阅读说明：本技术 用于数据中心中的灵活光互连的系统和方法 (System and method for flexible optical interconnects in a data center ) 是由 谢崇进 陆睿 王安斌 于 2019-05-15 设计创作，主要内容包括：本文描述的一个实施例提供一种通信系统。所述通信系统能够包括：第一交换机,所述第一交换机包括一个或多个光收发器模块；以及多根独立光缆,所述多根独立光缆耦合到所述第一交换机上相应的光收发器模块。(One embodiment described herein provides a communication system. The communication system can include: a first switch comprising one or more optical transceiver modules; and a plurality of individual optical cables coupled to respective optical transceiver modules on the first switch.)

1. A communication system, comprising:

a first switch, wherein the first switch comprises one or more optical transceiver modules; and

a plurality of independent optical cables coupled to respective optical transceiver modules of the first switch.

2. The communication system of claim 1, wherein the respective optical transceiver module comprises one or more of:

an SN-based optical interface;

an MDC-based optical interface; and

a multi-fiber push-pull (MPO) optical interface.

3. The communication system of claim 2, wherein the respective optical transceiver module comprises a plurality of SN-or MDC-based interfaces, and wherein the respective optical cables each comprise an SN-or MDC-based connector for coupling the respective optical cable to the optical transceiver module.

4. The communication system of claim 2, wherein the respective optical transceiver module comprises an MPO optical interface, and wherein the respective optical cable comprises an MPO connector or a duplex LC connector for coupling the respective optical cable to the optical transceiver module.

5. The communication system of claim 2, wherein the respective optical transceiver modules comprise MPO optical interfaces, and wherein respective optical cables are coupleable to the MPO optical interfaces via MPO converters that convert higher fiber count MPO interfaces to lower fiber count MPO interfaces.

6. The communication system of claim 1, wherein each of the plurality of independent optical cables is coupled to a different switch in the communication system.

7. The communication system of claim 1, wherein respective switches in the communication system have input/output (I/O) capacities of 256 x 50Gbps (gigabits per second) or 512 x 50 Gbps.

8. The communication system of claim 7, wherein the respective optical module has a speed of 200Gbps (gigabits per second) or 400 Gbps.

9. The communication system of claim 1, wherein the first switch comprises N optical transceiver modules, wherein each optical transceiver module is coupled to M independent optical cables, and wherein the first switch is coupled to M x N other switches in the communication system.

10. The communication system of claim 9, wherein the communication system comprises at least two stages of switches; wherein the first switch is on a first level and the corresponding port on the downlink of the first switch uses a triplet (i)₁，j₁,k₁) Marking, wherein i, j and k respectively represent a switch serial number, an optical module serial number and a port serial number; and wherein said port (i)₁,j₁,k₁) Port (i) coupled to an uplink belonging to a second switch on a second level₂,j₂,k₂) Wherein i₂＝j₁*M+k₁，j₂＝i₁% M, and k₂＝mod(i₁,M)。

11. A coupling mechanism for coupling among switches in a data center network, comprising:

a plurality of independent optical cables coupled to respective optical transceiver modules of respective switches, wherein the plurality of independent optical cables are coupled to a number of different switches in the data center network.

12. The coupling mechanism of claim 11, wherein the respective optical transceiver module comprises a plurality of SN-or MDC-based interfaces, and wherein the respective optical cables each comprise an SN-or MDC-based connector for coupling the respective optical cable to the optical transceiver module.

13. The coupling mechanism of claim 11, wherein the respective optical transceiver module comprises an MPO optical interface, and wherein the respective optical cable comprises an MPO connector or a duplex LC connector for coupling the respective optical cable to the optical transceiver module.

14. The coupling mechanism of claim 11, wherein the respective switch comprises N optical transceiver modules, wherein each optical transceiver module is coupled to M independent optical cables, and wherein M x N independent optical cables are used to couple the respective switch to M x N other switches in the data center network.

15. The coupling mechanism as recited in claim 14, wherein the data center comprises at least two stages of switches; wherein the corresponding port on the downlink of the first stage uses a triplet (i)₁,j₁,k₁) Marking, wherein i, j and k respectively represent a switch serial number, an optical module serial number and a port serial number; and wherein the coupling mechanism is configured such that the port (i)₁,j₁,k₁) Port (i) coupled to an uplink belonging to the second level₂,j₂,k₂) Wherein i₂＝j₁*M+k₁，j₂＝i₁% M, and k₂＝mod(i₁,M)。

16. A method for coupling among switches in a data center network, the method comprising:

selecting a switch;

coupling first ends of a plurality of individual optical cables to respective optical transceiver modules on the selected switch; and

coupling second ends of the plurality of optical cables to a plurality of other switches in the data center network.

