High-dimensional optical cross-connect cloud cluster node architecture

Abstract

Methods and apparatus for a reconfigurable optical add / drop wave multiplexer (ROADM) cluster node are provided. In some embodiments, the ROADM cluster node includes a set of g line side chassis for performing line functions. In some embodiments, the ROADM cluster node also includes a set of h add / drop wave side chassis for performing add / drop wave functions. In some embodiments, each of the g line side chassis includes a set of N line cards and a set of M interconnect cards. In some embodiments, the ROADM cluster node also includes a set of M interconnect chassis, and the set of M interconnect chassis is used to interconnect each line side chassis with each other line side chassis. In some embodiments, the set of M interconnect chassis is also used to interconnect each line side chassis with each of the h add / drop wave side chassis. In some embodiments, the ROADM cluster node separates the line function and the add / drop wave function. In some embodiments, 1.15N≤M≤1.5N.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This is the first application filed for the present invention. Technical Field

[0003] The present invention relates to the field of network communications, and in particular to methods and devices related to a high-dimensional OXC cloud cluster node architecture. Background Art

[0004] Existing fiber optic networks use optical nodes including reconfigurable optical add-drop multiplexers (ROADMs) to perform various functions on light beams of different wavelengths. Among other functions, ROADMs can add, drop, and redirect wavelengths. Existing ROADMs provide limited dimensions or directions that can be applied to wavelengths for redirection. In addition, existing ROADMs provide limited add-drop rates for adding wavelengths and / or dropping wavelengths at the ROADM. As the demand for network capacity increases, existing ROADMs may not be able to meet the growing demand. In addition, optical network stakeholders, including vendors and customers, have invested heavily in existing ROADMs, which are not only expensive but also have a long lifespan.

[0005] Therefore, a method and apparatus are needed for improving the existing ROADM functions to better meet the increasing network requirements and eliminate or alleviate one or more limitations of the prior art.

[0006] This background information is provided for the purpose of revealing information believed by the applicant to be potentially relevant to the present invention. It is not necessarily intended nor should it be construed that any of the foregoing information constitutes prior art against the present invention. Summary of the invention

[0007] An object of the embodiments of the present invention is to provide a method and apparatus for a high-dimensional ROADM cluster node.

[0008] One aspect of the present disclosure provides a reconfigurable optical add-drop multiplexer (ROADM) cluster node that separates line functionality and add-drop functionality. The ROADM cluster node includes a set of g line-side chassis for performing line functionality, where each of the g line-side chassis includes a set of N line cards and a set of M interconnection cards. The ROADM cluster node further includes a set of h add-drop chassis for performing add-drop functionality. The ROADM cluster node further includes a set of M interconnection chassis that are used to interconnect each line-side chassis with each other line-side chassis and to interconnect each line-side chassis with each of the h add-drop chassis. In some embodiments, N < M. In some embodiments, 1.15N ≤ M ≤ 1.5N. In some embodiments, 1.25N < M < 1.3N. In any of the above embodiments, each add-drop chassis includes a set of X add-drop cards and a set of P interconnection cards, where P = M. In any of the above embodiments, each of the M interconnection chassis includes a set of g interconnection cards, where each of the g interconnection cards is connected to a different line-side chassis in the set of line-side chassis. In any of the above embodiments, each of the M interconnection chassis further includes a set of h interconnection cards, where each of the h interconnection cards is connected to a different add-drop chassis in the set of add-drop chassis. In any of the above embodiments, each line-side chassis includes T slots for accommodating the set of N line cards and the set of M interconnection cards such that N + M = T. In any of the above embodiments, each interconnection chassis includes S interconnection cards such that S = g + h. In any of the above embodiments, each of the N line cards includes a wavelength selective switch. In any of the above embodiments, each of the M interconnection cards includes a wavelength selective switch. In any of the above embodiments, each of the X add-drop cards includes a wavelength selective switch. In any of the above embodiments, each of the g interconnection cards and the h interconnection cards includes a wavelength selective switch. In any of the above embodiments, X = N / 2.

[0009] Another aspect of the present disclosure provides a chassis for performing one of the line function and the add-drop function of a reconfigurable optical add-drop multiplexer (ROADM) cluster node that performs the line function and the add-drop function. The chassis includes a set of M interconnect cards, where each of the M interconnect cards connects the chassis to each of a set of M interconnected chassis of the ROADM cluster node. In any of the above embodiments, when the chassis performs the line function, the chassis further includes a set of N line cards. In any of the above embodiments, when the chassis performs the add-drop function, the chassis further includes a set of N / 2 add-drop line cards. In any of the above embodiments, N < M. In some embodiments, 1.15N ≤ M ≤ 1.5N. In some embodiments, 1.25N < M < 1.3N. In any of the above embodiments, the chassis further includes T slots for accommodating the set of N line cards and the set of M interconnect cards such that N + M = T. In any of the above embodiments, the chassis further includes T slots for accommodating the set of N / 2 add-drop cards and the set of M interconnect cards such that N + M = T.

[0010] Another aspect of the present disclosure provides an interconnection chassis for interconnecting each line-side chassis in a set of line-side chassis of a reconfigurable optical add-drop multiplexer (ROADM) cluster node to each add-drop-side chassis in a set of add-drop-side chassis of the ROADM cluster node. The ROADM cluster node is configured to separate line functions and add-drop functions. The set of line-side chassis is configured to perform the line functions of the ROADM cluster node. The set of add-drop-side chassis is configured to perform the add-drop functions of the ROADM cluster node. The interconnection chassis includes a first set of interconnection cards, wherein at least one interconnection card in the first set of interconnection cards is connected to a different line-side chassis in the set of line-side chassis. The interconnection chassis further includes a second set of interconnection cards, wherein at least one interconnection card in the second set of interconnection cards is connected to a different add-drop-side chassis in the set of add-drop-side chassis. In some embodiments, each line-side chassis in the set of line-side chassis includes a set of N line cards and a set of M interconnection cards, where N < M. In some embodiments, 1.15N ≤ M ≤ 1.5N. In some embodiments, 1.25N < M < 1.3N. In any of the above embodiments, each line-side chassis in the set of line-side chassis includes T slots for accommodating the set of N line cards and the set of M interconnection cards such that N + M = T.

[0011] Embodiments have been described above in connection with aspects of the present invention, and these embodiments can be implemented based on these aspects. Those skilled in the art will understand that embodiments can be implemented in combination with the aspects describing these embodiments, but can also be implemented with other embodiments of that aspect. When embodiments are mutually exclusive or incompatible with each other, it will be obvious to those skilled in the art. Some embodiments can be described in connection with one aspect, but can also be applicable to other aspects, which is obvious to those skilled in the art. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] In conjunction with the accompanying drawings, further features and advantages of the present invention will become apparent through the following detailed description.

[0013] Figure 1 is an example of an existing chassis for a ROADM node according to an embodiment of the present invention.

[0014] Figure 2 is an illustration of an optical backplane of slots of an interconnection Figure 1 chassis according to an embodiment of the present invention.

[0015] Figure 3is a diagram of a line side chassis, an upper and lower wave side chassis, and an interconnect chassis of a ROADM cluster node according to an embodiment of the present invention.

[0016] Figure 4 A ROADM cluster node configuration according to an embodiment of the present invention is shown, the ROADM cluster node configuration comprising M interconnected chassis interconnecting g line side chassis and h drop and add wave side chassis.

[0017] Figure 5 is another illustration of a ROADM cluster node connection architecture according to an embodiment of the present disclosure.

[0018] Figure 6 The embodiment according to the present invention is shown Figure 5 The first case of a ROADM cluster node.

[0019] Figure 7 The embodiment according to the present invention is shown Figure 5 The second case of ROADM cluster nodes.

[0020] Figure 8 The embodiment according to the present invention is shown Figure 5 The third case of ROADM cluster nodes.

[0021] Fig. 9 The embodiment according to the present invention is shown Figure 5 The fourth case of ROADM cluster nodes.

[0022] Fig.10 The embodiment according to the present invention is shown Figure 5 The fifth case of ROADM cluster nodes.

[0023] Fig.11 is a diagram of a three-level asymmetric WSS interconnect connection of a ROADM cluster node according to an embodiment of the present invention.

[0024] Fig.12 is a diagram of dropping a wavelength at a ROADM cluster node according to an embodiment of the present invention.

[0025] Fig.13 is a diagram of redirecting or switching wavelengths at a ROADM cluster node according to an embodiment of the present invention.

[0026] Fig.14 is a schematic diagram of an electronic device according to different embodiments of the present invention, which can perform any or all operations and features of the above methods explicitly or implicitly described herein.

[0027] It should be noted that in all the drawings, the same features are identified by the same reference numerals. DETAILED DESCRIPTION

[0028] A ROADM is an optical node that adds, blocks, passes, or redirects light beams of various wavelengths identified by their color in a fiber optic network. ROADMs are used in systems that employ wavelength division multiplexing, allowing data traffic modulated on a wavelength to be added at a source node, then passed through one or more ROADM nodes before being dropped at a destination node. Once the data traffic is dropped, the destination node demodulates the light and decodes the data into electronic bits.

[0029] ROADM plays a key role in the exchange and transmission of large amounts of data. ROADM is characterized by two parameters: one is the number of directions (or the number of fibers), and the other is the number of wavelengths that can be added or dropped at the ROADM. Each fiber can carry a predetermined number of wavelengths (e.g., 80 wavelengths for the International Telecommunication Union (ITU) 50GHz fixed grid). Without wavelength conversion at the ROADM node, wavelength n of the fiber in direction i is dropped or switched to wavelength n in direction j.

