WO2011027460A1

WO2011027460A1 - Transfer device, transmission device, and transmission method

Info

Publication number: WO2011027460A1
Application number: PCT/JP2009/065501
Authority: WO
Inventors: 真清水; 浩黒崎
Original assignee: 富士通株式会社
Priority date: 2009-09-04
Filing date: 2009-09-04
Publication date: 2011-03-10

Abstract

Provided is a transfer device (110) that terminates a frame received from a local area network and transfers the frame to a mapping device (120) of a synchronous network. A segment buffer (111) stores the received frame. A scheduler unit (113) transfers the frame stored by the segment buffer (111) to the mapping device (120), using a slot assigned to the frame's channel. A policer (115) monitors the frame transfer rate of the scheduler unit (113), for each of the channels. The scheduler unit (113) releases the slot of a channel with a transfer rate, monitored by the policer (115), that exceeds a threshold value and assigns the slot to another channel.

Description

Transfer device, transmission device, and transfer method

The present invention relates to a transfer device, a transfer device, and a transfer method for transferring data.

In a network that handles IP packets such as Ether (registered trademark) frames, it is common to provide a best-effort communication service. A communication carrier is designing a network so that over-subscription satisfying the relationship of (user line band> relay line band) is satisfied when channel lines are multiplexed. Effective use of the user line bandwidth and the relay line bandwidth is important in designing the network, and finer bandwidth control is required in designing the network.

In EOS (Ether Over Sonet / SDH) that switches to an Ethernet frame by using EOS, the Ether frame is encapsulated and sent to the Sonet / SDH (Synchronous optical network / Synchronous Digital Hierarchy) network. (For example, see Patent Document 1 below.) In an apparatus that terminates EOS, the buffer capacity of each device tends to increase as the transfer capacity of the channel line and the relay line increases.

JP 2008-236691 A

However, the above-described conventional technique has a problem that slots cannot be efficiently shared by a plurality of channels because slots are fixedly assigned to each channel. For this reason, for example, when the concentration rate (user line bandwidth / relay line bandwidth) increases in the oversubscription state, the transfer rate to the Sonet / SDH mapping device in the Ether frame decreases (see FIGS. 7 to 9). ). For this reason, there is a problem in that data underrun (depletion) occurs in Sonet / SDH mapping, and transmission quality deteriorates.

The disclosed transfer device, transmission device, and transfer method are intended to solve the above-described problems, and an object is to efficiently share a slot with a plurality of channels.

In order to solve the above-described problems and achieve the object, the transfer apparatus includes a storage unit that stores the received frame in the transfer apparatus that terminates the frame received from the local communication network and transfers the frame to the mapping device of the synchronous network. Transfer means for transferring the frame stored by the storage means to the mapping device by a slot assigned to the channel of the frame, and monitoring means for monitoring the transfer rate of the frame by the transfer means for each channel. And allocating means for releasing a slot of a channel whose transfer rate monitored by the monitoring means exceeds a threshold and allocating the released slot to another channel.

According to the disclosed transfer apparatus, transmission apparatus, and transfer method, there is an effect that slots can be efficiently shared by a plurality of channels.

It is a block diagram which shows the structural example of the transmission apparatus concerning embodiment. It is a block diagram which shows the specific example of the transfer apparatus shown in FIG. It is a flowchart which shows an example of operation | movement of a transfer apparatus. It is a block diagram which shows the structural example of the transmission function from WAN to LAN in a transmission apparatus. It is a block diagram which shows the structural example of ADM provided with the transmission apparatus shown in FIG. It is a figure which shows the structural example of the communication system containing ADM shown in FIG. It is a figure which shows an example of the slot managed by a scheduler. It is a figure which shows the example which set N = 220 in FIG. It is a figure which shows the example which set N = 240 in FIG.

Hereinafter, exemplary embodiments of the transfer device, the transmission device, and the transfer method will be described in detail with reference to the accompanying drawings. This transfer apparatus, transmission apparatus, and transfer method monitor the transfer rate for each channel, release the slot of the channel whose transfer rate exceeded the threshold value, and allocate it to other channels to equalize the transfer rate for each channel. Efficiently share slots with multiple channels.

