JP4330140B2 - Communication network system - Google Patents

Description

The present invention relates to a station device that transmits and receives at a terminal in a communication network system and a relay device such as a switch or a router that relays communication, and more particularly to transmission and reception of real-time data.

  As a conventional technique for transmitting real-time data, RTP (Real Time Protocol) is widely used (for example, see Non-Patent Document 1 and Non-Patent Document 2).

  The “RTP packet” is a protocol that is normally transmitted using an upper layer such as a transport layer protocol (UDP or TCP), and is used to monitor RTP that transmits real-time data, QoS monitoring, and session start / end. RTCP (RTP Control Protocol) to be controlled.

  RTP is assumed to be a translator that converts the payload format of a stream and a mixer that combines the payload formats of a plurality of streams into one payload format.

  FIG. 7 is a diagram showing a format in RTP.

  RTP uses the format shown in FIG.

  SSRC (Synchronization Source Identifier) shown in this format is an identifier indicating the transmission source of the stream. A CSRC (Contributing Source Identifier) is a list of transmission sources contributing to the stream. When passing through the translator, the identifier of the translator is added to the CSRC. When passing through the mixer, the previous SSRC is added to the CSRC, and the identifier of the mixer becomes a new SSRC.

  The “sequence number” is a random numerical value assigned to a certain stream data, and is monotonously increased by “1” for subsequent packets.

  The “time stamp” gives 32 bits as a relative value of the time at which the source packet is transmitted. The RTP packet created in this way is generally transmitted using UDP (User Data Protocol). This protocol introduces the possibility of unreliable transfer and the possibility of duplicate messages, instead of minimizing the transmission and reception of messages between stations. For this reason, the real-time data transfer using RTP over UDP does not control the reliability of data or the securing of traffic necessary for the data transfer.

  For this reason, a bandwidth control protocol RSVP (Resource Reservation Protocol) is established in RFC 2205 (see, for example, Non-Patent Document 3). When RSVP reserves a resource, it performs it on a series of streams.

  FIG. 8 is a diagram illustrating a configuration of a host and a router used for RSVP.

  In FIG. 8, when policy control in which the application claims priority to RSVP Process and authentication (AdmissionControl) are performed, the parameters in the packet classifier for the real-time stream generated from the application complete the setting of the setting packet scheduler. .

In these processes, a series of communication path resources from transmission of host → router →... → router → host to reception are secured. As described above, in RSVP, QoS is set for a series of communication paths between a host and a host, and a bandwidth is secured.
IETF Standard RFC1889 Internet <URL: http://www.ietf.org/rfc/rfc1889.txt?number=1889> IETF Standard RFC1890 Internet <URL: http://www.ietf.org/rfc/rfc1889.txt?number=1890> Internet <URL: http://www.ietf.org/rfc/rfc2205.txt?number=2205>

  However, in the above-described conventional real-time communication method, synchronization between streams can be achieved with a certain degree of accuracy, but it cannot be guaranteed that the process is executed after the time is guaranteed. That is, when stream data is transmitted using RTP, there is a problem that the playback time on the receiving side cannot be controlled.

In the real-time communication method, the present invention can guarantee that the process is executed after guaranteeing the time. That is, when stream data is transmitted using RTP, the reproduction time on the receiving side is controlled. It is an object of the present invention to provide a communication network system that can be used.

The present invention is used, the number a transmission station for transmitting a packet, and a plurality of receiving stations connected via different routes and the transmitting station, and a plurality of repeaters each transmission path between the transmitting station and the respective receiving station The plurality of repeaters are a first repeater that relays packets using information of the layer 2 header, and a second repeater that relays packets using information of the layer 2 header and the layer 3 header The plurality of receiving stations include: a receiving station connected to the transmitting station via the second repeater; and a receiving station connected to the transmitting station not via the second repeater. a communication network system comprising said first, second repeater, the counter information of the received packet, receiving the packet Relays a packet by subtracting the residence time before sending it, the first repeater, the counter information obtained by subtracting the residence time relays in addition to the layer 2 header, the second repeater Counter information that reflects the delay time in each transmission line to each receiving station by adding and relaying the counter information obtained by subtracting the residence time between the layer 2 header and the layer 3 header. Relay each packet to each receiving station, and when each receiving station counts until the counter information of the packet relayed from the repeater reaches a predetermined value, a predetermined process is started to start the process at each receiving station. A communication network system that synchronizes activation of the predetermined process.

