Optical pluggable transceiver arrangements in a switch

Abstract

This disclosure relates to a switch assembly, a removable line card, and a chassis switch. The switch assembly proposed in this disclosure comprises a housing, a host IC located within the housing, and a plurality of pluggable transceiver modules located within the housing. Each pluggable transceiver module is connected to the host IC. The pluggable transceiver modules are positioned in a multidimensional arrangement around the host IC. The removable line card proposed in this disclosure comprises a substrate; a host IC located on the substrate; and a plurality of pluggable transceiver modules located on the substrate, each pluggable transceiver module being connected to the host IC; wherein the transceiver modules are positioned in a multidimensional arrangement around the host IC. This disclosure also proposes a chassis switch comprising a plurality of removable line cards.

Description

[0001] OPTICAL PLUGGABLE TRANSCEIVER ARRANGEMENTS IN A SWITCH

[0002] TECHNICAL FIELD

[0003] The present disclosure relates to the technical field of computing and networking equipment design within data centers. The disclosure focuses on the development and optimization of pluggable transceiver switch designs for racks that house such equipment, and the architectural design considerations for achieving efficient interconnectivity and thermal management in high-speed data transmission devices. The disclosure relates to a switch assembly, a removable line card and a chassis switch.

[0004] BACKGROUND

[0005] In modem data centers, computing and networking equipment are conventionally installed in racks that utilize a front-to-back air cooling mechanism. This configuration necessitates the horizontal intake of cold air, typically maintained at temperatures between 21-23 degrees Celsius, and the expulsion of heated air into a hot aisle, from where it is recirculated for cooling. Given the criticality of managing thermal conditions within data centers, equipment is designed to withstand worst-case scenarios of up to 40 degrees Celsius, with a notable temperature differential of approximately 10 degrees to the hot aisle. This thermal management strategy significantly influences the density and arrangement of the equipment's subcomponents, particularly under adverse conditions such as fan failure.

[0006] The design complexities extend to the specific layout of data center networking switches, commonly referred to as “pizza box” configurations, or alternatively, chassis with insertable line cards. Both designs adhere to a principle that accommodates pluggable modules and host switch Application-Specific Integrated Circuits (ASICs), albeit with varying structural nuances. Strategic placement of components is crucial; transceiver modules, especially those containing sensitive optical components like lasers, are positioned at the front plate to benefit from the cooler air, whereas the more heat-tolerant switch ASICs are located further back. This arrangement underscores the importance of temperature management in preserving the functionality and reliability of analog optical subcomponents.

[0007] Further complexities may arise in the realm of on-board connectivity, where the design choices between pure Printed Circuit Board (PCB)-based routing and hybrid approaches involving both PCB and fly-over cables are critical. These design considerations are not merely structural but can have significant implications on the electrical performance, particularly in terms of insertion loss and signal integrity. The industry's ongoing efforts to standardize chip-to-module (C2M) interconnectivity for 200Gb / s PAM4 signals, and the challenges in accommodating the associated insertion losses through advanced equalization techniques, and the use of retimers, exemplify the intricate balance between thermal management, electrical performance, and physical design constraints.

[0008] Despite the advancements in design and thermal management techniques, existing architectures could face disadvantages, including high power consumption, increased costs, and the inherent limitations in scaling beyond current speed thresholds without compromising overall performance. These challenges are evident across different design paradigms, from pluggable switches and vertical line cards to on-board optics (OBO) and co-packaged optics (CPO), each presenting unique obstacles in terms of cooling efficiency, cost, and scalability.

[0009] Current designs might face limitations in power consumption, cost, scalability beyond 200Gb / s, and thermal management efficiency, underscoring the need for innovative solutions that can extend the viability of pluggable transceiver modules to next-generation interconnects (400Gb / s per lane), while minimizing the trade-offs in switch specifications and overcoming the hurdles associated with trace distances and losses between the host Integrated Circuit (IC) and the pluggable transceivers. SUMMARY

[0010] In view of the above-mentioned limitations, the present disclosure endeavors to explore solutions, drawing upon the current state of the art and identifying opportunities for advancement in the design and thermal management of computing and networking equipment in data centers. One objective of this disclosure is to provide dense and compact switch designs based on pluggable modules. Another objective is to reduce the trace distances and losses between the host IC and the pluggable transceivers.