(Embodiment)
(Configuration example of transmission function from LAN to WAN in transmission device)
FIG. 1 is a block diagram of a configuration example of the transmission apparatus according to the embodiment. FIG. 1 shows a configuration example of a transmission function from the LAN (Local Area Network) side in the transmission apparatus 100 to the WAN. The transmission apparatus 100 encapsulates the Ether frame and sends it to the Sonet / SDH network (EoS). As shown in FIG. 1, the transmission apparatus 100 (PE-mapper) according to the embodiment includes a transfer apparatus 110 (packet / segment) and a mapping device 120 (Sonet / SDH mapper).

The transfer device 110 terminates the frame (Ethernet frame (10G)) from the LAN (first communication network) and transfers it to the mapping device 120. Specifically, the transfer device 110 includes a segment buffer 111, a capacity monitoring unit 112 (CAP), a scheduler unit 113 (virtual slot scheduler), a route distribution unit 114 (DIS), and a policer 115 (POL). And.

The segment buffer 111 is a storage unit that stores frames received from the LAN. Specifically, the segment buffer 111 stores a frame received from the LAN by dividing it into segments of a predetermined length. Further, the segment buffer 111 outputs the stored segment to the route distribution unit 114 in accordance with the read request from the scheduler unit 113.

Further, a control signal related to the state of the segment buffer 111 is transmitted from the segment buffer 111 to the LAN side. For example, when the capacity of the segment buffer 111 decreases or a problem occurs, a control signal to that effect is transmitted to the LAN side, and transmission of frames from the LAN side to the transfer device 110 is suppressed.

The capacity monitoring unit 112 monitors the amount of data stored in the segment buffer 111 for each channel. The channel is a user line such as STS-SPE (Synchronous Transport Signal-Synchronous Payload Envelope). Then, the capacity monitoring unit 112 asserts to the scheduler unit 113 a read request for a channel in which data is stored in the segment buffer 111 based on the monitoring result.

The scheduler unit 113 is a transfer unit that transfers the segment stored in the segment buffer 111 to the mapping device 120 using the slot assigned to the channel of the frame. Specifically, the scheduler unit 113 allocates a slot to the channel for which the read request is asserted from the capacity monitoring unit 112 and notifies the capacity monitoring unit 112 of the allocation result. A slot is a communication resource such as a time slot.

The scheduler unit 113 makes a read request to the segment buffer 111 based on the assigned slot. As a result, the segment stored in the segment buffer 111 is output to the route distribution unit 114 by the slot assigned to the channel of the frame, and is transferred from the route distribution unit 114 to the mapping device 120.

The scheduler unit 113 is an allocating unit that releases a slot of a channel whose transfer rate monitored by the policer 115 exceeds a threshold value and allocates it to another channel. Specifically, when the excess flag is asserted from the policer 115, the scheduler unit 113 stops reading from the segment buffer 111 in the channel indicated by the excess flag.

The scheduler unit 113 assigns a slot vacated by stopping reading to another channel. The channel to which the vacant slot is allocated is, for example, a channel to which no slot is allocated among channels for which a read request is asserted from the capacity monitoring unit 112. In addition, after the excess flag is asserted from the policer 115, the scheduler unit 113 may stop reading after waiting for the end of the frame in the channel indicated by the excess flag to be transferred to the mapping device 120.

In this way, the scheduler unit 113 dynamically changes the slot allocation for each channel. Further, the scheduler unit 113 adjusts the transfer rate of the segment to be transferred to the mapping device 120 based on the control signal output from the mapping device 120. For example, when a transfer stop request is output from the mapping device 120, the scheduler unit 113 stops the read request to the segment buffer 111.

The policer 115 is a monitoring unit that monitors the transfer rate of the segment output from the segment buffer 111 to the route distribution unit 114 for each channel. When the segment transfer rate exceeds the threshold, the policer 115 asserts an excess flag to the scheduler unit 113. The policer 115 may have a transfer rate threshold value set for each channel.

In the route distribution unit 114, a distribution route for each channel is set. The route distribution unit 114 outputs the segment output from the segment buffer 111 to the route corresponding to the channel according to the set distribution route. The segment of each route output from the route distribution unit 114 is transferred to the mapping device 120 (OC-xx, OC-yy).