17. The method of claim 16, wherein the respective optical transceiver module comprises a plurality of SN-or MDC-based interfaces, and wherein coupling the first end of the respective optical cable to the respective optical transceiver module comprises coupling an SN-or MDC-based connector on the respective optical cable to a corresponding SN-or MDC-based interface on the respective optical transceiver module, respectively.

18. The method of claim 16, wherein the respective optical transceiver module comprises an MPO optical interface, and wherein coupling a first end of a respective optical cable to the respective optical transceiver module comprises coupling an MPO connector or a duplex LC connector on the respective optical cable to the MPO optical interface.

19. The method of claim 16, wherein the selected switch comprises N optical transceiver modules, wherein the method further comprises:

coupling M independent optical cables to each optical transceiver module; and

coupling the selected switch to M N other switches in the datacenter network.

20. The method of claim 19, wherein the data center comprises at least two stages of switches; wherein the corresponding port on the downlink of the first stage uses a triplet (i)₁,j₁,k₁) Marking, wherein i, j and k respectively represent a switch serial number, an optical module serial number and a port serial number; and wherein the method further comprises associating the port (i)₁,j₁,k₁) Port (i) coupled to an uplink belonging to the second level₂，j₂,k₂) Wherein i₂＝j₁*M+k₁，j₂＝i₁% M, and k₂＝mod(i₁,M)。

Technical Field

The present disclosure relates generally to data center design. More particularly, the present disclosure relates to designing optical interconnects among switches in a data center.

Background

The rapid growth in computing needs of cloud users continues to drive the computing power of cloud servers, thereby increasing the speed and scalability requirements for data centers. A typical data center may be a pool of resources (e.g., computing, storage, and network resources) interconnected using a communication network. A data center network plays an important role in a data center because it interconnects all data center resources.

Data center networks need to be scalable and efficient in order to connect into thousands or even hundreds of thousands of servers. Key characteristics of a data center network can include bandwidth, size, and latency. Designers of data center networks often pursue large-scale, low-latency, and low-cost goals. Designing large-scale data center networks while keeping costs and delays low can be challenging.

Disclosure of Invention

One embodiment described herein provides a communication system. The communication system can include: a first switch comprising one or more optical transceiver modules; and a plurality of independent optical cables coupled to respective optical transceiver modules on the first switch, thereby allowing the first switch to be coupled to a plurality of other switches in the communication system via at least the plurality of independent optical cables.

In a variation on this embodiment, the respective optical transceiver module can include one or more of the following: based on SN^TMAn MDC-based optical interface, and a multi-fiber push-pull (MPO) optical interface.

In another variation, the respective optical transceiver module can include a plurality of SN or MDC based interfaces, and the respective optical cables can each include an SN or MDC based connector for coupling the respective optical cable to the optical transceiver module.

In another variation, the respective optical transceiver module can include an MPO optical interface and the respective optical cable can include an MPO connector or a duplex LC connector for coupling the respective optical cable to the optical transceiver module.

In another variation, the respective optical transceiver module can include an MPO optical interface, and the respective optical cable can be coupled to the MPO optical interface via an MPO converter that converts a higher fiber count MPO interface to a lower fiber count MPO interface.

In a variation on this embodiment, each of the plurality of independent optical cables can be coupled to a different switch in the communication system.

In a variation on this embodiment, the respective switches in the communication system can have input/output (I/O) capacities of 256 × 50Gbps (gigabits per second) or 512 × 50 Gbps.

In another variation, the corresponding optical module can have a speed of 200Gbps or 400 Gbps.

In a variation on this embodiment, the first switch can include N optical transceiver modules, and each optical transceiver module can be coupled to M independent optical cables. The first switch is capable of coupling to M x N other switches in the communication system.

In another variation, the communication system can include two stages of switches. Triple (i) is used by the first switch on the first level and by the corresponding port on the downlink of the first switch₁,j₁,k₁) Where i, j, k represent switch serial number, optical module serial number, and port serial number, respectively. Port (i)₁,j₁,k₁) Port (i) coupled to an uplink belonging to a second switch on a second level₂,j₂,k₂) Wherein i₂＝j₁*M+k₁，j₂＝i₁% M, and k₂＝mod(i₁,M)。

One embodiment can provide a coupling mechanism for coupling among switches in a data center network. The coupling mechanism can include a plurality of independent optical cables coupled to respective optical transceiver modules on respective switches, thereby allowing the respective switches to be coupled to a plurality of other switches in the data center network.

One embodiment can provide a method for coupling among switches in a data center network. The method can include: selecting a switch; coupling first ends of the plurality of individual optical cables to respective optical transceiver modules on the selected switch; and coupling the second ends of the plurality of optical cables to a plurality of other switches in the data center network.

Drawings

Fig. 1 illustrates an exemplary network infrastructure of a data center.

