KR19990061519A - Method of communicating with information provider of packet network protocol connected to frame relay network - Google Patents

Abstract

The present invention relates to a personal computer (PC) communication technology using a frame relay network, and more particularly, to a method of allowing a frame relay network to receive an information provider of a packet network as it is and then communicating with an information provider using a frame relay network. will be.

The present invention is a communication system in which a packet network matching device connected to a high-speed switch and a frame relay network matching device are connected to a frame relay network, and are connected to a frame relay network to a PC communication by connecting an information provider of a packet network protocol to the frame relay network. The gateway is located between the information provider of the packet network protocol and the frame relay network, and the gateway extracts an X.25 packet from the frame relay frame received from the frame network, and loads it in an X.25 frame to transmit to the information provider of the packet network protocol. When the frame of the X.25 protocol is received from the information provider of the packet network protocol, the X.25 packet is extracted, and the predetermined unnecessary header is removed and loaded on the frame of the frame relay to be transmitted to the frame relay network.

Accordingly, the present invention provides a higher speed PC communication by accommodating a PC network by connecting an information provider of a packet network to a frame relay network that has a higher transmission speed than that of a packet network, and is capable of accommodating many information providers of a conventional packet network. have.

Description

Method of communicating a PC to X.25 IP's through frame relay network

The present invention relates to a personal computer (PC) communication technology using a frame relay network, and more particularly, to a method of allowing a frame relay network to receive an information provider of a packet network as it is and then communicating with an information provider using a frame relay network. will be.

In general, a public switched telephone network (PSTN) is a communication network for transmitting voice signals to other subscribers in a network by performing circuit switching according to call requests of telephone subscribers, and a packet network (PSDN) is used to transfer digital data between computers through packet switching. It is a network for.

In addition, these networks have been integrating with each other as the B-ISDN has been promoted, but since they are still composed of individual networks, a procedure for exchanging services between different types of networks was required.

The public telephone network is the most widely used communication network with almost all homes and businesses, mainly providing voice-based telephone service. However, in recent years, as the information society progresses, data transmission between computers is widely required, and various information providers have emerged, and the demand for access to packet networks is rapidly increasing.

Therefore, the service of the type connected to the packet network has been increased by using a telephone line used in a general home. An information communication processing system has been introduced for the connection between the public telephone network and the packet network.

As the evolution of the network has evolved, a wide variety of networks such as ISDN networks, frame relay networks, ATM networks, and the Internet have been newly established. In order to connect them together and increase the processing capacity, a large capacity communication system has been developed. Was improved.

1 is a configuration example of a communication processing system for communicating with an X.25 protocol IP connected to a packet network, and FIG. 2 is a diagram showing a data format according to the X.25 protocol.

Referring to FIG. 1, in the related art, PC communication is mainly performed through a packet network. At this time, a path from a PC connected to a public telephone network to an information provider (IP) connected to a packet network is a PC 101, a PSTN 102, and a large capacity. It was a path to the communication processing system 110, the packet network 104, and the information provider (IP: 106). At this time, the mass communication processing system is a packet network matching device (PNAS: 113) for connection between a public telephone network matching device (TNAS: 111) and a packet network (PSDN: 104) for connection with a public telephone network (PSTN: 102), and The high speed switch 112 is used to connect the public telephone network 102 and the packet network 104.

The public telephone network 102 and the TNAS 111 are connected by an E1 or T1 trunk, the packet network 104 and the PNAS 113 are connected according to the X.25 protocol, and the information provider 106 and the packet network 104 are also connected. Connected via X.25 protocol. As described above, the data format in the case of the connection according to the X.25 protocol is as shown in Fig. 2, and the frame of the frame layer is composed of a flag, an address, a control, an information area, a frame check sequence (FCS), and a flag. The packet layer packet is loaded in the information area. The X.25 packet consists of GFI, LCGN, LCN, PTI, calling terminal address length, called terminal address length, terminal address, additional area, and user data. Such X.25 protocols are widely known and will not be described further.

On the other hand, since the X.25 protocol performs error detection and error correction of the transmission data and retransmits the data when an error occurs, the recovery capability of the error is excellent. However, since the time required for error detection and data retransmission is high, Has a slow problem.

In addition, due to the development of semiconductor and communication technologies, errors in the network are significantly reduced, and high-speed transmission is required according to the broadband of service areas such as multimedia, so that a new protocol that improves the X.25 protocol is required.

In response to this need, the proposed frame relay network transmission protocol is designed on the premise that the error occurrence rate is very small. The error recovery capability is lower than that of the X.25 protocol, but the transmission speed is much higher than that of the X.25 protocol. Fast communication protocol.

