficient retransmission method for providing a reliable link between heterogeneous network matching devices having different transmission speeds and network characteristics distributed over an Ethernet network. To this end, the present invention provides reliable information transmission. In order to improve the efficiency of retransmission request, it stores the received data, and when retransmission request, it finds all data frames that have transmission error within the window size range and retransmits them at once. In case of error recovery through retransmission, if the sequence number of the currently received frame is not the expected sequence number, a request for retransmission of the corresponding frame is requested. However, in the present invention, when the sequence number is abnormal, it is stored in the reception buffer and received within the window range. Find all missing frames and request them at once To recover the error.

The above objects, features and advantages will become more apparent from the following detailed description taken in conjunction with the accompanying drawings. Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a diagram illustrating an embodiment of a network configuration for interworking with various network matching devices having an Ethernet as a backbone to which the present invention is applied, and each network matching device is interworked through Ethernet 101 while having respective protocols. .

The telephone network matching device 102 and the integrated information communication network matching device 103 are subscriber network matching devices supporting subscriber access, and the packet network matching device 104, the frame relay network matching device 105, and the Internet matching device 106 are Information provider network matching device that supports information provider access.

The subscriber of the subscriber network matching device establishes a call to the information providing center connected to the information provider network matching device via Ethernet, and receives various services through this. Therefore, each subscriber network matching device and the information provider network matching device should set up each link when installed in the Ethernet 101.

For example, the telephone network matching device 102 includes a packet network matching device 104, a frame relay network matching device 105, to support telephone network subscribers with information retrieval services on packet networks or frame relay networks or file transfer services over the Internet. And an internet network matching device 106, respectively. As each subscriber call-related message and information message is transmitted / received on the link thus configured, the connection between each network matching device must be a reliable connection type link that guarantees order control and flow control.

The Connection-Oriented Protocol (CO Protocol) applied to the present invention first finds the address of a new network matching device installed in the Ethernet 101, and is capable of communicating with a partner (ie, subscriber network matching device and information provider). Network matching device), and a link establishment request command is sent to the other party for each link. The receiving side, upon receiving the link establishment request, then sends an appropriate response to it, thereby establishing the link.

In order to guarantee the reliability of the message transmitted with the link established, the connected protocol delivers the message in a frame with sequence numbers. Receiving side performs the flow control to the designated window size for the frame assigned this sequence number, and performs the sequence control by checking the order of all frames.

2 is a state variable table of a receiving side, and shows a state variable table that must be managed and maintained at the receiving side for each link.

The reception state variable 201 is a number of protocol data units (PDUs) of data currently expected to be received, and is increased in accordance with the reception of sequential data PDUs.

The maximum allowable reception state variable 202 is a number of data PDUs that the reception side does not allow reception. If the sequence number of the received data PDU is equal to or greater than the maximum allowable reception state variable, the reception side discards the data PDU.

The receive buffer update state variable 203 is used to move the position of the receive window, and is created, maintained, and managed by the number of links formed.

FIG. 3 is a diagram illustrating an embodiment of a protocol data unit (PDU) format for retransmission information transmission used for connected communication according to the present invention, and is a data PDU format for retransmission request used for retransmission for order control. .

The PDU Type field 301 indicates a retransmission request PDU, and the PDU Length field 302 indicates the total PDU length, which has a different value for each PDU generation since the number of retransmission sequence number pairs is not constant.

The maximum allowable reception status variable of the receiving side of FIG. 2 is reflected in the maximum reception allowance sequence number field 303, and the reception status variable of FIG. 2 is reflected in the reception waiting sequence number field 304.

The remaining fields are sequence number pairs of data PDUs requiring retransmission and may be represented by a general expression as follows.

{[Nr (1), Na (1)], [Nr (2), Na (2)], ...., [Nr (n), Na (n)]}

Here, the Nr (n) field 305 is a PDU sequence number at which retransmission starts with the nth retransmission request sequence pair, and the Na (n) field 306 is a data PDU sequence number at which reception was successful. For example, {(3,6), (15,16)} indicates that data PDU 3 to 5 data PDU and 15 data PDU are required to be retransmitted.

FIG. 4 is a flowchart illustrating a method for requesting data retransmission between network matching devices distributed in Ethernet according to the present invention, and shows a process of receiving a data PDU having a sequence number and generating a retransmission request PDU of a missing data PDU.

A data PDU having a sequence number is received (401), and the sequence number of the received data PDU is compared with the maximum allowed reception state variable at the receiving side (402).