[0030] Currently on the market, the highest dimension (i.e., the number of directions) that ROADM may provide is 8 or 16. Assuming that the number of wavelengths in each direction is 80, the number of wavelengths that can be added or dropped is limited. For example, a ROADM node such as OSN 9800 has an up / down ratio of 45% when deployed as an 8-dimensional ROADM and a 15% when deployed as a 16-dimensional ROADM. Therefore, for an 8-dimensional ROADM, with each optical fiber accommodating 80 wavelengths, the number of added / dropped wavelengths is approximately 0.45×8×80=288 wavelengths; for a 16-dimensional ROADM, the number of added / dropped wavelengths is approximately 0.15w×16×80=192 wavelengths.

[0031] One of the challenges of the prior art is that the number of dimensions or directions that ROADM can accommodate is limited. In addition, another limitation of the prior art is the low up / down rates provided by current ROADMs. As discussed in this article, the highest number of dimensions that a ROADM may have is limited to 8 or 16 dimensions. As traffic increases, ROADMs with a higher number of dimensions are needed to allow transmission in multiple different directions with corresponding flexibility and an increase in up / down rates. In addition, it should be noted that the ROADMs used in existing optical networks include chassis that are quite expensive and have a lifespan of 15 to 20 years. Both suppliers and customers of optical networks have invested a lot of money in these chassis to build ROADMs throughout the network. Therefore, suppliers and customers may be unlikely to adopt ROADM improvements that require additional investment, such as purchasing new chassis. Therefore, there is a need for a low-cost ROADM solution that is scalable in terms of dimensions and can flexibly increase the up / down rates. The low-cost ROADM solution can use existing chassis to take advantage of the long life of the chassis while keeping the cost low. Therefore, as traffic grows and optical network capacity increases, ROADM nodes with dimensions higher than 8 or 16 and flexible add / drop rates are needed to adapt and respond to the increase in traffic and optical network capacity.

[0032] The embodiments discussed herein provide a number of solutions that support increasing the number of dimensions of a ROADM to 100. The embodiments discussed herein also provide flexible up / down rates ranging from 0% to 100%. The embodiments discussed herein utilize existing chassis to increase the dimensions of a ROADM and provide flexible up / down rates. Using existing chassis can minimize investment losses in existing chassis while expanding in the future. Using existing chassis further supports continued sales of existing chassis to customers as demand grows.

[0033] In addition to the low-cost and scalable solutions provided herein, embodiments provide adequate performance in terms of wavelength blocking rate.Embodiments provide acceptable blocking rates (better than 1e-3) for a wavelength in one direction to connect to the same wavelength in another direction.

[0034] Figure 1 is an example of an existing chassis for a ROADM node according to an embodiment of the present invention. Figure 1 The chassis 100 may include 32 slots 102 for holding and / or inserting one or more line cards 104 and one or more add / drop wave tributary cards 106. Each slot 102 may be connected to an optical backplane 200 ( Figure 2 ) are fully interconnected to the other 31 slots.

[0035] The line card 104 can perform line functions as it can be interconnected to other ROADM nodes. The drop / drop tributary card 106 handles dropped wavelengths to the node or adds traffic channels on the wavelengths of the line card 104.

[0036] The total dimension of a ROADM node is the total number of fiber pairs connected to the ROADM node. Each fiber pair is connected to a line card 104, one fiber on the receive side 114 and one fiber on the transmit side 116.

[0037] Each line card 104 occupies a single slot 102 of the chassis 100. Each line card 104 (each slot 102) may include one fiber pair, indicating a bidirectional direction. The line card 104 may include two 1×32 wavelength select switches (WSS) 108, one on the receiving side 114 and the other on the transmitting side 116. The line card 104 may also include two EDFA amplifiers 110 and circuit devices for optical service channels (OSCs) 112. On the receiving side, the WSS 108 is capable of extracting all 80 wavelengths and placing each wavelength at any one of its 32 outputs. If each line card is fully interconnected with the other line cards, any one or more wavelengths received at each line card can be sent to any one or more line cards in the other line cards (directions) through one or more of the 32 outputs. Since each slot 102 can be fully interconnected to the other 32 slots, the interconnection between the slots 102 allows a full mesh interconnection between the line cards 104.

[0038] The add / drop wave branch card 106 may occupy two slots 102. The add / drop wave branch card 106 may include 24 add / drop wave ports 124, allowing up to 24 wavelengths to be added / dropped at the ROADM. Each line card 104 may be optically interconnected to each of the add / drop wave branches 106 via an optical backplane 200.

[0039] Figure 2 is an interconnect according to an embodiment of the present invention Figure 1 Figure 1.1 shows the optical backplane slots in the chassis. Figure 2, the 32 slots 102 can be represented by slots 201, 202, ..., 231 and 232. Each slot 102 can be interconnected with the other 31 slots through the optical backplane 200. For example, slot 201 is interconnected with the other 31 slots (202, ..., 231 and 232) through the optical connection established by the optical backplane. Therefore, each line card 104 placed in slot 102 can be interconnected with each other line card placed in slot 102 and each up / down wave card 104. Similarly, each up / down wave card placed in slot 102 can be interconnected with each other up / down wave card placed in slot 102 and each line card.

[0040] In some embodiments, the chassis 100 can be used to design an 8-dimensional ROADM node. For an 8-dimensional ROADM node, the chassis 100 may include 8 line cards 104 occupying 8 slots 102. The remaining 24 slots (32 total slots minus 8 slots for 8 line cards 104) can be used for 12 add / drop wave branch cards 106, each of which occupies two slots 102. Accordingly, the number of add / drop wave wavelengths of the 8-dimensional ROADM node can be 288 (12 add / drop wave branch cards * 24 wavelengths / add / drop wave branch card). Therefore, for the case where there are 96 wavelengths in each direction, the add / drop wave rate of the 8-dimensional ROADM node may be 37.5% = (288 wavelengths / (8 line cards × 96 wavelengths / line card)). For the case of 80 wavelengths in each direction, the up / down ratio of an 8-dimensional ROADM node may be 45% = (288 wavelengths / (8 line cards x 80 wavelengths / line card)).

[0041] In other embodiments, the chassis 100 can be used to design a 16-dimensional ROADM node. For a 16-dimensional ROADM node, the chassis 100 may include 16 line cards 104 occupying 16 slots 102. The remaining 16 slots (32 total slots minus 16 slots for 16 line cards 104) can be used for 8 add / drop wave branch cards 106, each of which occupies two slots 102. Accordingly, the number of add / drop wave wavelengths of the 16-dimensional ROADM node can be 192 (8 add / drop wave branch cards * 24 wavelengths / add / drop wave branch card). Therefore, for a case where there are 96 wavelengths in each direction, the add / drop wave rate of the 16-dimensional ROADM node may be 12.5% ​​= (192 wavelengths / (16 line cards × 96 wavelengths / line card)). For the case of 80 wavelengths in each direction, the up / down rate of a 16-dimensional ROADM node may be 15% = (192 wavelengths / (16 line cards x 80 wavelengths / line card)).

[0042] The input wavelength can be dropped by the add / drop card 106 of the ROADM. The wavelength arriving at the line card of the ROADM is transmitted to the appropriate add / drop card 106 for dropping through the backplane 200. The wavelength is then dropped through one of the add / drop ports 124 that can be connected to the router.

[0043] The wavelengths may also be up-converted to the output wavelengths of the ROADM through the add / drop card 106. A router connected to the add / drop port 124 may send data to the up / drop card to be up-converted to the output wavelengths of the ROADM as wavelengths. Data may enter the add / drop card 106 through the add / drop port 124 and be converted to light and carried on the assigned wavelengths. The wavelengths may then be transmitted to the appropriate line card 104 through the optical backplane 200 to be sent at the assigned wavelength in the appropriate direction (associated with the line card).

[0044] Embodiments disclosed herein provide a ROADM cluster node that allows for a low-cost, scalable, and feasible solution for next-generation ROADM nodes. The ROADM cluster node can be built using an existing chassis (e.g., chassis 100). Using an existing chassis allows for reusability and flexibility, providing customers with the ability to pay for additional capacity as needed. Therefore, the size can be paid for as the line and up and down wave side chassis are increased. The ROADM cluster node can be described as follows.

[0045] As about Figure 1 As discussed, the ROADM cluster node is based on the separation of node functions (line functions and add / drop functions) that are currently performed in the same chassis. The ROADM cluster node may perform node functions in separate chassis, where each chassis performs a different function. The ROADM cluster node may have at least one chassis for line functions, where the chassis may be referred to as a line side chassis or a line node. The ROADM cluster node may have at least one chassis for add / drop functions, where the chassis may be referred to as an add / drop side chassis or an add / drop node.

[0046] The ROADM cluster node may also include at least one chassis (which may be referred to as an interconnect or interconnect chassis) for interconnecting at least one chassis (line side chassis or upper and lower wave side chassis) to at least one other chassis (line or upper and lower wave side chassis). Thus, the interconnect chassis may interconnect the line side chassis as well as the line side chassis and the upper and lower wave side chassis. In some embodiments, there may be more than one line side chassis without an upper and lower wave side chassis, wherein the interconnect chassis interconnects the line side chassis. The interconnect chassis itself may be a separate chassis, separate from the line side chassis and the upper and lower wave side chassis.

[0047] The ROADM cluster node has a connection manager server that deploys an algorithm that efficiently routes connections between ROADM chassis. There may be 3 types of connections: line to line, line to drop wave, and drop wave to line. The algorithm ensures non-blocking or acceptably low blocking better than 0.001. The execution time of the algorithm is preferably minimized. The present disclosure focuses on the architecture of the ROADM cluster node and the algorithm is not within its scope.

[0048] Figure 3 is a diagram of a line side chassis, an upper and lower wave side chassis, and an interconnect chassis of a ROADM cluster node according to an embodiment of the present disclosure.

