JP2005192120A - Frame multiplexing transmission apparatus and method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To perform data communication without decreasing a data amount per unit time with respect to a user frame on one side, in a frame multiplexing transmission apparatus and its method for multiplexing user frames of two ports into one optical transmission frame. <P>SOLUTION: In a frame multiplexing transmission section (OAM) for multiplexing master and slave user frames from network apparatuses #1 and #2 between a media access control layer (MAC) in a subscriber side frame multiplexing transmission apparatus (FTTH-CPE-MC) and an optical transmission line side physical layer (PHY2), the slave user frame is inserted into a frame gap of the master user frame and multiplexed. The media access control layer (MAC) and the network apparatuses #1 and #2 are connected in one-to-one correspondence by media-independent interfaces (MII12, MII22) via a physical layer (PHY1), so that the media access control layer (MAC) does not restrict user frame transmission/reception. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a frame multiplex transmission apparatus and method, and more particularly, to an optical network device such as a fiber-to-the-home (FTTH) that provides a communication service by laying an optical fiber cable, using an Ethernet (registered trademark) frame or the like. The present invention relates to a frame multiplexing transmission apparatus and method for multiplexing a 2-port user frame into one optical transmission frame.

  FIG. 11 shows a configuration of a conventional frame multiplex transmission apparatus that multiplexes Ethernet (registered trademark) frames. In FIGS. 2A and 2B, user frames transmitted from the network devices # 1 and # 2 are respectively input to the ports P1 and P2 of the physical layer (PHY1) of the frame multiplexing transmission device 11-1. From the physical layer (PHY1), the media independence interface (MII) frame is passed to the media access control layer (MAC). In the media access control layer (MAC), user frames from the ports P1 and P2 are transferred to one port. A configuration in which the transmission path frames are aggregated, passed to the physical layer (PHY2) by the media independence interface (MII) frame, and sent as one transmission path frame from the port P3 of the physical layer (PHY2) to the network device # 3. It has become.

  When the frames from each port are aggregated into a 1-port frame, the frames from each port are accumulated in the buffer memory, and then aggregated into a 1-port frame for transmission. By consolidating user frames from a plurality of ports into a single-port transmission frame, the amount of data that can be transmitted per unit time is reduced, so the data rate is limited.

  In order to avoid user frame loss between end stations due to data rate restrictions, the setting of enabling flow control in the media access control layer (MAC) is performed to control the outflow of user frames to the opposite network device. Perform flow control. In the flow control, as shown in FIG. 11B, the media access control layer (MAC) predicts the occurrence of a buffer overflow, and before the occurrence of the buffer overflow, a Pause frame for stopping transmission of a user frame is set. The network device temporarily transmits the user frame upon reception of the Pause frame.

As prior art documents related to the present invention, a technique relating to an extended FIFO buffer used in an Ethernet (registered trademark) system is disclosed in Patent Document 1 below, and a technique relating to multiplexing of a PPP frame is disclosed in Patent Document 2 below. Patent Document 3 below discloses a technique related to packet communication that transmits packetized packet information and an inter-packet gap filled with an idle code set.
JP 2003-188926 A Japanese Patent Laid-Open No. 2002-247098 JP 2002-344518 A

  In a frame multiplex transmission device having an Ethernet (registered trademark) frame format interface, when a 2-port physical port user frame is multiplexed into a single physical port transmission path frame, each 2-port user frame is identical to a single port. When transferring at a high speed, even if the user frames are efficiently stored and transferred in the buffer memory, the buffer overflow cannot be prevented, and the data amount per unit time is reduced.

  In the present invention, when a 2-port frame is aggregated into a 1-port optical transmission line frame in the media access control layer (MAC), the data amount per unit time is set for either one of the 2-port frames. An object of the present invention is to provide a frame multiplex transmission apparatus and method in an optical network that enables data communication in a 1-port optical transmission line frame without reduction.