Fig. 2A and 2B show an exemplary interconnection among two different levels of switches according to the prior art.

Figure 3A illustrates an exemplary interconnection among switches according to one embodiment.

Figure 3B illustrates an exemplary interconnection among switches according to one embodiment.

Figure 4 illustrates an exemplary network with two levels of switches, according to one embodiment.

Fig. 5A illustrates an exemplary optical interface of an optical transceiver module.

Fig. 5B shows an exemplary optical interface configuration of a light module according to the prior art.

FIG. 5C illustrates an exemplary output configuration of a light module according to one embodiment.

FIG. 5D illustrates an exemplary output configuration of a light module according to one embodiment.

Fig. 6A illustrates an exemplary arrangement of multiple fiber optic cables according to one embodiment.

Fig. 6B illustrates an exemplary arrangement of multiple fiber optic cables according to one embodiment.

FIG. 7A illustrates an exemplary output configuration of a light module according to one embodiment.

FIG. 7B illustrates an exemplary output configuration of a light module according to one embodiment.

Fig. 8A illustrates an exemplary arrangement of multiple fiber optic cables according to one embodiment.

Fig. 8B illustrates an exemplary arrangement of multiple fiber optic cables according to one embodiment.

Fig. 9 presents a flowchart illustrating an exemplary process for establishing a data center network, according to one embodiment.

In the figures, like reference numerals refer to the same graphical elements.

Detailed Description

The following description is presented to enable any person skilled in the art to make and use the embodiments, and is provided in the context of a particular application and its requirements. Various modifications to the disclosed embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other embodiments and applications without departing from the spirit and scope of the present disclosure. Thus, the present invention is not intended to be limited to the embodiments shown, but is to be accorded the widest scope consistent with the principles and features disclosed herein.

SUMMARY

Embodiments described herein address the technical problem of providing efficient and flexible optical interconnections among switches in a data center. More specifically, by implementing multiple parallel fiber outputs on each individual optical module, some embodiments increase the number of independent ports on each switch without modifying the internal structure of the switch or increasing the count of optical modules on the switch. In some embodiments, the optical module may conform to a standard form factor, such as quad small form-factor pluggable (QSFP) or octal small form-factor pluggable (OSFP), and may be capable of coupling the optical module to multiple optical cables using various types of optical interfaces, where each optical cable corresponds to a switch port. In some embodiments, the optical cables from a particular switch on a particular switch stage can be arranged such that they are coupled to other individual switches on the next stage, one switch per optical cable. Given a switch equipped with N optical modules, each coupled to M parallel output optical cables, the switch is capable of coupling to up to M × N other switches.

Optical interconnection of data centers

Fig. 1 illustrates an exemplary network infrastructure of a data center. In fig. 1, a data center network 100 can include three layers of network switches, namely an access layer, an aggregation layer, and a core layer. The server is connected to a switch within the access stratum. An aggregation layer switch interconnects a plurality of access layer switches. The aggregation layer module can also provide various important services such as content exchange, firewalls, Secure Sockets Layer (SSL) offload, intrusion detection, network analytics, and the like. All aggregation layer switches are interconnected through the core layer switches. The core layer switch is also responsible for connecting the data center to a network (e.g., the internet) external to the data center. To meet the ever increasing user demand for computing power, a data center should include a large number of interconnected high performance servers.

The hardware modules used to form a data center network (e.g., data center network 100 shown in fig. 1) can include electrical switches, optical transceiver modules (or simply optical modules), and optical cables. Current data centers typically implement networks at 100Gbps (gigabits per second) with an electrical switch chip having input/output (I/O) capacity of 128 x 25Gbps or 256 x 25Gbps and an optical transceiver module having 100Gbps speed. The Network Interface Card (NIC) of each server can have a speed of 25Gbps or higher. The next generation data centers may implement 400Gbps networks with switch chips having I/O capacity of 256 x 50Gbps or 512 x 50Gbps and optical transceiver modules having speeds of 400 Gbps. NIC speeds for servers in next generation data centers can reach 100 Gbps.

For high speed (e.g., 100Gbps and above) data center networks, optical interconnects (e.g., optical transceivers and optical cables) may be necessary to enable interconnections among the switches and coupling between the access stratum switches and servers. For large scale networks, it is desirable to have as many switch ports as possible. However, speed mismatches between the switch chip I/O and the optical transceivers may often result in a reduced number of ports on the switch, which can in turn limit the size of the data center network. For example, a switch chip I/O can include 512 electrical channels, where each channel operates at 50 GHz. On the other hand, optical transceiver modules may have a speed of 400Gbps, meaning that up to 8 electrical channels will need to be combined onto a single optical transceiver, which is often coupled to a single optical cable to serve as a single switch port. Thus, instead of providing 512 switch ports, the switch module can only provide up to 64 switch ports.