[0049] refer to Figure 3 As discussed herein, a ROADM cluster node may include three sets of chassis: a first set of at least one line-side chassis 302 for performing line functions (i.e., wherein at least one line-side chassis does not have add / drop functions); a second set of at least one add / drop wave-side chassis 304 for performing add / drop wave functions (i.e., wherein at least one add / drop wave-side chassis does not have line functions); and a third set of at least one interconnect chassis 306. In some embodiments, at least one line-side chassis 302 performs exclusively line functions. Similarly, in some embodiments, at least one add / drop wave-side chassis 304 performs exclusively add / drop wave functions.

[0050] The line side chassis 302 may include 32 slots 308 for accommodating WSS components including N line cards and M interconnect cards. Each line card may be similar to the line card 104. Each interconnect card may be a dual 1×32 WSS card. Some of these line cards may be used as line cards for connecting to external nodes (i.e., other ROADMs). The remaining line cards may be used for internal connections with other nodes of the ROADM cluster node. In some embodiments, the line side chassis 302 including 32 slots may include 32 cards. N of the 32 cards may be line cards, and M=32–N of the 32 cards may be interconnect cards. Line cards and interconnect cards are identical in terms of hardware, but their functions are different. Line cards are used for interconnection between ROADM cluster nodes and other ROADM nodes, while interconnect cards are used for internal connections between chassis within the ROADM cluster node, and internal connections refer to the above three types of connections between the line side chassis and the upper and lower wave side chassis of the ROADM cluster node.

[0051] Interconnect cards may be used to interconnect the line side chassis 302 to each interconnect chassis 306. The line side chassis 302 may include the same chassis 100 as described herein. The line side chassis 302 may also include an optical backplane similar to the optical backplane 200 to interconnect the line cards and the interconnect cards.

[0052] The upper and lower wave side chassis 304 may include 32 slots 310 for accommodating WSS components including N / 2 upper and lower wave cards and M interconnect cards. It should be noted that the N / 2 value is based on the size of the existing upper and lower wave cards having twice the width of the slot 310. Therefore, the number of upper and lower wave cards depends on the size of the upper and lower wave cards. Considering that the chassis includes 32 slots with M interconnect cards, the upper and lower wave side chassis can accommodate 32-M slots for accommodating upper and lower wave cards. Therefore, for upper and lower waves that may only occupy one slot, the upper and lower wave side chassis may include 32-M=N upper and lower wave cards.

[0053] Each add / drop wave card may be similar to the add / drop wave card 106, and each interconnect card may be a dual 1×32 WSS card. The add / drop wave tributary card is a transponder card tuned to the wavelength that needs to be added / dropped at the ROADM cluster node. The interconnect card may be used to interconnect the add / drop wave side chassis 304 to each interconnect chassis 306. The add / drop wave side chassis 304 may include the same chassis 100 described herein. The add / drop wave side chassis 304 may also include an optical backplane similar to the optical backplane 200 to interconnect the add / drop wave card and the interconnect card.

[0054] An interconnect node or chassis, such as interconnect chassis 306, is used for internal connections between components of the cluster node (i.e., line side chassis and upper and lower wave side chassis). Interconnect chassis 306 may include S slots for accommodating WSS components including S interconnect cards. Interconnect chassis 306 may also include an optical backplane for interconnecting each interconnect card to other S-1 interconnect cards. In some embodiments, the interconnect chassis may be a chassis similar to that used for the line side chassis, such as chassis 100, but such a chassis may be an expensive option. In other embodiments, the interconnect chassis may use a common equipment low-cost chassis, which may be based on a dual 1×16 WSS (which may be referred to as an interconnect card). In this case, S may be 16, and therefore, the interconnect chassis may include 16 slots, each slot corresponding to a dual 1×16 WSS. Therefore, the interconnect chassis may include 16 1×16 WSS cards and is referred to as a 16×16 WSS. The interconnect card may provide interconnection between at least one line side chassis 302 and at least one upper and lower wave side chassis 304 of the ROADM cluster node. In some embodiments, the S interconnect cards may include g interconnect cards and h interconnect cards, wherein each of the g interconnect cards is connected to one of the g line-side chassis, and each of the h interconnect cards is connected to one of the h upper and lower wave-side chassis. Therefore, S=g+h, where g is the number of interconnect cards connected to the line-side chassis, and h is the number of interconnect cards connected to the upper and lower wave-side chassis. In some embodiments, there may be g line-side chassis and h upper and lower wave-side chassis, and one interconnect card may be used to connect to each chassis, for example Figure 4In other embodiments, one or more interconnect cards may be used to connect to each of the line-side chassis or the upper and lower wave-side chassis.

[0055] Figure 4 The ROADM cluster node configuration provided by an embodiment of the present invention is shown. The ROADM cluster node configuration includes M interconnected chassis that interconnect g line side chassis and h add / drop wave side chassis.

[0056] refer to Figure 4 , the ROADM cluster node 400 may include M interconnect chassis 406, including interconnect chassis 420, 422, and 424. Each of the M interconnect chassis 406 may be an interconnect chassis 306 as described herein. The ROADM cluster node 400 may also include g line side chassis 402, including line side chassis 412 and 414. Each of the g line side chassis 402 may be a line side chassis 302 as described herein. The ROADM cluster node 400 may also include h upper and lower wave side chassis 404, including upper and lower wave side chassis 416 and 418. Each of the h upper and lower wave side chassis 404 may be an upper and lower wave side chassis 304 as described herein.

[0057] Each of the g line side chassis 402 may include N line cards 432 and M interconnect cards 434 for N input and output optical fibers. Each of the h up / down wave side chassis 404 may include M interconnect cards 435 and N / 2 up / down wave cards. As discussed elsewhere herein, the N / 2 value may be different if the size of the up / down wave cards varies, for example, if each up / down wave card occupies only one slot, each of the h up / down wave side chassis 404 may include M interconnect cards 435 and N up / down wave cards. Each of the M interconnect chassis 406 may include S interconnect cards 436 for interconnecting each of the g line side chassis 402 and each of the h up / down wave side chassis 404.

[0058] Each of the M interconnect cards 434 of each of the g line-side chassis 402 may be connected to each of the M interconnect chassis 406 via an optical fiber 438 (shown as a solid line). Similarly, each of the M interconnect cards 435 of each of the h upper and lower wave-side chassis 404 may be connected to each of the M interconnect chassis 406 via an optical fiber 440 (shown as a dashed line).

[0059] The ROADM cluster node architecture provides two levels of interconnection. The first level of interconnection can be an intra-chassis or internal connection level, which can be an optical backplane in each line side chassis, upper and lower wave side chassis, and interconnect chassis described herein. The second level of interconnection can be an inter-chassis or interconnection level, which can be each interconnect chassis in the M interconnect chassis 406, interconnecting each line side chassis in the g line side chassis 402 with each upper and lower wave side chassis in the h upper and lower wave side chassis 404.

[0060] The ROADM cluster node 400 may also include a cloud controller 408, which may be referred to as a cluster controller, for controlling the operation of the entire ROADM cluster node 400. The cluster / cloud controller 408 may be used for cloud ROADM control software. The cluster controller 408 may determine the routing and scheduling of connections by maintaining statistics of all connections of the ROADM cluster node. The cluster controller 408 may also determine the routing and scheduling of connections by transmitting management messages to all line-side chassis and add / drop wave-side chassis to establish new connections, such as connections from one chassis (line or add / drop wave) to another chassis (line or add / drop wave), or release existing connections between any two chassis of the cluster.

[0061] Each of the g line side chassis 402 may have a corresponding chassis controller, including line side chassis controllers 413 and 415. Each of the h upper and lower wave side chassis 404 may have a corresponding chassis controller, including upper and lower wave side chassis controllers 417 and 419. Each of the M interconnected chassis 406 may have a corresponding chassis controller, including interconnected chassis controllers 421, 423, and 425. The cluster controller 408 may be connected 410 to and send instructions to each of the g line side chassis controllers, including chassis controllers 413 and 415, each of the h upper and lower wave side chassis controllers, including chassis controllers 417 and 419, and each of the M interconnected chassis controllers, including chassis controllers 421, 423, and 425. Accordingly, the cluster controller and chassis controller provide two levels of control, one at the cluster level and one at the chassis level. At the chassis level, the chassis controller may receive instructions from the cluster controller 408 and operate the chassis according to the received instructions.

[0062] Accordingly, the ROADM cluster node 400 architecture may be based on the following considerations. M may refer to the number of low-cost, common equipment interconnect chassis 306. N may refer to the number of fibers or dimensions of each line side chassis in the g line side chassis 402. M plus N equals the total number of WSS components that the line side chassis 302 can support. For a given chassis size, such as 32 slots, the relationship between M and N is controlled by M+N=32. G plus h is the total number of interconnect cards that each of the M interconnect chassis 406 can support. In other words, g+h=S, where S may be 16 for low-cost, common equipment interconnect chassis. Therefore, g+h=16. Based on the considerations mentioned, the ROADM cluster node 400 may have a total number of dimensions of g line side chassis multiplied by N (i.e., the number of dimensions of each line side chassis 302). In other words, the total number of dimensions of the ROADM cluster node 400 may be g*N. The up and down waves of the ROADM cluster node 400 may be determined by the parameter h.

[0063] It should be noted that the values ​​chosen for parameters M and N may have cost and performance impacts. First, this disclosure examines the classic constraints that allow non-blocking performance, also known as the CLOS architecture. Then, this disclosure will describe proposed constraints that improve cost and expansion with minimal performance impact.

