JP2009218652A - Frame transmission system and frame transmission method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve transmission efficiency without an inter-frame gap, with respect to a frame transmission system for transmitting coupled frames and a frame transmission method. <P>SOLUTION: In the frame transmission system and frame transmission method for transmitting frames via a switch device 10, the switch device 10 is provided with: a frame coupling/decoupling processing section 1 which couples a plurality of frames to be transmitted by deleting an inter-frame gap between a plurality of frames, forms a coupled frame by adding a coupling frame header at its head, and transfers the received coupled frame as it is or separates the coupled frame into each frame to insert the inter-frame gap; an address management section 3 which stores address information including information as to whether or not a connected device as a recipient is compatible with the coupled frame; and a control section 2 which controls the frame coupling/decoupling processing section 1 in accordance with whether or not the device is compatible with the coupled frame in reference to the address management section 3. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a frame transmission system and a frame transmission method that enable transmission of a combined frame obtained by deleting inter-frame gaps of a plurality of frames.

  Various transmission systems that transmit frames via a switch device such as a layer 2 switch or a layer 3 switch in an IP network are known. As such a transmission system, for example, as shown in FIG. 6, clients (terminal devices) CL1 to CL7 are respectively connected to a server SV via switch devices SW1 to SW8 such as a layer 2 switch and a layer 3 switch. In the frame transmission system in which the clients CL1 to CL7 receive streaming data having a frame configuration from the server SV, the client CL1 is connected to the server via the switch devices SW1, SW2, and SW3. When data is downloaded from the SV and the client CL2 also downloads data from the server SL via the switch devices SW1 and SW2, as shown in FIG. 7, the frame C1 indicates that the client CL1 is transmitted from the server SV to the client CL1. First The frame C2 is transmitted to the client CL2 according to the destination address indicating the client CL2, and the frames C1 and C2 are mixed between the server SV and the switch device SW2, and the switch device SW2 and the client CL1 The frame C1 for the client CL1, and the frame C2 for the client CL2 are transmitted between the switch device SW2 and the client CL2.

  In this case, an inter-frame gap IFG (Inter Frame Gap) having a predetermined length, for example, 1 byte is inserted between the frames C1 and C2, regardless of the frame length of each frame. Each of the switch devices SW1 to SW8 performs a transfer process based on a transmission destination address or the like every time a frame arrives. The interframe gap IFG is inserted between each frame when a large number of frames having a short frame length are transmitted. Therefore, the ratio of the interframe gap IFG to the actual transmission data amount increases, and the frame transmission network Increase in traffic. For example, IEEE. The frame length defined in 802.3 is 64 to 1518 bytes long, and, on the other hand, means for transmitting by a combined frame having a length of 9000 to 16000 bytes has been proposed. However, such a combined frame is obtained by extending the frame length for the same transmission destination and is not standardized, and therefore is not guaranteed to be transmitted through a general network.

In a system that includes an edge router connected to the network, its lower router, and a plurality of clients (terminal devices) connected to this lower router, and transmits multicast data to the client, the edge router and the lower router The multicast data to be transmitted to the client is transmitted as a common frame between the routers, and the lower routers transmit the copied frames corresponding to the number of clients to the edge router and the lower router. Means for improving the transmission efficiency during the period have been proposed (see, for example, Patent Document 1). In the frame transmission system, a frame received once via a network is temporarily written in a large capacity memory, and a frame that is read from the large capacity memory is transferred to receive a large number of short frames. If the writing process to the large capacity memory is executed for each frame and the reading is also executed for each frame, the improvement in efficiency due to the provision of the large capacity memory cannot be obtained. When a frame having a minimum frame length of 64 bytes is repeatedly received from a large-capacity memory capable of performing batch reading, the frame length is 2048 bytes or less combined including additional information indicating frame combination. A maximum of 31 frames can be written at once so that the frame length can be as large as possible. The read frame collectively from memory, means for dividable based on the additional information has been proposed (e.g., see Patent Document 2).
JP 2003-32287 A JP 2005-328292 A

