JP2011176695A - Optical transmission apparatus, optical transmission system, and optical transmission method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce apparatus costs for an access network and a metro network, also to reduce power consumption, to lower delay, and to make efficient band control corresponding to the band used by a user. <P>SOLUTION: An optical transmission apparatus accommodating one or more user-side terminating devices, is equipped with: a transmission source user identifying section for identifying, from information of a frame received from the user-side terminating device, the transmission source user of the frame; a frame converting section for converting the frame into an ODU (Optical channel Data Unit) frame on the basis of a band which can be allocated to the user in accordance with user identification information from the user identifying section; and a frame multiplexing section for multiplexing one or more ODU frames into OTU (Optical channel Transport Unit) frame. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a transmission apparatus that performs data transfer between different networks.

  Currently, access networks centered in urban areas are user lines via ADSL (Asymmetric Digital Subscriber Line), FTTH (Fiber To The Home) GE-PON (Gigabit Ethernet (registered trademark)-Passive Optical Network), or wireless. Contained. At the top of the access network is a metro network that bundles city and regional networks, and above that is a core network that bundles prefecture and local level or submarine cable networks. FIG. 10 shows a configuration diagram of the entire communication network. In FIG. 10, 100 to 10N are access networks, 200 to 20N are metro networks, and 300 is a core network.

  FIG. 11 shows a specific system configuration example of the entire communication network of FIG. In FIG. 11, the access network is configured by a PON system, and the metro network is configured by ethering.

  The user bandwidth in the current access network is about 1 Mb / s in ADSL, and the maximum user bandwidth in the access network configured with GE-PON is 1 Gb / s. On the other hand, the metro network performs data communication at about 10 Gb / s, which is faster than the access network.

  The transmission system is realized by a WDM (Wavelength Division Multiplex) system that can transmit a large amount of data by multiplexing the signals of the access network and the metro network in the core network. Similarly, the capacity of metro networks has increased in recent years, and the number of cases in which networks are constructed with WDM devices is increasing. However, as described above, ADSL and PON having a low accommodation speed are mainstream as described above, and large-capacity communication using the WDM system has not been performed.

  As an example of a method for data transmission between networks having different transmission methods and transmission bands, a central node in a metro network is used to share a WDM signal used in a metro network as a signal for an access network. WDM signals separated via the network are sent to multiple access nodes, one or more of these WDM signal wavelengths being modulated with the user's signal and multiplexed to the WDM signal of the metro network via the central node A method is disclosed. (For example, Patent Document 1)

JP 2000-295182 A

  The available bandwidth of the current user is about 1 Gb / s at the maximum even if FTTH is used, but the bandwidth required by the user becomes larger due to the evolution of technology, and applications that require a large capacity will appear. Therefore, it is considered necessary to meet various user needs from low speed (1 Mb / s) to high speed (100 Gb / s). However, in the conventional technology, the wavelength is assigned to each access node, and the same wavelength is used in the access network and the metro network. However, the control is performed in units of access nodes or in units of wavelengths, so that a variety of users can be used. There is a problem in that it is impossible to control the bandwidth corresponding to the used bandwidth.

  Further, in order to transfer data of various bands of users, a method of multiplexing once by L2SW (Layer 2 Switch) in the conventional access network as shown in FIG. 11 and transferring to the metro network can be considered. Along with the increase in bandwidth, a large-capacity L2SW is required, which increases the cost of the access network device. In addition, even if a user of 10 Gb / s or less is accommodated by 10GE-PON and a user of 100 Gb / s class is accommodated by another system, the number of L2SW devices is increased, and an L2SW having a 100 GbE interface is required. There is a problem that the device cost of the access network becomes high.

  In addition, a metro network that accommodates a signal multiplexed with a large capacity by the L2SW requires a switch having a larger capacity, and the metro network also has a problem that the apparatus cost increases.

