Patent Publication Number: US-2017366881-A1

Title: Scalable Secure Hybrid Electrical-Optical Switched Network with Optical Wavelength Tunable Transceivers

Description:
The current application claims a priority to the U.S. Provisional Patent application Ser. No. 62/350,910 filed on Jun. 16, 2016. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates generally to a method of creating a centralized optical switch network. More specifically, the present invention creates a hybrid electric and optical data center network that utilizes the optical wavelength tunability of the optical transceivers to adapt the network topology and link capacities for changing traffic a variety of traffic demands. 
     BACKGROUND OF THE INVENTION 
     Currently, optical fiber is a major part of the communication infrastructures, be it the telecommunication networks, cable networks, or data center networks. The key requirement is the high bandwidth and the ability to communicate from one end of the network to the other end of the network with proper switching. This invention description is for the data centers applications, but the architecture is equally applicable to telecommunication and cable networks. 
     As the data centers become more modular and larger in sizes, they require higher aggregation or larger switches. Subsequently, the traffic become more stable/steady in addition to the usual bursty traffic. Using purely electrical packet switches to route the traffic and maintain the high bandwidth needed to reduce the over subscription becomes unnecessarily costly. As such, with proper traffic engineering, it is a lot more reasonable to route the traffic with more stable nature through circuit switches whereas the bursty traffic can stay in the packet switching part of the network. 
     A typical data center infrastructure consists of at least three levels of equipment. On the access level are the massive servers serving the function of calculation and storage. The servers are usually housed in racks or rows of racks. These servers are the hosts feeding the Top of the Rack (ToR) switches or End of Row (EoR) switches that perform the switching function as well as aggregate these servers and connect to higher level aggregators through copper and fiber networks. These aggregators then connect to core switches with optical transceivers before going across the outside connection demarcation and emanating from the data centers and traverse the telecommunication network and cloud to its destination. To facilitate effective communication and services inside the data center, data needs to be moved from server to server, rack to rack, aggregators to aggregators. As such, there exist the switches need to provide these functionalities in an as little blocking as possible fashion while utilizing the machines effectively with largest possible bandwidths. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  is a flowchart illustrating the basic overall process of the present invention. 
         FIG. 1B  is an illustration of the present invention being used within data center architecture. 
         FIG. 2  is an illustration of the optical central switch being used with the plurality of ToR/EoR switches. 
         FIG. 3  is an illustration of the outgoing assembly. 
         FIG. 4  is an illustration of the incoming assembly. 
         FIG. 5  is an illustration of the optical central switch. 
         FIG. 6  is an illustration of one of the plurality of space switches. 
         FIG. 7  is an illustration of the tunable optical filter being used with the present invention. 
     
    
    
     DETAIL DESCRIPTIONS OF THE INVENTION 
     All illustrations of the drawings are for the purpose of describing selected versions of the present invention and are not intended to limit the scope of the present invention. 
     The present invention introduces a method for creating a hybrid electrical and optical network to maximize efficiency and affect non-blocking traffic within a data center. In order to maximize efficiency and affect non-blocking traffic, the present invention uses electrical switches and a wavelength switching within tunable transceivers in conjunction with a software defined network to effectively direct the traffic within a data center. The present invention provides significant saving on capital expenditure, operational expenditure, and power consumption in the constantly growing data centers. Moreover, the present invention maximizes intra data center bandwidth, minimizes packet switching blockages, and promotes non-blocking optical switching. 