[0064] Given the relationship between the parameters as described above, an embodiment provides a relationship between M and N. In one embodiment, a 3-level CLOS relationship is applied to the proposed ROADM cluster node architecture as described herein. As described herein, the proposed ROADM cluster node architecture is based on separating the functions of the line card and the upper and lower wave cards currently combined in one chassis into separate g line side chassis 402 and h upper and lower wave side chassis 404, and using M interconnect chassis 406 to interconnect the separated g line side chassis and h upper and lower wave side chassis. The CLOS relationship is as follows: M≥2N–1. Solving for variables M and N, where M+N=32 and M≥2N–1, then M can be equal to 21 and N is equal to 11. Accordingly, a ROADM cluster node satisfying the CLOS relationship can have M or 21 common equipment interconnect chassis in each line side chassis, and N or 11 dimensions or line cards (optical fiber pairs for input and output traffic). In addition, such a ROADM cluster node can provide g*N dimensions. Given the relationship g+h=16, the dimensionality of the ROADM cluster node of the CLOS relationship can range from 88 dimensions to 176 dimensions. For any center-level allocation algorithm, the blocking probability of the ROADM cluster node architecture based on CLOS is zero.

[0065] Table 1: Possible dimensions of the proposed ROADM cluster node configuration and the corresponding range of uplink and downlink rates based on different combinations of g and h under the CLOS relationship

[0066]

[0067] Table 1 refers to the proposed cluster nodes using CLOS-based rules for the relationship between N and M. As shown in Table 1: In the case of g = 8 and h = 8, the CLOS-based ROADM cluster nodes provide 88 dimensions with an up / down wavelength rate of 100%; in the case of g = 10 and h = 6, the CLOS-based ROADM cluster nodes provide 110 dimensions with an up / down wavelength rate of 60%; in the case of g = 12 and h = 4, the CLOS-based ROADM cluster nodes provide 132 dimensions with an up / down wavelength rate of 33%; in the case of g = 14 and h = 2, the CLOS-based ROADM cluster nodes provide 154 dimensions with an up / down wavelength rate of 14%; in the case of g = 16 and h = 0, the CLOS-based ROADM cluster nodes provide 176 dimensions with an up / down wavelength rate of 0%.

[0068] In another embodiment, a relationship between M and N is proposed such that the ROADM cluster nodes can provide ROADM cluster nodes with higher dimensions than the CLOS-based ROADM cluster nodes, as well as significant cost and scalability advantages.

[0069] The first proposed relationship between M and N based on optimizing performance and reducing associated costs can be 1.25N < M < 1.3N or simply M < 1.3N. The ROADM cluster nodes based on the second proposed relationship can be referred to as enhanced ROADM cluster nodes. Similarly, solving for the variables M and N, where M + N = 32 and 1.25N < M < 1.3N, then M can be equal to 18 and N equal to 14. Accordingly, the enhanced ROADM cluster nodes satisfying the second proposed relationship can have M or 18 common device interconnection chassis in each line-side chassis, and N or 14 dimensions or line cards (fiber pairs for input and output traffic). In addition, the enhanced ROADM cluster nodes can provide g*N dimensions or directions. Given g + h = 16, the range of dimensions or directions of the enhanced ROADM cluster nodes can be from 112 dimensions to 224 dimensions. The blocking performance of the ROADM cluster nodes based on the first proposed relationship and the use of the algorithm discussed in another disclosure is 10^(–5) or 0.00001.

[0070] The second proposed relationship between M and N can be as follows: 1.15N ≤ M ≤ 1.5N. The second proposed relationship is not as optimized in terms of performance and cost as the first proposed relationship because, compared to the first relationship, M < 1.15 may provide reduced performance, while M > 1.5N may result in increased costs. However, embodiments using the range between the first relationship and the second relationship can still provide reasonable performance at a reasonable cost.

[0071] When comparing the enhanced ROADM cluster node with the CLOS-based ROADM cluster node, it can be observed that the enhanced ROADM cluster node provides a lower M value than the CLOS-based ROADM cluster node. A lower M value indicates a smaller number of common devices (such as interconnection chassis), and thus a smaller size of the ROADM cluster node, which provides both scalability and cost-effectiveness. In addition, the enhanced ROADM cluster node provides a higher N value than the CLOS-based ROADM cluster node. A higher N value means that a higher number of dimensions per line-side chassis can be obtained using the enhanced ROADM cluster node compared to the CLOS-based ROADM cluster node, as shown in Table 2.1 below.

[0072] Table 2.1: Possible dimensions and corresponding ranges of up / down conversion rates of the enhanced ROADM cluster node based on different combinations of g and h

[0073]

[0074] As shown in Table 2.1: In the case of g = 8 and h = 8, the enhanced ROADM cluster node provides 112 dimensions with an up / down conversion rate of 100%; in the case of g = 10 and h = 6, the enhanced ROADM cluster node provides 140 dimensions with an up / down conversion rate of 60%; in the case of g = 12 and h = 4, the enhanced ROADM cluster node provides 168 dimensions with an up / down conversion rate of 33%; in the case of g = 14 and h = 2, the enhanced ROADM cluster node provides 196 dimensions with an up / down conversion rate of 14%; in the case of g = 16 and h = 0, the enhanced ROADM cluster node provides 224 dimensions with an up / down conversion rate of 0%.

[0075] When comparing Table 2.1 with Table 1, it can be observed that the second proposed relationship 1.25N < M < 1.3N or simply M < 1.3N (enhanced ROADM cluster node) has an advantage over the CLOS relationship M ≥ 2N – 1 (CLOS-based ROADM cluster node). The proposed relationships (first and second) provide an increased number of dimensions for the same number of line-side chassis g and up / down-side chassis h in the CLOS relationship and a reduced number of interconnection chassis M. In some embodiments, the number of dimensions is increased by approximately 27% in the second proposed relationship compared to the CLOS relationship.

[0076] In another embodiment, where M + N = 16 (refer to 1×16 WSS chassis), the second proposed relationship 1.25N < M < 1.3N can provide M equal to 9 and N equal to 7. Accordingly, an enhanced ROADM cluster node that satisfies the second proposed relationship can have M or 9 common device interconnect chassis in each line-side chassis, and N or 7 dimensions or line cards (fiber pairs for input and output traffic). Table 2.2 provides the range of dimensions and corresponding up / down wavelength rates of the enhanced ROADM cluster node based on different combinations of g and h, where N = 7 and M = 9.

[0077] Table 2.2: Range of possible dimensions and corresponding up / down wavelength rates of the enhanced ROADM cluster node based on different combinations of g and h

[0078]

[0079] As shown in Table 2.2: In the case of g = 8 and h = 8, the enhanced ROADM cluster node provides 112 dimensions with an up / down wavelength rate of 100%; in the case of g = 10 and h = 6, the enhanced ROADM cluster node provides 70 dimensions with an up / down wavelength rate of 60%; in the case of g = 12 and h = 4, the enhanced ROADM cluster node provides 84 dimensions with an up / down wavelength rate of 33%; in the case of g = 14 and h = 2, the enhanced ROADM cluster node provides 98 dimensions with an up / down wavelength rate of 14%; in the case of g = 16 and h = 0, the enhanced ROADM cluster node provides 112 dimensions with an up / down wavelength rate of 0%.

[0080] Figure 5 is another illustration of the ROADM cluster node connection architecture provided according to an embodiment of the present disclosure. Refer to Figure 5 and the ROADM cluster node 500 can be similar to Figure 4The ROADM cluster node 400 of the present invention. The ROADM cluster node 500 may include g line side chassis 502 (similar to 402), including line side chassis 512, 513 and 514. Each of the g line side chassis 502 may be the line side chassis 302 (without wave add / drop function) as described herein. The ROADM cluster node 500 may also include h wave add / drop side chassis 504 (similar to 404), including wave add / drop side chassis 516, 517 and 518. Each of the h wave add / drop side chassis 504 may be the wave add / drop side chassis 304 as described herein. The ROADM cluster node 500 may also include M interconnect chassis 506 (similar to 406), including interconnect chassis 520, 522 and 524. Each of the M interconnect chassis 506 may be the interconnect chassis 306 (without line function) as described herein. Each of the M interconnect chassis 506 interconnects each of the g line side chassis 502 with each of the h upper and lower wave side chassis 504. The same g line side chassis 502 are shown on both sides of the M interconnect chassis 506 as an expanded architecture, indicating two fiber connections 538 from each of the g line side chassis 502 to each of the M interconnect chassis 506, shown as solid lines. The two fiber connections represent a fiber pair, one fiber for connection of input traffic and one fiber for connection of output traffic. Each of the g line side chassis can include M interconnect cards 534 (similar to 434) for connecting to each of the M interconnect chassis 506. In addition, each of the g line side chassis 502 can also include N line cards 532 (similar to 432), indicating the N directions that each of the g line side chassis 502 can support.

[0081] Similarly, identical h up / down waveside chassis 504 are shown on either side of the M interconnect chassis 506, indicating two fiber connections 540, shown as dashed lines, from each of the h up / down waveside chassis 504 to each of the M interconnect chassis 506. The two fiber connections represent one connection for adding traffic and one connection for dropping traffic. Each of the h up / down waveside chassis may also include M interconnect cards 535 (similar to 435) for connecting to each of the M interconnect chassis 506.

[0082] Each of the M interconnected chassis 506 may include S interconnected cards 536 (similar to 436) for interconnecting each of the g line-side chassis 502 and each of the g up / down conversion side chassis 504. It should be noted that the CLOS relationship N = 2M - 1, and the second proposed relationship 1.25N < M < 1.3N or simply M < 1.3N can be applied to the ROADM cluster node 500, similar to that applied to the ROADM cluster node 400.