One possible solution for increasing the port count on a switch is to increase the number of switch chips included in the switch. By cascading multiple switch chips, one can increase the total port count of the switch. However, such solutions can be expensive and can also increase network latency.

Another solution is to slow down the speed of the optical transceivers and use a much larger number of transceivers to service each switch, thereby increasing the number of ports on each switch equally. Fig. 2A and 2B show an exemplary interconnection among two different levels of switches according to the prior art. In fig. 2A, each switch is equipped with one optical module with a single fiber optic cable output. More specifically, the upper level switch 202 is equipped with a high-speed optical transceiver module 204 (e.g., a 400G optical module for a 400G network), and the lower level switch 212 is equipped with a high-speed optical transceiver module 214. The output of each optical module is a single optical cable (e.g., optical cable 206). As one can see, the switches at each level can be coupled to only a single switch at a different level, since each switch has only one port for each link (e.g., uplink or downlink). Note that here each switch actually includes both uplink and downlink. In the figures, only one link (uplink or downlink) is shown for simplicity. On the other hand, in the example shown in fig. 2B, the uplink or downlink of each switch is equipped with two optical modules with reduced speed. For example, instead of 400G optical transceivers, each switch can be equipped with two 200G optical transceivers. More specifically, the downlink of the upper switch 222 is equipped with optical transceiver modules 224 and 226, while the uplink of the lower switch 232 is equipped with optical transceiver modules 234 and 236. Similar to the example shown in fig. 2A, each optical transceiver module has a single output optical cable. For example, the optical module 224 has an output cable 228, while the optical module 226 has an output cable 230. As a result, each switch now has two switch ports that can be connected to two other switches. In the example shown in fig. 2B, each of the two upper level switches (e.g., switch 222 or 242) can be coupled to two lower level switches (e.g., switches 232 and 252). The size of the network shown in fig. 2B is twice as large as the example shown in fig. 2A.

However, increasing the number of optical transceivers without increasing network speed may not be cost effective because the cost per bit of the optical modules increases. Furthermore, the increased number of optical transceivers can also result in an upsizing of the switch box, which is not desirable in a data center.

To overcome these problems, some embodiments increase the number of switch ports on a switch without reducing the speed of its optical modules. More specifically, in some embodiments, instead of a single optical cable, the optical transceiver module can be coupled to multiple parallel optical cables, where each cable includes a single optical fiber or bundle of optical fibers. In other words, rather than having a single input/output cable to facilitate a single switch port, optical modules now have multiple parallel input/output cables to facilitate multiple switch ports, thereby increasing the number of ports on the switch without having to slow down the speed of the optical modules. Note that each individual switch port includes both input and output optical cables.

Figure 3A illustrates an exemplary interconnection among switches according to one embodiment. In fig. 3A, each link of each switch includes one optical module and each optical module includes two independent optical cables. For example, switch 302 is equipped with optical modules 304 in its downlink that are coupled to two optical cables, cables 306 and 308. Similarly, the switch 312 is equipped with an optical module 314, and the input/output of the optical module 314 is carried by two optical cables, optical cables 316 and 318. Note that each cable can include a single optical fiber or a bundle of optical fibers.

Fig. 3A also shows that two optical cables of an optical switch can be coupled to two optical cables of two different optical switches. For example, the superior switch 302 can be separately coupled to the inferior switches 322 and 324 via the optical cables 306 and 308. Similarly, the upper level switch 312 can also be separately coupled to the lower level switches 322 and 324 via optical cables 316 and 318. The size of the network shown in fig. 3A is twice as large as the example shown in fig. 2A, while keeping the speed of the optical modules (e.g., optical modules 304 and 314) unchanged.

The size of the network can be further increased by equipping each switch with a plurality of optical modules. Figure 3B illustrates an exemplary interconnection among switches according to one embodiment. In fig. 3B, each switch includes two optical modules in one link (e.g., uplink or downlink), and each optical module includes two input/output optical cables. Thus, the link of each switch is now provided with four switch ports, making it possible for the switch to couple to up to four other switches in either the uplink or downlink. In the example shown in fig. 3B, the upper level switch 342 can be coupled to the lower level switches 352, 354, 356, and 358 via four fiber optic cables of the switch 342 in its downstream link. Similarly, the upper level switch 344 can also be coupled to the same four lower level switches via four fiber optic cables in its downstream link. The size of the network has doubled compared to the example shown in fig. 2B, while keeping the switch fabric and optical module speed unchanged.