[0011] These and other objectives are achieved by the solutions of this disclosure as provided in the independent claims. Advantageous implementations are further defined in the dependent claims.

[0012] A first aspect of this disclosure provides a switch assembly, comprising: a housing; a host IC located within the housing; and a plurality of pluggable transceiver modules located within the housing, each pluggable transceiver module being connected to the host IC; wherein the pluggable transceiver modules are positioned in a multidimensional arrangement around the host IC.

[0013] This disclosure proposes to arrange the pluggable transceiver modules in a two-dimensional or three-dimensional arrangement around the host IC. It should be noted that the proposed switch assembly may comprise more than one host IC. The description for one host IC also holds for more host ICs.

[0014] In an implementation form of the first aspect, the multidimensional arrangement comprises at least a first array and a second array, wherein the first array extends along a first direction aligned with a front portion of the housing, and the second array extends along a second direction that is non-parallel with respect to the first direction.

[0015] It may be worth mentioning that in the conventional design, all pluggable transceiver modules are positioned in a onedimensional array along the front portion of the housing. In this disclosure, only a part of the pluggable transceiver modules are positioned in the array along the front portion of the housing, other pluggable transceiver modules are positioned in different arrangements.

[0016] In an implementation form of the first aspect, the multidimensional arrangement further comprises a third array that extends along a third direction that is non-parallel with respect to the first direction.

[0017] Optionally, the second direction and the third direction are both orthogonal to the first direction.

[0018] In an implementation form of the first aspect, the multidimensional arrangement further comprises a fourth array placed above or below the host IC. This structure would result in a three-dimensional arrangement of optics (e.g., pluggable transceiver modules) around the host IC.

[0019] In an implementation form of the first aspect, the fourth array is a two-dimensional array.

[0020] In an implementation form of the first aspect, the switch assembly further comprises a front plate patch panel, connected to each transceiver module of the plurality of pluggable transceiver modules with a patch cord. This design is for enabling front plate access to all pluggable modules in the shelf (e.g., inside the assembly). In an implementation form of the first aspect, each pluggable transceiver module is connected to the host IC with a transmission medium including one of the following: a fixed printed circuit board, a flexible cable, a fly-over cable, an optical cable, and a plastic waveguide.

[0021] This disclosure supports various options for designing a switch / router system with electrical or optical interfaces.

[0022] A second aspect of this disclosure provides a removable line card, comprising: a substrate; a host IC located on the substrate; and a plurality of pluggable transceiver modules located on the substrate, each pluggable transceiver module being connected to the host IC; wherein the transceiver modules are positioned in a multidimensional arrangement around the host IC.

[0023] Besides the switches, this disclosure can be applied to removable line cards as well.

[0024] In an implementation form of the second aspect, the multidimensional arrangement comprises at least a first array and a second array, wherein the first array extends along a first direction aligned with a front portion of the housing, and the second array extends along a second direction that is non-parallel with respect to the first direction.

[0025] In an implementation form of the second aspect, the multidimensional arrangement further comprises a third array that extends along a third direction that is non-parallel with respect to the first direction.

[0026] In an implementation form of the second aspect, the multidimensional arrangement further comprises a fourth array placed above or below the host IC.

[0027] In an implementation form of the second aspect, the fourth array is a two-dimensional array.

[0028] In an implementation form of the second aspect, the removable line card further comprises a front plate patch panel, connected to each of the plurality of pluggable transceiver modules with a patch cord.

[0029] In an implementation form of the second aspect, each pluggable transceiver module is connected to the host IC with a transmission medium including one of the following: a fixed printed circuit board, a flexible cable, a fly-over cable, an optical cable, and a plastic waveguide.

[0030] In an implementation form of the second aspect, the removable line card further comprises a direct current (DC) connector, connectable to a switch, wherein the direct current connector comprises a fixed connector or a cable. When the removable line card is inserted into a switch, it may connect the switch via the DC connector.

[0031] A third aspect of this disclosure provides a chassis switch, which comprises a chassis comprising a plurality of slots configured to accommodate a plurality of line cards, where each line card is a removable line card of the second aspect or any of its implementation forms. Communication equipment is also being offered in a chassis implementation, where different line cards can be combined which can interface with another central fabric switching ASIC. The proposed idea of this disclosure applies similarly to a chassis by the concept of removable line cards, which may or may not have a cabled backplane connector to support DC and RF signaling. In the chassis, each line card is individually removable and replaceable.