[0083] Figure 6 Shows a first case of a Figure 5 ROADM cluster node according to an embodiment of the present invention. The ROADM cluster node 600 is Figure 5 An embodiment of a ROADM cluster node, where both parameters g and h are set to 8. Thus, the ROADM cluster node 600 may include M interconnected chassis 606, 8 line-side chassis 602, and 8 up / down conversion side chassis 604. It should be noted that the values selected for g and h are based on commonly used low-cost devices used as interconnected chassis, where the low-cost commonly used devices include 16×16 WSS 306, such that g + h = S = 16. Applying the second proposed relationship 1.25N < M < 1.3N or simply M < 1.3N to the ROADM cluster node 600, where M + N = 32, N = 14, and M = 18, results in the following shown in Table 3.

[0084] Table 3: Enhanced ROADM cluster node, having 8 line-side chassis and 8 up / down conversion side chassis, which also reflects

[0085] The first case of

[0086]

[0087] As shown in Table 3, on this ROADM cluster node, the total number of channels, i.e., the total number of connections: 17920 connections. The total number of connections is based on the total number of channels of the up-conversion and down-conversion at this ROADM cluster node. The total number of channels for down-conversion is 112 * 80 = 8960, and the total number of channels for up-conversion (down-conversion to line connection) is 8960. Therefore, the total number of connections is 8960 + 8960 = 17920. It should be noted that each connection can be bidirectional, for example, (west to up-conversion) and (down-conversion to east).

[0088] Figure 7 Shows a second case of a Figure 5 ROADM cluster node according to an embodiment of the present invention. The ROADM cluster node 700 is Figure 5An embodiment of the ROADM cluster node, where parameter g is set to 10 and parameter h is set to 6. Thus, the ROADM cluster node 700 may include M interconnected chassis 706, 10 line-side chassis 702, and 6 add-drop-side chassis 704. Applying the second proposed relationship 1.25N < M < 1.3N or simply M < 1.3N to the ROADM cluster node 700, where M + N = 32, N = 14, and M = 18, yields the following results shown in Table 4.

[0089] Table 4: Enhanced ROADM cluster node with 10 line-side chassis and 6 add-drop-side chassis, which also reflects

[0090] the second case of Table 2.1

[0091]

[0092] Figure 8 Shows a third case of the Figure 5 ROADM cluster node according to an embodiment of the present invention. The ROADM cluster node 800 is Figure 5 An embodiment of the ROADM cluster node, where parameter g is set to 12 and parameter h is set to 4. Thus, the ROADM cluster node 800 may include M interconnected chassis 806, 12 line-side chassis 802, and 4 add-drop-side chassis 804. Applying the second proposed relationship 1.25N < M < 1.3N or simply M < 1.3N to the ROADM cluster node 800, where M + N = 32, N = 14, and M = 18, yields the following results shown in Table 5.

[0093] Table 5: Enhanced ROADM cluster node with 12 line-side chassis and 4 add-drop-side chassis, which also reflects

[0094] the third case of Table 2.1

[0095]

[0096] Fig. 9 Shows a fourth case of the Figure 5 ROADM cluster node according to an embodiment of the present invention. The ROADM cluster node 900 is Figure 5An embodiment of the ROADM cluster node, where parameter g is set to 14 and parameter h is set to 2. Thus, the ROADM cluster node 900 may include M interconnected chassis 806, 14 line-side chassis 902, and 2 add / drop-side chassis 904. Applying the second proposed relationship 1.25N < M < 1.3N or simply M < 1.3N to the ROADM cluster node 900, where M + N = 32, N = 14, and M = 18, yields the following results shown in Table 6.

[0097] Table 6: Enhanced ROADM cluster node with 14 line-side chassis and 2 add / drop-side chassis, which also reflects

[0098] the fourth case of Table 2.1

[0099]

[0100] Fig.10 shows an embodiment of the Figure 5 ROADM cluster node according to an embodiment of the present invention. The ROADM cluster node 1000 is Figure 5 an embodiment of the ROADM cluster node, where parameter g is set to 16 and parameter h is set to 0. Thus, the ROADM cluster node 1000 may include M interconnected chassis 806, 16 line-side chassis 1002, and 0 add / drop-side chassis. Applying the second proposed relationship 1.25N < M < 1.3N or simply M < 1.3N to the ROADM cluster node 900, where M + N = 32, N = 14, and M = 18, yields the following results shown in Table 7.

[0101] Table 7: Enhanced ROADM cluster node with 14 line-side chassis and 2 add / drop-side chassis, which also reflects

[0102] the fourth case of Table 2.1

[0103]

[0104] The following Table 8 is a summary of Tables 3 to 7, listing the characteristics of the proposed ROADM cluster node architectures in multiple deployment scenarios.

[0105] Table 8: Summary of Tables 3 to 7, illustrating the characteristics of the proposed ROADM cluster node architectures in multiple deployment scenarios

[0106]

[0107] Referring to Table 8, Case 1 features a ROADM cluster node with 112 dimensions (112 fiber inputs and 112 fiber outputs, 80 wavelengths per fiber), where all wavelength connections are dropped (terminated) at the node and new connections originate from the node. On the other hand, Case 5 has no terminated or uplinked connections because all wavelengths are switched to other fibers in other directions. Cases 1 and 5 may not be deployed, but they provide corner cases for performance analysis.

[0108] It should be noted that although even numbers are used for different combinations of g and h in Table 8, it should be noted that g and h can also be odd numbers as long as the relationship g+h=S is satisfied, where S is 16 for low-cost and commonly used equipment.

[0109] As discussed herein, the proposed ROADM cluster nodes 400, 500 feature a collection of many nodes (line side chassis, up and down wave side chassis, and interconnect chassis) and a cluster controller 408 that instructs each node controller so that connections between the inputs and outputs of the cluster nodes can be established.

[0110] Embodiments provide an optical cluster node architecture, including a plurality of functional nodes interconnected to each other through an interconnect node array. The functions of the optical cluster node can be distributed between the nodes (as opposed to all functions being in the same node). The functions can be performed by one or more nodes. In addition, the interconnection bandwidth between the functional nodes and the interconnection nodes can be expanded by no more than 30%.

[0111] An example of an optical cluster node is a ROADM cluster node 400, 500 (or a wavelength cross-connect cluster node) as described herein. The functions of line, add and drop waves can be distributed in the nodes of the ROADM cluster node. Each node can be a wavelength cross-connect built by WSS. Although the line nodes and the add and drop wave nodes are separate, they can be interconnected by low-cost wavelength cross-connect (WXC) nodes. The bandwidth of the line or add and drop wave node connected to the WXC node (and vice versa) does not exceed 1.3 times the node bandwidth (i.e., no more than 30% expansion). The connection blocking of the ROADM cluster node can be zero or acceptably very low because the existing connections will not be rearranged to accommodate the new connection between two functional nodes through the interconnection node. It should be noted that the functional nodes include line nodes, add and drop wave nodes and / or interconnection nodes.

[0112] Although the concept of a ROADM cluster node as described in this paper is novel, its differences on various optical node architectures including 3-stage optical switches and existing ROADM nodes can be described.

[0113] Table 9 below shows the features of the proposed ROADM cluster node (eg, cluster node 400 or 500). It should be noted that the interconnection of the ROADM functions in the proposed cluster node is performed by a WSS optical switch.

[0114] Table 9: Characteristics of the proposed ROADM cluster nodes

[0115]

[0116] It should be noted that in optical networks, rearrangement of existing connections is usually not allowed because rearrangement may affect the service. Therefore, non-blocking ROADM without rearrangement is the preferred method.

[0117] Referring to Table 9, the cluster node 400 or 500 architecture provides separation or distribution of line cards and up and down wave cards with zero or minimal blocking. The cluster node provides scalability by varying the values ​​selected for parameters g and h, as described herein.

[0118] The cluster node 400 or 500 provides a multi-level (three-level) WSS interconnection connection. The three levels can be a receiving level, an intermediate level or an interconnection level, and an exit level. At the receiving level, light can enter the cluster node at the receiving chassis. At the intermediate or interconnection level where the receiving chassis is connected to the exit chassis, light is passed from the receiving chassis to the exit chassis through the interconnection chassis. At the exit chassis, light leaves the cluster node. The receiving chassis and the exit chassis are connected to the interconnection chassis via optical fibers. At each level, light passes through two WSS components and an optical backplane connecting the two WSS components. Therefore, the light passing through the cluster node can pass through six WSS components and three optical backplanes. Between the receiving chassis and the interconnection chassis, light passes through the optical fiber connecting the two chassis. Similarly, between the interconnection chassis and the exit chassis, light passes through the optical fiber connecting the two chassis.

[0119] The light may enter the cluster node through a receiving WSS component of a receiving chassis. The receiving WSS component may be a line card or a wave-adding portion of a wave-adding and wave-adding card. If the line card and wave-adding and wave-adding card functions are separated in the cluster node, i.e., in separate chassis, then in the case where the receiving WSS component is a line card, the receiving chassis is the line side chassis 302. Similarly, in the case where the receiving WSS component is the wave-adding portion of a wave-adding and wave-adding card, the receiving chassis is the wave-adding and wave-adding side chassis 304.

[0120] After entering the cluster node, light can leave the cluster node through the egress WSS component of the egress chassis. If the line card and the multiplexer / demultiplexer functions are separated in the cluster node, i.e., in separate chassis, then when the egress WSS component is the line card, the egress chassis is the line-side chassis 302. Similarly, when the egress WSS component is the demultiplexing part of the multiplexer / demultiplexer, the egress chassis is the multiplexer / demultiplexer-side chassis 304. Between the ingress WSS component and the egress WSS component, light can pass through four WSS components, which can be four interconnection cards.