The size of the network can be determined based on the number of optical modules per switch and the number of independent inputs/outputs per optical module. Figure 4 illustrates an exemplary network with two levels of switches, according to one embodiment. Each switch can be equipped with N optical modules in its uplink or downlink, where each optical module can have M independent inputs/outputs, where each input/output is a separate optical cable. Note that the individual cables may be a single optical fiber or a single multi-fiber bundle. In the example shown in fig. 4, the optical modules included in the downlink of the upper switch 402 can be labeled as module _0 (or MOD _0) to module _ N-1 (or MOD _ N-1), and the switch ports (i.e., input/output optical cables) of the optical modules 404 can be labeled as port _0 to port _ M-1. As one can see from fig. 4, the downlink or uplink of each switch has N × M ports, making it possible for the switch to couple in its downlink or uplink to at most N × M other switches.

In some embodiments, the switch can have various I/O capacities, such as 256 × 50Gbps and 512 × 50 Gbps. The scope of the present disclosure is not limited by the type or capacity of the switch module. Similarly, optical modules equipped on the switch can have various speeds and conform to various types of form factors. In some embodiments, the optical module can have a speed of 200Gbps or 400 Gbps. The optical module can have an eight-way mini (OSFP), a four-way mini-dual density (QSFP-DD), or a QSFP form factor. Furthermore, the types of Photophysical Medium Dependent (PMD) used by the optical module can include SR8 (which refers to 8 pairs of multimode fibers), DR4 (which refers to 4 pairs of single mode fibers), and SR4.2 (which refers to 4 pairs of multimode fibers with 2 wavelength channels per fiber).

In the example shown in fig. 4, each switch stage includes N × M switches, and each switch is coupled to N × M switches located at different stages, thereby maximizing the size of the network. In some embodiments, a switch port at a higher level can be defined as (i)₁,j₁,k₁) And a switch port at a lower stage can be defined as (i)₂,j₂,k₂) Wherein i, j, k respectively refer to the number of the switch, the optical module on the switch and the output optical cable of the optical module. The number (or serial number) of the switch (i.e., i) may range from 0 to nxm-1, the number of the optical modules on the switch may range from 0 to N-1, and the number of the output cables on the optical modules may range from 0 to M-1. Subscript (1 or 2) refers to the switch level (up or down, respectively). In some embodiments, connections among switch ports can be arranged using the following formula:

where M refers to the number of cables per optical module and the% symbol indicates an integer division operation. According to the above formula, the leftmost switch port in the upper stage, i.e., port (0,0,0), should be connected to switch port (0,0,0), which is the leftmost port in the lower stage. Similarly, the adjacent switch port (i.e., port (0,0,1)) should be connected to switch port (1,0,0), meaning that it is connected to the leftmost port on the second leftmost switch at the lower level. One can see that the above formula describes the connection shown in fig. 3B. Note that a symmetrical pattern can be observed where connections from switch ports on one side of the top stage may be a mirror image of connections from switch ports on the other side. In the example shown in fig. 3B, the connections from the two switches on the left on the top level are symmetric to the connections from the two switches on the right. For example, the switch ports on the leftmost switch are sequentially (from left to right) coupled to the leftmost port on each subordinate switch, and the switch ports on the rightmost switch are sequentially (from right to left) coupled to the rightmost port on each subordinate switch. Such an arrangement ensures that the connections among all switches are maximized (i.e., each individual switch is connected to a maximum number of other switches) while keeping the overall length of the connection cable short.

The switch ports may also have different types of connection relationships than those defined by the foregoing equations, as long as the number of interconnected switches can be maximized. For example, there may be more or fewer switch stages. In the case of three switch levels, a mid-level switch may have some ports coupled to an upper level switch and some ports coupled to lower level switches. The scope of the present disclosure is not limited by the actual connection pattern among the switch ports.

Optical cables can be assembled differently depending on the type of optical modules used in the switch. More particularly, the optical cable can be assembled differently depending on the type of optical interface provided by the optical module.

In some embodiments, an optical module may include an optical module having 4 pluggable fiber optic interfaces such as the SN manufactured by US Conec, ltd^TM(trademark of Senko Advanced Components of Marlborough, Mass.) interface and the 400G-QSFP-DD-DR4 optical module of the MDC interface. Fig. 5A illustrates an exemplary optical interface of an optical transceiver module. In fig. 5A, the optical interface 500 of the optical module can include a 4-pair fiber connector, such as a fiber optic connectionAnd pairs 502 and 504. In some embodiments, each fiber optic connector can comprise an LC style connector. Each fiber optic connector can facilitate coupling between a single optical fiber and an optical module. In some embodiments, each fiber pair (i.e., the fiber pair coupled to the connector pair) can individually carry both transmitted and received optical signals. In the example shown in fig. 5A, up to 8 individual optical fibers can be coupled to 4-pair fiber optic connectors.