  For example, as described above, it may be possible to improve transmission efficiency by deleting the inter-frame gap IFG in the frame transmission system from the same transmission destination to form a combined frame. However, since it is not standardized as described above, there is a problem that the transmission of the combined frame is not guaranteed through all networks. In addition, in a network that enables frame transmission by deleting the inter-frame gap IFG into a combined frame, when a switch device such as a layer 2 switch is newly connected to the network and a client is connected to the switch device, If the switch device is set so as not to control the transfer of the combined frame, it is determined that the frame length is not less than the specified length and is not a normal frame, and the frame is discarded. As described above, there is a problem that the frame transmission side cannot identify whether or not the new switch device is compatible with the combined frame. In addition, when the inter-frame gap is deleted, there is a problem that the transmission side cannot identify the maximum frame length that can be transmitted by the switching device on the transmission path. That is, there is a problem that the transmission side cannot recognize the transmittable frame length when the interframe gap IFG is deleted to form a combined frame.

  Also, when transmitting the same content data to multiple clients like a multicast data frame, it is transmitted as a common frame as if the inter-frame gap IFG is omitted, and the common frame is transmitted during the transmission process. The means such as Patent Document 1 of the above-described conventional example that copies and transmits to each client cannot be applied to frame transmission of data different for each client. Further, in the above-described conventional patent document 2 in which a plurality of frames are combined and written in a large-capacity memory so as to be equal to or less than a predetermined length, the inter-frame gap IFG is omitted, instead of using additional information. Thus, the additional information indicates a case of a 32-bit length. Therefore, it cannot be applied as a means for improving transmission efficiency.

  An object of the present invention is to solve the above-mentioned conventional problems, to delete a gap between frames of a plurality of frames in a frame transmission path to form a combined frame, and to transmit the original frames in a separable manner. The frame transmission efficiency can be improved, and the frame transmission side can recognize whether or not the frame reception side can receive and transfer the combined frame by reducing the gap between frames and the combined frame length that can be received and transferred. To do.

  The frame transmission system according to the present invention is a frame transmission system that performs frame transmission via a switching device. The switching device deletes gaps between frames of a plurality of frames to be transmitted to form a combined frame, and the received coupling A frame coupling / separation processing unit that separates the frame into frames and inserts inter-frame gaps; an address management unit that holds address information including information on whether or not the connected destination device is a coupled frame compatible device; And a control unit that controls the frame coupling / separation processing unit according to whether or not it is a combined frame compatible device with reference to the address management unit.

  The frame combining / separating unit deletes the inter-frame gaps of a plurality of frames and combines them, and adds a combined frame header including identification information of the combined frame and frame length information of the combined frame at the head. And a means for separating the frame into information based on the frame length information of the combined frame header of the received combined frame and the frame length information of the header of each frame.

  Further, the control unit controls the frame combination processing unit to empty the combined frame payload and to form and transmit a combined frame in which fragment prohibition is set, and depending on the presence or absence of a response frame to this combined frame, Means are provided for recognizing the frame length capable of transmitting and receiving the combined frame and setting it in the address management unit.

  The frame transmission method of the present invention is a frame transmission method for performing frame transmission via a switch device, and deletes inter-frame gaps of a plurality of frames transmitted to the same device connected to face the switch device. And forming a combined frame with the combined frame header added, and transmitting the combined frame to a transmission destination where the received frame is different from the transmission destination of the received combined frame and where the combined frame cannot be received. On the other hand, it includes a process of separating and transmitting each frame and inserting an inter-frame gap.

  Further, in the device connected opposite to the switch device depending on the process of transmitting the combined frame in which the payload of the combined frame is emptied and the fragment prohibition is set, and the presence / absence of a response frame to the combined frame And a process of recognizing a frame length capable of transmitting and receiving the combined frame.

  Even if the destination terminal devices are different frames, if they are connected oppositely and transmitted on the same transmission path, a combined frame is formed by deleting the inter-frame gaps of multiple frames and combining them. Thus, transmission efficiency when transmitting a plurality of frames can be improved. Whether or not the device is compatible with the combined frame transmission / reception and the frame length that can be transmitted / received, a combined frame with a null payload and a fragment prohibited setting is transmitted, and a response as a response can be identified to transmit as a combined frame. The maximum frame length can be easily recognized.