  The frame multiplexing transmission apparatus of the present invention (1) receives user frames as a group of transfer data from users from two ports, multiplexes the two user frames, and transmits the optical transmission path frame to one port. In the frame multiplex transmission apparatus having the function of transmitting as one of the user frames input from the two ports, the flow of the user frame input from one port is not limited to the one port. Out of user frames input from the two ports, the user frames input from the other port are inserted into the gap between the user frames input from the one port. Provided with means for multiplexing and sending to the one port as an optical transmission line frame A.

  (2) a means for compressing a user frame input from the other port to a frame length shorter than a predetermined frame interval of the user frame input from the one port; and the compressed user frame And means for inserting into a gap between frames of the user frame inputted from the one port.

  Further, (3) the user frame input from the other port at a rate of once in a period twice as long as the sum of the user frame input from the one port and the subsequent frame interval, Means for inserting and multiplexing in a gap between frames of user frames inputted from one port is provided.

  (4) The optical transmission line frame is monitored with a period twice as long as the total of the user frame input from the one port and the gap between the following frames being monitored, and the optical transmission line frame And a means for separating a user frame shorter than a predetermined frame length inserted in a gap between the frames.

  In the frame multiplex transmission method of the present invention, (5) a user frame, which is a group of transfer data from a user, is received from each of two ports, and the two user frames are multiplexed and optically transmitted to one port. In a frame multiplex transmission method for transmitting as a road frame, optical transmission to the one port without limiting the flow of user frames input from one of the user frames input from the two ports A user frame input from the other port, and a user frame input from the other port is inserted into a gap between user frames input from the one port. Multiplexed and sent as an optical transmission path frame to the one port.

  (6) The user frame input from the other port is compressed to a frame length shorter than a predetermined frame interval of the user frame input from the one port, and the compressed user frame is It is characterized by being inserted into a gap between frames of user frames input from one port.

  (7) User frames input from the other port at a rate of once in a period twice as long as the sum of the user frame input from the one port and the gap between subsequent frames. , And inserting and multiplexing in a gap between frames of user frames input from the one port.

  (8) The optical transmission line frame is monitored with a period that is twice the period of the sum of the user frame input from the one port and the gap between subsequent frames as a monitoring period, and the optical transmission line frame From the above, a user frame shorter than a predetermined frame length inserted in a gap between the frames is separated.

  The frame multiplexing according to the present invention is conventionally performed by using a user frame in an Ethernet (registered trademark) frame format such as 10BASE-T for a metallic transmission cable standardized as IEEE 802.3, 100BASE-X using an optical transmission line, or the like. When transmitting in the Ethernet (registered trademark) frame format, a sufficient space is generated in the frame interval. Therefore, the other user frame is inserted into the gap between the frames of one user frame and multiplexed. Prioritizes user frames, sends them without restricting the flow of user frames with higher priorities, and multiplexes by inserting frames that do not require guarantee of communication quality between the frames Therefore, a user frame with a high priority can be processed without flow control. It is obtained to be able to communicate data without reducing the amount of data per time.

  According to the present invention, out of user frames input from two ports, the flow of user frames input from one port is sent as an optical transmission line frame to one port without any restriction, and the other port is transmitted. The user frame input from one port is inserted into the gap between the frames of the user frame input from one port, and multiplexed, so that the user frame input from one port per unit time Without reducing the amount of data, data of user frames of two ports can be communicated with one port of optical transmission path frame.

  FIG. 1 shows a configuration of a frame multiplexing transmission apparatus for multiplexing two user frames according to the present invention into one optical transmission line frame. In the figure, FTTH-CPE-MC is a subscriber-side frame multiplex transmission device, and FTTH-CO-MC is a receiving station-side frame multiplex transmission device. The subscriber-side frame multiplex transmission device (FTTH-CPE-MC) and the accommodating station-side frame multiplex transmission device (FTTH-CO-MC) are connected by an optical transmission line (optical fiber cable) 1-1.

  Network devices # 1 and # 2 are connected to a subscriber-side frame multiplex transmission device (FTTH-CPE-MC), network device # 1 is a device that transmits and receives a main frame of a user frame, and network device # 2 is a user frame. It is assumed that the device transmits and receives slave frames. Further, it is assumed that the network device # 3 and the network device # 4 are devices connected to the accommodating station side frame multiplex transmission device (FTTH-CO-MC).