Therefore, it is necessary to use high-speed transmission using a frame relay network in PC communication. Most information providers are still providing services based on the X.25 protocol as information providers connected to packet networks. Therefore, if the information provider connected to the packet network can be directly connected to the frame relay network, a lot of information can be obtained from the frame relay network, and the PC communication by the frame relay network will be active.

Accordingly, the present invention provides a method of communicating with an information provider of a packet network protocol connected to a frame relay network to enable PC communication by allowing an information provider of a packet network protocol to be accommodated in the frame relay network as it is. The purpose is to provide.

In order to achieve the above object, in the method of the present invention, a packet network matching device connected to a high-speed switch and a frame relay network matching device are connected to a frame relay network, and the information provider of a packet network protocol is connected to a frame relay network to a PC. In a communication system capable of communication, a gateway is located between an information provider of a packet network protocol and a frame relay network, and the gateway extracts an X.25 packet from a frame of a frame relay received from the frame network. When the frame is transmitted to the information provider of the packet network protocol, and the frame of the X.25 protocol is received from the information provider of the packet network protocol, the X.25 packet is extracted, and the predetermined unnecessary header is removed and loaded into the frame of the frame relay. Characterized in that the transmission to the frame relay network side do.

1 is a configuration example of a communication processing system for communicating with an X.25 protocol IP connected to a packet network;

2 illustrates a data format according to the X.25 protocol;

3 is a configuration example of a communication processing system for communicating with an X.25 protocol IP connected to a frame relay network according to the present invention;

4 is a format diagram showing a packet of an X.25 protocol in a frame of a frame relay protocol according to the present invention;

FIG. 5 is a diagram illustrating a protocol stack of the devices illustrated in FIG. 3.

Explanation of symbols for main parts of the drawings

301: PC 302: PSTN

311: TNAS 312: switch

313: packet network matching device (PNAS) 314: frame relay network matching device (FNAS)

304: frame relay network 320: gateway

306: Information Provider (IP)

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

3 is a configuration example of a communication processing system for communicating with an X.25 protocol IP connected to a frame relay network according to the present invention, and FIG. 4 shows a packet of an X.25 protocol in a frame of the frame relay protocol according to the present invention. In fact, it is a format diagram.

When the PC communication using the frame relay network according to the present invention, the configuration of the system, as shown in Figure 3, PC 301, PSTN 302, TNAS 311, switch 312, PNAS (313) ), A FNAS 314, a frame relay network 304, a gateway 320, and an information provider (IP: 306), and the gateway 320 includes a packet extracting unit 321 and an X.25 forming unit 322. It consists of.

Referring to FIG. 3, the PSTN 302 and the TNAS 311 are connected to the E1 / T1 trunk, the FNAS 314 and the frame relay network 304 are connected to the LAP-F, and the frame relay network 304 and the packet are connected. The extraction unit 321 is connected to the LAP-F. In addition, the packet extraction unit 321 and the X.25 forming unit 322 are connected by X.25 L3, and the X.25 forming unit 322 and IP 306 are connected by the X.25 protocol.

In FIG. 3, in the connection between the PNAS and the FNAS, the PNAS side 313 converts the layer 3 data of the X.29 protocol inputted from the PC 301 through the TNAS of the AICPS into the layer 3 packets of the X.25 protocol, and vice versa. Do this. In the connection between the PNAS and the FNAS, the FNAS side 314 deletes some of the headers of the layer 3 packets of the X.25 protocol inputted from the PNAS, converts the headers into layer 2 frames of the frame relay network transmission protocol, and performs inverse conversion.

The packet extracting unit 321 belonging to the gateway 320 is connected to the frame relay network to extract the layer 3 packet of the X.25 protocol from the layer 2 frame of the frame relay network transmission protocol received from the frame relay network 304, or 3 Insert a packet and convert it into a LAP-F frame.

The X.25 forming unit 322 belonging to the gateway inserts a layer 3 packet of the X.25 protocol inputted from the packet extracting unit 321 into an X.25 frame and converts the X.25 protocol into a data format of the X.25 protocol. Output to the information provider (IP) side or perform the reverse conversion.

As described above, the format of inserting an X.25 packet into a frame of the frame relay is shown in FIG. Referring to FIG. 4, a frame of a frame relay is composed of a flag, an address (DLCI), a control, an NLPID, an L2 PID, an L3 PID, an X.25 packet, and a flag, and the control, an NLPID, an L2 PID, an L3 PID, and an X.25. The packet is called an information field and it can be seen that an X.25 layer 3 packet is loaded.

