KR100191836B1 - Bridge formatted data transmission in atm - Google Patents

Abstract

In the ATM communication method, in processing various types of bridge format data of an AAL 5 data packet formed in an ATM adaptation layer, 4 bytes of VCI information, 6 bytes of MAC address information, and 4 bytes of IP data All 14 bytes of memory are allocated to record header information, and information related to bridge format data is written to the memory at the time of data transmission. When a data packet is transferred from the upper layer to the AAL layer, The present invention provides a method of transmitting bridge format data in an asynchronous transfer mode communication method comprising a series of steps of accurately generating bridge format data of various types and sending the data to an ATM layer, The resulting bridge format data It has an effect that allows you to send precisely.

Description

Method of transmitting bridge format data in asynchronous transfer mode communication method

The present invention relates to a method and apparatus for processing various types of bridge format data of an AAL 5 data packet generated in an ATM adaptation layer in an asynchronous transfer mode (ATM) communication scheme, in which VCI information of 4 bytes, 6 bytes of MAC address information, 14 bytes of memory are allotted so that 4 bytes of IP data header information can be recorded and the information related to the bridge format data is written to the memory at the time of data transmission and when the data packet is transferred from the upper layer to the AAL layer, The present invention relates to a bridge format data transmission method in an asynchronous transmission mode communication method in which bridge format data formed of various types according to a data request protocol is accurately generated and sent to an ATM layer so that data of various types of bridge formats can be transmitted more accurately.

In the Broadband Integrated Services Digital Network (BISDN), a backbone network of a high-speed information communication network which is currently the main axis of the next generation communication network, not only dedicated lines or public networks for telephone or data communication, but also Ethernet A variety of networks such as a LAN / WAN / MAN (International Area Network / Wide Area Network / Metropolitan Area Network) or an international network using optical fiber or satellite are connected to provide a narrowband service such as telephone, data transmission, Service) to a broadband service such as precision image transmission, high-speed data transmission, and video signal transmission, all of which are connected with continuous real-time signals and clustered data signals.

Accordingly, an effective processing method that can handle such various services in common has been required, and an ATM (Asynchronous Transfer Mode) communication method, which is an asynchronous transmission method, is proposed as a solution thereof.

As the demand for various broadband services including video service, which is the background of the emergence of the BISDN concept, has increased, the ability to integrate broadcast services such as video telephony with distributable services such as CATV to accommodate all of these broadband signals And a function capable of providing both a line mode service and a packet mode service in common.

On the other hand, there was a need for a method of receiving both a very low transmission rate of several bps, such as telemetering, and a very high transmission rate, such as a voice rate of several tens of kbps and a video signal of several hundred Mbps. As a solution to this problem, a variety of service signals have been unified so as to have the same appearance, and these services have been stacked and multiplexed. At this time, ATM cells are externally unified, and ATM cells are collected and multiplexed, which is an Asynchronous Time Division Multiplexing (ATDM) method. The ATM cell and ATDM communication method ATM communication system.

The ATM communication method is a communication method that integrates the digital communication method and the packet mode communication method of the existing circuit mode. First, since the ATM communication method uses the ATM cell as the basic transmission method, it is closely related to the packet communication method In contrast, the ATM communication method has a difference in that it can treat signals of real time and constant bit rate (CBR) equally.

In addition, although the packet method is generally used locally in a local area network (LAN), since the ATM method is used for a PSTN (Public Signal Telecommunication Network), addressing, connection and flow control · There are various difficulties in exchanging and transmitting.

On the other hand, in comparison with the line mode communication method, in the line mode, the channel is allocated to each service and the information signal is transmitted through the channel through the continuous bit string. However, in the ATM method, VC (Virtual Channel).

It is the ATM communication system that implements various new necessary data processing methods in the connection setting, signal processing, transmission, exchange, and so on.