  Multiplexing of the main user frame from the network device # 1 and the sub user frame from the network device # 2 is performed with the media access control layer (MAC) and the optical transmission in the subscriber side frame multiplexing transmission device (FTTH-CPE-MC). By performing the frame multiplexing transmission unit (OAM) with the roadside physical layer (PHY2), the media access control layer (MAC) and each network device # 1, # 2 are independent of media via the physical layer (PHY1). Therefore, the media access control layer (MAC) does not limit user frame transmission / reception.

  Hereinafter, a method of multiplexing a plurality of user frames into one optical transmission line frame in the frame multiplexing transmission unit (OAM) will be described with reference to FIG. FIG. 2A shows a data signal frame configuration (Ethernet (registered trademark) frame format) according to the IEEE 802.3u standard.

  In the data signal frame configuration, (1) is a preamble / SFD (8 bytes), (2) is a destination address field (6 bytes), (3) is a source address field (6 bytes), and (4) is a length field. (2 bytes), (5) is a data field (46 to 1500 bytes), (6) is a frame inspection sequence field (4 bytes), and (7) is a frame interval (IFG: Inter Frame Gap) (12 bytes or more). is there. The maximum frame length of the data signal frame (above (2) to (6)) is 1518 bytes, and the minimum frame length (above (2) to (6)) is 64 bytes. The frame interval (IFG) is also referred to as an interpacket gap (IPG).

  FIG. 2B shows the frame insertion position. In a regular data signal frame, an inter-packet gap (IPG) of at least 12 bytes is opened between data signals, and an idle signal is inserted into the inter-packet gap (IPG). A frame 2-1 is inserted in the idle signal section of the inter-packet gap (IPG) of at least 12 bytes of the main frame, and frame transfer is performed by 1-port serial. Note that, in the inter-packet gap (IPG) of at least 12 bytes, the subframe is inserted so that the front and back of the subframe are separated by an idle signal of at least 4 bytes. As a result, the slave frame is a frame having a length of at least 4 bytes.

  FIG. 3 shows a subframe format multiplexed according to the present invention. As shown in the figure, the slave frame has an 8-bit identifier SSD ("10101010") indicating the start of the signal at the head and a 4-bit identifier ESD ("1010") indicating the end of the signal at the end. In the meantime, the user data of the follow frame is stored. Therefore, the slave frame having a length of at least 4 bytes includes therein an 8-bit signal start identifier SSD (1 byte) and a 4-bit signal end identifier ESD (0.5 bytes). .5 (= 4-1.5) bytes.

  The frame multiplexing transmission unit (OAM) generates slave frame user data having a length of at least 2.5 bytes that does not require communication quality, and inserts it into the transmission data transmission unit TXD (4B) of the physical layer (PHY2) on the transmission line side. . Also, a slave frame signal of the interpacket gap (IPG) is received from the received data input unit RXD (4B) of the physical layer (PHY2) on the transmission line side and terminated. By performing transmission / reception of slave frames in the idle period (IPG) of the main frame, the main frame and slave frame multiplex transfer in one physical port is realized.

  Next, a method for avoiding data frame collision without performing flow control will be described. When multiplexing user frames from two ports into a transmission path frame of one port in a frame multiplex transmission unit (OAM) unit, the frame interval of the main data frame is always kept longer than a certain time, and the transmission time of the main data frame is obeyed. In the case of overlapping with the data frame, as shown in FIG. 4, by delaying the main data frame and sending the main data frame after the timing of 8 CLK (for 4 bytes) after completion of sending the sub data frame, The main data frame and the sub data frame can be communicated with each other while avoiding a collision between the main data frame and the sub data frame.

  Next, the insertion position of the slave frame according to the present invention will be described. FIG. 5 shows the relationship between the main user frame and the sub user frame in the frame multiplex transmission unit (OAM) unit. This figure shows the timing relationship of the subframes inserted into the inter-packet gap (IPG) of the main frame. As shown in FIG. 5A, the maximum frame length of the main frame (1530 bytes = 12.4 μS in the embodiment of FIG. 5) and the minimum frame interval (12 bytes = 0.96 μS) is 123.36 μS. Basically, a sub user frame is inserted into 246.72 us which is a double interval at a rate of once.