  On the other hand, in order to transmit a large amount of data, OTN (Optical Transport Network) is an ITU-T (International Telecommunication Union Telecommunication Standardization Sector). 709 is standardized. G. 709 currently standardizes an ODU (Optical channel Data Unit) suitable for the transmission rate of user signals from 1 Gb / s to 100 Gb / s. Furthermore, it is possible to support up to N times (number of wavelengths) transmission capacity by transferring them by WDM using them. In addition to the conventional ODU, the ODUflex (Optical channel Data Unit, flexible) standard that can flexibly respond to the transmission speed of the user and transfer signals from low speed to high speed is also G.264. Newly added to 709.

  In the present invention, when accommodating users, an access network does not use L2SW to multiplex, but defines a channel based on ODU or ODUflex according to the user's use band. In a metro network, multi-channel ODU / ODUflex is defined as OTU. An optical transmission apparatus that can eliminate the L2SW of the access network and reduce the network cost by mapping to an (Optical channel Transport Unit) frame and transferring by OTN is provided.

  An optical transmission apparatus according to the present invention is an optical transmission apparatus that accommodates one or a plurality of user-side termination devices, and that identifies a transmission source user of the frame from information on a frame received from the user-side termination device An identification unit, a frame conversion unit that converts the frame into an ODU frame based on a band that can be allocated to the user from user identification information from the user identification unit, and one or more ODU frames are multiplexed into an OTU frame A frame multiplexing unit.

  Realize equipment cost reduction, power consumption reduction, and low delay of access network and metro network. In addition, efficient bandwidth control corresponding to the bandwidth used by the user is realized.

It is a block diagram of the communication network in Embodiment 1 of this invention. It is a block diagram of OLT121 in Embodiment 1 of this invention. It is a conceptual diagram which shows the multiplexing to the OTU frame in ODU frame in Embodiment 1 of this invention. It is a block diagram of OLT121 in Embodiment 2 of this invention. It is a block diagram of the communication network in Embodiment 3 of this invention. It is a block diagram of OLT141-14N in Embodiment 3 of this invention. It is a block diagram of the communication network in Embodiment 4 of this invention. It is a block diagram of OLT14N in Embodiment 4 of this invention. It is a block diagram of the communication network in Embodiment 5 of this invention. It is a whole block diagram of the conventional communication network. It is a block diagram of the conventional communication network.

Embodiment 1 FIG.
Embodiments of an optical transmission apparatus according to the present invention will be described below in detail with reference to the drawings. The following embodiment is an embodiment for embodying the present invention, and is not intended to limit the present invention within the scope thereof.

  FIG. 1 is a configuration diagram of a communication network according to the present embodiment. In FIG. 1, 100 indicates an access network, and 200 indicates a metro network. In the following description, it is assumed that the access network is configured by a PON system. 11 to 1N of the access network 100 is an ONU (Optical Network Unit) that is a user-side terminal device. The optical transmission device according to the present embodiment corresponds to an OLT 121 (Optical Line Terminal) that is a terminal device on the management station side. The OLT 121 accommodates user data transmitted from the ONUs 111 to 11N.

  FIG. 2 shows a configuration diagram of the OLT 121 in the present embodiment. In FIG. 2, reference numeral 131 denotes a transmission source user identification unit that receives a PON frame from an ONU and identifies a transmission user from transmission source information of an LLID (Logical Link ID) in the PON frame. Here, the PON frame indicates a frame format for transmission between the ONUs 111 to 11N and the OLT 121. For example, when the PON system is G-PON, a GTC (G-PON Transmission Convergence) frame is applicable. Reference numeral 132 denotes a user bandwidth information holding unit that holds contract bandwidth information for each user set from a network management system (not shown). 133 is a method for mapping a PON frame to an ODU frame corresponding to a user's use band based on transmission source user identification information from the transmission source user identification unit 131 and contract bandwidth information for each user from the user band information holding unit 132. This is a frame conversion unit for determining the channel information. At this time, the ODU frame to be mapped includes framing with ODUflex. A frame multiplexing unit 134 multiplexes one or a plurality of ODU frames generated by the frame conversion unit 133 into an OTU frame. After frame multiplexing is performed, the user data is transferred to the metro network as an OTU frame.