The communication environment in the ATM communication method is developed in such a manner that these various communication services are integrated into one service, unlike the case where individual services such as telephone, data communication, video transmission, have. Accordingly, technologies have been developed in which a variety of networks individually constructed in the network side are integrated into a single network. In particular, in integrating and providing a continuous real-time signal and a cluster signal having a wide band distribution including a video transmission service requiring a wide bandwidth from a voice service using a narrow band such as a telephone, In order to connect to a single network, it is necessary to integrate independently constructed systems and networks into a more integrated computer network in terms of resource sharing, resource distribution, and distributed processing. For this, the necessity of standardization of network architecture has emerged and international standardization organizations such as ISO (International Standard Organization) and CCITT (International Telegraph and Telephone Consultative Committee) have developed Open System Interconnetion (OSI) ) Standards have been established.

In this OSI system, unlike the development of the partial and individual protocols in the standardization of the conventional transmission control procedures, the architecture of the network is focused on the integrated and systematic development of the protocols, so that not only the simple data transmission between the systems, It is aiming to standardize the protocols up to the level that allows access to resources such as files, programs, databases, etc., and seeks to open up the interconnection between systems to a great extent. In addition, it is important to ensure adaptability to a wide range of communication networks (telephone switching network, local area information communication network, digital switching network, etc.), scalability to cope with introduction of new technologies such as addition of new communication service functions, optical communication and satellite communication. In order to adapt to such a communication environment, OSI defines the communication network as a logical hierarchical structure as shown in FIG. The network structure based on the logical hierarchical structure is referred to as OSI reference model, and systematic protocols are standardized, and various advantages are gained in constructing, expanding and adapting computer networks accordingly.

The OSI reference model, as set out above, is:

The definition of concepts for inter-system interconnections,

In designing the OSI specification,

Establishment of a common basis for coordinating the conformity of relevant standards

The purpose of this paper is to establish the concept of communication and the criteria for its functions so that the protocols of each layer can be performed productively and independently.

The OSI reference model as described above defines a logical structure of a computer network by using universal concepts and terms in consideration of protocol scalability due to the reliance on a specific system and future technological advances. It is possible to treat each of various devices and circuits as a unified one, and it becomes possible to design a systematic protocol by a consistent concept and functions.

These OSI reference models consist of application processes, open systems and physical media.

Looking at each of these;

Application Processes: As an operator of the terminal device or an application program,

A subject who exchanges information and performs office processing,

Open System: A device that provides a communication function for communicating between application processes such as a host computer, a communication control device, a terminal control device, and a terminal device,

Physical medium: An electrical medium that allows information and signals to be exchanged between devices, such as communication lines and channels.

This open system can be viewed as only one physical device or a complex of several devices coupled together. For example, the computer network itself may be viewed as an open system, in which case each physical device need not necessarily operate as an open system.

In order to provide various communication services of voice and non-voice in such an open system communication environment, individual networks which have been individually constructed according to respective services are now connected to each other through a single communication network, In this case, BISDN, which is a broadband integrated information communication network, is used not only for private line or public network for telephone or data communication, but also for LAN, optical fiber or satellite using an Ethernet And various networks are connected to provide a variety of communication services.

In this BISDN network, Transmission Control Protocol / Internet Protocol (TCP / IP), which is an international standard protocol for interworking between OSI reference model, which is an open system interface defined by ISO, Protocol), as shown in the following Table 1, it is the IP over ATM communication method in which the IP layer, which is the network layer of the third layer, is connected to the ATM layer, which is the second layer, the data link layer. In this case, since there are various protocols under the IP layer, it is DLPI (Data Link Provider Interface) method that standardizes the connection between the IP layer and the ATM layer. In this DLPI method, the received packet is divided into the IP layer and the ARP The layers have different service access points (SAPs). Thus, the type of protocol for processing the received data packet is determined.

