JP2006121434A - Atm communication apparatus and its communication method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ATM communication apparatus for increasing the transfer efficiency of data by reducing header information. <P>SOLUTION: This ATM communication apparatus 10 is provided with: an omission condition registration table 11 for showing which information in header information has to be omitted under what type of conditions a protocol at a terminal side is put; and a transmission header processing part 12 for deleting the header information in the data frame of the protocol at the terminal side by referring to the omission condition registration table 11, and for generating a transmission data frame by setting an identifier showing the type of the deleted header information in an LLC header, and for generating a transmission data frame at a transmission side. This ATM communication equipment 10 is provided with: a restoration header information storing part 14 for storing header information for restoration; and a reception header processing part 13 for reading the identifier from an LLC header in the reception data frame, and for restoring the header information corresponding to the identifier by referring to the restoration header information storing part 14, and for generating the data frame of the protocol at the terminal side at a reception side. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an ATM (Asynchronous Transfer Mode) communication apparatus and a communication method thereof, and more particularly to an ATM communication apparatus and a communication method thereof that reduce header information of a predetermined protocol.

  In a network using ATM as a data link layer such as an ATM network or ADSL (Asymmetric Digital Subscriber Line), many protocol layers are interposed in an upper layer to transmit user data. There is a format for data transfer for each protocol layer. For this reason, the amount of header information added to the user data is large, and the ratio of header information to the total amount of data transferred in data transfer increases, resulting in a decrease in data transfer efficiency.

  Thus, a technique for reducing such header information has been conventionally known. For example, Patent Document 1 discloses that 10 bytes of LLC / SNAP (Logical Link Control / Subnetwork Access Point) header information in encapsulation conforming to RFC2684 is converted into 1-byte information, and AAL5 (ATM Adaptation Layer type 5) protocol. A technique for reducing header information by setting in a common part identifier (CPI) area in a data unit format is described.

JP 2002-335285 A

  However, in the technique of Patent Literature 1, the target of header information reduction is limited to header information that is a fixed value. Therefore, variable header information given from the server after the start of communication cannot be omitted, which is insufficient in terms of data transfer efficiency.

  An object of the present invention is to provide an ATM communication apparatus and a communication method therefor that reduce the size of header information including header information whose value is determined after the start of communication, and increase data transfer efficiency.

  An ATM communication apparatus according to an aspect of the present invention includes an abbreviation condition registration unit that holds information for determining which information in the header information according to the terminal-side protocol is omitted when the terminal-side protocol is in the abbreviated condition Then, with reference to the omission condition registration unit, the predetermined information in the header information of the data frame according to the terminal side protocol input from the terminal side is deleted, and an abbreviated identifier indicating the type of the deleted information is transmitted in the transmission data frame A transmission header processing unit that generates a transmission data frame to be set in the header and output to the network side. In addition, a restoration header information storage unit that stores header information for restoration, an abbreviation identifier is read from a reception header in a reception data frame input from the network side, an omission condition registration unit, a restoration header information storage unit, A reception header processing unit that restores the terminal-side header information corresponding to the abbreviation identifier based on the contents, generates a data frame according to the terminal-side protocol, and outputs the data frame to the terminal side.

  In the ATM communication apparatus of the first development form, the omission condition registration unit holds an omission identifier, information indicating the omission condition, and omission location information indicating which information in the header information is omitted. May be configured.

  In the ATM communication apparatus of the second development form, the transmission header processing unit indicates the header omission start when the header information in the data frame according to the terminal side protocol matches the information indicating the omission condition for the first time in a predetermined communication. When the start flag and the abbreviated identifier are set in the transmission header and the second and subsequent matches, the information indicated by the abbreviated location information in the data frame according to the terminal side protocol is deleted, and the abbreviated identifier is replaced with the transmission header. The reception header processing unit stores the information indicated by the omitted portion information in the restoration header information storage unit when the omitted identifier and the start flag exist in the reception header of the received data frame. Delete the received header of the received data frame, generate a data frame according to the terminal side protocol, If there is an abbreviated identifier in the header and no start flag is present, the received header of the received data frame is deleted, and the information indicated by the abbreviated portion information stored in the restored header information storage unit is received. A function of generating a data frame that is inserted into the data frame and conforms to the terminal-side protocol may be provided.