[0121] The first interconnection card can be the second WSS component of the ingress chassis (the first WSS component is the ingress WSS component). The ingress WSS component and the first interconnection card (the second WSS component) of the ingress chassis are interconnected through an optical backplane. The second and third interconnection cards can be the first and second WSS components of the interconnection chassis 306 that connects the ingress chassis and the egress chassis. The second and third interconnection cards of the interconnection chassis 306 are interconnected through the optical backplane of the interconnection chassis. The fourth interconnection card can be the first WSS component of the egress chassis, and the second WSS component of the egress chassis is the egress WSS component. The fourth interconnection card (the first WSS component) and the egress WSS component of the egress chassis are interconnected through the optical backplane of the existing chassis.

[0122] The ingress WSS component can be the line card of the line-side chassis 302, where light is demultiplexed or redirected (its direction is changed) at the egress WSS component of the cluster node. In the case where light is demultiplexed, the egress WSS component can be the multiplexer / demultiplexer of the multiplexer / demultiplexer-side chassis 304. In the case where light is redirected, the egress WSS component can be another line-side chassis or another line card of the same line-side chassis.

[0123] When light is multiplexed at the cluster node, the ingress WSS component can be the multiplexer / demultiplexer of the multiplexer / demultiplexer-side chassis. In this case, the egress WSS component can be the line card of the line-side chassis to which light is multiplexed.

[0124] Referring to Table 9, the cluster nodes 400, 500 can provide the following component sizes: at least one line-side chassis can be an N×M WSS; at least one interconnection chassis can be an S×S WSS, where S is arbitrary (i.e., S can be 16, referring to the low-cost common device 16×16 WSS); at least one multiplexer / demultiplexer-side chassis can be an M×N WSS. As described herein, the cluster node provides a three-stage WSS interconnection, where the architecture provides asymmetric first and last stage WSSs (the first stage is N*M, the last stage is M*N), where N < M ≤ 1.3*N, as described herein.

[0125] Furthermore, the proposed cluster node provides a reasonably low or acceptable blocking of less than 10^(–5) without rearranging existing connections to accommodate new connections between two functional nodes. Furthermore, the proposed cluster node can allow two levels of control, namely, a cluster controller at the cluster level and a chassis controller at the chassis level, as discussed in this paper.

[0126] Fig.11 FIG. 1 is a diagram of a three-level asymmetric WSS interconnect connection of a ROADM cluster node according to an embodiment of the present invention. Fig.11 , each line side chassis 1102 of the g line side chassis of the cluster node 400 or 500 may include N line cards 1108 and M interconnection cards 1110. Each line card of the N line cards 1108 may be optically interconnected with each line card of the M interconnection cards 1110 through an optical backplane (N×M WSS) as shown. Although not shown, it should be noted that each line card of the N line cards 1108 may be interconnected with other N-1 line cards, and the N-1 line cards may be used for intra-chassis connections. Similarly, each interconnection card of the M interconnection cards 1110 may be interconnected with other M-1 interconnection cards (not shown).

[0127] Each interconnect chassis 1106 of the M interconnect chassis of the cluster node 400 or 500 may include S interconnect cards 1112. Each interconnect card of the S interconnect cards 1112 may be optically interconnected with each interconnect card of the S-1 interconnect cards through an optical backplane, as shown in the figure. For low-cost commonly used equipment, S may be 16, referring to the 16×16 WSS (S×SWSS) discussed in this article.

[0128] In addition, each upper / lower wave side chassis 1104 of the h upper / lower wave side chassis of the cluster node 400 or 500 may include M interconnection cards 1116 and N upper / lower wave cards 1110. Each upper / lower wave card of the N upper / lower wave cards 1118 may be optically interconnected with each interconnection card of the M interconnection cards 1116 through an optical backplane (M×N WSS) as shown. Although not shown, it should be noted that each upper / lower wave card of the N upper / lower wave cards 1118 may be interconnected with other N-1 upper / lower wave cards, and similarly, each interconnection card of the M interconnection cards 1116 may be interconnected with other M-1 interconnection cards.

[0129] It should be noted that Fig.11 , Fig.12 and Fig.13The line cards in it can be represented by circles, for example, N line cards 1108, the interconnection cards or connection cards can be represented by rectangles, for example, M interconnection cards 1110, 1116 and S interconnection cards 1112, and the up / down wavelength cards can be represented by hexagons, for example, N up / down wavelength cards 1118. Based on the second proposed relationship discussed herein, the proposed relationship between N and M can be N < M ≤ 1.3N. In the case of N + N = 32, N can be 14 and M can be 18. Additionally, for low-cost common devices, the parameter S can be 16 such that g + h = S, as discussed herein.

[0130] Fig.12 It is an illustration of dropping a wavelength at a ROADM cluster node according to an embodiment of the present invention. Wavelength 1202 can reach the receiving WSS component at cluster node 400 or 500, and the receiving WSS component can be the line card 1204 for direction N–1 of the receiving chassis, and the receiving chassis can be the line-side chassis 1102.

[0131] The cluster controller 408 can determine that wavelength 1202 will be dropped at the egress WSS component, and the egress WSS component can be the up / down wavelength card 1214 of the up / down wavelength side chassis 1104. Thus, the cluster controller can send an instruction to the chassis controller of the receiving chassis (i.e., the line-side chassis 1102) for establishing or setting the wavelength connection of wavelength 1202 to the appropriate interconnection chassis 1106 and egress chassis 1104. Then, the chassis controller of the line-side chassis 1102 can establish the wavelength connection according to the received instruction. The chassis controller of the line-side chassis 1102 can establish a wavelength connection from the line card N–1 1204 to the appropriate interconnection card 1206 through its optical backplane 1205 to establish a connection to the interconnection chassis 1106. Therefore, through the fiber optic interconnection 1207 connecting the line-side chassis 1102 to the interconnection chassis 1106, the wavelength path of wavelength 1202 is established through the established wavelength connection to the interconnection chassis 1106.

[0132] The cluster controller 408 can send an instruction to the chassis controller of the intermediate chassis (i.e., the interconnection chassis 1106) for establishing a wavelength connection for dropping wavelength 1202 to the appropriate up / down wavelength side chassis 1104. The interconnection chassis 1106 can receive wavelength 1202 at its interconnection card 1208 from the interconnection card 1206 of the line-side chassis 1102. Then, the chassis controller of the interconnection chassis 1106 can establish the wavelength connection according to the received instruction. The chassis controller of the interconnection chassis 1106 can establish a wavelength connection from the interconnection card 1208 to the interconnection card 1210 through its optical backplane 1209 to establish a wavelength connection to the up / down wavelength side chassis 1104. Therefore, through the established wavelength connection to the fiber optic interconnection 1211, the wavelength path of wavelength 1202 is established to connect to the up / down wavelength side chassis 1104.

[0133] The cluster controller 408 may send an instruction to the chassis controller of the egress chassis (i.e., the upper and lower wave side chassis 1104) to drop the wavelength 1202 at the egress WSS component. The upper and lower wave side chassis 1104 may receive the wavelength 1202 from the interconnect card 1210 of the interconnect chassis 1106 at its interconnect card 1212. Then, the chassis controller of the upper and lower wave side chassis 1104 may establish a wavelength connection according to the received instruction. The chassis controller of the upper and lower wave side chassis 1104 may establish a wavelength connection of the wavelength 1202 received at the interconnect card 1212 to the upper and lower wave card 1214 through its optical backplane 1213.

[0134] Therefore, the flow of wavelengths (e.g., wavelength 1202) entering and dropping wavelengths at the ROADM cluster node 400 or 500 and the wavelength connections established therewith may be as follows: line side chassis 1102 (through line card 1204 and interconnect card 1206), interconnect chassis 1106 (through interconnect card 1208 to interconnect card 1210), and drop and drop wavelength side chassis 1104 (through interconnect card 1212 and drop and drop wavelength cards 1214).

[0135] Conversely, the wavelength connection for adding a wavelength at the ROADM cluster node 400 or 500 may be the reverse of the wavelength connection for dropping a wavelength at the ROADM cluster node, as described herein with respect to Fig.12 Accordingly, in order to transfer the wavelength received at the upper portion of the upper and lower wave cards 1214 of the upper and lower wave side chassis 1104 to the direction N-1 supported by the line card 1204 of the line side chassis 1102 of the ROADM cluster node 400 or 500, the wavelength flow may be as follows: the upper and lower wave side chassis 1104 (through the upper and lower wave cards 1214 and the interconnection card 1212), the interconnection chassis 1106 (through the interconnection cards 1210 and 1208), and the line side chassis 1102 (through the interconnection card 1206 and the line card 1204).

[0136] Fig.13 1 is a diagram of redirecting or switching wavelengths at a ROADM cluster node according to an embodiment of the present invention. Line side chassis 1322 and 1324 can each be one of the g line side chassis of cluster node 400 or 500 as described herein. Interconnect chassis 1326 can be one of the M interconnect chassis of cluster node 400 or 500 as described herein. Wavelength 1302 can arrive at the receiving WSS component, i.e., line card 1304 of the receiving chassis (which can be line side chassis 1322) from direction 2.

[0137] The cluster controller 408 may determine that the wavelength 1302 is to be redirected or switched to direction 1 supported by the line card 1314 of the line side chassis 1324. Therefore, the cluster controller 408 may send instructions to the chassis controller of the receiving chassis (i.e., the line side chassis 1322) for establishing a wavelength connection of the wavelength 1302 to the appropriate interconnect chassis 1326 and the egress chassis 1324. The chassis controller of the line side chassis 1322 may then establish the wavelength connection according to the received instructions. The chassis controller of the line side chassis 1322 may establish a wavelength connection between the line card 1304 and the interconnect card 1306 through its optical backplane 1305 for connection to the appropriate interconnect chassis 1326. Therefore, by connecting the line side chassis 1322 to the optical fiber interconnect 1307 of the interconnect chassis 1326, a wavelength connection of the wavelength 1302 to the interconnect chassis 1326 is established.