OSI Reference Model TCP / IP and various services Layer 7 Layer 6 Layer 5 Layer Application layer presentation layer Session layer SMTP, FTP, TELNET, rcp, rlogin, NFS (Network File System) socket interface NETBIOS The fourth layer Transport layer TCP UDP Third layer Network layer IP ARP Second layer Data link layer Ethernet X.25 DDCMP SDLC, ALOHA, TDMA The first layer Physical layer IEEE 802, Ethernet, X.21bis, V.24, V.28, ISDN

3 is a reference model of the BISDN protocol. The first to third layers of the OSI reference model correspond to the physical layer, the ATM layer, and the ATM Adaptation Layer (AAL), respectively. I have to.

The user data generated by the user is packetized by the upper layer protocol in the upper layer of the third level and sent to the AAL layer. The data with the header and the trailer added to the AAL layer are sent to the ATM layer again, Finally, 53 bytes of ATM cells are created and multiplexed in the ATM switch.

The access interface between the upper layer and the AAL layer and the ATM layer is referred to as a service access point (SAP). As shown in FIG. 4, when the user data is made into U-SDU packets in the upper layer and sent to the AAL layer, AAL-SDU, and then the CS sublayer of the AAL layer adds header and trailer information to the AAL-SDU to form a continuous variable-length CS-PDU, and then the CS sub- And adds a header and a trailer to finally generate 53 bytes of ATM data cells, and then transmits the data cells to the ATM switch for transmission.

In such ATM communication, an ATM switch is relayed between a user and a user. As shown in 5a and 5b, an ATM card is interposed between a user and a switch, and the user performs a lot of work necessary for transmitting data. This ATM card is a device for physically transmitting data through an optical fiber, a coaxial cable, etc., and enables ATM data of a small transmission unit called a cell to be transmitted at a high speed. On the other hand, the ATM switch sets 0 virtual path and 5 virtual channel (VPI = 0 and VCI = 5) in order to set a channel required for transmission of data requested by the user between ATM cards between the transmitting side and the receiving side And assigns a virtual channel to the user. Therefore, the user does not directly deal with many things required for data transfer, but merely stores the data file to be transmitted, which is created using the application program, in the memory, and only transmits the data file to the ATM card. It can be done.

In order to transmit data cells in the ATM communication environment, a path for transmitting data from the sender side to the receiver side must be set as described above. For this purpose, in the ATM communication, 53 bytes of ATM data are transmitted in one cell unit And sets a path of an arbitrary capacity called a virtual path to set 65,000 virtual channels for one VP. This is a logical connection between specific terminals through an ATM switch, and connects with the number of the virtual channel in the ATM cell and the destination information.

In this case, CALL PROCEEDING, CONNECT, CONNECT ACKNOWLEDGE, and SETUP messages are used for call establishment and RELEASE (Call Forwarding) is used for call clearing. , Use RELEASE CPMPLETE message, and also use STATUS and STATUS ENQUIRY messages for other status check. The signaling procedure is briefly described. First, the data transmission is performed between the sender side and the receiver side through the call setup, and the actual data is transmitted after the transmission path is secured after completing the call setup. Since the data transmission path at this time uses the virtual path allocated by the ATM switch, it is not known from the user side, and this path is referred to as a virtual path.

In the conventional data transmission method using a virtual channel as described above, an ATM card interfaced between a user and an ATM switch, as shown in FIGS. 5A and 5B, is not used for setting a channel every time a user requests transmission of information, When a SETUP message is transmitted through signaling for data transmission, the switch analyzes the SETUP message and designates a VCI (Virtual Channel Identifier) that can be processed by the switch itself, . Then, the ATM card transmits data through the channel secured by the VCI.

FIG. 6 shows a format of a SETUP message transmitted transparently by an ATM network between a calling user and a receiving user during a call setup. This message includes a protocol discriminator field for processing one byte of user data, a call reference field, a 4-byte message type field, a 2-byte message length field, and an AAL parameter of 4-21 bytes Field, an ATM traffic descriptor field of 12-30 bytes, a broadband bearer function field of 6-7 bytes, a broadband upper layer information field of 4-13 bytes, a broadband repeat indicator field of 4-5 bytes, and a broadband sub- A layer number information field, a 5-byte receiving side number field, a 4-25 byte receiving side number field, a 4-26 calling party number field, a 4-25-byte calling party side number field, a 9- Byte quality of service (QoS) parameter field, a 4-5 byte wideband transmission complete field, a 4-8 byte transmission network selection field, and a 4-7 byte endpoint reference (Endpoi nt refence) fields.