     As illustrated in  FIG. 1A  and  FIG. 1B , to maximize efficiency and affect non-blocking traffic, the present invention is provided with a plurality of servers  5 , a plurality of top-of-the-rack (ToR)/end-of-the-row (EoR) switches  7 , and an optical central switch  1 . The plurality of servers  5  and the plurality of ToR/EoR switches  7  are interconnected such that each of the plurality of servers  5  is electronically connected to a corresponding ToR/EoR switch from the plurality of ToR/EoR switches  7 . To direct traffic from one server to another server of the plurality of servers  5 , the plurality of ToR/EoR switches  7  is communicatively coupled amongst each other through a network of electronic pathways  19  or a network of optical pathways  9 . To do so, the optical central switch  1  is communicatively coupled to a subset of routable optical pathways  10  within the network of optical pathways  9 . The remaining pathways in the network of optical pathways  9  and the network of electronic pathways  19 , which are outside the subset of routable optical pathways, are communicatively coupled through a plurality of core and aggregator switches. However, the optical central switch  1  and the subset of routable optical pathways  10  enable a wavelength-tunable signal to reach its intended destination via the most optimal path. More specifically, when a wavelength-tunable signal is generated at an arbitrary server  6  from the plurality of servers  5 , the corresponding ToR/EoR switch associated to the arbitrary server  6  transmits the wavelength-tunable signal to the optical central switch  1  through the subset of routable optical pathways  10 . Upon receiving the wavelength-tunable signal, the optical central switch  1  optically directs the wavelength-tunable signal in order to direct the wavelength-tunable signal to a specific server from the plurality of servers  5 . In doing so, the wavelength-tunable signal is transmitted from the optical central switch  1  to the corresponding ToR/EoR switch of the specific server through the subset of routable optical pathways  10 . 
     As illustrated in  FIG. 2 , to execute wavelength switching, the present invention provides at least one outgoing assembly  11  for each optical routed pathway. The outgoing assembly  11  includes a plurality of transceivers  12  and a combiner  13  that is used simultaneously for wavelength switching purposes. More specifically, the wavelength-tunable signal is generated with the plurality of transceivers  12  and is multiplexed with the combiner  13  before being transmitted to the optical central switch  1  via the subset of routable optical pathways  10 . 
     As illustrated in  FIG. 7 , to significantly reduce relative intensity noise (RIN) from the wavelength-tunable signal, the present invention is provided with a tunable optical filter  14  for the outgoing assembly  11 . The tunable optical filter  14  modifies the wavelength-tunable signal before transmitting the wavelength-tunable signal to the optical central switch  1 . Thus, the noise in the combined wavelength-tunable signal is minimized. The tunable optical filter  14  can be integrated into the outgoing assembly  11  differently in varying embodiments of the present invention. As an example, the tunable optical filter  14  can be integrated at an input port of the combiner  13 . 
     As illustrated in  FIG. 3  and  FIG. 4 , different kinds of transceiver can be electronically integrated into each of the plurality of ToR/EoR switches  7 . Thus, when the present invention is provided an optional electrical transceiver, the optional electrical transceiver is communicably coupled to the network of electronic pathways  19 . As an example, the optional electrical transceiver can be used to connected to the plurality of core and aggregator switches  21 . When the present invention is provided with an optional non-wavelength specific transceiver for each of the plurality of ToR/EoR switches  7 , the optional non-wavelength specific transceiver is communicably coupled to the network of optical pathways  9 , outside of the subset of routable optical pathways  10 . Thus, the optional non-wavelength specific transceiver can be used for optical signals that are not routed through the optical central switch  1 . When the present invention is provided with an optional fixed wavelength transceiver for each of the plurality of ToR/EoR switches  7 , the optional fixed wavelength transceiver is communicably coupled to the subset of routable optical pathways. However, the optional fixed wavelength transceiver can also be communicably coupled to the network of optical pathways  9 , outside of the subset of routable optical pathways  10 . In the preferred embodiment of the present invention, the optional fixed wavelength transceiver is a dense wavelength division multiplexing (DWDM) grid. When the present invention is provided with at least one tunable wavelength transceiver for each of the plurality of ToR/EoR switches  7 , the at least one tunable wavelength transceiver is communicably coupled to the subset of routable optical pathways  10 . The wavelength tunability allows the wavelength-tunable signal to originate from any of the plurality of ToR/EoR switches  7  and allows the wavelength-tunable signal to be directed to any of the plurality of ToR/EoR switches  7 . Data collisions are avoided by utilizing the wavelength tunability of the present invention. 