According to the present invention, even if transmission is performed from a transmitting station to a plurality of receiving stations in different networks, the processes of the plurality of receiving stations can be controlled synchronously, so that time information for the plurality of receiving stations is accurate. It is possible to perform distribution of machines, control of machines, and the like.

  The best mode for carrying out the invention is the following embodiment.

  FIG. 1 is a diagram showing details of a network interface block inside a station constituting the communication network system 100 according to the first embodiment of the present invention.

  The network interface block is output from the count register 101, the count register 101 that stores the initial value of the counter header, the transmission FIFO 102, the block 103 that calculates the CRC32 of the header and payload part as FrameCheckSequence (FCS), and the transmission FIFO 102. A frame generation block 104 to which the FCS 103 is added together with a header and a payload, and a block 105 for conversion to an MII / GMII interface. Further, the data is output to MEDIAUM as a communication medium through the PHY 116.

  Next, the input side will be described.

  Data received by the PHY 116 from the MEDIUM is input to the frame analysis block 107 through the MII / GMII reception interface 106. As a result of the frame analysis, the FIFO 108 extracts the count value of the count header and inputs it to the counter 109. After counting the remaining amount, the counter 109 notifies the CPU 114 of the occurrence of an event through the internal bus 115. On the other hand, the other header and payload portions of the data are input to the reception FIFO 110 and output to the internal bus.

  FIG. 2 is a diagram illustrating a network interface block in a switch apparatus that interconnects stations of the same network among the node apparatuses constituting the network system according to the first embodiment of the present invention.

  In this block, the switch device 201 is a switch device that exchanges information in units of frames from an arbitrary MAC to an arbitrary MAC, and includes a first MAC block 202, a first PHY 203, and a second MAC block 204. A second PHY 205, an Nth MAC block 206, and an Nth PHY 212 are provided.

  Frames input from MEDIUM are analyzed through the MII / GMII interface block 213. If they are normal frames, they are input to the receive FIFO as they are. If a frame with a counter header is input, the counter value is uniquely set. After rewriting to a fixed ID value, it is input to the switch device 201.

  The counter value separated by the counter 216 continues counting while being switched.

  Next, when output from the switching device 201 to MEDIUM, first, if it is a frame with an ID after being stored in the transmission FIFO 207, it is changed to the count value counted by the counter 216 that matches the ID in the frame, Input to the frame generation block 210. Here, the FCS (CRC-32) of the reconstructed frame is calculated again, the calculation result is replaced as a new FCS, and is output to the PHY 212 via the MII / GMII interface 211.

  In addition to the MAC, each PHY is controlled via the MDIORegister 220, the MDIOController 218, and the MDIOInterface in order to control an interface called MDIO that monitors / controls the state of the PHY. The MDIO Interface is described as “MDIO” connecting the line connecting the MDIOController 218 and the PHY 212, connecting the PHY 203 and 205 with “MDIO”, and connecting the PHY 205 and 212 with each other. It is with the line.

  Next, the operation of the network system in the first embodiment will be described.

  FIG. 3 is a diagram illustrating a configuration example of the network system in the present embodiment.

  In the configuration example shown in FIG. 3, Terminals 1 to 3 are connected as stations on the network, and SW1 to SW4 are used as means for connecting the stations in the same network to each other. In the example shown in FIG. 3, although not shown, it may be considered that there are stations other than these Terminals.

  In the example shown in FIG. 3, a packet called a synchronization frame is output from each terminal to each station.

  FIG. 4A is a diagram showing a MAC frame structure defined in IEEE 802.3.

  The first field of the frame is a header used in a physical layer called “Preamble”, and is a pattern in which “1” and “0” of 64 bits indicating the beginning of the frame are alternately repeated (however, only the last 2 bits) Is “11”).

  Next, a Source Address field indicating a 48-bit transmission source address, followed by a Destination Address field that is a 48-bit destination address.

  The next field of the Ethernet frame is the Type / Length field. Here, the type or length information of the payload is stored. If the Type / Length field contains a value greater than or equal to 0x600 (hexadecimal), it is recognized as a Type field.

  For example, if IP is used for the upper layer, 0x800 (hexadecimal) is stored. In the VLAN (see IEEE standard 802.1Q), 0x8100 (hexadecimal) is stored (FIG. 4B).

  When 0x8100 is set in the Type field, it indicates that VLAN tag control information is contained in the next two bytes, followed by payload and FCS. Management of this Type / Length field is performed by the IEEE 802 committee, and publicly used fields can be found on the Internet <http://standards.ieee.org/regauth/ethertype/type-pub.html> Can do.

