KR20040104775A - Apparatus and Method for efficient re-transmission of packets between different networks - Google Patents

Abstract

PURPOSE: A network device for effectively retransmitting a packet between different kinds of networks and a packet retransmitting method are provided to suggest an effective packet retransmission method in order to prepare for a moment when an error is generated during a packet transmission, like a case when a packet is lost between a client and a server. CONSTITUTION: A wired network interface(440) transceives a packet with a wired network(480). A wireless network interface(450) transceives a packet with a wireless network(490). A packet storage(420) stores the transceived packets. A timeout check module(430) checks a time when the packets are stored, and processes a packet which exceeds a predetermined storage time. A packet transmission controller(410) performs a packet conversion between the wired and wireless networks(480,490), and retransmits the stored packets if the transceived packets are lost.

Description

Network device and packet retransmission method for efficient packet retransmission between heterogeneous networks {Apparatus and Method for efficient re-transmission of packets between different networks}

The present invention relates to packet retransmission in network communication, and more particularly, to a network device and a packet retransmission method for improving packet retransmission efficiency between heterogeneous networks.

With the development of the information industry, various types of network systems suitable for different user environments have emerged. Accordingly, devices for relaying data between heterogeneous networks have been developed. Thus, even a heterogeneous network can transmit and receive data.

1 is an exemplary diagram illustrating an internet environment between heterogeneous networks, and heterogeneous networks are described using wired networks and wireless networks as examples, respectively, and wired networks and wireless networks are referred to as access points (hereinafter, referred to as 'AP') 120 ) Is connected. In a wireless network environment, each terminal device (130, 140, 150) is generally equipped with a TCP / IP protocol on the 802.11x MAC protocol layer, and is connected to the wired Internet network 100 through the AP, the wired network on the wired network It is possible to communicate with the device 110. At this time, the AP serves as a gateway that connects different networks. That is, in order for the terminal devices 130, 140, and 150 to communicate with the wired network device 110, a protocol data unit (hereinafter referred to as 'PDU') implemented according to the protocol shown next to the terminal device. To the AP 120). The AP 120 converts the 802.11x frame for the received PDU into a frame suitable for the wired network connected to the AP 120 and transmits the frame to the wired network device 110. That is, the AP 120 converts a protocol. Meanwhile, the frame transmitted from the wired network device 110 is transmitted as an 802.11x frame by the AP 120 and transmitted to the wireless terminal devices 130, 140, and 150.

FIG. 2 is an exemplary diagram illustrating a structure of a TCP / IP protocol layer, in which TCP for explaining a specific embodiment of the present invention is located in a transport layer of the OSI 7 layer.

FIG. 3 is an exemplary diagram illustrating a packet transmission process over time in TCP / IP communication. In TCP / IP communication, a connection establishment 330 and a packet transmission 310 between a client and a server are shown. ), And performs communication in three stages of connection termination (320). Since TCP / IP communication is connection-oriented communication, a mechanism for establishing a connection between a client and a server is required and generally uses a 3-way handshaking method. Once a connection is established between the client and the server, the packet is transmitted and received between the client and the server while maintaining flow control while ensuring reliability (310). If a packet is to be exchanged or disconnected from either the client or the server, In step 320, the connection is released using the 4-way handshaking method. More detailed TCP transmissions are described in the "RFC 1180 TCP / IP tutorial" and the "RFC793 Transmission Control Protocol".

In the wired network and the wireless network, which are heterogeneous networks, as shown in FIG. 1, since the wired network device 110 and the AP 120 are connected by wire, there is a probability that the packet is lost. It is much lower than sending and receiving packets between (130, 140, 150). Therefore, in a wireless network environment, retransmission in TCP due to packet loss occurs frequently. In this case, retransmission is performed by a TCP-specific function. When the retransmission is performed between the client and the server, for example, the client is called the wireless mobile terminal 150 and the server is the wired network device 110, the AP 120 Via the wireless portable terminal 150 and the wired network device 110 is made through. As a result, since packet loss is severe on the wireless network, although the actual packet arrives from the wired network device 110 to the AP 120, retransmission is performed by the wireless mobile terminal 150 and the wired network device ( 110) will happen again. In this case, since a packet retransmission time and a backbone load may be generated, it is necessary to improve the packet retransmission method as described above.