  In the third communication form of the ATM communication device, when there are a plurality of communications satisfying the omission conditions, an identification number for distinguishing header information in the plurality of communications, and omission location information corresponding to the omission conditions for each identification number, The transmission header processing unit further includes a header information storage unit that stores the header information in the data frame in accordance with the terminal-side protocol for the first time with information representing an abbreviated condition for each communication in a plurality of communications. Sets the start flag indicating the header omission start, the omission identifier, and the identification number in the transmission header, and when the second and subsequent matches, information indicated by the omission location information in the data frame according to the terminal side protocol And a function for setting an abbreviated identifier and an identification number in the transmission header, and the restoration header information storage unit uses restoration header information. The header information indicated by the omitted part information and the identification number in the received header are stored in association with each other, and the received header processing unit searches for the omitted identifier from the received header in the received data frame, and starts when the omitted identifier exists. It is determined whether or not the flag exists, and when the start flag is present, the header information indicated by the omitted part information and the identification number in the received header are stored in the restored header information storage unit as the restored header information. If the reception header is deleted and a data frame is generated according to the terminal side protocol, and the start flag does not exist, the reception header is deleted and stored in the restored header information storage unit corresponding to the identification number in the reception header. A function of generating the data frame according to the terminal-side protocol by adding the restored header information to the received data frame may be provided.

  In the ATM communication device of the fourth development form, a data unit that becomes a payload portion of an ATM cell is created from a transmission data frame output by the transmission header processing unit and output to the ATM processing unit, and data input from the ATM processing unit An AAL5 (ATM Adaptation Layer type 5) processing unit that generates a reception data frame from the unit and outputs it to the reception header processing unit, and an ATM cell generated by adding an ATM header to the data unit output by the AAL5 processing unit And an ATM processing unit that outputs the data unit generated by removing the ATM header from the ATM cell received from the ATM network to the AAL5 processing unit.

  In the ATM communication apparatus according to the fifth development form, the transmission header and the reception header may be LLC (Logical Link Control) headers.

  In the ATM communication apparatus of the sixth development form, the terminal-side protocol is an Ethernet (registered trademark) protocol, and header information in the Ethernet (registered trademark) frame may be deleted and restored.

  In the ATM communication apparatus of the seventh development form, header information in other protocols in the payload of the Ethernet (registered trademark) frame may be deleted and restored together.

  In the ATM communication apparatus according to the eighth development form, the other protocol may be PPPoE (Point to Point Protocol over Ethernet (registered trademark)).

  In the ATM communication device according to the ninth development form, the ATM communication devices may communicate with each other via an ATM network.

  The communication method according to the first aspect of the present invention is a method in which an ATM communication apparatus performs communication by deleting and restoring header information in accordance with a terminal-side protocol. In this method, on the transmitting side, a step of inputting a data frame according to the terminal side protocol from the terminal side, and what information in the header information according to the terminal side protocol is omitted when the terminal side protocol is in what condition The header information in the data frame is deleted, and an abbreviated identifier indicating the type of the deleted header information is set in the transmission header to generate a transmission data frame for output to the network side. Steps. In addition, on the receiving side, a step of inputting a received data frame from the network side, a step of reading an abbreviated identifier from a received header in the received data frame, contents of abbreviated conditions stored in advance and header information for restoration And restoring the header information corresponding to the abbreviated identifier, generating the data frame according to the terminal-side protocol by adding the restored header information, and outputting the data frame to the terminal side.

  The communication method according to the second aspect of the present invention is a method in which an ATM communication apparatus performs communication by deleting / restoring header information according to a terminal-side protocol. In this method, on the transmitting side, a step of inputting a data frame in accordance with the terminal-side protocol from the terminal side, and what information in the header information in the data frame is omitted when the terminal-side protocol is under what conditions A step of referring to abbreviated location information for determining the header, a step of determining whether or not the header information first matches the abbreviated condition in a predetermined communication, and a start indicating a header skip start when the result of the determination is the first time The flag and the abbreviated identifier indicating the type of header information to be deleted are set in the transmission header, and if the second and subsequent matches, the header information indicated by the abbreviated location information in the data frame according to the terminal side protocol is deleted. At the same time, a step of setting an abbreviation identifier in the transmission header and adding the set transmission header to the network side And generating a transmission data frame for the. Also, on the receiving side, a step of inputting a received data frame from the network side, a step of searching for an abbreviated identifier from the received header in the received data frame, and determining whether a start flag exists if an abbreviated identifier exists If the start flag is present, the header information indicated by the omitted part information is stored as restored header information, the received header is deleted to generate a data frame according to the terminal side protocol, and the start flag is not present. Includes a step of deleting the received header, adding the stored restoration header information to the received data frame to generate a data frame in accordance with the terminal-side protocol, and outputting the generated data frame to the terminal side .