  In the above, user data from the access network is transferred to the metro network, but the OLT 121 transfers OTU frames from the metro network to the ONUs 111 to 11N. 135 is a frame dividing unit that decomposes an OTU frame input from a metro network into ODU frames, 136 is a destination user identifying unit that identifies a destination user from channel information of the divided ODU frame, and 137 is a destination user identified It is a frame conversion unit that converts an ODU frame into a PON frame. After frame conversion, the PON frame is transferred to the destination ONU.

  FIG. 3 is a conceptual diagram showing multiplexing of one or a plurality of ODU frames into an OTU frame. As shown in the figure, the data transmitted from the user is mapped to an ODU frame corresponding to the user's use band such as 20 Gb / s or 100 Mb / s based on the user identification information and the contract band information for each user. In this way, in addition to the conventional mapping by ODU, mapping by ODUflex enables bandwidth control according to the band used by the user, and the bandwidth of the OTU frame can be utilized without waste, and the bandwidth efficiency of the entire transmission system Operation becomes possible.

  By configuring the OLT 121 as described above, user data is mapped to an ODU or ODUflex channel based on contract bandwidth information for each user, and further multiplexed into an OTU frame that can be transmitted in a metro network. As a result, the OLT 121 can be directly connected to the metro network. That is, comparing FIG. 1 with FIG. 11, which is a configuration example of a conventional communication network, it can be seen that the L2SW is not necessary. Instead of directly connecting the OLT to the metro network, for example, a device having an optical add / drop function in a metro network such as ROADM (Reconfigurable Optical Add / Drop Multiplexer) is provided with an interface with the OLT. It is also possible to adopt a configuration in which a plurality of OLTs according to embodiments are connected. In this configuration, each OLT multiplexes user data from subordinate ONUs and transfers the multiplexed data to a device having an optical add / drop function. Since the number of branches of the transmission line in the PON system is limited, such a configuration is effective when there are many ONUs to be accommodated.

  As described above, by adding a mapping function to the OTU frame by ODU or ODUflex to the OLT 121, it becomes possible to efficiently operate the band according to the band used by the user, and further, no L2SW is required, and the access network It is possible to reduce the equipment cost, installation space, and power consumption of the entire system. Further, since the number of devices is reduced, the delay time can be shortened.

  In this embodiment, the description has been made on the premise that the access network is accommodated by PON. However, in the apparatus connected to the metro network, if the user identification is obtained by frame inspection or the like, it is not limited to PON but also in other transmission forms. This embodiment can be applied.

Embodiment 2. FIG.
In the first embodiment, the OLT 121 maps the PON frame from the access network to the ODU frame based on the use band of the transmission source user. However, in this embodiment, an OTU frame sent from the metro network is also a destination. Conversion to a PON frame is made possible based on the user's bandwidth.

  FIG. 4 is a configuration diagram of the OLT 121 corresponding to the optical transmission apparatus according to the present embodiment. The difference from the first embodiment is that the contract bandwidth information from the user bandwidth information holding unit 132 can be referred to in the frame conversion unit 137. This embodiment is suitable for, for example, a multirate PON having a plurality of transmission rates in the upstream and downstream directions between the OLT 121 and the ONUs 111 to 11N.

  In the OLT 121, the OTU frame received from the metro network is divided into ODU frames by the frame division unit 135, and then the destination information of the ODU frame is read by the destination user identification unit 136. Next, when the frame conversion unit 137 converts the ODU frame to the PON frame, the user bandwidth information holding unit 132 reads the contract bandwidth information for each user corresponding to the destination user described above. Then, a PON frame is transmitted to the destination ONU at a plurality of transmission rates in accordance with the bandwidth available to the user.

  By configuring the OLT 121 as described above, in addition to the effects of the first embodiment, it is possible to control the band according to the user use band for the transmission from the OLT 121 to the ONUs 111 to 11N. As a result, the bandwidth can be utilized without waste, and the transmission system can be efficiently operated. Although it is assumed that the access network is a PON system, the present invention is not limited to this, and it can be applied to other transmission modes as in the first embodiment.