[0138] The cluster controller 408 may send an instruction to the chassis controller of the intermediate chassis (i.e., the interconnect chassis 1326) to establish a wavelength connection of the wavelength 1302 to the appropriate egress chassis (i.e., the line side chassis 1324) for redirection. The interconnect chassis 1326 may receive the wavelength 1302 from the interconnect card 1306 of the line side chassis 1322 at its interconnect card 1308. Then, the chassis controller of the interconnect chassis 1326 may establish a wavelength connection according to the received instruction. The chassis controller of the interconnect chassis 1326 may establish a wavelength connection between the interconnect card 1308 and the interconnect card 1310 through its optical backplane 1309 for connection to the line side chassis 1324. Accordingly, a wavelength connection of the wavelength 1302 to the line side chassis 1324 is established through the optical fiber interconnect 1311.

[0139] The cluster controller 408 may send an instruction to the chassis controller of the egress chassis (i.e., the line side chassis 1324) to establish a wavelength connection of the wavelength 1302 to the egress WSS component 1314. The line side chassis 1324 may receive the wavelength 1302 from the interconnect card 1310 of the interconnect chassis 1326 at its interconnect card 1312. Then, the chassis controller of the line side chassis 1324 may establish the wavelength connection according to the received instruction. The chassis controller of the line side chassis 1324 may establish a wavelength connection between the interconnect card 1312 and the line card 1314 through its optical backplane 1313. Therefore, the wavelength 1302 may leave the ROADM cluster node 400 or 500 at the line card 1314 of the line side chassis 1324 in direction 1.

[0140] Thus, the flow of wavelength 1302 and / or wavelength connection used to change its direction from direction 2 to direction 1 at ROADM cluster node 400 or 500 can be as follows: line side chassis 1322 (through line card 1304 and interconnect card 1306), interconnect chassis 1326 (through interconnect card 1308 to interconnect card 1310), and line side chassis 1324 (through interconnect card 1312 and line card 1314).

[0141] The embodiments discussed herein provide an architecture for ROADM cluster nodes that supports expansion using existing ROADM nodes, which maximizes the return on investment for both providers and customers. In some embodiments, the proposed architecture separates ROADM functions, such as line functions and add / drop functions, in separate nodes interconnected by interconnect nodes, as discussed herein.

[0142] The proposed ROADM cluster node architecture provides many benefits. The proposed architecture provides ideas for higher dimensional ROADM node architectures (e.g., 100 dimensions or higher), supporting flexible add / drop rates up to 100%. The proposed architecture further provides a marketing story that convinces customers that chassis purchased today can be reused without losing investment; expansion is possible based on software upgrades only. The proposed architecture further provides a scheme that maximizes the reuse of today's technology, i.e., using existing WSS 1×16 or 1×32 or existing chassis. The proposed architecture also provides a low-cost scalable architecture based on existing chassis with WSS 1×16 cards, or chassis with WSS 1×32 cards, and a minimum set of existing tributary cards to provide high-dimensional ROADM with flexible add / drop. The proposed architecture also provides non-blocking or low blocking (at acceptable blocking levels better than 1e–3) without the need to rearrange existing connections.

[0143] It should be noted that, as discussed in this article, for level 3 network connections, the first proposed relationship and the second proposed relationship, 1.15N≤M≤1.5N and M≤1.3N, respectively, are not limited to wavelength cross-connections, but can also be used in the digital layer. For example, the proposed relationship of the ROADM cluster node can be applied to Layer 0 (L0) to allow the expansion of ROADM as discussed in this article. In addition, the proposed relationship can be applied to Layer 1 (L1) of TDM / OTN switches / nodes to achieve: providing higher add and drop waves for existing customers, where the add and drop wave pools can be shared, and providing better connection scheduling for OTN / TDM. Therefore, the proposed architecture of the ROADM cluster node and the proposed relationship between N and M can be used at the photonic layer and the digital L1 layer.

[0144] The term "about" as used herein should be understood to include variations relative to the nominal value, for example, + / -10% variations relative to the nominal value. It should be understood that such variations are always included in the given values ​​provided herein, whether or not the given value is specifically mentioned.

[0145] Embodiments of the present invention may be implemented using electronic hardware, software, or a combination thereof. In some embodiments, the present invention is implemented by one or more computer processors executing program instructions stored in a memory. In some embodiments, the present invention is implemented in part or in whole in hardware, such as using one or more field programmable gate arrays (FPGA) or application specific integrated circuits (ASIC) to quickly perform processing operations.

[0146] Fig.14 1400 is a schematic diagram of an electronic device provided by different embodiments of the present invention, and the electronic device can perform any or all operations and features of the above methods explicitly or implicitly described herein. For example, a computer equipped with a network function can be configured as the electronic device 1400.

[0147] As shown, the electronic device includes a processor 1410, such as a central processing unit (CPU) or a special processor, such as a graphics processing unit (GPU) or other such processor unit, a memory 1420, a non-transient mass storage 1430, an I / O interface 1440, a network interface 1450, and a transceiver 1460, all of which are coupled to each other through a bidirectional bus 1470. According to certain embodiments, any or all of the described elements may be used, or only a subset of these elements may be used. In addition, the device 1400 may include multiple instances of certain elements, such as multiple processors, memories, or transceivers. In addition, the elements of the hardware device may be directly coupled to other elements without a bidirectional bus. In addition to or in place of a processor and a memory, other electronic components such as integrated circuits may be used to perform the desired logic operations.

[0148] The memory 1420 may include any type of non-transitory memory, such as static random access memory (SRAM), dynamic random access memory (DRAM), synchronous DRAM (SDRAM), read-only memory (ROM), or a combination thereof. The mass storage element 1430 may include any type of non-transitory storage device, such as a solid-state drive, a hard disk drive, a disk drive, an optical drive, a USB drive, or any computer program product configured to store data and machine executable program code. According to some embodiments, the memory 1420 or the mass storage 1430 may record thereon statements and instructions executable by the processor 1410 for performing any of the above-mentioned method operations.

[0149] One aspect of the present disclosure provides a method for establishing a wavelength connection from a first direction to a second direction at a reconfigurable optical add-drop multiplexer (ROADM) cluster node. The method includes receiving a wavelength from a first direction at a first line side chassis of the ROADM cluster node. The method also includes establishing a first wavelength connection from the first line side chassis of the ROADM cluster node to an interconnect chassis, wherein the first line side chassis and the interconnect chassis are connected by a first optical fiber. The method also includes establishing a second wavelength connection from the interconnect chassis of the ROADM cluster node to the second line side chassis. In some embodiments, the second line side chassis and the interconnect chassis are connected by a second optical fiber. In some embodiments, the second line side chassis is associated with the second direction. In some embodiments, establishing a first wavelength connection from the first line side chassis of the ROADM cluster node to the interconnect chassis includes: establishing a wavelength connection from a line card of the first line side chassis to an interconnect card of the first line side chassis through an optical backplane of the first line side chassis, wherein the line card of the first line side chassis is associated with the first direction, and the interconnect card of the first line side chassis is associated with the interconnect chassis. In some embodiments, the step of establishing a second wavelength connection from the interconnect chassis of the ROADM cluster node to the second line side chassis includes: establishing a wavelength connection from a first interconnect card of the interconnect chassis to a second interconnect card of the interconnect chassis through an optical backplane of the interconnect chassis, wherein the first interconnect card of the interconnect chassis is associated with the first line side chassis, and the second interconnect card of the interconnect chassis is associated with the second line side chassis. In some embodiments, the method further includes establishing a wavelength connection from an interconnect card of the second line side chassis to a line card of the second line side chassis through an optical backplane of the second line side chassis, wherein the interconnect card of the second line side chassis is associated with the interconnect chassis, and the line card of the second line side chassis is associated with the second direction. In some embodiments, the ROADM cluster node separates line functions and add / drop functions, and wherein the first line side chassis and the second line side chassis are part of a set of line side chassis that perform line functions of the ROADM cluster node.

[0150] Another aspect of the present disclosure provides a method for dropping a wavelength at a reconfigurable optical add-drop multiplexer (ROADM) cluster node. The method includes receiving a wavelength at a line side chassis of a ROADM cluster node. The method also includes establishing a first wavelength connection from the line side chassis of the ROADM cluster node to an interconnect chassis, wherein the line side chassis and the interconnect chassis are connected by a first optical fiber. The method also includes establishing a second wavelength connection for dropping a wavelength from the interconnect chassis of the ROADM cluster node to the add-drop side chassis, wherein the add-drop side chassis and the interconnect chassis are connected by a second optical fiber. The method also includes dropping a wavelength at the add-drop side chassis. In some embodiments, establishing a first wavelength connection from the line side chassis of the ROADM cluster node to the interconnect chassis includes: establishing a wavelength connection from a line card of the line side chassis to an interconnect card of the line side chassis through an optical backplane of the line side chassis, wherein the interconnect card of the line side chassis is associated with the interconnect chassis. In some embodiments, establishing a second wavelength connection from an interconnect chassis of the ROADM cluster node to an add / drop waveside chassis for dropping a wavelength includes: establishing a wavelength connection from a first interconnect card of the interconnect chassis to a second interconnect card of the interconnect chassis through an optical backplane of the interconnect chassis, wherein the first interconnect card of the interconnect chassis is associated with a line side chassis, and the second interconnect card of the interconnect chassis is associated with an add / drop waveside chassis. In some embodiments, dropping a wavelength at the add / drop waveside chassis includes: establishing a wavelength connection from an interconnect card of the add / drop waveside chassis to an add / drop wave card of the add / drop waveside chassis through an optical backplane of the add / drop waveside chassis, wherein the interconnect card of the add / drop waveside chassis is associated with the interconnect chassis, and the wavelength is dropped at the add / drop wave card of the add / drop waveside chassis. In some embodiments, the ROADM cluster node separates a line function and an add / drop wave function, and wherein the line side chassis is part of a line side chassis set that performs the line function of the ROADM cluster node, and the add / drop waveside chassis is part of a add / drop waveside chassis set that performs the add / drop wave function of the ROADM cluster node.