  A communication method according to the third aspect of the present invention is a method in which an ATM communication apparatus performs communication by deleting / restoring header information in accordance with a terminal-side protocol. In this method, on the transmitting side, a step of inputting a data frame in accordance with the terminal-side protocol from the terminal side, and what information in the header information in the data frame is omitted when the terminal-side protocol is under what conditions When the header information in the data frame according to the terminal-side protocol matches the information indicating the omission condition for the first time for each communication in a plurality of communications, the header omission start is indicated. A start flag, an abbreviated identifier indicating the type of header information to be deleted, and an identification number for distinguishing header information in a plurality of communications are set in a transmission header. The information indicated by the omitted part information in the data frame is deleted, and the abbreviated identifier and identification number are sent to the transmission head. Comprising a step of setting in, and generating a transmission data frame for output to the network side by adding the set transmission header, a. Also, on the receiving side, a step of inputting a received data frame from the network side, a step of searching for an abbreviated identifier from the received header in the received data frame, and determining whether a start flag exists if an abbreviated identifier exists When the start flag is present, the header information indicated by the omitted part information and the identification number in the received header are stored in association with each other as the restored header information, and the received header is deleted and the data frame conforming to the terminal-side protocol is stored. If the start flag does not exist, the received header is deleted, the restored header information stored in correspondence with the identification number in the received header is added to the received data frame, and the data frame conforming to the terminal-side protocol And a step of outputting the generated data frame to the terminal side.

  According to the present invention, in the data frame of the upper layer protocol of ATM, in addition to header information which is a fixed value, communication is performed by deleting header information whose value is determined after starting communication. The data transfer efficiency in the network used for the layer can be further increased.

  The ATM communication apparatus (10 in FIG. 1) according to the embodiment of the present invention registers a condition for registering information indicating which information in the header information is omitted when the upper layer protocol is under what condition. A table (11 in FIG. 1), a transmission header processing unit (12 in FIG. 1) that sets an identifier indicating the omitted header information type in the LLC header information, and reads the identifier from the LLC header of the received frame; A reception header processing unit (13 in FIG. 1) that restores the header information corresponding to the identifier and a restoration header information storage unit (14 in FIG. 1) that stores header information for restoration are provided.

  The ATM communication apparatus (10 in FIG. 1) omits the header information of the upper layer from AAL5 at the time of transmission and sets an identifier indicating the omission in the LLC header information, and sets the header information omitted based on this identifier at the time of reception. By restoring, the total amount of header information in data transfer is reduced. That is, when the header content of the upper layer protocol matches the omitted condition registered in the omitted condition registration table (11 in FIG. 1), the omitted header information is stored in the restored header information storage unit (14 in FIG. 1). Therefore, not only a fixed value but also header information whose value is determined after the start of communication can be omitted or restored. Examples of header information whose values are determined after the start of communication include MAC (Media Access Control) address information and session ID of the access server in PPPoE (Point to Point Protocol over Ethernet (registered trademark)).

  The ATM communication device (10 in FIG. 1) is applied in an ATM network (30 in FIG. 1) or an upper layer protocol relay network using ATM as a data link layer such as ADSL. In the multiprotocol transfer method using AAL5 LLC encapsulation compliant with RFC2684 (revised version of RFC1483), the LLC header specification is extended to have additional information without changing the LLC header size. As a result, when communication is performed with the ATM communication device (10 in FIG. 1) facing each other via the ATM network, it is possible to perform communication with a reduced header information size in a higher layer protocol than AAL5. Therefore, data transfer efficiency can be increased in data transfer in an ATM network or a network using ATM as a data link layer. Hereinafter, a detailed description will be given in accordance with examples.

  FIG. 1 is a block diagram showing a configuration of an ATM communication apparatus according to the first embodiment of the present invention. In FIG. 1, an ATM communication device 10 is disposed between a terminal device 20 and an ATM network 30, and includes an omission condition registration table 11, a transmission header processing unit 12, a reception header processing unit 13, a restored header information storage unit 14, and an AAL5. A processing unit 15 and an ATM processing unit 16 are provided.

  The omission condition registration table 11 registers information indicating which information in the header information is omitted when the upper layer protocol is under what conditions.

  The transmission header processing unit 12 refers to the omission condition registration table 11 and deletes the header information in the data frame of the higher layer protocol input from the terminal device 20, and an identifier indicating the type of the deleted header information Is set in the LLC header information to generate a transmission data frame, which is output to the AAL5 processing unit 15.

  The reception header processing unit 13 reads the identifier from the LLC header in the received data frame input from the AAL5 processing unit 15 and restores the header information corresponding to the identifier with reference to the restoration header information storage unit 14. Are generated and output to the terminal device 20. The restoration header information storage unit 14 stores header information for restoration in the reception header processing unit 13.

  The AAL5 processing unit 15 performs processing for converting the data frame received from the transmission header processing unit 12 into an ATM cell, and passes a data unit serving as a payload portion of the ATM cell to the ATM processing unit 16. Further, the data unit input from the ATM processing unit 16 is processed to generate a reception data frame and output it to the reception header processing unit 13.