As described above, the transfer device 110 temporarily stores the frame from the LAN in the segment buffer 111, and transfers the stored data to the mapping device 120 as a segment matching the bandwidth of the relay line of the Sonet / SDH network. When the number of slots N is 240, the total of the segment (OC-xx) and the segment (OC-yy) transferred from the transfer apparatus 110 to the mapping device 120 is set to be less than the OC240.

The mapping device 120 is a mapping device of a Sonet / SDH network (synchronous network). That is, the mapping device 120 maps the segment transferred from the transfer apparatus 110 to a frame of the Sonet / SDH network, and sends the mapped frame to the Sonet / SDH network. Specifically, the mapping device 120 includes write control units 121 and 123 (WTCTL) and reassemble buffers 122 and 124 (Resemble Buffer).

The segment (OC-xx) transferred from the transfer device 110 is written to the reassemble buffer 122 under the control of the write control unit 121. The segments (OC-xx) written to the reassembly buffer 122 are sequentially read out, mapped to the frame (STS1) of the Sonet / SDH network, and sent to the Sonet / SDH network (EoS (OC192)).

The segment (OC-yy) transferred from the transfer device 110 is written to the reassemble buffer 124 under the control of the write control unit 123. The segment (OC-yy) written to the reassembly buffer 124 is sequentially read out, mapped to the frame (STS1) of the Sonet / SDH network, and sent to the Sonet / SDH network (EoS (OC48)).

Further, the write control unit 121 outputs a control signal to the transfer device 110 in accordance with the write state to the reassembly buffer 122. For example, when the free capacity of the reassembly buffer 122 decreases, the write control unit 121 outputs a transfer stop request to the transfer device 110 to stop the transfer of the segment. Similarly, the write control unit 123 outputs a control signal to the transfer device 110 in accordance with the state of writing to the reassembly buffer 124.

(Specific example of transfer device)
FIG. 2 is a block diagram showing a specific example of the transfer apparatus shown in FIG. As shown in FIG. 2, the transfer device 110 includes a frame analysis unit 201, a write control unit 202, a flag insertion unit 203, a segment buffer 204, a capacity monitoring unit 205, a fixed bandwidth scheduler unit 206, a read A control unit 207, an address management unit 208, a flag determination unit 209, a band monitoring unit 210, a route distribution unit 211, and an interface unit 212 are provided.

The frame analysis unit 201 receives a frame (for example, an Ether frame) from the LAN side. The frame analysis unit 201 performs frame analysis of the input frame. The frame analysis unit 201 outputs a frame length identification signal indicating the frame length of the frame obtained by the frame analysis to the write control unit 202. Further, the frame analysis unit 201 outputs the actual data obtained by the frame analysis and the in-device control signal to the flag insertion unit 203. In-device control signals include, for example, SOP (Start Of Packet) and EOP (End Of Packet).

The write control unit 202 controls data writing to the segment buffer 204. Specifically, when the frame length identification signal is output from the frame analysis unit 201, the write control unit 202 sends an address acquisition request for requesting the address of the segment buffer 204 for writing a frame to the address management unit 208. Do it. When the address is output from the address management unit 208, the write control unit 202 generates an enable to write a frame to the segment buffer 204 according to the frame length indicated by the frame length identification signal.

Also, the write control unit 202 notifies the capacity monitoring unit 205 of capacity information indicating the capacity of the frame written to the segment buffer 204 and channel information indicating the channel of the frame. The flag insertion unit 203 inserts a tail flag that identifies the end of the frame into the actual data of the frame output from the frame analysis unit 201.

The segment buffer 204 has a configuration corresponding to, for example, the segment buffer 111 shown in FIG. The segment buffer 204 stores the frame in which the tail flag has been inserted by the flag insertion unit 203 in accordance with the enable generated by the write control unit 202. For example, the segment buffer 204 stores each segment obtained by dividing a frame into segments of a predetermined length.

The capacity monitoring unit 205 has a configuration corresponding to, for example, the capacity monitoring unit 112 illustrated in FIG. The capacity monitoring unit 205 monitors the capacity of the frame written to the segment buffer 204 for each channel based on the capacity information and channel information output from the write control unit 202. Then, the capacity monitoring unit 205 asserts a read request regarding a channel with a capacity of 0 or more to the fixed band scheduler unit 206.