7 shows a broadband high layer information element (B-HLI) in the setup message format of FIG. The first byte of the message is a broadband upper layer information element identifier field, the second byte is a 1-bit flag, a 2-bit coding standard field and an IE command field, a 3-4th field is a B-HLI length field The fifth field is a 1-bit flag and a 7-bit upper layer information type field, and the 6th to 13th fields are upper layer information fields.

8 is a diagram illustrating a format of a broadband low layer information element (B-LLI) among the format of the setup message of FIG.

In this message, the first byte is a broadband lower layer information element identifier (B-LLI) field, the next 3-4th byte is a field indicating the length of the B-LLI, 3 Identifier and User Information Layer 1, 2 and 3 are the information fields of the protocol. The bytes 6a and 7a are the protocol information fields of the user-dedicated layers 2 and 3, and the other fields 8-8.5 comprise the OUI field 1-3 of the AAL5 data packet and the field indicating the value of the PDI field 1-2 have.

When the user data to be transmitted in the ATM communication method as described above is first transmitted from the upper layer to the user data to be transmitted stored in the ATM card memory, the AAL 5 is processed into the CPCS-PDU form and sent to the ATM layer A header of 5 bytes is added, and the packet is divided into 53-byte cells. The packet is transmitted to the lower layer physical layer, and 53 bytes of packet data are transmitted through a predetermined physical transmission medium.

As shown in FIG. 9, a CPCS-PDU generated in the AAL 5 layer is preceded by a 3-byte LLC header and a 2-byte SNAP header followed by a data PDU. In this case, if the LLC header value is 0xAA-AA-03, it means that the SNAP header is followed. If the 3-byte OUI field value in the SNAP header is 0x00-80-C2, the protocol used in the AAL- And indicates the type of the actual bridge medium according to the PID field value of the next 2 bytes.

In processing the AAL 5 CPCS-PDU data, various types of data formats are configured according to the value of the PID field. Therefore, very accurate processing is required in processing the AAL 5 CPCS-PDU data, The transmission is delayed.

In order to solve the above problems, the present invention provides a method and apparatus for accurately transmitting IP data of various types of bridging formats in processing AAL 5 CPCS-PDU data generated in an ATM adaptation layer in an asynchronous transfer mode (ATM) In the asynchronous transfer mode communication method in which a memory capable of recording information about a bridge format data packet at the time of opening the VCI is configured and then data of the correct bridge format is transmitted using the memory at the time of data transfer, The present invention has been made in view of the above problems.

1 is an ATM network structure in which various types of users are connected to a network in an asynchronous transfer mode (ATM) communication environment,

Figure 2 also shows an OSI reference model in which the network is diagrammed as a logical hierarchy,

Figure 3 also shows the BISDN protocol reference model,

4 is a data format structure diagram of an AAL5 data packet,

5A is a block diagram illustrating an interface between a user and an ATM card and an ATM switch in a logical interconnection relationship of ATM communication settings;

FIG. 5B is a block diagram showing a logical configuration state of the ATM card in FIG. 5A,

FIG. 6 is a diagram showing a format for storing information of setup messages used in ATM signaling,

FIG. 7 is a format showing the format of the B-HLI information element in the setup message format of FIG. 6;

8 is a format showing the format of the B-LLI information element in the setup message format of FIG. 6,

FIG. 9 is a data format structure diagram showing a configuration of various types of bridge format data made in an ATM adaptation layer (AAL)

10 is a flowchart illustrating a procedure for processing data when transmitting bridge format data in an asynchronous transfer mode according to the present invention.