  Referring to FIG. 1, the frame transmission system of the present invention is a frame transmission system that performs frame transmission via the switch device 10, and the switch device 10 deletes inter-frame gaps of a plurality of frames to be transmitted. Information to determine whether or not the connected transmission destination device is a combined frame compatible device, and a combined frame separation / separation processing unit 1 that forms a combined frame, separates the received combined frame into frames, and inserts an inter-frame gap. Including an address management unit 3 that holds address information, and a control unit 2 that refers to the address management unit 3 and controls the frame coupling / separation processing unit 1 according to whether or not it is a coupled frame compatible device. .

  The frame transmission method of the present invention is a frame transmission method for performing frame transmission via the switch device 10, and the inter-frame gaps of a plurality of frames transmitted to the same device connected to face the switch device 10. A process for transmitting a combined frame by deleting and adding a combined frame header and transmitting the combined frame is different from a transmission destination of each frame of the received combined frame and a transmission destination in which combined frame reception processing is impossible On the other hand, it includes a process of transmitting by inserting an inter-frame gap separately into each frame.

  FIG. 1 is an explanatory diagram of a main part of the frame transmission system according to the first embodiment of the present invention. 1 is a frame coupling / separation processing unit, 2 is a control unit, 3 is an address management unit, 4 and 5 are input / output ports, 6 Denotes a network, 10 denotes a switch device such as a layer 2 switch or a layer 3 switch. A case where a network 6 is connected to the input / output port 4 is shown, and other switch devices and the like are connected via the network 6, and other switch devices, networks and client terminals not shown are connected to the input / output port 5. Devices etc. are connected. For example, the frame coupling / separation management processing unit 1 is configured such that a received frame has a normal frame length, an interframe gap IFG is inserted between the received frames, and an opposite device connected to the input / output port If processing is possible, the inter-frame gap IFG is deleted and transmitted as a combined frame configuration, and if the opposite device connected to the input / output port has the function of processing only normal frames, combining between frames is performed. Instead, the inter-frame gap IFG is inserted and transmitted as a normal frame, and when a combined frame is received, it is separated into normal frames and the inter-frame gap IFG is inserted and transmitted.

  The address management unit 3 has a configuration including an address table. The address table can transmit a combined frame from the input / output ports 4 and 5 and the source and destination addresses including the MAC address and the IP address. And the maximum frame length information that can be processed by the counterpart device connected to each other corresponding to the input / output ports 4 and 5 can be stored. In this case, the frame length information of each frame forming the combined frame can be added to obtain the frame length of the combined frame. Therefore, the combined frame is formed by combining a plurality of frames so as to be equal to or less than the maximum frame length. Can be formed. The control unit 2 can control the frame coupling / separation processing unit 1 together with the management control of the address management unit 3 to form a coupled frame limited to a maximum frame length or less. Such a function of the control unit 2 can be realized by a processor or the like. The input / output ports 4 and 5 include an interface function for performing frame transmission / reception processing between the transmission / reception buffer and the transmission path, and other switch devices and client terminal devices not shown are connected to the network 6 and the like. Connect through. The number of input / output ports 4 and 5 can be made larger or smaller.

  2A and 2B are explanatory diagrams of frame combination, where FIG. 2A is a basic frame, FIG. 2B is a plurality of basic frames with interframe gap IFG inserted, and FIG. 2C is an implementation of the present invention with interframe gap IFG deleted. An overview of each of the combined frames by example is shown. As shown in (A), the general configuration of the basic frame is an Ether (registered trademark) header (Header) a1 (MAC header), an IP header (IP Header) a2, and an IP payload (IP Payload) a3. And a trailer a4 as a frame check sequence. The header a1 includes a destination address DA, a source address SA, a frame length or a type LP, and the IP header 2a is not shown. It includes 2-byte frame length information a21 and 1-byte protocol number information a22 together with the transmission destination IP address and transmission source IP address. The frame length as a basic frame is standardized as 64 to 1518 bytes. ing. In the case of transmitting a plurality of basic frames shown in (A), conventionally, as shown in (B), an interframe gap IFG is inserted between the basic frames for transmission. Note that FCS at the position of the trailer a4 indicates a frame check sequence.