  This is because when main frame data having the maximum frame length (122.4 μS) is continuously transmitted and received at the minimum frame interval (0.96 μs), synchronization processing is stably performed in consideration of link detection by the enhanced link algorithm. As described above, a sub user frame is inserted into at least two inter-packet gaps (IPG) at a rate of one.

  If the main user frame is being transmitted when the sub user frame is inserted, the user data according to the inter-packet gap (IPG) after the transmission of the main user frame being transmitted is completed as shown in FIG. Insert and send. When a slave frame is inserted, transmission enable (TXEN) is set to “H”. In addition, when the frame interval is 0.96 μS or less, insertion of the slave frame is prohibited.

  FIG. 6 shows a functional block configuration of the frame multiplexing transmission unit (OAM) of the present invention. The frame multiplexing transmission unit (OAM) of the present invention includes a main frame interface 6-1 that transmits and receives main frame data via the media independence interface MII11 and a subframe that transmits and receives subframe data via the media independence interface MII21. An interface 6-2, an insertion timing unit 6-3 for adjusting the insertion timing of the slave frame, a frame multiplexing unit 6-4 for multiplexing the main frame and the slave frame while avoiding a collision, and a media independent interface MII31. And an optical physical layer interface unit 6-5 for transmitting / receiving transmission line frame data to / from the optical transmission line side.

  The frame multiplex transmission unit (OAM) includes a period monitoring unit 6-6 for extracting the slave frame from the transmission line frame data received from the optical physical layer interface unit 6-5, and the transmission line frame data as the main frame. A frame separation unit 6-7 that separates the subframe into a subframe, and a frame compression unit that sends a subframe shortened to a frame having a length of 4 bytes or less to the insertion timing unit 6-3 when the subframe data has a length of 4 bytes or more. 6-8, a frame check unit 6-9 for checking the slave frame separated by the frame separation unit 6-7, and a frame having a minimum frame length (for example, 64 bytes) defined as a regular frame as a slave frame. An SSD / ESD check unit 6-10 that recognizes and checks the signal start identifier SSD and the signal end identifier ESD of the slave frame. It decompresses the compressed sub-frame and a frame extension part 6-11 to be transmitted to the slave frame interface 6-2.

  Note that the cycle monitoring unit 6-6 performs monitoring for extracting a slave frame at a cycle of 400 μS. As described above, the slave frame is inserted once into 246.72 us, which is twice the interval of 123.36 μS, which is the sum of the maximum frame length (122.4 μS) and the minimum frame interval (0.96 μS). However, if the main user frame is being transmitted when the sub user frame is inserted, the user data is inserted according to the interpacket gap (IPG) after the transmission of the main user frame being transmitted. Since the maximum period is 246.72 μS + 122.4 μS + 0.96 μS = 370.08 μS, the period for monitoring the subframe is about 400 μS.

  7 to 10 show embodiments of the frame multiplex transmission apparatus of the present invention. FIG. 7 shows a first embodiment of the present invention, in which both the main frame and the sub-frames respectively coming from the two user ports are terminated by the media access control layer (MAC), and the one-core optical fiber 7-1 is used. 2 shows an example of the configuration of a transmission apparatus that performs multiplex transmission.

  Assuming that the port P1 and the port P2 of the subscriber-side frame multiplexing transmission device (FTTH-CPE-MC) are the ports to which the main frame and the subframe are input, respectively, the main frame of the port P1 and the subframe of the port P2 are In the media access control layer (MAC), since the physical layer (PHY1) side and the frame multiplexing transmission unit (OAM) side are one-to-one facing each other, the existing Ethernet (registered trademark) standardization technology does not involve flow control. It is possible to communicate.

  The frame multiplex transmission unit (OAM) serially multiplexes the media independence interface frame MII11 from the port P1 and the media independence interface frame MII21 from the port P2 into the media independence interface frame MII31. Using frame MII11 as the main frame and media independence interface frame MII21 as the subframe, using the above-mentioned technique to avoid flow control, logically compresses the frame data to 2.5 bytes or less according to the frame interval of the main frame To insert.