  The ATM processing unit 16 adds an ATM header to the data unit received from the AAL5 processing unit 15 to generate an ATM cell, and sends it to the ATM network 30. Further, the data unit obtained by removing the ATM header from the ATM cell received from the ATM network 30 is passed to the AAL5 processing unit 15.

  The ATM communication apparatus 10 configured as described above receives a data frame in a higher-layer protocol than AAL5 from the terminal apparatus 20 when transmitting data from the terminal apparatus 20, and in this data frame, the AAL5 LLC encapsulation, in AAL5 Processing for dividing into ATM cells is performed, and the cells are divided into ATM cells and sent to the ATM network 30. In receiving data from the ATM network 30, the reverse process of data transmission is performed, and the ATM cells received from the ATM network 30 are combined and output to the terminal device 20 as data frames in the higher layer protocol of AAL5. Hereinafter, each part will be described in more detail.

  As shown in FIG. 2, the omission condition registration table 11 is a table in which a plurality of header omission information composed of three elements of an omission identifier 11a, an omission condition 11b, and an omission place 11c can be registered. The abbreviated identifier 11a is used for identifying header omission in combination with the abbreviated condition 11b and the abbreviated portion 11c. The omission condition 11b specifies what value the header content of the upper layer protocol is to be omitted. The omitted portion 11c designates a field in the header information that is the target of the omission / restoration process when the omission condition 11b is satisfied. The omitted condition 11b and the omitted part 11c can be specified by combining a plurality of conditions and omitted parts.

  When the transmission header processing unit 12 receives the data frame from the terminal device 20, the transmission header processing unit 12 checks whether the header information in each protocol layer higher than AAL5 matches the omitted condition 11 b registered in the omitted condition registration table 11. If they match, the omitted portion 11c corresponding to the omitted condition 11b is deleted from the data frame received from the terminal device 20, and the data frame size is reduced. Furthermore, new header information in which the omitted identifier 11 a is embedded in the conventional LLC header information is added to the data frame from the terminal device 20 and encapsulated, and passed to the AAL5 processing unit 15. On the other hand, when the header information in each protocol layer higher than AAL5 of the data frame received from the terminal device 20 does not match the omission condition 11b registered in the omission condition registration table 11, the conventional LLC header information is changed to the terminal. It is added to the data frame from the device 20 and encapsulated, and passed to the AAL5 processing unit 15.

  When receiving a data frame from the AAL5 processing unit 15 when receiving data from the ATM network 30, the reception header processing unit 13 confirms the LLC header information. If the confirmed header information is header information corresponding to the omission condition, the omission identifier 11a included in the portion corresponding to the LLC header information is read. Next, the abbreviation information corresponding to the read abbreviation identifier 11a is extracted from the restoration header information storage unit 14, and the header information portion of the higher layer protocol from AAL5 is restored to the data frame received from the AAL5 processing unit 15, and the LLC The header information is deleted and passed to the terminal device 20. If the confirmed header information is conventional LLC header information, the LLC header information is deleted from the data frame received from the AAL5 processing unit 15 and is passed to the terminal device 20.

  Next, the LLC header information added in the transmission header processing unit 12 and the LLC header information deleted in the reception header processing unit 13 will be described. The AAL5 LLC encapsulation in this embodiment is an expansion of the encapsulation method compliant with RFC2684 (revised version of RFC1483). The LLC header in RFC 2684 compliant encapsulation consists of 1 byte each of DSAP (Destination Service Access Point), SSAP (Source Service Access Point), and Ctrl (Control). The value differs depending on whether the frame is ISO compliant. In the order of DSAP, SSAP, and Ctrl, if the data frame of the upper layer protocol to be encapsulated is ISO compliant, the hexadecimal value “FEFE03” is obtained, and if it is not ISO compliant, the hexadecimal value “AAAA03” is obtained. The LLC header is followed by an NLPID (Network Level Protocol Identifier) if it is ISO compliant, and a SNAP header if it is not ISO compliant.

  In this embodiment, the Ctrl part of the LLC header is always a hexadecimal value “03” regardless of whether the data frame of the higher layer protocol to be encapsulated is ISO compliant or ISO compliant. In the upper 6 bits of the Ctrl part which is fixed to 0, the abbreviation identifier 11a described above, a header abbreviation start flag for telling the start of header abbreviation described later, and a “child number” described in the second embodiment are also provided. assign. As a result, new information in the present invention can be transmitted by additionally defining the value set in the Ctrl part of the LLC header without changing the LLC header configuration or size. As a specific example, 2 bits are assigned to the abbreviation identifier, 1 bit is assigned to the header omission start flag, and 3 bits are assigned to the “child number”.

  Next, with reference to PPPoE in PPPoEoA (Point to Point Protocol over Ethernet (registered trademark) over ATM) communication as an example, the operation in the case of performing communication by omitting header information after establishing a PPP session will be described with reference to FIGS. It explains using.