As a result of the comparison, if the sequence number of the received data PDU is equal to or larger than the maximum allowable reception state variable of the receiving side, the received data PDU is discarded and the reception state variable value is adjusted (403). At this time, the reception state variable value adjustment is performed as in Equation 1 below.

Maximum allowed receive status variable = Receive status variable + window size

Receive buffer update status variable = Receive status variable + window size / 2

As a result of the comparison, if the sequence number of the received data PDU is smaller than the maximum allowable receiving state variable on the receiving side, that is, the range of the maximum allowable receiving state variable is satisfied, it is checked whether the received data PDU sequence number is the same as the receiving state variable (404). ).

As a result of the check, if the received data PDU sequence number is equal to the reception status variable, that is, if the received data PDU is a normal data PDU, the received data PDU is forwarded to a higher application (405), and if the received data PDU sequence number is the reception status If not equal to the variable again checks if the received data PDU sequence number is greater than the received status variable (406).

If the received data PDU sequence number is smaller than the received state variable, the received data PDU is discarded and the received state variable value is adjusted (407).

If the result of the check is that the received data PDU sequence number is greater than the receive standby sequence number, that is, has a sequence number greater than the data PDU still expected to be received, the received data PDU is stored in the receive buffer (408), and the data having an error occurs. The PDU is found and a data PDU requesting retransmission is generated (409) and transmitted (410).

Then, the transmitting side retransmits the data PDU according to the retransmission request.

FIG. 5 is an embodiment configuration diagram of a receive buffer, which is composed of four fields: a flag 501, a sequence number 502, a length 503, and a received data PDU 504.

The flag field 501 indicates whether the data PDU stored in the index exists, the sequence number field 502 indicates the sequence number of the stored data PDU, and the length field 503 indicates the total length of the stored data PDU.

The received data PDU field 504 stores data PDUs that arrive at the receiving side but cannot be delivered to a higher level application due to an order error and wait for error recovery.

When stored in the receive buffer, the index and the sequence number of the receive buffer have the same relationship as (Equation 2).

Location index to be stored in the receive buffer = data PDU sequence number% window size

Therefore, a position in the reception buffer to be stored in the sequence number of the data PDU is generated, and the received data as large as the window size can always be stored. Since all error control such as flow control and sequence control are operated based on window size, all errors within the window range can be recovered. Also, by using modulo, the receive buffer is used as a ring buffer.

6 is a flowchart illustrating an embodiment of receiving a search buffer and generating a retransmission request PDU for a retransmission request according to the present invention.

The search of the receive buffer consists of two parts. The search of the first receive buffer consists of a modulo of the receive state variable divided by the window size of the receive state variable (that is, divided by the window size). To the window size index (that is, the last index). The search of the second receive buffer is performed from index 0 to before the start point of the first search.

In other words, since the receive buffer is operated as a ring buffer, the index is divided into two parts to search the entire buffer.

First, the initial value of each variable is set (601). The low and high variables are missing, i.e., a sequence number pair that needs to be retransmitted.

low is the initial receive value of the receiving state variable as the initial value (low = receiving state variable), and high is one greater than low (high = low + 1). The search start index (index_start) of the receive buffer, i.e., i has a low window size modulo and indicates that the first search is a first_search variable (601).

Check whether there is a data PDU already received and stored at index i of the receive buffer (602), if there is no data PDU already received, increase only the search index i of the receive buffer (i = i + 1) and continue searching. If there is already received data PDU, it is determined whether the sequence number of the data PDU stored in the index of the reception buffer coincides with the low value (604).

As a result, if the sequence number of the data PDU stored in the index of the receive buffer matches low, the low and high values are increased (low = low + 1, high = low + 1) (605), and then the receive buffer index is changed. Increment (i = i + 1) and continue searching.

As a result of determination, if the sequence number of the data PDU stored in the index of the receive buffer does not match low, it is again checked whether the sequence number of the data PDU stored in the index of the receive buffer corresponds to high (606). After increasing (high = high + 1) 607, the search continues and if it matches, it means that there is a missing data PDU, and thus generates a retransmission sequence number pair (608).

At this time, the start sequence number (= Nr (x)) requiring retransmission becomes low (Nr (x) = low), and the last retransmission sequence number + 1 (= Na (x)) becomes high (Na (x) = high). This sequence number information is added to and stored in the retransmitted linked list (608).

low again has a high + 1 value (low = high + 1), and high has one greater value than the new low value (high = low + 1) (609). After the reception buffer index i is increased (i = i + 1) (603), the search is continued.

Then, it is checked whether it is the first search (610).