[0032] In an implementation form of the third aspect, the chassis switch further comprises a central fabric IC and / or a backplane interface within the chassis for providing data interconnections between the plurality of line cards and the chassis switch. It may be understood that the central fabric IC, also known as a switch fabric or switching fabric, is responsible for the intelligent routing and forwarding of data packets between the switch's ports. It is usually one or more chips located on the switch's mainboard or on specific modules within the switch. The backplane interface is the physical infrastructure within the switch chassis where modules are inserted, often with connectors or slots for attaching various components.

[0033] Implementation forms of the chassis switch of the third aspect may correspond to the implementation forms of the removable line card of the second aspect described above. The chassis switch of the third aspect and its implementation forms achieve the same advantages and effects as described above for the removable line card of the second aspect and its implementation forms.

[0034] It has to be noted that all modules, elements, units, and means described in the present application could be implemented in the software or hardware elements or any kind of combination thereof. All steps that are performed by the various entities described in the present application as well as the functionalities described to be performed by the various entities are intended to mean that the respective extender module is adapted to or configured to perform the respective steps and functionalities. Even if, in the following description of specific embodiments, a specific functionality or step to be performed by external entities is not reflected in the description of a specific detailed element of that extender module that performs that specific step or functionality, it should be clear for a skilled person that these methods and functionalities can be implemented in respective software or hardware elements or any kind of combination thereof.

[0035] BRIEF DESCRIPTION OF DRAWINGS

[0036] The above-described aspects and implementation forms will be explained in the following description of specific embodiments in relation to the enclosed drawings, in which

[0037] FIG. 1 shows a switch assembly according to an embodiment of the disclosure.

[0038] FIG. 2 shows an exemplary switch.

[0039] FIG. 3 shows a switch assembly according to an embodiment of the disclosure.

[0040] FIG. 4 shows a switch assembly according to an embodiment of the disclosure.

[0041] FIG. 5 shows a switch assembly according to an embodiment of this disclosure.

[0042] FIG. 6 shows (a) a removable line card and (b) a switch according to an embodiment of the disclosure.

[0043] FIG. 7 shows a chassis switch according to an embodiment of the disclosure.

[0044] DETAILED DESCRIPTION OF EMBODIMENTS

[0045] Illustrative embodiments of a switch assembly, a removable line card, and a chassis switch are described with reference to the figures. Although this description provides a detailed example of possible implementations, it should be noted that the details are intended to be exemplary and in no way limit the scope of the application.

[0046] Moreover, an embodiment / example may refer to other embodiments / examples. For example, any description including but not limited to terminology, element, process, explanation, and / or technical advantage mentioned in one embodiment / example is applicable to the other embodiments / examples. The same elements are labeled with the same reference signs and may function similarly or likewise.

[0047] FIG. 1 shows a switch assembly 100 according to this disclosure. The switch assembly 100 may comprise a processor or processing circuitry (not shown) configured to perform, conduct, or initiate the various operations of the switch assembly 100 described herein. The processing circuitry may comprise hardware and / or the processing circuitry may be controlled by software. The hardware may comprise analog circuitry digital circuitry, or both analog and digital circuitry. The digital circuitry may comprise components such as application-specific integrated circuits (ASICs), field-programmable arrays (FPGAs), digital signal processors (DSPs), or multi-purpose processors. The switch assembly 100 may further comprise memory circuitry, which stores one or more instructions) that can be executed by the processor or by the processing circuitry, for example, under the control of the software. For instance, the memory circuitry may comprise a non-transitory storage medium storing executable software code which, when executed by the processor or the processing circuitry, causes the various operations of the switch assembly 100 to be performed. In one embodiment, the processing circuitry comprises one or more processors and a non-transitory memory connected to the one or more processors. The non-transitory memory may carry executable program code which, when executed by the one or more processors, causes the switch assembly 100 to perform, conduct, or initiate the operations or methods described herein.

[0048] The switch assembly 100 comprises a housing 101, a host IC 102 located within the housing 101, and a plurality of pluggable transceiver modules 103 located within the housing 101, each pluggable transceiver module 103 being connected to the host IC 102. The pluggable transceiver modules 103 are positioned in a multidimensional arrangement around the host IC 102.