  When the terminal device 20 tries to establish a session with a PPPoE server (access concentrator) (not shown) existing ahead of the ATM network 30, the terminal device 20 acquires the MAC address and session ID of the PPPoE server. Discovery in RFC2516 (A Method for Transmitting PPP Over Ethernet (registered trademark)) is started. At the time of discovery, the contents of the Ethernet (registered trademark) header and the PPPoE header that are transmitted and received change depending on the stage. For example, in the frame format of FIG. 4, DESTINATION_ADDRESS (6 bytes) is a broadcast address in a PADI (The PPPoE Active Discovery Initiation) packet sent from the terminal device 20 at the start of discovery, but upon receiving a reply from the PPPoE server. After that, the unicast address of the PPPoE server is set. SESSION_ID (2 bytes) is also fixed to 0 when a PADI packet is sent, but when an ID is specified from the PPPoE server, the specified ID is set as SESSION_ID thereafter. In this way, the values of the DESTINATION_ADDRESS and SESSION_ID fields are not fixed in the discovery stage, and are not known before the session is established, and can be obtained only when the session is established. However, when the session is established and the PPP session phase is entered from the discovery phase, until the PPPoE session is terminated, the values of the fields shown in the omitted portion 11c in FIG. 3 such as DESTINATION_ADDRESS and SESSION_ID in the format in FIG. Become immutable. For this reason, header entry can be used when entering the PPP session stage.

  Next, the header omitting process in the PPP session stage after the PPPoE session is established will be described. FIG. 5 is a flowchart showing the operation of the transmission header processing unit. The transmission header processing unit 12 receives the Ethernet (registered trademark) frame from the terminal device 20 (step A10), and the ETHER_TYPE field value of the Ethernet (registered trademark) header is set to the omitted condition 11b in the omitted condition registration table 11 (for example, ETHER_TYPE = 0x8864: PPP session stage) is compared (step A11). If the ETHER_TYPE field value does not match the omission condition 11b in step A11, the conventional LLC header information is added to the Ethernet (registered trademark) frame from the terminal device 20 and encapsulated (step A12), and output to the AAL5 processing unit 15 (Step A13), and the series of processes is terminated.

  In step A11, if the ETHER_TYPE field value of the Ethernet® frame received from the terminal device 20 matches the omission condition 11b (ETHER_TYPE = 0x8864: PPP session stage), it is confirmed whether or not the match is the first (step A21). ). In step A21, when the omission condition 11b is matched for the first time, an LLC header in which an omission identifier 11a and a flag indicating that omission of header omission is embedded is added to the conventional LLC header information. (Step A22), the data is output to the AAL5 processing unit 15 (Step A13), and the series of processing ends.

  On the other hand, if the abbreviation condition 11b has already been matched in step A21, the header information size is reduced by deleting the DESTINATION_ADDRESS, SOURCE_ADDRESS, ETHER_TYPE, VER, TYPE, CODE, and SESSION ID fields that are the abbreviations 11c (step A41). ). Subsequently, an LLC header in which the abbreviated identifier 11a is embedded in the conventional LLC header information is added (step A42) and output to the AAL5 processing unit 15 (step A13), and the series of processes is terminated.

  Next, the operation of the reception header processing unit 13 will be described. FIG. 6 is a flowchart showing the operation of the reception header processing unit. In FIG. 6, the cell received from the ATM network 30 is combined with the data frame via the ATM processing unit 16 and the AAL5 processing unit 15, and is input to the reception header processing unit 13 (step B10). The reception header processing unit 13 first confirms whether the LLC header of the data frame is a conventional LLC header (step B11). If it is a conventional LLC header, the LLC header part is deleted (step B13), an Ethernet (registered trademark) frame is output to the terminal device 20 (step B14), and a series of processing ends.

  In step B11, if the LLC header is an LLC header corresponding to an omission target, the reception header processing unit 13 reads the omission identifier 11a from the LLC header of the received data frame, and then sets a header omission start flag in the LLC header. It is confirmed whether it has been performed (step B21). When the header omission start flag is set in the LLC header, the omission location 11c corresponding to the omission identifier 11a is acquired from the received data frame and stored in the restored header information storage unit 14 (step B22). Then, it progresses to step B13.

  If the header omission start flag is not set in the LLC header in step B21, the contents of the omission location 11c corresponding to the omission identifier 11a are extracted from the restoration header information storage unit 14 and the data frame of the higher layer protocol is restored (step S21). B31), the process proceeds to step B13.

  Since the ATM device 10 operates as described above and saves omitted header information in the restored header information storage unit 14, header information whose value is determined after starting communication at the PPP session stage after the PPPoE session is established. Even so, it can be omitted or restored.