As a specific embodiment of the present invention, in the packet transmission / reception 310 of FIG. 3, when a packet is transmitted and received between the client and the server, the packet is lost or lost. In case an error occurs in transmission and reception, a method for efficient packet retransmission is proposed.

1 is an exemplary view showing an internet environment between heterogeneous networks.

2 is an exemplary diagram illustrating a TCP / IP protocol layer structure.

3 is an exemplary diagram illustrating a packet transmission process over time in TCP / IP communication.

Figure 4 is an exemplary view showing the configuration of a packet transmission and reception network relay apparatus between heterogeneous networks according to the present invention.

5A is an exemplary diagram illustrating a packet storing process in a network relay apparatus according to the present invention.

5B is an exemplary diagram illustrating retransmission of a packet in the network relay apparatus according to the present invention.

5C is an exemplary diagram illustrating deleting a pre-stored packet in the network relay apparatus according to the present invention.

5D is an exemplary diagram showing deleting a pre-stored packet by a timeout check module in the network relay apparatus according to the present invention.

Figure 6 is an embodiment processing flow diagram illustrating a method for storing a packet received from a network in a network relay apparatus according to the present invention.

7 is a flowchart illustrating a method for retransmitting a packet by a network relay apparatus according to the present invention.

8 is a flowchart illustrating a method of deleting a pre-stored packet by a timeout check module of a network relay apparatus according to the present invention.

In order to achieve the above object, a network apparatus for efficient packet retransmission between heterogeneous networks according to the present invention, in the packet transmission and reception relay between heterogeneous networks, the first network interface module for transmitting and receiving packets with the first network, and the second network And a second network interface module for transmitting and receiving a packet, a packet storage module for storing a packet received from the first network interface module, a packet received from the first network interface module and using packet information of the received packet. A control 1 mode for determining whether to store the packet in the packet storage module and a packet from a second network, and when the received packet is a request for retransmission of a previously transmitted packet, the packet information is stored in the packet storage module using the packet information. Select control 2 mode to resend the same packet It includes a packet transmission control module for performing a.

In addition, in order to achieve the above object, the packet transmission and reception relay method for efficient packet retransmission between heterogeneous networks according to the present invention comprises the first step of receiving a packet from a first network, and by using the packet information of the received packet A second step of storing the received packet; and a second step of retransmitting the same pre-stored packet using the packet information when the packet received from the second network is a retransmission request of the previously transmitted packet.

Hereinafter, a network device and a retransmission method for efficient packet retransmission between heterogeneous networks according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

On the other hand, the heterogeneous network means that the physical configuration of the network is different, for example, a wired network and a wireless network, or Ethernet and FDDI, for example. In the present invention, a TCP packet transmission and reception generated between a wired network and a wireless network will be described with an example.

4 is an exemplary diagram showing the configuration of a packet transmission / reception network relay device 400 between heterogeneous networks, that is, between a wired network and a wireless network, and an AP may be exemplified as the relay device.

The relay device includes a wired network interface 440 for transmitting and receiving a packet to and from a wired network 480, a wireless network interface 450 for transmitting and receiving a packet to and from a wireless network 490, and a packet for storing packets to be transmitted and received between wired and wireless networks. The storage unit 420, a timeout check module 430 for checking a stored time of a packet stored in the packet storage unit 420 and processing a packet after a predetermined stored time, and packet conversion between wired and wireless networks. And a packet transmission control unit 410 for retransmitting the packet stored in the packet storage unit 420 when a packet transmitted or received between wireless networks is lost or lost. Hereinafter, the details of the operation will be described based on the contents shown in FIGS. 5A to 5D.