[0049] Embodiments of this disclosure propose to arrange the pluggable transceiver modules in a two-dimensional or three- dimensional arrangement around the host IC. This would require changes in the mechanical chassis design to accommodate the serviceability and airflow. For clarity, it is emphasized that all figures presented in this disclosure represent top-view diagrams.

[0050] The multidimensional arrangement comprises at least a first array and a second array, as the example arrangement shown in FIG. 1. The first array extends along a first direction aligned with a front portion of the housing 101, and the second array extends along a second direction that is non-parallel with respect to the first direction.

[0051] For ease of understanding of the application, a state-of-the-art switch assembly is depicted in FIG. 2. The switch assembly typically comprises a housing structure with a front and a rear portion, wherein the front portion is configured to receive a plurality of pluggable transceiver modules.

[0052] The host IC is located within the housing structure and positioned to be in thermal communication with an airflow path established from the front portion to the rear portion of the housing. A plurality of fans disposed at the rear portion of the housing, the fans generate airflows across the host IC and the pluggable transceiver modules to facilitate cooling. At least one power supply unit (PSU) is located at the rear portion of the housing, for providing power to the host IC, the fans, and the pluggable transceiver modules. A set of fiber-cabling interfaces is positioned at the front portion of the housing and connected to the pluggable transceiver modules, the fiber-cabling interfaces are arranged to route communication signals between the pluggable transceiver modules and external devices.

[0053] It can be seen that the pluggable transceiver modules are positioned in a one-dimensional array along the front portion of the housing. It can also be seen that the host IC is connected to the pluggable transceiver modules via a series of electrical interconnects. Typically, for pure PCB-based connectivity, the shortest channel (electrical interconnects) to connect the pluggable transceiver module to the host IC may have a length of 3.5 inches, and the longest channel to connect the pluggable transceiver module to the host IC may have a length of 12 inches. That is, in such an arrangement, the difference between the shortest and the longest trace can be up to 8.5 inches and the electrical channel has to be designed to accommodate the longest link. Cabling can reduce the insertion loss of PCBs but can come at an additional transmission penalty due to p / n signaling delays in the differential transmission. While a PCB-based design has 36 dB worst-case insertion loss which includes PCB, chip packages and transceiver connectors, cabling replacing the PCB could reduce the worst-case comer to 32 dB.

[0054] FIG. 3 shows a proposed switch design according to an embodiment of this disclosure. In this disclosure, it is proposed to arrange the pluggable transceiver module 103 around the host IC 102 of the switch assembly 100. It can be seen that such arrangments greatly reduce the trace length.

[0055] The pluggable transceiver modules 103 are arranged in a multidimensional arrangement. This multidimensional arrangement comprises a first array, a second array, and a third array. The first array extends along a first direction aligned with a front portion of the housing 101, the second array extends along a second direction that is non-parallel with respect to the first direction, and the third array extends along a third direction that is non-parallel with respect to the first direction.

[0056] As shown in FIG. 3, the second array may be the array shown on the left side of the switch assembly 100, and the third array may be the array shown on the right side of the switch assembly 100.

[0057] In a particular example, the second direction and the third direction are both orthogonal to the first direction. That is, the first array extends in a horizontal direction (aligned with a front portion of the housing), and the second array and the third array extend in a vertical direction.

[0058] In this embodiment, the first array, the second array, and the third array are all one-dimensional arrays. It may be understood that the switch assembly 100 comprises the plurality of pluggable transceiver module 103 that are arranged in a two- dimensional arrangement.

[0059] In the embodiment shown in FIG. 3, the second array and the third array of the pluggable transceiver module 103 are arranged in the direction that is vertical to the first array. FIG. 4 shows another switch design based on FIG. 3 where the difference is that the second array and the third array are arranged with varying angular alignment. According to this embodiment, the angle of the pluggable alignment versus the front plate (in all dimensions) is variable and can be optimized to improve serviceability and airflow.

[0060] In another embodiment, the multidimensional arrangement further comprises a fourth array placed above or below the host IC 102. FIG. 5 shows another switch design based on FIG. 3 where the difference is that there are some pluggable transceiver modules 103 are arranged above or below the host IC 102.