In a conventional data center setting, the output of the optical modules comprises only a single optical cable, which can comprise a bundle of optical fibers, where one half of the optical fibers carries the transmitted optical signals and the other half carries the received optical signals. Fig. 5B shows an exemplary optical interface configuration of a light module according to the prior art. In fig. 5B, an optical module 510 on the switch has a single optical cable 512. Note that although not shown in fig. 5B, a single fiber optic cable 512 can actually include four pairs of optical fibers. The fiber pair is always stay together because it represents the different directions of a single optical link. In the example shown in fig. 5B, the four pairs of optical fibers may be multimode fibers (MMF) or Single Mode Fibers (SMF). As previously discussed, the switch can be coupled to another switch via an optical cable 512. The optical module 510 shown in figure 5B provides at most a single switch port for coupling to different switches. Fig. 5B also shows a front view of a connector 514 coupling a single optical cable 512 to an optical interface 516 on an optical module 510 in a dashed oval. More specifically, the connector 514 can include four separate fiber optic connectors, with each connector having both an input port and an output port.

To increase the number of switch ports on each switch module, in some embodiments, the individual optical cables coupled to the optical modules can be divided into multiple groups. FIG. 5C illustrates an exemplary output configuration of a light module according to one embodiment. In fig. 5C, the eight fibers coupled to optical module 520 are divided into two separate groups, where each fiber group forms a separate switch port, such as switch ports 522 and 524. More specifically, each fiber group can include a fiber optic cable representing a single optical link, and each fiber optic cable can include four optical fibers bundled together. These fibers can include single mode or multimode fibers. Because the optical module 520 includes two independent switch ports (i.e., switch ports 522 and 524), a switch equipped with the optical module 520 can be coupled to at least two other switches via the two switch ports (i.e., switch ports 522 and 524) of the optical module 520. FIG. 5C also shows a front view of a connector 526 that couples the optical cable 522 or 524 to an optical interface 528 of the optical module 520 in a dashed circle. More specifically, the connector 526 can include two separate fiber optic connectors. In some embodiments, the optical interface 528 can include an SN, MDC, or duplex LC connector, and one can select the connector 526 based on the type of fiber optic connector located on the optical interface 528.

FIG. 5D illustrates an exemplary output configuration of a light module according to one embodiment. In fig. 5D, the eight fibers coupled to the optical module 530 can be grouped into four separate groups, where each fiber group forms an independent switch port, such as switch ports 532 or 534. More specifically, each fiber group can include a pair of fibers representing a single optical link. Each optical fiber within the pair carries an optical signal in one direction. These fibers can include single mode or multimode fibers. Because the optical module 530 includes four independent switch ports, a switch equipped with the optical module 530 can be coupled to at least four other switches via the four switch ports of the optical module 530. FIG. 5D also shows a front view of the connector 536 coupling the fiber pair to the optical interface 538 on the optical module 530 in a dashed circle. More specifically, the connector 536 can include a separate fiber optic connector. In some embodiments, optical interface 538 can include an SN, MDC, or duplex LC connector, and one can select connector 536 based on the type of fiber optic connector located on optical interface 538. For example, if the optical interface 538 includes four SN connectors, the connector 536 can include a corresponding SN connector.

Fig. 6A illustrates an exemplary arrangement of multiple fiber optic cables according to one embodiment. In fig. 6A, fiber bundle 602 can include eight fibers (SMFs or MMFs) grouped into two groups. Each group can include four optical fibers bundled together as a single fiber optic cable (e.g., cables 604 and 606). Four-fiber connectors (e.g., two SN, MDC, or duplex LC connectors grouped together) can be attached to each end of each cable. For example, four-fiber optical connectors 608 and 610 can be attached to the left and right ends of the optical cable 604, respectively. Each quad fiber optic connector can be used to couple one end of a corresponding optical cable to an optical interface of an optical transceiver module. For example, connectors 608 and 610 can be coupled to optical interfaces 612 and 614, respectively. More specifically, an optical connector or fiber connector on an optical cable is mated with a corresponding optical interface such that the optical connector can mate with the corresponding optical interface to achieve low loss coupling. For example, if the optical interface on an optical module is an SN, the optical connector on the corresponding optical cable will be an SN connector. Note that in real life implementations, the fiber bundle 602 can be held together as a single bundle before it is fanned out at each end to allow separate fiber cables to be coupled to different switches. This can reduce the number of hanging cables in the data center.

In some embodiments, the optical module can include an eight-core fiber optic interface, allowing up to eight optical fibers to be simultaneously coupled to the optical module. By assembling eight optical fibers coupled to the same optical module into two separate fiber optic cables in a manner similar to that shown in fig. 6A and by attaching separate connectors to the fiber optic cables, some embodiments provide a single optical module with the ability to couple to two other optical modules without any changes to the design of the optical interface on the optical module. If a single optical module belongs to a particular switch and two other optical modules belong to two other different switches, this particular fiber arrangement can now allow the particular switch to be coupled to two other different switches, thereby increasing the size of the network formed by the switches.