  FIG. 4C is a diagram illustrating a synchronization frame format according to the first embodiment.

  According to the communication network system 100 shown in FIG. 1, the Destination Address and the Type / Length field in the normal frame format are accumulated in the Tx FIFO 102, and when an event occurs, as shown in FIG. Tag is inserted, and then a counter value is added.

  The Counter value has a certain time granularity, and is a value for causing a destination station to execute an arbitrary process at a specified time.

  Further, the CRC 32 that is an error detection code is calculated over the entire frame, and the calculated value is added to the end of the frame.

  As described above, a transmission frame is created and issued from the station.

According to the embodiment shown in FIG. 3, the frame transmitted from Terminal 1 is received by SW 1 that is a switching device. According to the switching device shown in FIG. 2, the frame information received from MEDIUM is received by the physical layer block PHY (203, 205, 212, etc.) and sent to the MAC block. For example, when transmitted to the MAC-N block, it is received by the MII / GMIRxInterface 213 of the MAC-N block with the preamble part removed from the frame information. Done.

  As a result, when the Counter extension Tag is added, the Counter value is held in any Counter of the Counter group 216, and the ID value corresponding to the held Counter is given to the Counter portion of the frame. After that, the frame once stored in the reception FIFO 217 is switched to the Destination Address destination by the SW Fabric 201.

  If the switching destination is MAC-N, the frame information stored in the transmission FIFO 207 is a counter having an ID that matches the CounterID in the case of a frame having a counter extension tag in the ID code counter grant block 208. The value is replaced with the Counter ID and sent to the frame generation unit 210.

  The Counter group 216 includes the time during which frames are accumulated in the transmission / reception FIFO, SWFab. Since the Counter group is counted down, including the time of staying in, the time can be accurately measured.

  As shown in FIG. 4 (c), the counter following the counter extension tag in the frame information is replaced with the counter ', and then updated to a value obtained by recalculating the FCS, and then passed through the MII / GMITxInterface 211. Preamble is added to the head and the data is sent from PHY to MEDIUM.

The operation so far, the Counter extension Tag with frame sent from Terminal1, by way of SW1, the delay time D1 caused by SW1 is, the Counter, is added as the information is sent to the switching device SW2.

  Similarly, when a frame with a counter extension tag is sent from Terminal 1 to Terminal 3, it is sent to Terminal 3 via SW1 → SW2 → SW3. Therefore, from the initially assigned Counter value, the delay value TD123 = SW D1 + D2 + D3 is subtracted, and this subtraction result is received by Terminal3.

  In addition, when a synchronous frame is transmitted from Terminal 1 that communicates over the network to Terminal 4, communication is performed via the Router. Therefore, the Router rewrites and transmits the MAC address of the Router to Source Address.

  In the Router, as with the switching device, the presence or absence of the Counter extension Tag, which is an L2 header, is detected. When the Counter extension Tag is detected, the time taken for routing is counted and the Counter information in the payload is updated. Then, the data is sent to the next switch device or router device.

  As described above, frame information received at the destination station is received at the MII / GMIRxInterface 106 and frame analyzed after the physical layer header is removed by the PHY 116. When the header with the counter extension tag is confirmed, the counter value is extracted, and the remaining counter value is subtracted in the counter in the receiving station.

  When the specified count is reached, the system is notified that the event has been received, and a desired process can be started.

As described above, in the first embodiment, the extension tag and the counter value associated with the extension tag are added to the frame, and the delay time required for switching or the like is subtracted from the SW / Router that is the midway path of the frame. Thus, in the same network, it is possible to instruct a frame destination station to perform a specific process at an arbitrary time designated by the frame transmission source.

  FIG. 5 is a diagram illustrating a configuration example of a network system that is Embodiment 2 of the present invention.

  In the second embodiment, a network constituted by the switch device SW5 and Terminal 4 is added to the network system shown in FIG. 3, and Router 1 and Router 2 are used to connect the networks to each other. Router1 and Router2 are connected via a WAN. It is assumed that a node device based on the concept of claim 1 of the present invention shown in FIG. 2 is used in a network device that connects them.