If the result of the check is a first search, the receive buffer index i is compared with the window size (i.e., check if the receive buffer index i is the last index) (611), if the receive buffer index i is less than or equal to the window size ( That is, the search proceeds if the receive buffer index i is not the last index, and if the receive buffer index i is larger than the window size (that is, if the receive buffer index i is the last index), the receive buffer index goes to the second search. Is initialized to 0 (i = 0) (612) and search continues.

If it is the second search, check whether the receiving buffer index i is the last index of the second search, and if the last index of the second search, copy each sequence number pair information in the retransmission linked list to the retransmission request PDU and retransmit it. The PDU is created (614) and the search continues if it is not the last index of the second search. The method of the present invention as described above is implemented as a program and can be read by a computer-readable recording medium (CD-ROM, RAM, ROM, floppy). Disk, hard disk, magneto-optical disk, etc.).

The present invention described above is capable of various substitutions, modifications, and changes without departing from the spirit of the present invention for those skilled in the art to which the present invention pertains, and the above-described embodiments and accompanying It is not limited by the drawings.

In the present invention as described above, when an error occurs in the sequence number of the received data PDU when receiving data between various network matching devices distributed in Ethernet, the data is stored in the window size through the reception buffer operation. There is an effect that the efficiency of order control can be increased by searching and requesting retransmission at once.

Claims (7)

In the data retransmission request method between network matching devices distributed in Ethernet, Receiving a data protocol data unit (PDU) from a sender and comparing a sequence number of the received data PDU with a reception state variable; A second step of storing the received data PDU in a storage means if the sequence number of the received data PDU is greater than the reception state variable according to the comparison result of the first step; A third step of retrieving data PDUs requiring retransmission within a predetermined window size in said storage means; And A fourth step of generating a retransmission request data PDU using the retrieved data PDU and requesting retransmission from the sender; Method of requesting data retransmission between network matching devices distributed in Ethernet. The method of claim 1, The first step is, A fifth step of receiving the data PDU having the sequence number from the sender and confirming the sequence number of the received data PDU; A sixth step of comparing a sequence number of the identified received data PDU with a maximum allowable reception state variable; A seventh step of discarding the received data PDU and changing the received state variable if the sequence number of the received data PDU is greater than or equal to the maximum allowable received state variable as a result of the comparison in the sixth step; And An eighth step of checking whether the sequence number of the received data PDU is equal to the received state variable if the sequence number of the received data PDU is smaller than the maximum allowable received state variable as a result of the comparison in the sixth step; Method of requesting data retransmission between network matching devices distributed in Ethernet. The method of claim 1, The second step, A fifth step of delivering the received data PDU to a higher application if the sequence number of the received data PDU is equal to the received state variable as a result of the comparison of the first step; A sixth step of discarding the received data PDU and changing the received state variable if the sequence number of the received data PDU is smaller than the received state variable as a result of the comparison of the first step; And A seventh step of storing the received data PDU in the storage means if the sequence number of the received data PDU is greater than the reception state variable as a result of the comparison of the first step; Method of requesting data retransmission between network matching devices distributed in Ethernet. The method of claim 1, The third step, A fifth step of retrieving data PDUs not received from the storage location index corresponding to the window size modulo of the reception state variable to the last storage location index corresponding to the window size in the storage means; And A sixth step of retrieving data PDUs not received from the first storage location index of the storage means to the previous index of the storage location index corresponding to the window size modulo of the received state variable; Method of requesting data retransmission between network matching devices distributed in Ethernet. The method according to any one of claims 1 to 4, The retransmission request data PDU in step 4 is A data PDU type field indicating a data PDU requesting retransmission, a data PDU length field indicating the length of the entire data PDU, a maximum reception allowable sequence number field, a reception wait sequence number field, and a sequence number and reception of a data PDU at which retransmission starts And a retransmission request data PDU sequence pair field composed of pairs of sequence numbers of the successful data PDUs. The method of claim 5, The storage means of the second step, Substantially, as a ring buffer, storing the received data PDU in the position index corresponding to the window size modulo of the sequence number, the data retransmission request method between the network matching devices distributed over Ethernet. In a communication system having a processor for requesting data retransmission between network matching devices distributed over Ethernet, A first function of receiving a data protocol data unit (PDU) from a sender and comparing a sequence number of the received data PDU with a reception state variable; A second function of storing the received data PDU in a storage means if the sequence number of the received data PDU is greater than the reception state variable according to a comparison result of the first function; A third function of retrieving data PDUs requiring retransmission within a predetermined window size in said storage means; And A fourth function of requesting the sender to retransmit after generating a retransmission request data PDU using the retrieved data PDU A computer-readable recording medium having recorded thereon a program for realizing this.