Embodiment 3 FIG.
FIG. 5 is a configuration diagram of a communication network according to the present embodiment. In FIG. 5, unlike the configuration of FIG. 1, the OLTs 141 to 14N corresponding to the optical transmission apparatus according to the present embodiment are arranged in a ring shape in the metro network 200 to configure the metro ring. Note that the interfaces on the metro network side of the OLTs 141 to 14N conform to the OTN standard.

  FIG. 6 shows a configuration diagram of the OLTs 141 to 14N. In the present embodiment, an Add / Drop unit 138 for exchanging OTU frames on the metro ring is added to each OLT. Add / Drop unit 138 drops (termination) if the OTU frame flowing on the ring is addressed to its own subordinate ONU, transmits it in other cases, and receives a PON frame from the subordinate ONU In addition, the OTU frame accommodating the same is added (transferred) on the ring to realize transfer of the OTU frame within the metro ring. For the OLT 14N that connects the metro network and the core network, an add / drop unit 138 adds an interface portion with the core network. By configuring the OLTs 141 to 14N of the PON system in a ring shape as described above, the metro network can be configured by the OLT, and the data from the user is mapped from the PON frame to the ODU frame and multiplexed into the OTU frame. Then, you can transfer the metro network as it is.

  According to the above configuration, it is possible to integrate the OLT of the access network and the edge node of the metro network, which are separate devices, with the OLT. As a result, the types of access network and metro network and the number of devices can be reduced, and the device cost, power consumption, and delay can be reduced. In addition, the transmission band of the core network or the metro network can be matched with the transmission band of the access network by using, for example, OFDM-PON or 100G-PON capable of 100G class transfer as the transfer between the OLT 141 and the ONUs 111 to 11N. If possible, band conversion is not required, and large-capacity data can be transmitted seamlessly from the core network to the access network.

Embodiment 4 FIG.
FIG. 7 is a configuration diagram of a communication network according to the present embodiment. In FIG. 7, the OLT 141 to 14N corresponding to the optical transmission apparatus according to the present embodiment is arranged in a ring shape to form the metro network 200 as in the configuration of FIG. 5, but the OLT 14N and the core network 300 are arranged. A router 151 is arranged. This embodiment is a case where transmission between the OLT 14N and the router 151 using an Ethernet (registered trademark) frame is possible.

  FIG. 8 is a configuration diagram of the OLT 14N. In FIG. 8, an Ethernet (registered trademark) frame conversion unit 139 is provided in an interface portion connected to the core network, and a function of converting an OTU frame and an Ethernet (registered trademark) frame is provided. As described above, since the device corresponding to the core network side has an inexpensive Ethernet (registered trademark) interface instead of an expensive OTN interface, the device cost can be reduced. When there are both a path for transferring data between the OLT 14N and the core network using an OTU frame and a path for transferring data between the OLT 14N and the router 151 using an Ethernet (registered trademark) frame, a function for transmitting the OTU frame as it is, The Ethernet (registered trademark) frame conversion unit 139 may convert the OTU frame into an Ethernet (registered trademark) frame and transmit / receive the function.

Embodiment 5 FIG.
FIG. 9 is a configuration diagram of a communication network in the present embodiment. In FIG. 9, reference numeral 111 denotes an ONU that accommodates a user line, and 161 to 16N corresponding to the optical transmission apparatus according to the present embodiment are OLTs that accommodate user data from the ONU and transfer them to apparatuses on the metro network. Here, the OLT that transmits and receives signals to and from the core network is the central office 16N, and the other OLTs are remote nodes. In this embodiment, the OLT of the access network and the central office and remote node of the metro network are integrated. As shown in the figure, the remote node 161 includes a PON-IF (interface) unit 171, a frame conversion unit 172, and an Add / Drop unit 173. The PON-IF unit 171 receives the PON frame signal from the ONU and passes it to the frame conversion unit 172. The frame conversion unit 172 maps the PON frame to the ODU frame by ODU / ODUflex according to the band used by the user, and multiplexes the PON frame to the OTU frame. Also, the OTU frame received from the metro network is divided into ODU frames and converted into PON frames. The Add / Drop unit 173 has a function to Add / Drop the OTU frame on the ring.