     As mentioned earlier, when being combined into a single fiber with the use of the combiner  13 , the wavelength-tunable signal can encounter a notable optical loss. To address the optical loss, the outgoing assembly  11  for each optical routed pathway includes an optical amplifier  16  as seen in  FIG. 3  and  FIG. 4 . By utilizing the optical amplifier  16 , the wavelength-tunable signal is amplified before being transmitted to the optical central switch  1 . In the preferred embodiment of the present invention, the optical amplifier  16  is an Erbium-doped fiber amplifier (EDFA). The EDFA is used since the wavelengths associated with the present invention are in the C band and the L band. However, other optical amplifiers can be used in different embodiments of the present invention when different wavelengths are involved. 
     The space switching portion of the present invention is executed as part of the optical central switch  1 . As seen in  FIG. 5  and  FIG. 6 , the present invention is provided with a plurality of internal demultiplexers  2 , a plurality of space switches  3 , and a plurality of internal combiners  4  for the optical central switch  1 . Furthermore, the plurality of internal demultiplexers  2  is communicatively coupled with each of the plurality of space switches  3 , and each of the plurality of space switches  3  is communicatively coupled with each of the plurality of internal combiners  4 . Moreover, each of the plurality of space switches  3  includes an equal number of inputs and outputs. For instance, if the optical central switch  1  consists of a K-number of inputs, the optical central switch  1  will have a K-number of outputs so that the optical central switch  1  is a K×K switch. The wavelength-tunable signal is received with an arbitrary internal demultiplexer from the plurality of internal demultiplexers  2 . The arbitrary internal demultiplexer is associated to the arbitrary server  6  that generated the wavelength-tunable signal. Upon receiving the wavelength-tunable signal at the plurality of internal demultiplexers  2 , the wavelength-tunable signal is routed from the arbitrary internal demultiplexer through a specific space switch from the plurality of space switches  3 . The specific space switch is determined by the network management software that is used with the present invention. More specifically, the traffic orchestration of the network management software determines the specific space switch. Upon routing to the least traffic-burdened switch, the present invention routes the wavelength-tunable signal from the least traffic-burdened switch to a specific internal combiner, wherein the specific internal combiner is associated to the specific server. Each output is associated with an internal combiner of the plurality of internal combiners  4 . Thus, in a K×K switch, the plurality of internal combiners  4  consists of a K-number of internal combiners. 
     For the wavelength-specific signal to reach the specific server, the present invention is provided with at least one incoming assembly  17  for each optical routed pathway. To execute the process of transmitting the wavelength-tunable signal to the specific server, the incoming assembly  17  includes an incoming demultiplexer  18  and a plurality of transceivers  12 . The wavelength-tunable signal is demultiplexed with the incoming demultiplexer  18 . Next, the wavelength-tunable signal is received with the use of the plurality of transceivers  12  so that the wavelength-tunable signal reaches the specific server. The present invention provides a pre-optical amplifier  30  for each of the plurality of transceivers  12  so that the wavelength-tunable amplifier can be amplified before the wavelength-tunable signal is received by the plurality of transceivers  12 . 
     The tunability of the present invention enables software defined network (SDN) and network function virtualization (NFV) orchestration. More specifically, the present invention eliminates the need to closely monitor traffic patterns and alter software and hardware for efficiency. The present invention also provides transparent integration between the electrical packet switching and optical packet switching. To do so, the present invention directs traffic by considering switching time and buffering the traffic according to the switching time. Thus, no data loss occurs during the optical or electric switching. 
     The present invention can be used to establish optimal and flexible network communication internal to data centers with linearly scalable switches. To do so, the present invention combines electrical packet switching and optical circuit switching to obtain a conceptually non-blocking network. Moreover, the present invention enhances network security on the wavelength level so that the cost of securing is also reduced. 
     Although the invention has been explained in relation to its preferred embodiment, it is to be understood that many other possible modifications and variations can be made without departing from the spirit and scope of the invention as hereinafter claimed.