[0151] Another aspect of the present invention provides a method for uploading a wavelength associated with a direction at a reconfigurable optical add-drop multiplexer (ROADM) cluster node. The method includes receiving a wavelength at an add-drop wave side chassis of the ROADM cluster node. The method also includes establishing a first wavelength connection from the add-drop wave side chassis of the ROADM cluster node to an interconnect chassis, wherein the add-drop wave side chassis and the interconnect chassis are connected by a first optical fiber. The method also includes establishing a second wavelength connection from the interconnect chassis of the ROADM cluster node to the line side chassis, wherein the line side chassis and the interconnect chassis are connected by a second optical fiber. The method also includes uploading the wavelength to the associated direction at the line side chassis. In some embodiments, establishing a first wavelength connection from the add-drop wave side chassis of the ROADM cluster node to the interconnect chassis includes: establishing a first wavelength connection from the add-drop wave card of the add-drop wave side chassis to the interconnect card of the add-drop wave side chassis through the optical backplane of the add-drop wave side chassis, wherein the interconnect card of the add-drop wave side chassis is associated with the interconnect chassis. In some embodiments, establishing a second wavelength connection from an interconnect chassis of the ROADM cluster node to a line side chassis includes: establishing a wavelength connection from a first interconnect card of the interconnect chassis to a second interconnect card of the interconnect chassis through an optical backplane of the interconnect chassis, wherein the first interconnect card of the interconnect chassis is associated with an add / drop wave side chassis, and the second interconnect card of the interconnect chassis is associated with a line side chassis. In some embodiments, bringing the wavelength up to the associated direction at the line side chassis includes: establishing a wavelength connection from an interconnect card of the line side chassis to a line card of the line side chassis through an optical backplane of the line side chassis, wherein the interconnect card of the line side chassis is associated with the interconnect chassis, and the line card of the line side chassis is associated with the direction of the wavelength to be brought up. In some embodiments, the ROADM cluster node separates line functions and add / drop wave functions, and wherein the line side chassis is part of a set of line side chassis that perform line functions of the ROADM cluster node, and the add / drop wave side chassis is part of a set of add / drop wave side chassis that perform add / drop wave functions of the ROADM cluster node.

[0152] It should be understood that although specific embodiments of the technology have been described herein for illustrative purposes, various modifications may be made without departing from the scope of the technology. The specification and drawings are to be considered merely as an illustration of the invention as defined by the appended claims and any and all modifications, variations, combinations or equivalents falling within the scope of the specification are contemplated. In particular, within the scope of the technology is provided a computer program product or program element, or a program storage device such as a magnetic or optical fiber, tape or optical disk, for storing machine-readable signals for controlling the operation of a computer according to the method of the technology and / or constructing some or all of its components according to the system of the technology.

[0153] The actions associated with the method described herein may be implemented as coded instructions in a computer program product. In other words, a computer program product is a computer-readable medium having software code recorded thereon, which, when the computer program product is loaded into a memory and executed on a microprocessor of a wireless communication device, performs the method.

[0154] Furthermore, each operation of the method can be executed on any computing device (e.g., personal computer, server, PDA, etc.) according to one or more of one or more program elements, modules or objects generated from any programming language (e.g., C++, Java, etc.), or a portion of one or more program elements, modules or objects. Furthermore, each operation or a file or object that implements each of the operations, etc., can be executed by dedicated hardware or circuit modules designed for this purpose.

[0155] Through the description of the above embodiments, the present invention can be implemented using only hardware, or it can be implemented using software and necessary general hardware platforms. Based on such an understanding, the technical solution of the present invention can be embodied in the form of a software product. The software product can be stored in a non-volatile or non-transient storage medium, and the non-volatile or non-transient storage medium can be a compact disk read-only memory (CD-ROM), a USB, a flash drive, or a mobile hard disk. The software product includes many instructions that enable a computer device (a personal computer, a server, or a network device) to perform the method provided in the embodiments of the present invention. For example, such execution may correspond to a simulation of the logical operations described herein. In addition or alternatively, the software product may include the number of instructions that enable a computer device to perform the operations provided by the embodiments of the present invention for configuring or programming a digital logic device.

[0156] Although the present invention has been described with reference to specific features and embodiments of the present invention, it is apparent that various modifications and combinations of the present invention may be made without departing from the present invention. The specification and drawings are to be regarded only as an illustration of the present invention as defined by the appended claims and any and all modifications, variations, combinations or equivalents falling within the scope of this specification are contemplated.

Claims

1. A reconfigurable optical add / drop multiplexer (ROADM) cluster node, which separates line functions from add / drop functions, the ROADM cluster node comprising: A set of g line-side chassis, a set of h upper and lower wave-side chassis, and a set of M interconnect chassis, where: The set of g line side chassis is used to perform line functions, wherein each of the g line side chassis includes: a set of N line cards, and a set of M interconnect cards; The set of h wave-adding and wave-adding side chassis is used to perform wave-adding and wave-adding functions; and The set of M interconnected chassis is configured to: interconnect each line side chassis with each other line side chassis; and interconnect each line side chassis with each upper and lower wave side chassis of the h upper and lower wave side chassis.

2. The ROADM cluster node according to claim 1, wherein N <M。 3. The ROADM cluster node according to claim 1 or 2, wherein 1.15N≤M≤1.5N.

4. The ROADM cluster node according to claim 1 or 2, wherein 1.25N <M<1.3N。 5. The ROADM cluster node according to claim 1 or 2, wherein each of the upper and lower wave side chassis comprises: A collection of X upper and lower waves; as well as There is a set of P interconnected cards, where P=M.

6. The ROADM cluster node according to claim 1 or 2, wherein each of the M interconnected chassis comprises: having a set of g interconnect cards, wherein each of the g interconnect cards is connected to a different line-side chassis in the set of line-side chassis; and There is a set of h interconnect cards, wherein each of the h interconnect cards is connected to a different upper and lower wave-side chassis in the set of upper and lower wave-side chassis.

7. The ROADM cluster node according to claim 1 or 2, wherein each line-side chassis comprises T slots, and the T slots are used to accommodate the set of N line cards and the set of M interconnect cards, such that N+M=T.

8. The ROADM cluster node of claim 6, wherein each interconnect chassis comprises S interconnect cards, such that S=g+h.

9. The ROADM cluster node according to any one of claims 1, 2 or 8, wherein: Each of the N line cards includes a wavelength selective switch.

10. The ROADM cluster node according to any one of claims 1, 2 or 8, wherein: Each of the M interconnect cards includes a wavelength selective switch.

11. The ROADM cluster node according to claim 5, wherein: Each of the X add / drop wavelength cards includes a wavelength selective switch.

12. The ROADM cluster node according to claim 6, wherein: Each of the g interconnect cards and the h interconnect cards includes a wavelength selective switch.

13. The ROADM cluster node of claim 5, wherein X=N / 2.

14. A chassis, for performing one of a line function and a wave add / drop function of a reconfigurable optical add / drop multiplexer (ROADM) cluster node, wherein the ROADM cluster node separates the line function from the wave add / drop function, wherein the chassis comprises: There is a set of M interconnect cards, wherein each of the M interconnect cards connects the chassis to each interconnect chassis in a set of M interconnect chassis of the ROADM cluster node.

15. The chassis of claim 14, wherein the chassis performs line functions, the chassis further comprising a set of N line cards.

16. The chassis according to claim 14 or 15, wherein the chassis performs wave add / drop functions, and the chassis further comprises a set of N / 2 wave add / drop line cards.

17. The chassis of claim 15, wherein N <M。 18. The chassis of claim 15 or 17, wherein 1.15N≤M≤1.5N.

19. The chassis of claim 15 or 17, wherein 1.25N <M<1.3N。 20. The chassis of claim 15 or 17, further comprising T slots, the T slots being used to accommodate the set of N line cards and the set of M interconnect cards, such that N+M=T.

21. The chassis of claim 16, further comprising T slots, the T slots being used to accommodate the set of N / 2 upper and lower wave cards and the set of M interconnection cards, such that N+M=T.

22. An interconnect chassis for interconnecting each line side chassis in a set of line side chassis of a reconfigurable optical add / drop multiplexer (ROADM) cluster node to each add / drop wave side chassis in a set of add / drop wave side chassis of the ROADM cluster node, wherein: The ROADM cluster node separates the line function and the wave adding and dropping function; The set of line-side chassis performs the line functions of the ROADM cluster node; The set of the add / drop wave side chassis performs the add / drop wave function of the ROADM cluster node; and The interconnect chassis comprises: a first set of interconnect cards, wherein at least one interconnect card in the first set of interconnect cards is connected to a different line-side chassis in the set of line-side chassis; and A second set of interconnect cards, wherein at least one interconnect card in the second set of interconnect cards is connected to a different upper and lower waveside chassis in the set of upper and lower waveside chassis.

23. The interconnect chassis of claim 22, wherein each line-side chassis in the set of line-side chassis comprises: A set of N line cards; as well as A set of M interconnected cards, where N <M。 24. The interconnect chassis of claim 22 or 23, wherein 1.15N≤M≤1.5N.

25. An interconnect chassis according to claim 22 or 23, wherein 1.25N <M<1.3N。 26. The interconnect chassis of claim 23, wherein each line side chassis in the set of line side chassis comprises T slots for accommodating the set of N line cards and the set of M interconnect cards, such that N+M=T.

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