  In the embodiment of the present invention, as shown in FIG. 2C, the interframe gap IFG of a plurality of frames transmitted from the same input / output port is omitted, that is, a continuous frame configuration, A combined frame structure HD is added, and a combined frame header HD including a header (Header) c1 and an IP header (IP Header) c2 is added to the head. That is, this combined frame header HD is added to the head, and a plurality of frames are encapsulated. For example, 2-byte frame length information c21 as a combined frame and, for example, 1-byte protocol number information c22 indicating a combined frame are added to the IP header c2 of the combined frame header HD. With this protocol number information c22, it is possible to identify that the received frame is a combined frame. If the destination addresses of the MAC header a1 and the IP header a2 of each frame are the same, they are transferred as they are. Depending on whether or not the input / output ports are different, if different, each frame is divided and transmitted based on the frame length information c21 of the IP header c2 and the frame length information a21 of the IP header a2.

  The frame combination / separation processing unit 1 shown in FIG. 1 performs processing of frame combination for forming and transmitting such a combined frame and frame separation for receiving the combined frame and dividing it into each frame. The frame connection / separation processing unit 1 is performed by the control unit 2 with reference to the address management unit 3. For example, when there are a plurality of frames transmitted from the same port, the frame coupling / separation processing unit 1 combines the frames without inserting an interframe gap IFG to form a combined frame configuration, and the header c1 and the IP header c2 The frame length information c21 and the protocol number information c22 as a combined frame are added to the IP header c2. The frame length information c21 in this case can be obtained by adding the frame length information a21 of each frame. As for the frame length of the combined frame, the maximum frame length information that can be received by the opposite device is held in the address management unit 3 to limit the frame length within the range that can be received. Is possible.

  FIG. 3 is an explanatory diagram of the second embodiment of the present invention. A switch device such as a layer 2 switch or a layer 3 switch is used as an existing connection-compatible device 31, a new connection-compatible device 32, and a non-compatible device 33. An outline of a frame transmission system connected via the network 34 is shown, and a control frame is transmitted via the network 34 in order to connect the newly connected device 32 to the network 34 and confirm whether the combined frame can be transmitted. Send. This control frame indicates that it is a combined frame by the protocol number information c22 in the IP header c2 shown in FIG. 2C, and the IP payload a3 is null. In this case, since the existing connection compatible device 31 has a configuration corresponding to the transmission / reception of the combined frame, the control frame responding to the control frame from the new connection compatible device 32 is transmitted. The IP payload a3 is also null in the response control frame from the existing corresponding device 31. Thereby, it can be recognized that the existing connection compatible device 31 and the new connection compatible device 32 can correspond to the address and the combined frame. In this case, the existing connection compatible device 31 and the new connection compatible device 32 have, for example, the configuration of the switch device shown in FIG.

  When a non-compatible device 33 that cannot support the combined frame is connected to the network 34, when the control frame is transmitted from the newly connected compatible device 32 via the network 34, the control frame as the combined frame has a frame length. Because it is long, it is discarded as nonstandard, and no response control frame is transmitted. As a result, the new connection compatible device 32 cannot recognize the response control frame even after a lapse of a predetermined time after transmitting the control frame, so that it can recognize that the device cannot respond to the combined frame due to timeout. As a result, a frame for the non-compatible device 33 is transmitted by inserting a normal inter-frame gap IFG. Such a combined frame compatible device and a non-compatible device can be managed by the address management unit 3 shown in FIG.

  FIG. 4 is an explanatory diagram of Embodiment 3 of the present invention, 41 and 42 are devices as switch devices such as layer 2 switches corresponding to combined frames, 43 is a router, 44 is a network, 45 and 46 are terminal devices, and the like. For example, a normal frame (a) having a transmission destination as the communication device 46 from the communication device 45 via the network 44 is transmitted to the device 41 via the network 44. If it is detected, the transmission destination IP address and the transmission destination MAC address of the frame are extracted, and the control frame (b) is transmitted to the communication device 46. This control frame (b) indicates that it is a combined frame by the protocol number information c22 in the IP header c2 of the combined frame header HD shown in (C) of FIG. 2, and its IP payload a3 is null. The router 43 can transmit the combined frame, and if the device 42 is a device compatible with the combined frame, it receives this control frame (b) and returns a response control frame (c) to the device 41. To do. Accordingly, the device 41 can recognize that the device 42 connected via the network 44 is a combined frame compatible device. Therefore, on the basis of this, the device 41 and the device 42 can transmit each other as a combined frame in which the inter-frame gap IFG is deleted and combined. Further, the devices 41 and 42 can be configured as a switch device having a frame coupling / separating function shown in FIG.