  Logical compression is performed by a known technique. When the main frame and slave frame after logical compression are serially multiplexed, if there is transmission data of the main frame, the main frame of the media independence interface frame MII is delayed for a certain time from the input phase, and the phase before the delay is followed. By inserting the frame, an interpacket gap (IPG) of the main frame into which the subframe is inserted is secured.

  When the main frame transmission data does not exist, the link by the enhanced link algorithm when main frame data having the maximum frame length (1530 bytes) in the media independence interface frame MII is continuously received at the minimum frame interval (12 bytes). In consideration of detection, subframe insertion is performed once every 246.72 us ((maximum frame length + minimum frame interval) × 2).

  Conversely, in the accommodating station side frame multiplex transmission apparatus (FTTH-CO-MC), the extraction of the slave frame from the frame interval of the main frame is performed by the effective section (RXDV high level) of the received data of the media independent interface frame MII41. 12 bytes corresponding to the frame interval are extracted as slave frames from the section), slave frame data of 2.5 bytes or less is expanded to an Ethernet (registered trademark) frame of 64 bytes or more, and a media independent interface frame for slave frames By outputting to the MII 61, it can be handled in the same manner as the original Ethernet (registered trademark) frame, and communication between network devices becomes possible.

  Multiplexing into a one-core optical cable is performed by transmission on the transmission path side physical layer (PHY2) of the subscriber side frame multiplexing transmission device (FTTH-CPE-MC) and on the receiving station side frame multiplexing transmission device (FTTH-CO-MC). A section with the roadside physical layer (PHY3) can be configured to transmit, for example, by a wavelength division multiplexing (WDM) system standardized as 100BASE-FX.

  FIG. 8 shows a second embodiment of the present invention. For a main frame and a sub frame coming from two user ports, respectively, only the main frame is terminated at the media access control layer (MAC), and the sub frame is subjected to media access control. A configuration example in which multiplexing is performed on a one-core optical cable 7-1 without terminating at a layer (MAC) is shown. In the second embodiment, since the slave frame is not terminated by the media access control layer (MAC), when inserting the frame according to the frame interval of the master frame, if the slave frame data is originally 2.5 bytes or less, Serial multiplexing is possible without logical compression.

  Since the slave frame does not have a media access control layer (MAC) frame configuration, a user frame on the network device # 2 side is not limited to an Ethernet (registered trademark) frame, but can be converted into a media independent interface frame MII22. Can be applied.

  FIG. 9 shows a third embodiment of the present invention, in which both a main frame and a subframe arriving from two user ports are terminated at the media access control layer (MAC), and the subscriber premises equipment and the accommodation station equipment Is a configuration example of a transmission apparatus in which the optical fiber 9-1 is separated from each other. The difference from the first embodiment is that in the first embodiment, the transmission physical medium between the subscriber premises equipment and the accommodation station side is a single-core optical cable according to the wavelength division multiplexing (WDM) method, whereas in the third embodiment, the direction is It is a separated two-core optical cable. Depending on whether the transmission medium is a single-core type or a two-core type, the serial multiplexing of the main frame and the subframe is not limited, and the multiplex transmission is performed by inserting the frame according to the frame interval of the main frame. Can do.

  FIG. 10 shows a fourth embodiment of the present invention, and for the main frame and subframes respectively coming from two user ports, only the main frame is terminated by the media access control layer (MAC), and the subframe is media access controlled. An example of the configuration of a transmission apparatus in which subscriber home equipment and accommodation station equipment are connected by optical fibers separated in direction without terminating at a layer (MAC) is shown. The difference from the second embodiment is that, in the second embodiment, the transmission medium between the subscriber premises and the accommodation station side is a single-core optical cable according to the wavelength division multiplexing (WDM) method, whereas in the fourth embodiment, the direction is It is a separated two-core optical cable. Similarly in this case, the serial multiplexing of the main frame and the subframe is not limited depending on whether the transmission medium is a single core type or a two core type, and the frame is inserted according to the frame interval of the main frame. Multiple transmission can be performed.