DESCRIPTION OF THE REFERENCE NUMERALS

Step 110: Memory configuration step

Step 120: Medium Access Control (MAC) address recovery step

Step 130: Service connection point (SAP) information recovery step

Step 140: Internet Protocol (IP) layer data discrimination step

Step 150: Direct Memory Access (DMA)

Step 160: Create Internet Protocol (IP) data header

Step 170: Data transfer step

Step 180: Address Resolution Protocol (ARP) layer data discrimination step

Step 190: Address Resolution Protocol (ARP) data processing step

In order to achieve the above object, the present invention allocates 14 bytes of memory in order to record 4 bytes of VCI information, 6 bytes of MAC address information and 4 bytes of IP data header information when the VCI is opened, After the information related to the bridge format data is recorded in the memory, when a data packet is transferred from the upper layer to the AAL layer, a series of bridge format data, which are formed in various types by the unit data request protocol, Steps.

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

In processing the AAL 5 CPCS-PDU data generated in the ATM adaptation layer in such an asynchronous transfer mode (ATM) communication method, the present invention provides a method for accurately transmitting IP data of various types of bridge formats configured as shown in FIG. 10 , 14 bytes of memory are all allocated on the ATM card memory so that 4 bytes of VCI information, 6 bytes of MAC address information and 4 bytes of IP data header information can be recorded when the call setup is performed, (Step 110). When a data transmission step is started and a data packet is delivered from an upper layer, a MAC address for recovering a received MAC address from the unit data request protocol is recovered (step 120) After recovering the SAP information for recovering the service connection point (SAP) information between the IP layer and the ATM layer (step 130) Data to be transmitted on the basis of the recall distinguish whether the data that the IP ARP data (step 140). If the SAP information value is the IP data of 0x800, the DMA memory area indicated by the VCI of the packet is searched. If there is no corresponding content, the error information is processed (150). Otherwise, the header of the bridge format data in the DMA memory (Step 160). Then, the created complete IP data packet is DMA-mapped and the data is transferred (step 170).

At this time, it is determined whether the data to be transmitted is IP data or ARP data in step 140. If it is determined that the SAP information value is 0X806 or not, the process proceeds to step 180. If the SAP information value is 0X806, To 0X800 and then to 0X806 when the data transfer is completed (step 190).

According to the present invention as described above, in processing an AAL 5 data packet generated in an ATM adaptation layer in an ATM communication method, bridge header and VCI mapping are accurately performed, thereby transmitting bridge format data of various types more accurately There is an effect to be able to.

Claims (1)

A method for transmitting IP data in a bridge format in an asynchronous transfer mode communication method, A 14-byte memory is allocated on the ATM card memory so that 4-byte VCI information, 6-byte MAC address information, and 4-byte IP data header information can be recorded when the VCI is opened in the call setup, A memory configuration step (110) of writing to the memory; A MAC address recovery step 120 for recovering a received MAC address from a unit data request protocol when a data packet is delivered from an upper layer; An SAP information recovery step 130 for recovering service connection point (SAP) information between the IP layer and the ATM layer; An IP data discrimination step 140 for discriminating whether data to be transmitted is IP data or ARP data based on the recovered SAP information; A DMA memory search step 150 for searching for a DMA memory area indicated by the VCI of the packet when the SAP information value is IPX data of 0X800 and performing an error process if there is no corresponding content; A header creating step 160 of reading the header of the bridge format data in the DMA memory and copying the header of the bridge format data to the head of a data packet to be transmitted to form a complete IP data packet; A data transfer step 170 for DMA-mapping the created complete IP data packet to transfer data; An ARP data discrimination step 180 of discriminating whether the SAP information value is 0X806 or an error processing in step 140; And an ARP data processing step 190 in which the SAP information value is changed to 0X800 in case of the ARP data when the SAP information value is 0X806 and is then changed to 0X806 when the data transmission is completed. Format data transmission method.