In addition, when the data amount read for the channel for which the read request is asserted is notified from the fixed bandwidth scheduler unit 206, the capacity monitoring unit 205 subtracts the capacity of the channel by the notified data amount. Then, when the channel capacity becomes 0, the capacity monitoring unit 205 deasserts the read request to the fixed bandwidth scheduler unit 206.

The fixed bandwidth scheduler unit 206 has a configuration corresponding to, for example, the scheduler unit 113 shown in FIG. The fixed bandwidth scheduler unit 206 allocates slots to channels based on the read request signal from the capacity monitoring unit 205 and the excess flag from the bandwidth monitoring unit 210. The fixed band scheduler unit 206 also outputs a read request for the channel to which the slot is assigned to the read control unit 207 together with the channel information at a constant period.

In addition, when the excess flag for the channel to which the slot is assigned is asserted from the bandwidth monitoring unit 210, the fixed bandwidth scheduler unit 206 releases the slot assigned to the corresponding channel. Note that the fixed bandwidth scheduler unit 206 may release part of the slots allocated to the channel corresponding to the excess flag, or may release all the slots allocated to the channel corresponding to the excess flag. .

Further, the fixed bandwidth scheduler unit 206 may release the slot after waiting for the end determination flag for the corresponding channel to be asserted from the flag determination unit 209. The fixed bandwidth scheduler unit 206 allocates the released slot to another channel for which the read request signal is asserted from the capacity monitoring unit 205.

When the read request and the channel information are output from the fixed bandwidth scheduler unit 206, the read control unit 207 outputs an address acquisition request to the address management unit 208. The address acquisition request is a control signal for requesting the address of the segment buffer 204 in which the channel segment indicated by the channel information is stored. Then, the read control unit 207 performs reading from the segment buffer 204 based on the address output from the address management unit 208. The segment read from the segment buffer 204 by the read control unit 207 is output to the flag determination unit 209.

The address management unit 208 performs address management of the segment buffer 204. Specifically, when an address request is output from write control unit 202, address management unit 208 assigns an address to the channel indicated by the address request, and outputs the assigned address to write control unit 202. The address management unit 208 manages the address assigned to the address request for each channel. Further, when an address request is output from the read control unit 207, the address management unit 208 outputs an address assigned to the channel indicated by the address request to the read control unit 207.

The flag determination unit 209 outputs the segment output from the segment buffer 204 to the route distribution unit 211. The flag determination unit 209 monitors the segment output from the segment buffer 204. When the segment output from the segment buffer 204 includes a tail flag, the flag determination unit 209 asserts the tail determination flag together with the channel information to the fixed band scheduler unit 206.

The bandwidth monitoring unit 210 has a configuration corresponding to, for example, the policer 115 illustrated in FIG. The bandwidth monitoring unit 210 monitors the transfer rate of the segment output from the flag determination unit 209 to the route distribution unit 211 for each channel. In the bandwidth monitoring unit 210, a transfer rate threshold is set for each channel. The bandwidth monitoring unit 210 asserts an excess flag for the channel whose transfer rate exceeds the threshold value to the fixed bandwidth scheduler unit 206.

The route distribution unit 211 has a configuration corresponding to, for example, the route distribution unit 114 shown in FIG. In the route distribution unit 211, a distribution route for each channel is set. The route distribution unit 211 outputs the segment output from the flag determination unit 209 to the route corresponding to the channel according to the set distribution route.

The interface unit 212 is an interface between the transfer device 110 and software. For example, the threshold of the transfer rate for each channel of the bandwidth monitoring unit 210 is set from the outside via the interface unit 212. Further, for example, a distribution route for each channel of the route distribution unit 211 is set via the interface unit 212 from the outside.

Frame analysis unit 201, write control unit 202, flag insertion unit 203, capacity monitoring unit 205, fixed band scheduler unit 206, read control unit 207, address management unit 208, flag determination unit 209, band monitoring unit 210, and route allocation The dividing unit 211 can be realized by arithmetic means such as a DSP (Digital Signal Processor).

(Transfer device operation)
FIG. 3 is a flowchart illustrating an example of the operation of the transfer apparatus. For example, the transfer device 110 repeatedly performs the following steps for each channel. Here, the operation of the transfer apparatus 110 will be described focusing on the processing in the fixed bandwidth scheduler unit 206.