  As a second embodiment of the present invention, a method will be described in which a header can be omitted in each communication without confusion even if there are a plurality of communications satisfying one omission condition 11b. The operation when the PPPoE protocol is used and a plurality of PPP sessions are established will be described below with reference to FIGS.

  FIG. 7 is a block diagram showing the configuration of the ATM apparatus according to the second embodiment of the present invention. In FIG. 7, the same reference numerals as those in FIG. An ATM device 10a shown in FIG. 7 has an omitted header information storage unit 17 added to the ATM device of FIG. When the transmission header processing unit 12a receives a data frame that matches the omission condition 11b registered in the omission condition registration table 11, the omission header information storage unit 17 stores the omission place 11c corresponding to the omission condition 11b. . At this time, when there are a plurality of header information satisfying the omission condition 11b, an identification number (for example, a session identification number or the like, referred to as a child number here) for distinguishing them is also stored.

  Next, the operation of the ATM device 10a will be described. FIG. 8 is a flowchart showing the operation of the transmission header processing unit according to the second embodiment of the present invention. In FIG. 8, the same reference numerals as those in FIG.

  When the value of the ETHER_TYPE field of the Ethernet (registered trademark) frame received from the terminal device 20 matches the abbreviated condition 11b for the first time in the process (step A21) when the value matches the abbreviated condition 11b (ETHER_TYPE = 0x8864: PPP session stage) The contents indicated by the omitted portion 11 c from the header information received this time are stored in the omitted header information storage unit 17. At this time, if there are a plurality of header information satisfying the omission condition 11b, the child number for distinguishing them is also stored (step A23). After that, in the Ethernet (registered trademark) frame, in the Ctrl part of the conventional LLC header information, when there are a plurality of abbreviated identifiers 11a indicating header omitted contents and a plurality of headers satisfying the same abbreviated condition, a child number for distinguishing them Then, an LLC header embedded with an omission start flag indicating that header omission is to be started is added (step A24), and is output to the AAL5 processing unit 15 (step A13), and a series of processing ends.

  In step A21, if the omission condition 11b has already been matched, the values of the DESTINATION_ADDRESS, SOURCE_ADDRESS, ETHER_TYPE, VER, TYPE, CODE, and SESSION ID fields that have been registered as the contents of the omission part 11c are the next received Ethernet It is confirmed whether the information is different from the Ethernet (registered trademark) header or PPPoE header information in the (registered trademark) frame (step A40). If the header information of the Ethernet (registered trademark) frame received this time in step A40 is different from the contents of the omitted portion 11c registered in the omitted header information storage unit 17, the process proceeds to step A23. If the header information of the Ethernet (registered trademark) frame received this time in step A40 matches the contents of the omitted portion 11c registered in the omitted header information storage unit 17, the received Ethernet (registered trademark) frame has the omitted portion 11c. DESTINATION_ADDRESS, SOURCE_ADDRESS, ETHER_TYPE, VER, TYPE, CODE, and SESSION ID fields are deleted (step A41) to reduce the header information size. Subsequently, an LLC header in which the abbreviated identifier 11a and the child number are embedded is added to the conventional LLC header information (step A43), and is output to the AAL5 processing unit 15 (step A13), and a series of processing ends.

  FIG. 9 is a flowchart showing the operation of the reception header processing unit according to the second embodiment of the present invention. In FIG. 9, the same steps as those in FIG. 6 are performed. When a data frame is received from the ATM network 30, the child number is also saved when it is saved in the restored header information storage unit 14 in step B23. In step B32, when restoring the contents of the omitted portion 11c, the contents of the omitted portion 11c that matches not only the omitted identifier 11a but also the child number are extracted from the restored header information storage unit 14, and the data frame of the upper layer protocol To restore.

  As described above, even if there are a plurality of communications (for example, PPP sessions) having the same omission condition 11b but having different header information, the plurality of communications are confused by identifying the plurality of communications by the child numbers. It is possible to omit / restore the header in each communication without doing so.

It is a block diagram which shows the structure of the ATM communication apparatus which concerns on 1st Example of this invention. It is a figure showing the structure of an omission condition registration table. It is a figure showing the detail of a structure of an omission condition registration table. It is a figure showing the format of an Ethernet (trademark) frame. It is a flowchart showing operation | movement of the transmission header process part which concerns on 1st Example of this invention. It is a flowchart showing operation | movement of the reception header process part which concerns on 1st Example of this invention. It is a block diagram showing the structure of the ATM apparatus which concerns on the 2nd Example of this invention. It is a flowchart showing operation | movement of the transmission header process part which concerns on 2nd Example of this invention. It is a flowchart showing operation | movement of the reception header process part which concerns on 2nd Example of this invention.