5A is an exemplary diagram illustrating a process of storing a received packet in the network relay apparatus according to the present invention, wherein the wired network interface 508 receives a packet from the wired network 512, and transmits the received packet to the packet transmission control unit. In step 502, the packet transmission control unit 502 transfers the packet to the wireless network interface 510 when the received packet is a packet for TCP connection establishment or a packet for TCP connection release. The wireless network interface 510 sends the forwarded packet to the wireless network 514. If the packet received from the wired network 512 is not a packet for TCP connection establishment or TCP disconnection, the packet transmission control unit 502 may include a source IP address and a sender included in the received packet. The packet storage unit 504 uses packet information such as a communication port number, a source IP address, a destination port number, and a packet sequence number. Check for the same packet. If the same packet exists, the packet transfer control unit 502 transmits the packet received from the wired network 512 to the wireless network interface 510, and if the same packet does not exist, receives it from the wired network 512. A packet is stored in the packet storage unit 504, wherein the stored packet is used when a packet retransmission request is requested later, and the time at which the packet is stored for the packet deletion function by the timeout check module 506. Information may also be stored with the packet. Meanwhile, the packet storage unit 504 may include software or hardware for storing information such as a hash table, a user's mini-DB, and the like.

5B is an exemplary diagram illustrating an operation of retransmitting a packet in the network relay apparatus according to the present invention. When the wireless network interface 530 receives a packet from the wireless network 534, the received packet is a packet transmission control unit ( 522, the packet transmission control unit 522 transfers the packet to the wired network interface 528 when the received packet is a packet for establishing a TCP connection or a packet for TCP disconnection. Network interface 528 sends the forwarded packet to wired network 532. If the packet received from the wireless network 534 is not a packet for TCP connection establishment or TCP disconnection, a source IP address and a source communication port number included in the received packet are source port. The packet storage unit 524 checks whether the same packet exists by using packet information such as a number, a destination IP address, a destination communication port number, and a packet sequence number. . If the same packet does not exist, the packet transfer control unit 522 transfers the packet received from the wireless network 534 to the wired network interface 528 and transmits the packet to the wired network 532. On the other hand, if there is a packet received from the wireless network 534 in the packet storage unit 524, and the received packet is not an ACK response to the previously transmitted packet, that is, the packet is not received normally If the packet information for retransmission is included, the packet transmission control unit 522 extracts the same packet as the packet received from the wireless network 534 from the packet storage unit 524 and transmits the same packet to the wireless network interface 530. The transmitted packet is retransmitted to the sender who requested the packet retransmission through the wireless network 534.

5C is an exemplary diagram illustrating deleting a pre-stored packet in the network relay apparatus according to the present invention. The packet transmission control unit 542 receives an ACK response packet indicating normal packet reception from the wireless network 554. The packet storage unit 544 checks whether a packet identical to the received packet exists. If the same packet exists, the packet stored in the packet storage unit 544 is deleted by the packet transmission control unit 542 because it does not need to be retransmitted, but if the same packet does not exist, the packet received from the wireless network 554 The packet is sent to the wired network 552 via the wired network interface 548.

FIG. 5D illustrates an example of deleting a pre-stored packet by a timeout check module in the network relay apparatus according to the present invention. The packet stored in the packet storage unit 584 for packet retransmission is not permanently stored. Instead, the packet corresponding to the preset condition is deleted by the timeout check module 586 in comparison with the reference value set by the timeout check module 586. At this time, the timeout check module 586 has a re-transmit timer, and calculates a timeout value based on a round-trip time (RTT). The calculated value can be used as the reference value.