The central office 16N is a device that connects the metro network and the core network, and includes an Add / Drop unit 173, a frame conversion unit 172, and a PON control unit 174 as shown in FIG.

  The PON control unit 174 performs PON bandwidth management or LLID management of remote nodes other than the central office (extended PON control). This lightens the control function of the PON-IF unit 171 of the remote node. In addition, it is possible to provide not only one central office but also a plurality of central offices.

  Specifically, the PON control unit 174 recognizes the remote edge number and the PON-IF number of the distribution destination by looking at the MAC address or VLAN (Virtual Local Area Network) -ID of the Ethernet (registered trademark) frame, and PON And an Ethernet (registered trademark) frame are encapsulated in a PON frame, and an ODU / ODUflex channel number is assigned. The frame conversion unit 172 of the central office 16N assigns a channel number based on the information from the PON control unit 174, maps the PON frame to the ODU frame, and multiplexes the OTU frame in consideration of the wavelength.

  By integrating the OLT of the access network and the central office and remote nodes of the metro network, the equipment cost of the entire metro network can be reduced. As a result, the number of relaying devices is reduced, so that low delay transfer can be realized. In the present embodiment, the PON system (TDM, WDM, OFDM, etc.) does not matter.

  By configuring as described above, a PON control unit is not provided in each OLT and conversion between the PON and the ODU / ODUflex is performed, but the control functions are integrated into one OLT of the metro network, and the ODU / ODUflex is integrated. By coordinating with the channel information, it is possible to reduce other OLT circuits and reduce the power consumption of the entire metro network.

100 to 10N access network 111 to 11N user terminal device 121 OLT
131 Transmission source user identification unit 132 User band information holding unit 133 Frame conversion unit 134 Frame multiplexing unit 135 Frame division unit 136 Destination user identification unit 137 Frame conversion unit 138 Add / Drop unit 139 Ethernet (registered trademark) frame conversion unit 141- 14N OLT
151 router 161 to 164 remote node 16N central office 171 PON-IF unit 172 frame conversion unit 173 Add / Drop unit 174 PON control unit 200 to 20N metro network 300 to 30N core network

Claims (8)

An optical transmission device accommodating one or a plurality of user-side termination devices,
A transmission source user identification unit for identifying a transmission source user of the frame from information of the frame received from the user side termination device;
A frame conversion unit that converts the frame into an ODU (Optical channel data Unit) frame based on a band that can be allocated to the user from user identification information from the user identification unit;
An optical transmission device comprising: a frame multiplexing unit that multiplexes one or a plurality of ODU frames into an OTU (Optical channel Transport Unit) frame. The optical transmission device according to claim 1,
If the destination of the OTU frame received from the network is the user-side termination device accommodated by itself, the optical transmission further includes an Add / Drop unit that captures the OTU frame and transfers the frame received from the user-side termination device to the network apparatus.   The optical transmission apparatus according to claim 2, wherein the Add / Drop unit includes means for converting an OTU frame into an Ethernet (registered trademark) frame.   The optical transmission apparatus according to claim 1, wherein the optical transmission apparatus is an OLT (Optical Line Terminal) in a PON system.   5. An optical transmission system in which the optical transmission devices according to claim 1 are arranged in a ring shape to form an optical ring network. The optical transmission system according to claim 5,
An optical transmission system in which one or a plurality of optical transmission devices constituting an optical ring network perform bandwidth management of data transmission between another optical transmission device on a ring shape and a user-side termination device. The optical transmission system according to claim 5,
An optical transmission system in which one or a plurality of optical transmission devices constituting an optical ring network perform LLID (Logical Link ID) management between another optical transmission device on a ring shape and a user-side termination device. A transmission source user identification step for identifying the transmission source user of the frame from the information of the frame received from the user side termination device;
A frame conversion step of converting the frame into an ODU frame based on a band assignable to the user from the user identification information from the user identification unit;
And a frame multiplexing step of multiplexing one or a plurality of the ODU frames into an OTU frame.

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