[0061] It may be understood that the fourth array is a two-dimensional array, as depicted in FIG. 5. This structure would result in a three-dimensional arrangement of optics around the host IC 102 to maximize the density of connectivity per rack space. The connection of pluggable modules placed vertically versus the host IC 102 would, e.g., require flex cable connectivity from the package itself or the PCB that the host IC 102 is mounted on.

[0062] Embodiments of the present disclosure thus propose switch designs with different pluggable geometries. In the previous embodiments, the switch assembly may further comprise a front plate patch panel, which is connected to each transceiver module of the plurality of pluggable transceiver modules 103 with a patch cord, in order to enable front plate access to all pluggable modules in the shelf (e.g., inside the assembly). The proposed switch assembly may be an Ethernet switch, an Infiniband switch, an OTN switch, or an IP router.

[0063] Besides the switches, this disclosure can be applied to removable line cards as well.

[0064] FIG. 6(a) shows a removable line card 200 according to this disclosure. The removable line card (200) comprises a substrate 201, a host IC 202 located on the substrate 201, and a plurality of pluggable transceiver modules 203 located on the substrate 201. Each pluggable transceiver module 203 is connected to the host IC 202. The pluggable transceiver modules 203 are positioned in a multidimensional arrangement around the host IC 202.

[0065] Similar as discussed in the previous embodiments for the switch assembly 100, the multidimensional arrangement in the removable line card 200 comprises at least a first array and a second array, wherein the first array extends along a first direction aligned with a front portion of the substrate 201, and the second array extends along a second direction that is non-parallel with respect to the first direction.

[0066] As shown in FIG. 6(a), the multidimensional arrangement further comprises a third array that extends along a third direction that is non-parallel with respect to the first direction.

[0067] Similar to the embodiment shown in FIG. 5, the multidimensional arrangement for the removable line card 200 may also comprise a fourth array placed above or below the host IC 202. It may be understood that the fourth array is a two-dimensional array.

[0068] Optionally, the removable line card (200) may further comprise a front plate patch panel, connected to each of the plurality of pluggable transceiver modules 203 with a patch cord.

[0069] Optionally, each pluggable transceiver module 203 is connected to the host IC with a transmission medium including one of the following: a fixed printed circuit board, a flexible cable, a fly-over cable, an optical cable, and a plastic waveguide.

[0070] FIG. 6(b) shows a switch comprising the removable line card 200, where the switch connects the removable line card 200 via a DC connector. The removable line card 200 may further comprise a DC connector 204, wherein the DC connector 204 comprises a fixed connector or a cable. It should be understood that there may be more than one removable line card connected to the switch, and each line card is individually removable and replaceable.

[0071] Embodiments of this disclosure support the implementation of a variant of the two-dimensional pluggable architecture, which allows for easy service of the pluggable modules. Here, the main functionality is installed on the removable line card, which allows to access the transceiver modules in the rear. The DC connector 204 of the line card 200 can either be fixed, like for regular chassis line cards, or via a cable, which would allow for a non-interrupted power and control signaling supply to the line card during field replacement of modules. Even if the power supply is interrupted with a fixed connector, the servicing time of such an assembly is in the range of minutes and not comparable to fixed installations using OBO / CPO, which require whole line cards to be spared, instead of single modules.

[0072] FIG. 7 shows a chassis switch 300 according to this disclosure. The chassis switch 300 comprises a chassis 301 comprising a plurality of slots configured to accommodate a plurality of line cards 302, where each line card 302 is the removable line card 200 as shown in FIG. 6(a). Communication equipment is also being offered in a chassis implementation, where different line cards can be combined which can interface with another central fabric switching ASIC. The proposed idea of this disclosure applies similarly to a chassis by the concept of removable line cards, which may or may not have a cabled backplane connector to support DC and RF signaling.

[0073] Optionally, the chassis switch may further comprise a central fabric IC and / or a backplane interface within the chassis 301 for providing data interconnections between the plurality of line cards 302 and the chassis switch 300.

[0074] It may be understood that the central fabric IC, also known as a switch fabric or switching fabric, is responsible for the intelligent routing and forwarding of data packets between the switch's ports. It is usually one or more chips located on the switch's mainboard or on specific modules within the switch. The backplane interface is the physical infrastructure within the switch chassis where modules are inserted, often with connectors or slots for attaching various components.