First, it is determined whether or not there is a segment to be transferred in the target channel in the segment buffer 204 (step S301) and waits until it is determined that there is a segment to be transferred (step S301: No loop). For example, when the read request is asserted from the capacity monitoring unit 205, it is determined that there is a segment to be transferred, and when the read request is deasserted from the capacity monitoring unit 205, it is determined that there is no segment to be transferred.

If there is a segment to be transferred in step S301 (step S301: Yes), it is determined whether the transfer rate of the target channel is equal to or less than the threshold value of the target channel (step S302). For example, when the excess flag is not asserted from the bandwidth monitoring unit 210, it is determined that the transfer rate is equal to or lower than the threshold, and when the excess flag is asserted from the bandwidth monitoring unit 210, it is determined that the transfer rate exceeds the threshold. . If the transfer rate of the target channel exceeds the threshold (step S302: No), the process returns to step S301.

In step S302, when the transfer rate of the target channel is equal to or less than the threshold value of the target channel (step S302: Yes), it is determined whether or not there is an empty slot (step S303). If there is no empty slot (step S303: No), the process returns to step S301. If there is an empty slot (step S303: Yes), a slot is assigned to the target channel (step S304). As a result, the segment of the target channel is read from the segment buffer 204 and transferred to the mapping device 120.

Next, it is determined whether or not the transfer rate of the segment transferred to the mapping device 120 exceeds the threshold value of the target channel (step S305), and waits until the transfer rate exceeds the threshold value of the target channel (step S305: No loop). ). For example, as in step S302, when the excess flag is not asserted from the bandwidth monitoring unit 210, it is determined that the transfer rate is equal to or lower than the threshold value, and when the excess flag is asserted from the bandwidth monitoring unit 210, the transfer rate is It is determined that the threshold has been exceeded.

If the transfer rate exceeds the threshold value of the target channel in step S305 (step S305: Yes), it is determined whether the segment of the target channel has been transferred to the end of the frame (step S306), and the segment is transferred to the end of the frame. (Step S306: No loop). For example, when the end determination flag is output from the flag determination unit 209, it is determined that the segment of the target channel has been transferred to the end of the frame.

If the segment of the target channel is transferred to the end of the frame in step S306 (step S306: Yes), the slot allocated to the target channel in step S304 is released (step S307), and the series of operations is terminated. When the slot is released in step S307, the released slot is assigned to another channel in steps S301 to S304 for another channel as a target channel.

(Configuration example of transmission function from WAN to LAN in transmission apparatus)
FIG. 4 is a block diagram illustrating a configuration example of a transmission function from the WAN to the LAN in the transmission apparatus. The mapping device 120 includes segment buffers 421 and 423 and read control units 422 and 424 (WRR) as a configuration of the WAN-to-LAN transmission function in addition to the configuration of the LAN-to-WAN transmission function shown in FIG. ing.

The mapping device 120 terminates the frame received from the Sonet / SDH network (EoS (OC192)) and transfers it to the transfer device 110. Specifically, data (STS1) from the Sonet / SDH network is stored in the segment buffer 421. The data stored in the segment buffer 421 is read under the control of the read control unit 422 and transferred to the transfer device 110 (OC-xx).

Also, the mapping device 120 terminates a frame received (EoS (OC48)) from another route of the Sonet / SDH network and transfers the frame to the transfer device 110. Specifically, data (STS1) from another route of the Sonet / SDH network is stored in the segment buffer 423. The data stored in the segment buffer 423 is read under the control of the read control unit 424 and transferred to the transfer device 110 (OC-yy).

The transfer apparatus 110 includes a multiplexing unit 411 (MUX), a policer 412 and an assemble buffer 413 as a configuration of the WAN-to-LAN transmission function in addition to the configuration of the LAN-to-WAN transmission function shown in FIG. Yes. Each data read from the segment buffers 421 and 423 of the mapping device 120 is input to the multiplexing unit 411. The multiplexing unit 411 multiplexes each input data and outputs the multiplexed data (10G) to the policer 412.