Explanation of symbols

10, 10a ATM communication device 11 Omission condition registration table 11a Omission identifier 11b Omission condition 11c Omission location 12, 12a Transmission header processing section 13 Reception header processing section 14 Restore header information storage section 15 AAL5 processing section 16 ATM processing section 17 Omission header information Storage unit 20 Terminal device 30 ATM network

Claims (18)

An omission condition registration unit that holds information that determines which information in the header information according to the terminal side protocol is omitted when the omission condition is in the terminal side protocol;
Referring to the omission condition registration unit, the predetermined information in the header information of the data frame according to the terminal side protocol input from the terminal side is deleted, and an abbreviated identifier indicating the type of the deleted information is set in the transmission data frame A transmission header processing unit for generating the transmission data frame to be set in the transmission header and output to the network side;
A restoration header information storage unit for storing header information for restoration;
The abbreviation identifier is read from the reception header in the reception data frame input from the network side, and the header information on the terminal side corresponding to the abbreviation identifier based on the contents of the abbreviation condition registration unit and the restored header information storage unit A reception header processing unit that restores, generates a data frame according to the terminal-side protocol, and outputs the data frame to the terminal side;
An ATM (Asynchronous Transfer Mode) communication device.   The omission condition registration unit is configured to hold the omission identifier, information indicating the omission condition, and omission location information indicating which information in the header information is omitted in a set. The ATM communication device according to claim 1. When the header information in the data frame according to the terminal-side protocol matches the information indicating the abbreviation condition for the first time in a predetermined communication, the transmission header processing unit includes a start flag indicating a header abbreviation start and the abbreviation identifier. When it is set in the transmission header and matches the second or later, the information indicated by the omitted portion information in the data frame according to the terminal-side protocol is deleted, and the abbreviation identifier is included in the transmission header. The function to set,
The reception header processing unit, when the abbreviation identifier and the start flag are present in the reception header of the reception data frame, stores the information indicated by the abbreviation location information in the restoration header information storage unit, If the received header of the received data frame is deleted to generate a data frame according to the terminal-side protocol, the abbreviation identifier is present in the header of the received data frame, and the start flag is not present, The received header of the received data frame is deleted, and the information indicated by the omitted portion information stored in the restored header information storage unit is inserted into the received data frame to generate a data frame according to the terminal-side protocol The ATM communication device according to claim 2, further comprising a function. Abbreviated header information for storing an identification number for distinguishing header information in the plurality of communications and the abbreviated portion information corresponding to the abbreviated condition for each identification number when there are a plurality of communications satisfying the abbreviated condition A storage unit;
The transmission header processing unit starts the header omission start when the header information in the data frame according to the terminal-side protocol matches the information representing the omission condition for the first time for each communication in the plurality of communications. A flag, the abbreviated identifier, and the identification number are set in the transmission header, and when the second and subsequent matches, information indicated by the abbreviated location information in the data frame according to the terminal side protocol is deleted. And a function of setting the abbreviated identifier and the identification number in the transmission header,
The restored header information storage unit stores the header information indicated by the omitted part information as restored header information in association with the identification number in the received header,
The reception header processing unit searches for the abbreviation identifier from the reception header in the reception data frame, determines whether the start flag exists when the abbreviation identifier exists, and when the start flag exists Includes storing the header information indicated by the omitted part information as the restoration header information and the identification number in the reception header in the restoration header information storage unit, deleting the reception header, and complying with the terminal-side protocol. When the frame is generated and the start flag does not exist, the received header is deleted, and the restored header information stored in the restored header information storage unit corresponding to the identification number in the received header is 3. A function of generating a data frame in accordance with the terminal-side protocol by adding to a received data frame. The placing of the ATM communication device. A data unit that is a payload part of an ATM cell is created from the transmission data frame output by the transmission header processing unit and output to the ATM processing unit, and the reception data frame is generated from the data unit input from the ATM processing unit. An AAL5 (ATM Adaptation Layer type 5) processing unit that outputs the received header processing unit,
An ATM cell generated by adding an ATM header to the data unit output by the AAL5 processing unit is sent to the ATM network, and the data unit generated by removing the ATM header from the ATM cell received from the ATM network is processed by the AAL5 processing. An ATM processing unit for outputting to the unit;
The ATM communication apparatus according to claim 1, further comprising:   The ATM communication apparatus according to claim 1, wherein the transmission header and the reception header are LLC (Logical Link Control) headers.   The said terminal side protocol is a protocol of Ethernet (trademark), Comprising: The header information in an Ethernet (trademark) frame is deleted and decompress | restored, It is any one of Claims 1-5 characterized by the above-mentioned. ATM communication device.   8. The ATM communication apparatus according to claim 7, wherein header information in another protocol in the payload of the Ethernet (registered trademark) frame is also deleted and restored together.   9. The ATM communication apparatus according to claim 8, wherein the other protocol is PPPoE (Point to Point Protocol over Ethernet (registered trademark)).   The ATM communication apparatus according to claim 1, wherein the ATM communication apparatuses communicate with each other via an ATM network. A method in which an ATM communication device communicates by deleting and restoring header information according to a terminal-side protocol,