Fig. 6B illustrates an exemplary arrangement of multiple fiber optic cables according to one embodiment. In fig. 6B, fiber bundle 622 can include eight fibers (SMFs or MMFs) grouped into four groups. Each group can include two optical fibers bundled together as a single fiber optic cable (e.g., cables 624 and 626). A two-core fiber optic connector (e.g., an SN, MDC, or LC connector) can be attached to each end of each cable. For example, two-core fiber optic connectors 628 and 630 can be attached to the left and right ends of fiber optic cable 624, respectively. Each two-fiber optical connector can be used to couple one end of a corresponding optical cable to an optical interface on an optical transceiver module. For example, connectors 628 and 630 can be coupled to optical interfaces 632 and 634, respectively. By assembling eight fibers into four separate fiber optic cables and by attaching separate optical connectors to each end of the fiber optic cables, some embodiments allow each end of fiber bundle 622 to be coupled to up to four other optical modules, and thus, up to four other switches.

In some embodiments, an optical module provisioned on a switch may have a multi-fiber push-pull (MPO) interface, wherein a plurality of optical fibers are capable of coupling to the optical module via the MPO interface. In addition, additional MPO connectors can be employed in order to group multiple fibers into separate groups. FIG. 7A illustrates an exemplary output configuration of a light module according to one embodiment. In fig. 7A, an optical module 700 has an MPO interface 702. A fiber bundle having an MPO connector 704 can be coupled to the optical module 700 via the MPO interface 702 and the MPO connector 704. In some embodiments, the MPO connector 704 may be a 16-core fiber MPO connector and the fiber bundle can include 16 SMFs or MMFs individually contained in its fiber jacket.

To achieve the desired number of switch ports supported by the optical modules, in some embodiments, the individual fiber bundles can be divided into multiple groups. In the example shown in fig. 7A, 16 fibers have been divided into two groups, where each group includes 8 fibers. Each group of eight fibers can also be coupled to a second stage MPO connector (e.g., eight-fiber MPO connector 706 or 708), allowing these 16 fibers to be coupled to other optical modules via their MPO connectors. Note that the eight fibers in each group can also be divided into two sub-groups, where each sub-group carries signals in one direction. In some embodiments, the MPO connectors 706 and 708 can have a different gender from that of the MPO connector 704. For example, if the MPO connector 704 is male, the MPO connectors 706 and 708 may be female, allowing fiber cables having male connectors to be coupled to the MPO connectors 706 and 708. Typically, the MPO connector 704 and 708 can act as a converter that converts the 16-core fiber MPO interface 702 to two eight-core fiber MPO interfaces 706 and 708.

As one can see in fig. 7A, the optical module 700 now includes two separate ports (i.e., MPO connectors 706 and 708), allowing the optical module 700 to be coupled to up to two other optical modules. In other words, the switch equipped with the optical module 700 can be coupled to at most two other switches via the MPO connectors 704, 706, and 708. In this example, a high-fiber-count to low-fiber-count MPO converter (which includes MPO connector 704 and 708) allows an optical module to have two independent inputs/outputs, making it possible for the optical module to couple to up to two other optical modules.

FIG. 7B illustrates an exemplary output configuration of a light module according to one embodiment. In fig. 7B, the optical module 720 has an MPO interface 722. A fiber bundle having an MPO connector 724 can be coupled to the optical modules 720 via an MPO interface 722 and the MPO connector 724. In some embodiments, the MPO connector 724 may be a 16-core fiber MPO connector and the fiber bundle can include 16 SMFs or MMFs. The 16 fibers attached to the MPO connector 724 can be grouped into four groups, with each group including four fibers. A second stage MPO connector (e.g., a four-core fiber MPO connector 726 or 728) can be attached to the other end of each group. In addition to the quad fiber MPO connectors, other types of connectors can be used at the other end of each quad fiber group, such as a pair of duplex LC or SN connectors. In the example shown in fig. 7B, a converter including a 16-core fiber MPO connector and four-core fiber connectors allows an optical module to have four independent switch ports, making it possible for the optical module to couple to up to four other optical modules.

Fig. 8A illustrates an exemplary arrangement of multiple fiber optic cables according to one embodiment. In fig. 8A, a fiber bundle 802 can include sixteen fibers (SMFs or MMFs) grouped into two groups. Each group can include eight optical fibers bundled together as a single fiber optic cable (e.g., cables 804 and 806). An eight-core fiber MPO connector can be attached to each end of each cable. For example, eight-fiber MPO connectors 808 and 810 can be attached to the left and right ends of cable 804, respectively. Each eight-core optical network MPO connector is capable of coupling an optical cable to a corresponding MPO interface on the optical transceiver module.