The policer 412 outputs the data output from the multiplexing unit 411 to the assemble buffer 413. Further, the policer 412 monitors the transfer rate of the data output from the multiplexing unit 411 for each channel. In the policer 412, a threshold for the transfer rate is set for each channel. The policer 412 discards the data of the channel whose transfer rate has exceeded the threshold without outputting it to the assemble buffer 413. Thereby, buffer leakage in the assemble buffer 413 can be prevented.

The assemble buffer 413 stores the data output from the policer 412 by dividing it into segments. The segments stored in the assemble buffer 413 are sequentially read out and reconstructed into an Ether frame, and the reconstructed Ether frame (10G) is sent to the LAN (Ether Frame (10G)).

(Configuration example of ADM)
FIG. 5 is a block diagram illustrating a configuration example of an ADM including the transmission apparatus illustrated in FIG. In FIG. 5, the same components as those shown in FIG. In FIG. 5, a dotted arrow (Sonet / SDH format) indicates the flow of the Sonet / SDH frame, and a solid arrow (Ether (packet) format) indicates the flow of the Ethernet (packet) frame. As shown in FIG. 5, the ADM 500 includes a transmission device 100,

termination cards

510, 520, 550, 560, and switches 530, 540.

The termination card 510 (Card # 0) is an interface card that terminates a WAN (for example, a Sonet / SDH network). Specifically, the termination card 510 includes ports 511 to 514, an interface 515, and a framer 516. The framer 516 receives a frame from the WAN via the ports 511 to 514 and the interface 515, and outputs the received frame to the switch 530. The framer 516 transmits the frame output from the switch 530 to the WAN via the interface 515 and the ports 511 to 514.

The termination card 520 (Card # 1) is an interface card that terminates the WAN. The ports 521 to 524, the interface 525, and the framer 526 provided in the termination card 520 have the same configurations as the ports 511 to 514, the interface 515, and the framer 516 of the termination card 510, respectively, and thus description thereof is omitted.

The switch 530 (SSW: SonetSW) is a Sonet / SDH path level cross-connect switch. The switch 530 switches the route of each frame output from the termination card 510 and the termination card 520 and outputs the frame to the transmission apparatus 100. In addition, the switch 530 switches the route of each frame output from the transmission apparatus 100 and outputs it to the termination card 510 and the termination card 520.

The transfer device 110 and the mapping device 120 of the transmission device 100 include the components shown in FIG. 1 and the components shown in FIG. The transmission apparatus 100 converts the Sonet / SDH frame output from the switch 530 into an Ether frame and outputs the Ether frame to the switch 540. Also, the transmission apparatus 100 converts the Ether frame output from the switch 540 into a Sonet / SDH frame and outputs the frame to the switch 530.

The switch 540 (PSW: PacketSW) realizes a switch in an Ether frame (Packet) unit. The switch 540 performs route switching of each frame output from the transmission apparatus 100 and outputs the result to the termination card 550 and the termination card 560. In addition, the switch 540 performs route switching of each frame output from the termination card 550 and the termination card 560 and outputs the result to the transmission apparatus 100.

The termination card 550 (Card # 2) is an interface card that terminates a LAN (for example, an Ether network). Specifically, the termination card 550 includes an IG / EG 551 (Ingress / Egress), an interface 552, and ports 553 to 556. The frame from the transmission apparatus 100 is sent to the LAN via the IG / EG 551, the interface 552, and the ports 553 to 556. A frame from the LAN is output to the transmission apparatus 100 via the ports 553 to 556, the interface 552, and the IG / EG 551.

The termination card 560 (Card # 3) is an interface card that terminates the LAN. The IG / EG 561, the interface 562, and the ports 563 to 566 included in the termination card 560 have the same configurations as the IG / EG 551, the interface 552, and the ports 553 to 556 of the termination card 550, respectively, and thus description thereof is omitted.

(Configuration example of communication system)
6 is a diagram illustrating a configuration example of a communication system including the ADM illustrated in FIG. As shown in FIG. 6, the communication system 600 includes

WANs

610 and 620 and

LANs

630 and 640. Each of the

WANs

610 and 620 is a Sonet / SDH network. The WAN 610 includes ADMs 601 to 604 (Add / Drop Multiplexer). The WAN 620 includes ADMs 604 to 607. The ADM 604 is a branch node that connects the WAN 610 and the WAN 620.