On the sending side,
Inputting a data frame according to the terminal side protocol from the terminal side;
When the terminal-side protocol is under what omission conditions, referring to information defining which information in the header information according to the terminal-side protocol is omitted, and deleting the header information in the data frame;
Generating a transmission data frame for setting an abbreviated identifier indicating the type of the deleted header information in a transmission header and outputting it to the network side;
Including
On the receiving side,
Inputting a received data frame from the network side;
Reading the abbreviated identifier from the received header in the received data frame;
Restoring header information corresponding to the abbreviation identifier based on the contents of the omission conditions stored in advance and header information for restoration;
Adding the restored header information to generate a data frame according to the terminal side protocol and outputting the data frame to the terminal side;
A communication method comprising: A method in which an ATM communication device communicates by deleting and restoring header information according to a terminal-side protocol,
On the sending side,
Inputting a data frame according to the terminal side protocol from the terminal side;
A step of referring to abbreviated location information that determines which information in the header information in the data frame is omitted when the terminal-side protocol is under what abbreviated conditions;
Determining whether or not the header information matches the omitted condition for the first time in a predetermined communication;
As a result of the determination, when matching is made for the first time, a start flag indicating header omission start and an abbreviation identifier indicating the type of header information to be deleted are set in the transmission header. Deleting the header information indicated by the omitted part information in the data frame according to the terminal-side protocol, and setting the omitted identifier in the transmission header;
Generating a transmission data frame for adding to the set transmission header and outputting to the network side;
Including
On the receiving side,
Inputting a received data frame from the network side;
Searching for the abbreviated identifier from the received header in the received data frame and determining whether the start flag is present if the abbreviated identifier is present;
When the start flag is present, the header information indicated by the omitted part information is stored as restoration header information, the reception header is deleted to generate a data frame according to the terminal-side protocol, and the start flag is If not, deleting the received header, adding the stored restoration header information to the received data frame to generate a data frame according to the terminal-side protocol;
Outputting the generated data frame to the terminal side;
A communication method comprising: A method in which an ATM communication device communicates by deleting and restoring header information according to a terminal-side protocol,
On the sending side,
Inputting a data frame according to the terminal side protocol from the terminal side;
A step of referring to abbreviated location information that determines which information in the header information in the data frame is omitted when the terminal-side protocol is under what abbreviated conditions;
When the header information in the data frame according to the terminal-side protocol for the first time in a plurality of communications matches the information indicating the omission condition, the start flag indicating the header omission start and the header information to be deleted are deleted. An abbreviation identifier indicating a type and an identification number for distinguishing header information in a plurality of communications are set in the transmission header, and when the second and subsequent matches, in the data frame according to the terminal side protocol, Deleting the information indicated by the omitted part information, and setting the abbreviated identifier and the identification number in the transmission header;
Generating a transmission data frame for adding to the set transmission header and outputting to the network side;
Including
On the receiving side,
Inputting a received data frame from the network side;
Searching for the abbreviated identifier from the received header in the received data frame and determining whether the start flag is present if the abbreviated identifier is present;
When the start flag exists, the header information indicated by the omitted part information and the identification number in the reception header are stored in association with each other as restoration header information, and the reception header is deleted and the terminal side When a data frame is generated according to a protocol and the start flag does not exist, the received header is deleted, and the restored header information stored corresponding to the identification number in the received header is stored in the received data frame. Adding to generate a data frame according to the terminal-side protocol;
Outputting the generated data frame to the terminal side;
A communication method comprising: On the sending side,
Creating a data unit to be a payload part of an ATM cell from the generated transmission data frame;
Sending an ATM cell generated by adding an ATM header to the created data unit to an ATM network;
Further including
On the receiving side,
Removing an ATM header from an ATM cell received from the ATM network to generate a data unit;
Generating the received data frame from the generated data unit;
The communication method according to claim 11, further comprising:   The communication method according to claim 11, wherein the transmission header and the reception header are LLC (Logical Link Control) headers.   The terminal-side protocol is an Ethernet (registered trademark) protocol, and header information in an Ethernet (registered trademark) frame is deleted and restored. Communication method.   The communication method according to claim 16, wherein header information in another protocol in the payload of the Ethernet (registered trademark) frame is also deleted and restored together.   18. The communication method according to claim 17, wherein the other protocol is PPPoE (Point to Point Protocol over Ethernet (registered trademark)).

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