It is a figure which shows the structure of the frame multiplexing transmission apparatus which multiplexes two user frames by this invention on one optical transmission line frame. It is explanatory drawing of the method of multiplexing two user frames by this invention on one optical transmission line frame. It is a figure which shows the subordinate frame format multiplexed by this invention. It is explanatory drawing of the method of avoiding the collision of the data frame by this invention. It is explanatory drawing about the insertion position of the subframe by this invention. It is a figure which shows the functional block structure of the frame multiplexing transmission part (OAM) of this invention. It is a figure which shows Example 1 of the frame multiplex transmission apparatus of this invention. It is a figure which shows Example 2 of the frame multiplexing transmission apparatus of this invention. It is a figure which shows Example 3 of the frame multiplexing transmission apparatus of this invention. It is a figure which shows Example 4 of the frame multiplexing transmission apparatus of this invention. It is a figure which shows the structure of the conventional frame multiplexing transmission apparatus which multiplexes an Ethernet (trademark) frame.

Explanation of symbols

1-1 Optical transmission path FTTH-CPE-MC Subscriber side frame multiplex transmission device FTTH-CO-MC Housing station side frame multiplex transmission device P1, P2, P3, P4 port PHY1, PHY2, PHY3, PHY4 Physical layer MAC Media access Control layer OAM Frame multiplexing transmission part MII Independent interface

Claims (8)

In a frame multiplex transmission apparatus having a function of receiving user frames as a group of transfer data from a user from two ports, multiplexing the two user frames, and sending them to one port as an optical transmission line frame ,
Out of user frames input from the two ports, the user frame input from one port is sent as an optical transmission line frame to the one port without restriction.
Of the user frames input from the two ports, a user frame input from the other port is inserted and multiplexed in a gap between frames of the user frames input from the one port, and the one frame A frame multiplexing transmission apparatus comprising means for sending an optical transmission line frame to a port.   Means for compressing a user frame input from the other port to a frame length shorter than a predetermined frame interval of a user frame input from the one port; and compressing the user frame to the one port The frame multiplex transmission apparatus according to claim 1, further comprising means for inserting into a gap between frames of a user frame input from the frame.   A user frame input from the other port is input from the one port at a rate of once every two times the cycle of the user frame input from the one port and the subsequent frame interval. 3. The frame multiplexing transmission apparatus according to claim 1, further comprising means for multiplexing by inserting into a gap between frames of user frames to be transmitted.   The optical transmission line frame is monitored with a period twice as long as the total of the user frame inputted from the one port and the gap between the subsequent frames as a monitoring period. 4. The frame multiplexing transmission apparatus according to claim 3, further comprising means for separating a user frame shorter than a predetermined frame length inserted in the gap. In a frame multiplex transmission method for receiving a user frame as a group of transfer data from a user from each of two ports, multiplexing the two user frames, and sending them to one port as an optical transmission line frame,
Out of user frames input from the two ports, the user frame input from one port is sent as an optical transmission line frame to the one port without restriction.
Of the user frames input from the two ports, a user frame input from the other port is inserted and multiplexed in a gap between frames of the user frames input from the one port, and the one frame A frame multiplex transmission method, wherein the frame is transmitted to a port as an optical transmission line frame.   The user frame input from the other port is compressed to a frame length shorter than a predetermined frame interval of the user frame input from the one port, and the compressed user frame is input from the one port. 6. The frame multiplex transmission method according to claim 5, wherein the frame is inserted into a gap between frames of user frames to be transmitted.   A user frame input from the other port is sent to the one port at a rate of once in a period twice as long as a sum of a user frame input from the one port and a gap between subsequent frames. 7. The frame multiplexing transmission method according to claim 5 or 6, wherein multiplexing is performed by inserting into a gap between frames of user frames input from.   The optical transmission line frame is monitored with a period twice as long as the total of the user frame input from the one port and the gap between subsequent frames as a monitoring period. 8. The frame multiplex transmission method according to claim 7, wherein a user frame shorter than a predetermined frame length inserted in the gap is separated.

Images