The ADM 603 is a branch node that connects the WAN 610 (synchronous network) and the LANs 630 and 640 (private communication network). The ADM 500 shown in FIG. 5 can be applied to the ADM 603, for example. The LAN 630 includes L2 layer path changeover switches 631 to 634 (L2SW) and nodes 635 to 637. The LAN 640 includes a path changeover switch 641 (ASW) and

nodes

642 and 643.

For example, an Ether frame transmitted from the node 635 of the LAN 630 is transmitted to the ADM 603 via the path changeover switch 631, mapped to a Sonet / SDH frame, and transmitted to the WAN 610. Also, the frame destined for the node 642 transmitted from the ADM 602 of the WAN 610 is converted into an Ether frame by the ADM 603 and received by the node 642 via the path changeover switch 641.

(When the slot assignment is fixed)
As described above, the transfer apparatus 110 dynamically changes the slot assignment for each channel. Here, the case where the slot assignment to each channel is fixed will be described as a reference.

FIG. 7 shows an example of slots managed by the scheduler. As indicated by reference numeral 710 in FIG. 7, slots in the transfer apparatus 110 are designated as slot 1 to slot N. Reference numeral 720 represents an internal clock of the transfer apparatus 110. Here, the clock frequency of the internal clock 720 is set to 200 [MHz].

It is also assumed that the data bus width is 64 [bits], 1 slot is the data bus × 2 [clock], the total number of slots is N, and a maximum of 128 [bits] is transferred in each slot periodically in N slot cycles. In this case, the transfer rate from the transfer apparatus 110 to the mapping device 120 is 64 [bit] × 200 [MHz] = 12.8 [Gbps].

FIG. 8 is a diagram showing an example in which N = 220 in FIG. Reference numeral 810 in FIG. 8 indicates a channel assigned to each slot. Here, transfer apparatus 110 assigns channel Ch1 to slot 1 to slot 192, and assigns channel Ch2 to slot 193 to slot 220. As shown in FIG. 8, when N = 220, the rate for each slot is 12.8 [Gbps] /220=58.18 [Mbps].

The transfer information from the transfer device 110 to the mapping device 120 is 4 [bytes], and the GFP-F header is 8 [bytes]. In the transfer from the transfer apparatus 110 to the mapping device 120, an unused band exists depending on the frame length L of the frame to be transferred, and the transfer rate considering the unused band is the frame length L / (128 × (roundup (frame length L + (Transfer information between devices) / 128)) × 58.18 [Mbps].

Also, the effective bandwidth increment generated when GFP-F is encapsulated is (frame length L + GFP-F Header) / frame length L. Here, since the transfer information from the transfer apparatus 110 to the mapping device 120 is transferred only between devices, it is ignored during mapping. Therefore, the transfer rate is (frame length L + GFP-F Header) / (128 × (roundup (frame length L + inter-device transfer information) / 128)) × 58.18 [Mbps].

Here, as a worst case, when the frame length L is 77 [bytes], the transfer rate is 51.52 [Mbps]. Thus, when N = 220, the worst-case transfer rate is 51.52 [Mbps].

FIG. 9 is a diagram showing an example in which N = 240 in FIG. Reference numeral 910 in FIG. 9 indicates a channel assigned to each slot. Here, the transfer apparatus 110 assigns the channel Ch1 to the slots 1 to 192 and assigns the channel Ch2 to the slots 193 to 240.

As shown in FIG. 9, when N = 240, the worst-case transfer rate is 47.22 [Mbps]. Thus, when N = 240, where the number of channels increases, the transfer rate decreases. When the transfer rate to the mapping device 120 decreases, the data read from the reassembly buffers 122 and 124 underrun (depletion) in mapping of the mapping device 120 to the Sonet / SDH frame. For this reason, the frame data that should be continued when mapping is interrupted, and the transmission quality deteriorates.

On the other hand, in the transfer device 110, by dynamically changing the allocation of slots to each channel, the transfer rate for each channel can be made uniform, and slots can be efficiently shared by a plurality of channels. For this reason, underrun in the mapping device 120 can be reduced.

As described above, according to the disclosed transfer apparatus and transfer method, the transfer rate for each channel can be monitored, and the slot of the channel whose transfer rate exceeds the threshold value can be released and assigned to another channel. Thereby, the transfer rate for each channel is made uniform, and slots can be efficiently shared by a plurality of channels.