  As in the first embodiment, when a synchronization frame is transmitted from Terminal 1 to Terminal 4, since Terminal 1 and Terminal 4 belong to different networks, the header configuration transmitted from Terminal 1 is the MAC address of Router 1 in the destination MAC address of the L2 header. In the destination IP address of the L3 header, the IP address of Terminal 4 is given. The same communication is performed in the communication between Routers, and when a destination 4 destination packet arrives, Router 2 rewrites the destination address of the L2 header to the MAC address of Terminal 4 and sends the packet. In this way, in communication exceeding Router, the L2 header is rewritten, so even if option information indicating time information is added to the L2 header in the first embodiment, it may be rewritten. Therefore, when it is necessary to exceed the IP-Router, or when communication is performed using an L3 switch that performs switching based on IP information, the problem can be solved by adding time information on the L3 header (IP header). It can be solved.

  FIG. 6 is a format example in which time information is added as option information of the L3 header.

  FIG. 6A shows an example of a frame including a typical L3 header. Information regarding various IPs is described in the L3 header, and the header length of the L3 header is described in the header length (H. len) portion thereof. FIG. 6B is a diagram in which Counter information is added to the L3 header by redefining this header length. In FIG. 6B, Header Length is rewritten to the header length including Counter, and 16 bits are added as Counter information after Distination IP Address which is the destination IP address.

  Based on these, when a synchronization frame with a certain Counter value is output from Terminal 1 to Terminal 4, first, the synchronization packet arriving at Router 1 is delayed from the initial Counter value by the L2 switch from Terminal 1 to Router 1. [D1 + D2] is subtracted, and the updated Counter value is present in the L2 header. In Router1, which is a gateway of the network to which Terminal1 belongs, the delay information on the L2 header so far is replaced on the L3 header, and updated to the counter value obtained by subtracting the new delay information [D1 + D2 + DR1]. . Further, in Router2, the delay information subtracted up to Router2 has [D1 + D2 + DR1 + DNW] on the L3 header, and the delay information [D1 + D2 + DR1 + DNW + DR2] on Router2 is transferred to the L2 header and sent to SW5.

  With the above operation, the synchronous packet output transmitted from Terminal 1 is received at Terminal 4 with delay information written on the Counter header on L2.

In this way, in the second embodiment, by adding delay information on the L3 header (IP header), even when the communication is beyond the network, the layer handling the delay information is moved appropriately. Appropriate delay information can be transmitted between different networks.

It is a figure which shows the detail of the network interface block in the station which comprises the communication network system 100 which is Example 1 and Example 2 of this invention. It is a figure which shows the network interface block in the switch apparatus which mutually connects the station of the same network in the node apparatus which comprises the network system which is Example 1 and Example 2 of this invention. It is a figure which shows the example of 1 structure of the network system in Example 1 of this invention. It is a figure which shows the frame structure defined by IEEE802.3 and the frame structure used in Example 1 and Example 2 of this invention. It is a figure which shows one structural example of the network system in Example 2 of this invention. It is an example of the packet format of the layer 3 in Example 2 of this invention. It is a figure which shows the format in RTP. It is a figure which shows the structure of Host and Router used for RSVP.

Explanation of symbols

100: communication network system,
101: Count register,
102 ... FIFO for transmission,
103 ... Block,
104 ... Frame generation block,
105 ... conversion block,
106 ... interface,
107: Frame analysis block,
108 ... FIFO,
109 ... Counter,
110: Receive FIFO.

Claims (2)

A transmission station for transmitting a packet, and a plurality of receiving stations connected via different routes and the transmitting station, and a plurality of repeaters each transmission line between said transmission station and said each receiving station, said plurality Includes a first relay that relays a packet using information of the layer 2 header, and a second relay that relays a packet using information of the layer 2 header and the layer 3 header, The plurality of receiving stations include a receiving station connected to the transmitting station via the second repeater and a receiving station connected to the transmitting station without going through the second repeater. Because
The first and second repeaters relay the packet by subtracting the dwell time from reception of the packet to transmission from the counter information of the received packet, and the first repeater The counter information obtained by subtracting the dwell time is added to the layer 2 header and relayed. The second repeater adds the counter information obtained by subtracting the dwell time by moving between the layer 2 header and the layer 3 header. By relaying, relay packets with counter information reflecting the delay time in each transmission path to each receiving station to each receiving station,
When each receiving station counts until the counter information of the packet relayed from the repeater reaches a predetermined value, the predetermined process is started to synchronize the start of the predetermined process at each receiving station. A communication network system. The repeater starts counting time after receiving a packet, and writes the counter information obtained by subtracting the timing result until the packet is output from the counter information of the received packet to the output packet. The communication network system according to claim 1, wherein:

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