[0075] It should be noted that embodiments of this disclosure as above discussed also support implementations with one or several host ICs on the line card / switch. Further, the pluggables (e.g., the pluggable transceiver modules) inside the housing can be connected to a front plate patch panel with a patch cord, enabling front plate access to all pluggable modules in the shelf. The embodiments of this disclosure as above discussed also support all possible interconnect types between host IC and pluggable module (fixed PCB, flex cable, fly-over cable, optical cable, plastic waveguide) using any type of communication bands (base band, THz, IR optical, visible light).

[0076] To summarize, embodiments of the present disclosure introduce a multidimensional arrangement of pluggable modules around the host IC. This approach enables the shortening of the electrical traces to support higher interface speeds, while maintaining the pluggable concept which leads to easy serviceability and multi-vendor / multi-service transceivers in operation. In addition, the density of the switch (number of transceivers per height unit) can be increased compared to the classical one-dimensional designs.

[0077] The present disclosure has been described in conjunction with various embodiments as examples as well as implementations. However, other variations can be understood and effected by those persons skilled in the art and practicing the claimed matter, from the studies of the drawings, this disclosure, and the independent claims. In the claims as well as in the description the word “comprising” does not exclude other elements or steps and the indefinite article “a” or “an” does not exclude a plurality. A single element or other unit may fulfill the functions of several entities or items recited in the claims. The mere fact that certain measures are recited in the mutual different dependent claims does not indicate that a combination of these measures cannot be used in an advantageous implementation.

Claims

CLAIMS1. A switch assembly (100), comprising: a housing (101); a host integrated circuit, IC, (102) located within the housing (101); and a plurality of pluggable transceiver modules (103) located within the housing (101), each pluggable transceiver module (103) being connected to the host IC (102); wherein the pluggable transceiver modules (103) are positioned in a multidimensional arrangement around the host IC (102).

2. The switch assembly (100) according to claim 1, wherein the multidimensional arrangement comprises at least a first array and a second array, wherein the first array extends along a first direction aligned with a front portion of the housing (101), and the second array extends along a second direction that is non-parallel with respect to the first direction.

3. The switch assembly (100) according to claim 2, wherein the multidimensional arrangement further comprises a third array that extends along a third direction that is non-parallel with respect to the first direction.

4. The switch assembly (100) according to claim 2 or 3, wherein the multidimensional arrangement further comprises a fourth array placed above or below the host IC (102).

5. The switch assembly (100) according to claim 4, wherein the fourth array is a two-dimensional array.

6. The switch assembly (100) according to one of the claims 1 to 5, further comprising: a front plate patch panel, connected to each transceiver module of the plurality of pluggable transceiver modules (103) with a patch cord.

7. A removable line card (200), comprising: a substrate (201); a host integrated circuit, IC, (202) located on the substrate (201); and a plurality of pluggable transceiver modules (203) located on the substrate (201), each pluggable transceiver module (203) being connected to the host IC (202); wherein the pluggable transceiver modules (203) are positioned in a multidimensional arrangement around the host IC (202).

8. The removable line card (200) according to claim 7, wherein the multidimensional arrangement comprises at least a first array and a second array, wherein the first array extends along a first direction aligned with a front portion of the substrate (201), and the second array extends along a second direction that is non-parallel with respect to the first direction.

9. The removable line card (200) according to claim 8, wherein the multidimensional arrangement further comprises a third array that extends along a third direction that is non-parallel with respect to the first direction.

10. The removable line card (200) according to claim 8 or 9, wherein the multidimensional arrangement further comprises a fourth array placed above or below the host IC (202).

11. The removable line card (200) according to claim 10, wherein the fourth array is a two-dimensional array.

12. The removable line card (200) according to one of the claims 7 to 11, further comprising: a front plate patch panel, connected to each of the plurality of pluggable transceiver modules (203) with a patch cord.

13. A chassis switch (300), comprising: a chassis (301) comprising a plurality of slots configured to accommodate a plurality of line cards (302), where each line card (302) is a removable line card (200) according to one of the claims 9 to 12.

14. The chassis switch (300) according to claim 13, further comprising: a central fabric IC and / or a backplane interface within the chassis (301) for providing data interconnections between the plurality of line cards (302) and the chassis switch (300).

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