In this case, when the layer 3 packet of the X.25 protocol is converted to the layer 2 frame of the frame relay network transport protocol, the deleted part of the header of the layer 3 packet of the X.25 protocol will be described in detail as follows.

1) When the layer 3 packet of the X.25 protocol is a calling packet

In the header of the packet, the remaining areas except the Q-bit area of the GFI, the LCN and LCGN areas, the address and address length areas of the calling or called terminal are deleted, and the length of the packet type identifier (PTI) area and the additional function area. The extra function area and the user data area are left.

In other words, the D-bit of GFI can be deleted because it is used to use the end-to-end method which reduces transmission efficiency, and bit 5 which tells how to use modulo and Bit 6 can also be cleared by using modulo 128 fixedly. The address and address length fields of the LCN and LCGN and the calling or called terminal may be deleted because the DLCI in the frame relay format delivers them to their final destination. On the other hand, the packet type identifier (PTI) is necessary because the type of the packet must be distinguished.

2) When the layer 3 packet of the X.25 protocol is a data packet

The remaining areas except the Q-bit area of the GFI and the LCN and LCGN areas are deleted for the same reason as described above, leaving the R (R), M-bit, P (S) and user data areas.

3) When Layer 3 packet of X.25 protocol is RR, RNR, REJ packet

The remaining areas except the Q-bit area of the GFI and the LCN and LCGN areas are deleted for the same reason as described above, leaving the packet type identifier (PTI) and R (R) areas.

4) When the layer 3 packet of the X.25 protocol is an interrupt packet

The remaining areas except the Q-bit area of the GFI and the LCN and LCGN areas are deleted for the same reason as described above, leaving the packet type identifier (PTI) and the interrupt user data area.

5) When the layer 3 packet of the X.25 protocol is a reset packet

The remaining areas except for the Q-bit area and the LCN and LCGN areas of the GFI are deleted for the same reason as described above, leaving the packet type identifier (PTI), the reset cause code area and the diagnostic code area.

6) When the layer 3 packet of the X.25 protocol is a release packet

In the header of the packet, the remaining areas except the Q-bit area of the GFI, the LCN and LCGN areas, and the address and address length areas of the calling or called terminal are deleted for the same reason as described above, and the packet type identifier (PTI) The area, the release cause code, the diagnostic code, the length of the additional function area, the additional function area and the user data area are left.

FIG. 5 is a diagram illustrating a protocol stack of the devices illustrated in FIG. 3. Referring to FIG. 5, the PSNA 313 is configured to access PC communication data inputted from a personal computer (PC) via a TNAS 311 of AICPS, that is, layer 3 data (L3) of the X.29 protocol. Converts into Layer 3 packets of the X.25 protocol (L3 in X.25) to provide access to AICPS FNAS.

The FNAS 314 deletes some of the headers according to the type of the Layer 3 packet (L3 of X.25) of the X.25 protocol inputted from the PSNA 313, thereby applying the layer 2 frame (LAPF) of the frame relay network transmission protocol. ) And output to frame relay network.

When the layer 2 frame (LAPF) of the frame relay network transmission protocol is input to the packet extractor of the gateway via the frame relay network, the packet extractor 321 performs the X.25 protocol in the layer 2 frame (LAPF) of the frame relay network transmission protocol. The layer 3 packet (L3 of X.25) is extracted and output to the X.25 forming unit 322.

The X.25 forming unit 322 converts the layer 3 packet of the X.25 protocol inputted from the packet extracting unit 321 into the complete data format of the X.25 protocol to the information provider (IP: 306) side of the packet network protocol. Output Information transmitted by the information provider (IP) of the packet network protocol to the public telephone network subscriber is transferred in the reverse order of the above-described process.

As described above, the present invention provides PC communication by connecting an information provider of a packet network to a frame relay network having a higher transmission speed than that of a packet network as it is, thereby providing high-speed PC communication and accommodating many information providers of a conventional packet network. It can be effective.

Claims (1)

A communication system in which a packet network matching device connected to a high speed switch and a frame relay network matching device are connected to a frame relay network, and a PC communication can be performed by connecting an information provider of a packet network protocol to a frame relay network. A gateway is located between the information provider of the packet network protocol and the frame relay network. The gateway extracts an X.25 packet from a frame of a frame relay received from the frame network and loads the X.25 packet in an X.25 frame to transmit to an information provider of the packet network protocol; When the frame of the X.25 protocol is received from the information provider of the packet network protocol, the frame relay network is characterized by extracting the X.25 packet, removing the unnecessary headers, and loading the frame in the frame relay frame to the frame relay network side. A method of communicating with an information provider of a packet network protocol connected to a network.