Fig. 8B illustrates an exemplary arrangement of multiple fiber optic cables according to one embodiment. In fig. 8B, fiber bundle 822 can include sixteen fibers (SMFs or MMFs) grouped into four groups. Each group can include four optical fibers bundled together as a single fiber optic cable (e.g., cables 824 and 826). A four-fiber optical connector (e.g., MPO or four-way LC connector) can be attached to each end of each cable. For example, four-core fiber MPO connectors 828 and 830 can be attached to the left and right ends of the fiber optic cable 824, respectively. Each quad fiber optic connector can facilitate coupling between an optical cable and a corresponding optical transceiver module. By assembling 16 fibers into four separate fiber optic cables, some embodiments allow one optical module to be coupled to up to four other optical modules, thereby quadrupling the size of the network.

Fig. 9 presents a flowchart illustrating an exemplary process for establishing a data center network, according to one embodiment. During operation, a high performance data center switch can be selected (operation 902). The switch can be equipped with many optical transceiver modules that typically conform to a standard form factor (e.g., SFP, QSFP-DD, OSFP, etc.). The PMD type of the optical transceiver module may be SR8, DR4, or SR 4.2. The optical interface on the optical transceiver module may be SN, MDC, or MPO. Each optical interface may allow coupling of many individual optical fibers. For example, an optical module can allow up to 16 individual optical fibers (SMF or MMF) to be coupled to its optical interface. The coupling between the optical fiber and the optical module can be realized via an optical interface of the SN, MDC or MPO type.

Following the selection of the switch, a person can couple a number of individual optical cables to one or more optical modules on the switch (operation 904). In some embodiments, multiple optical cables can be coupled to a single optical module. Each fiber optic cable can include a single optical fiber or a bundle of multiple optical fibers. For example, two fiber optic cables, each including four individual optical fibers, can be coupled to an optical module having an eight-core fiber optic interface. Each optical cable may be equipped with an appropriate optical connector depending on the type of interface on the optical transceiver module. For example, if the optical transceiver module has an SN or MDC type optical interface, each fiber optic cable will have an SN or MDC connector. For example, if the optical module has an eight-core fiber SN interface, the two optical cables can each have a four-core fiber-optic dual SN connector for plugging into the SN interface on the optical module. In different examples, four fiber optic cables can be coupled to an eight-core fiber SN interface on an optical module, where each fiber optic cable has an SN connector. On the other hand, if the optical transceiver module has an MPO interface, each cable can also have an MPO connector, but the number of fibers is smaller. An MPO converter similar to the converter formed by the MPO connector 704 and 708 shown in fig. 7A can facilitate coupling between the fiber optic cable and the optical transceiver module.

Following the coupling of multiple fiber optic cables to each optical module on the switch, one can couple the other end of each fiber optic cable to a different switch on another level according to a predetermined switch interconnection diagram (operation 906). For example, each switch port (i.e., each individual fiber optic cable) can use a triplet (i)_a,j_a,k_a) Where subscript a specifies the switch level and i, j, and k specify the switch number, optical module number, and cable number, respectively. In some embodiments, there are two switch stages. A particular switch port on an upper level (e.g., port (i)₁,j₁,k₁) Can be coupled to a predetermined switch port (e.g., port (i)) on an inferior level₂,j₂,k₂)). More specifically, the lower level port can be determined based on the following formula:

after coupling all of the individual cables from one switch to a different switch on the next level, one can determine if all of the switches are connected (operation 908). If not, a different switch is selected (operation 902) and the process repeats until each switch has been connected to the maximum number of other switches.

In general, embodiments of the present invention provide a solution for scaling up a data center network by increasing the number of switch ports supported by each switch without making changes to the switch fabric and optical transceiver modules. More specifically, to increase the number of ports per switch, some embodiments allow multiple independent fiber optic cables to be coupled to a single optical module, where each fiber optic cable represents a separate switch port. The individual fiber optic cables can be routed to other different switches, thereby connecting the switch to those other switches. Because the number of optical cables coupled to the switch can be greater than the number of optical modules on the switch, some embodiments can significantly increase the number of ports per switch, and thus increase the size of the network, compared to conventional approaches where a single optical cable is coupled to each optical module. In certain scenarios where there are two stages of switches, the coupling among the switch ports of the two stages can follow a predetermined pattern, which can ensure that each switch is coupled to a maximum number of other switches while keeping the total cable length short. The optical transceiver module can employ various types of optical interfaces. Thus, the optical cable may employ different types of optical connectors. The scope of the present disclosure is not limited by the particular type of connector used by each cable.

The foregoing description of various embodiments has been presented for the purposes of illustration and description only. They are not intended to be exhaustive or to limit the invention to the forms disclosed. Accordingly, many modifications and variations will be apparent to practitioners skilled in the art. Additionally, the above disclosure is not intended to limit the present invention. The scope of the embodiments described herein is defined by the appended claims.