  FIG. 5 is an explanatory diagram of Embodiment 4 of the present invention, where the devices A and B are the above-described combined frame compatible devices, but the device C is a combined frame compatible device and the processable frame length is If unknown, as shown in (A), the ICMP (Internet Control Message Protocol) non-partitionable (fragment prohibited) flag is set to “1” from the device A to the device B via the device C, and the frame A Ping command in which an MTU (Maximum Transfer Unit) indicating the maximum length information can be processed is transmitted. If the device C is not configured to support the maximum frame length, the frame is discarded and an error response is transmitted from the device C to the transmission source device B.

  Further, as shown in FIG. 5B, when the device C is a combined frame compatible device, the PNIg command for MTU setting by ICMP from the device B can be transferred from the device C to the device A. Is returned to the device B. In this case, the device B can recognize that the device C is also a combined frame compatible device. Also, as an MTU of such a fragment-inhibited Ping command, a Ping command in which the frame length is set shorter from the maximum frame length is transmitted, and the combined frame between the devices A and B is determined according to the frame length when there is no error response. A maximum frame length can be set. The information on the maximum frame length of the combined frame can be set in correspondence with the devices A and B, for example, in the address management unit 3 in FIG.

It is explanatory drawing of Example 1 of this invention. It is explanatory drawing of the frame coupling | bonding of Example 1 of this invention. It is explanatory drawing of Example 2 of this invention. It is explanatory drawing of Example 3 of this invention. It is explanatory drawing of Example 4 of this invention. It is explanatory drawing of the frame transmission system of a prior art example. It is explanatory drawing of the frame transmission of a prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Frame coupling | bonding isolation | separation processing part 2 Control part 3 Address management part 4,5 Input / output port 6 Network 10 Switch apparatus

Claims (5)

In a frame transmission system that performs frame transmission via a switch device,
The switching device is connected to a frame combining / separating processing unit that forms a combined frame by deleting inter-frame gaps of a plurality of frames to be transmitted, separates the received combined frame into each frame, and inserts the inter-frame gap. An address management unit that holds address information including information on whether or not the destination device is a combined frame compatible device, and the frame combined separation processing according to whether or not the combined frame compatible device is referenced with reference to the address management unit A frame transmission system comprising: a control unit that controls the unit.   The frame combining / separating processing unit deletes the inter-frame gaps of a plurality of frames and combines them, and adds a combined frame header including identification information of the combined frame and frame length information of the combined frame to the head, 2. The frame transmission system according to claim 1, further comprising means for separating each frame based on the frame length information of the combined frame header of the combined frame and the frame length information of the header of each frame.   The control unit controls the frame combination processing unit to form and transmit a combined frame in which the payload of the combined frame is emptied and fragment prohibition is set, and depending on the presence / absence of a response frame to the combined frame 2. The frame transmission system according to claim 1, further comprising means for recognizing a frame length capable of transmitting and receiving the combined frame and setting the frame length in the address management unit. In a frame transmission method for performing frame transmission via a switch device,
Removing a gap between frames of a plurality of frames transmitted to the same device connected to the switch device facing the switch device, forming a combined frame with a combined frame header added thereto, and transmitting the combined frame;
Including a process in which a transmission destination of each frame of the received combined frame is different and a transmission destination in which the reception process of the combined frame is impossible is performed by inserting an inter-frame gap and transmitting the separated frame. A characteristic frame transmission method.   In a device connected opposite to the switch device according to the process of transmitting a combined frame in which the payload of the combined frame is emptied and the fragment prohibition is set, and the presence / absence of a response frame to the combined frame 5. The frame transmission method according to claim 4, further comprising a step of recognizing a frame length capable of transmitting and receiving the combined frame.

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