6 is a flowchart illustrating a method of storing a packet received from a network in a network relay apparatus according to the present invention. The relay apparatus is in a waiting state for receiving a packet (S600). When receiving a packet (S610), it is checked whether the received packet is a packet for TCP connection establishment or TCP connection release (S620). If it is a packet for establishing or releasing a TCP connection, the received packet is transmitted to the wireless network (S660), and the relay device is in a waiting state waiting for reception of the packet again (S600). If it is not a packet for establishing or releasing a TCP connection, packet information is extracted from the received packet (S630), and it is determined whether the packet is already stored by the relay apparatus from the extracted packet information (S640). If it is stored, the relay device transmits the received packet to the wireless network (S660) and enters the standby state again (S600). If it is not stored, the relay device stores the received packet (S650), and receives the received packet from the wireless network. The packet is transmitted (S670).

7 is a flowchart illustrating a method for retransmitting a packet by a network relay apparatus according to the present invention. The relay apparatus is in a waiting state for receiving a packet (S700) and receives a packet from a wireless network. If the received packet is a packet for TCP connection establishment or TCP disconnection (S710), the received packet is transmitted to the wired network as it is (S720, S770). Otherwise, the caller IP is received from the received packet. Extract packet information such as address (Source IP Address), source communication port number (Source Port Number), destination IP address (Destination IP Address), destination port number (Destination Port Number) and packet sequence number In operation S730, it is checked whether a packet corresponding to the extracted packet information is stored in the relay device in operation S740. If it is not stored, the received packet is transmitted to the wired network (S770), but if it is stored, the stored packet is deleted (S790) because it is no longer necessary to store the ACK response to normal packet reception. The received packet is transmitted to the wired network (S780). If a packet retransmission is requested by the received packet, the stored packet is extracted and retransmitted to the wireless network (S760).

8 is a flowchart illustrating a method of deleting a packet previously stored by a timeout check module of a network relay apparatus according to the present invention. When the timeout check module is operated (S800). In operation S810, timeout information of each packet stored in advance is checked. The timeout information includes time information of the moment when the packet is stored. The timeout information is compared with a reference value set by the timeout check module (S820). In step S810, the timeout packet is deleted (S830), and after a predetermined time (S840), the timeout information for each pre-stored packet is checked again (S810).

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. It is not limited to drawing.

According to the present invention made as described above, in the transmission and reception of packets between heterogeneous networks having different packet transmission efficiency, by providing a mechanism for efficient packet retransmission can be more smoothly packet transmission and effect of reducing the network load.

Claims (11)

In the packet transmission and reception relay device between heterogeneous networks, A first network interface module for transmitting and receiving packets with the first network; A second network interface module for transmitting and receiving a packet with a second network; A packet storage module for storing a packet received from the first network interface module; And A control 1 mode for determining whether to receive a packet from the first network interface module and to store the packet in the packet storage module using the packet information of the received packet; and receiving a packet from a second network and receiving the packet from the second network. And a packet transmission control module selectively performing a control mode 2 for retransmitting the same packet stored in the packet storage module using the packet information when the request is for a retransmission of the transmitted packet. The method of claim 1, And wherein the first network is a wired network and the second network is a wireless network. The method of claim 1, Wherein said packet comprises an IP protocol packet. The method of claim 1, The packet information includes a sequence number of a TCP packet. The method of claim 1, The packet storage module includes a hash table. The method of claim 1, The packet storage module includes time information at which a packet is stored; And a timeout check module for deleting a packet previously stored in the packet storage module by comparing a predetermined reference value with time information stored in the packet storage module. In the packet transmission and reception relay method between heterogeneous networks, A first step of receiving a packet from a first network; A second step of storing the received packet using the packet information of the received packet; and And retransmitting the same pre-stored packet using the packet information when the packet received from the second network is a retransmission request of the previously transmitted packet. The method of claim 7, wherein And the first network is a wired network and the second network is a wireless network. The method of claim 7, wherein The packet is a packet retransmission method comprising an IP protocol packet. The method of claim 7, wherein The packet information includes a sequence number of a TCP packet. The method of claim 7, wherein And a second step of forming a hash table and storing the received packet in the first step.