Also, by equalizing the transfer rate for each channel, underrun in the mapping device of the synchronous network can be reduced even in an oversubscription state where (user line band)> (relay line band). For this reason, synchronous network mapping can be performed stably and transmission quality can be improved.

Also, slots can be efficiently shared by multiple channels without increasing the interface speed between devices. In addition, since the frame transfer of the channel whose transfer rate exceeds the threshold is stopped, the overrun in the buffer of the mapping device can be reduced.

Also, for a channel whose transfer rate exceeds the threshold, the frame is transferred to the mapping device without being divided by releasing the slot after the end of the frame is transferred. Also, by setting the threshold for each channel, the transfer rate of each channel can be set according to the priority for each channel.

Also, by assigning slots released from channels whose transfer rate exceeds the threshold to channels to which slots among other channels are not assigned, the transfer rate for each channel can be equalized more efficiently.

Further, according to the disclosed transmission device, the same effects as the disclosed transfer device can be obtained, and underrun in mapping to the frame of the synchronous network can be reduced. For this reason, the mapping of the synchronous network to the frame can be performed stably, and the transmission quality from the local area communication network to the synchronous network can be improved.

In the above-described embodiment, the SONET / SDH network is illustrated as an example of the synchronization network. However, the present invention is not limited to the SONET / SDH network, and various synchronization networks can be applied. In the above-described embodiment, the Ether network is exemplified as the local communication network. However, the present invention is not limited to the Ether network, and various packet communication networks can be applied.

DESCRIPTION OF SYMBOLS 100 Transmission apparatus 110 Transfer apparatus 111,204,421,423 Segment buffer 112,205 Capacity monitoring part 113 Scheduler part 114,211 Route distribution part 115,412 Policer 120 Mapping device 121,123 Write control part 122,124 Assemble

buffer

422, 424 Read controller 411 Multiplexer 413 Assemble

buffer

510, 520, 550, 560 Termination card 511-514, 521-524, 553-556, 563-566

Port

515, 525, 552, 562 Interface 516 526

Framer

530, 540 Switch 600 Communication system 631 to 634, 641 Path changeover switch 635 to 637, 642, 643 Node

Claims

In the transfer device that terminates the frame received from the first communication network and transfers it to the mapping device of the synchronous network,
Storage means for storing the received frame;
Transfer means for transferring a frame stored by the storage means to the mapping device by a slot assigned to a channel of the frame;
Monitoring means for monitoring the transfer rate of the frame by the transfer means for each channel;
An allocation unit that releases a slot of a channel whose transfer rate monitored by the monitoring unit exceeds a threshold, and allocates the released slot to another channel;
A transfer device comprising:
The storage means stores the frame divided into segments,
The transfer device according to claim 1, wherein the transfer unit transfers the segment stored by the storage unit.
2. The transfer apparatus according to claim 1, wherein the allocating unit releases the slot after the end of a frame of a channel whose transfer rate has exceeded a threshold is transferred by the transfer unit.
The transfer device according to claim 1, wherein the threshold is set for each channel.
2. The transfer apparatus according to claim 1, wherein the allocating unit allocates the released slot to a channel to which a slot among the other channels is not allocated.
Storage means for storing frames received from the first communication network;
Transfer means for transferring the frame stored by the storage means by a slot assigned to the channel of the frame;
Monitoring means for monitoring the transfer rate of the frame by the transfer means for each channel;
An allocating unit that releases a slot of a channel whose transfer rate monitored by the monitoring unit exceeds a threshold and allocates the slot to another channel;
A mapping device for mapping a frame transferred by the transfer means to a frame of a synchronous network;
A transmission apparatus comprising:
In the transfer method of terminating the frame received from the first communication network and transferring it to the mapping device of the synchronous network,
A storage step of storing the received frame;
A transfer step of transferring the frame stored by the storage step to the mapping device by a slot assigned to a channel of the frame;
A monitoring step of monitoring the transfer rate of the frame by the transfer step for each channel;
An allocation step of releasing a slot of a channel whose transfer rate monitored by the monitoring step exceeds a threshold and allocating it to another channel;
A transfer method comprising: