CN201075868Y - Multi spider route device with multipath optical interlinkage parts - Google Patents

Abstract

The utility model provides a multi-frame network device including a plurality of nodes operated as a single device in the network and an exchange structure transmitting a data plane packet among a plurality of nodes. The exchange structure includes a group of multi-way light mutual connecting parts that couple the nodes. For example, a multi-frame router includes a plurality of routing nodes used as the single router in the network and the exchange structure transmits packets among a plurality of nodes. The exchange structure includes at least one multi-way light mutual connecting part that couples the nodes. The nodes of the multi-frame router can lead a plurality of parts of the optical signal to be into mutually different parts on the multi-way light mutual connecting part through using the wavelength division multiplexing.

Description

Multi-chassis router with multi-way optical interconnect

technical field

The utility model relates to computer network technology, more specifically, to a multi-rack router in the computer network.

Background technique

A computer network is a collection of interconnected computer devices that can exchange data and share resources. In a packet-based network, such as Ethernet, data is communicated between computing devices by dividing it into variable-length chunks called packets, which are routed individually from source to destination through the network . The destination device extracts the data from the packets and assembles the data into its original form.

Certain devices known as routers maintain routing information in terms of network topology. These routers exchange routing information in order to maintain an accurate representation of available routes through the network. A "route" is generally defined as a path between two locations in a network. When receiving an incoming data packet, the router examines information often called a "key" in the packet to select the appropriate next hop to forward the packet based on the routing information.

Typically, service providers, such as Internet providers that provide network services in the core of the Internet, have struggled to meet ever-increasing bandwidth demands. One way to meet growing bandwidth demands is to use "multi-chassis" routers. A multi-chassis router is a router in which multiple routing nodes are physically connected and configured to operate as a single routing node. An example of a multi-chassis router includes multiple line card chassis (LCCs), which include one or more interface cards (IFCs) for sending and receiving packets, and a central switch control chassis ( central switchcontrol chassis, referred to as SCC, which provides top-down management of the LCC). This type of multi-chassis router is often referred to as a single-head multi-chassis router, ie, a routing system in which all routing calculations are done in a single routing engine in a host computer designated as the routing system. To peer routers on the network, a multi-chassis router appears as a single routing node. Because multi-chassis routers combine the resources of multiple routing devices, these multi-chassis routers have higher bandwidth performance than stand-alone routers. For example, using a multi-chassis router simplifies and improves routing on a service provider network by consolidating routing functionality on fewer routers.

Utility model content

In general, this paper describes a multi-chassis router in which multiple routing nodes in a multi-chassis router are coupled (coupled) through the use of multiplexed optical connections. A multi-level switch fabric, such as a 3-level Clos switch fabric, relays packets between these routing nodes. The stages of the switch fabric can be distributed to individual routing nodes of the multi-chassis router, while the multi-way optical interconnect forwards packets between these nodes.

For example, a multi-chassis router may include multiple line card chassis (LCCs) that cooperate to operate as a single router in the network without including a disparate, centralized switching fabric. The implementation of the multi-stage switch fabric can be distributed to LCCs, and these LCCs can communicate using multiplexing over the optical interconnect components. Additionally, one or more central switching nodes, such as a central switching control chassis, may be incorporated into a multi-chassis router. In either case, the use of multiplexing reduces the overall length of fiber optic cables required to implement the switch fabric and reduces the number of fiber optic cable interfaces required on each LCC. As a result, multi-chassis routers can be more easily scaled to incorporate increased numbers of routing nodes without reaching or exceeding any physical size limit in the environment in which the multi-chassis router will be deployed.

In one embodiment, the present invention is introduced into a multi-chassis multi-chassis router comprising: a plurality of routing nodes operating as a single router in the network, and a packet forwarder between said plurality of routing nodes the exchange structure. The switch fabric includes at least one multipath optical interconnect coupling the routing nodes.

In another embodiment, the present invention is introduced into a multi-chassis multi-chassis router comprising: a plurality of N routing nodes operating as a single router in the network, and a multi-chassis router with M A multi-level switching structure for forwarding packets between multiple routing nodes. The multi-chassis router also includes N x (M-1) multi-way point-to-point data interconnect components coupling the data planes of the routing nodes via the switch fabric.

In another embodiment, the invention is incorporated into fiber optic cables for connecting multiple routing nodes in a multi-chassis router. The fiber optic cable comprises: a fiber optic cable input for receiving an optical signal from a first routing node of said plurality of routing nodes, and a plurality of optical cables for outputting a portion of said optical signal to each of the remaining routing nodes Optical splitter (optical tap). The plurality of optical splitters divide the optical energy of the optical signal substantially equally among the remaining nodes of the plurality of routing nodes.

In yet another embodiment, the present invention is incorporated into a set of optical cables for interconnecting N network devices, the set of optical cables includes N optical cables, where N is an integer greater than or equal to 2. Each of the N optical cables includes an input for receiving an optical signal from a first of said N network devices, and for outputting an optical signal to said N-1 remaining network devices N-1 optical splitters. The N-1 optical splitters split the optical signal to output substantially equal portions of the optical signal to the N-1 remaining network devices.

In a further embodiment, a method is presented that includes receiving a packet at one of a plurality of routing nodes in a multi-chassis router, selecting a wavelength based on information in the packet (wherein the wavelength corresponds to a routing node in the multi-chassis router), and forwarding the packet via the optical signal with the selected wavelength from a first routing node of the routing nodes in the multi-chassis router via a switch fabric having an optical interconnect transmitted to the second routing node of the routing node.

In yet a further embodiment, the invention is incorporated into a network arrangement comprising a plurality of forwarding nodes and a set of multi-way optical interconnection components coupling the forwarding nodes. The network device connects other devices on the network.

In still further embodiments, the present invention is incorporated into a plurality of network devices coupled to a network, and a multi-chassis network device connected to a plurality of network devices on the network. The multi-chassis network device includes a plurality of nodes operating as a single device in the network, and a switch fabric that forwards data plane packets between the plurality of nodes. The switch fabric includes a set of multiplexed optical interconnects coupling the nodes.

Embodiments of the present invention may provide one or more beneficial effects. For example, the described technology provides an option for multi-chassis routers that include a centralized switching fabric in a dedicated chassis. Instead of having a dedicated chassis containing a centralized switching fabric, each chassis in a multi-chassis router can also include an external network interface. The described techniques allow scaling of multi-rack routers without limiting the bandwidth capacity of a centrally located switching fabric and without limiting the number of fiber optic cable connector jacks that can physically fit on a single central rack. Multiplexing combines multiple logical connections in the LCCs of a multi-chassis router, thereby reducing the number of cable connector jacks and the number of fiber optic cables required to interconnect the LCCs. This reduces the physical complexity of the multi-chassis router and increases the physical space available for other purposes such as external network interfaces.

The details of one or more embodiments of the invention are set forth in the accompanying drawings and the description below. Other features, purposes and advantages of the present utility model will become clear from the specification, drawings, and claims.

Description of drawings

1 is an example block diagram of a computing environment including multi-chassis routers in a service provider network;

Figure 2 is a block diagram illustrating an exemplary multi-chassis router;

3 is a schematic diagram of a system including an optical cable carrying a multi-channel signal containing multiple channels from one switch fabric to another switch fabric;

Figure 4 is a block diagram illustrating in greater detail an exemplary line card shelf having a Routing Engine and multiple line cards;

Figure 5 is a block diagram illustrating a three-level network;

6 is a schematic diagram of an optical cable including a plurality of optical splitters configured to equally split an optical input signal;

7 is a block diagram illustrating an exemplary multi-chassis router including sixteen line card chassis arranged in a circular layout.

Detailed ways

FIG. 1 is a block diagram illustrating an example of a network environment 2 including a multi-chassis router 4 within a service provider network 6 . For exemplary purposes, the principles of the present invention are described with respect to the simplified network environment 2 in FIG. 8A-8C ("client network 8") to access the network 6. Multi-chassis router 4 may exchange routing information with edge router 5 in order to maintain an accurate representation of the topology of network environment 2 . The multi-chassis router 4 may consist of multiple cooperating routing components operating as a single node within the service provider network 6 .

Although not shown, the service provider network 6 may connect to one or more networks managed by other providers, and thus may form part of a large-scale public network infrastructure such as the Internet. Furthermore, the customer network 8 can be regarded as an edge network of the Internet. Service provider network 6 may provide computing devices in customer network 8 with Internet access and may allow computing devices in customer network 8 to communicate with each other. In another example, service provider network 6 may provide network services in the core of the Internet. In any of the above examples, service provider network 6 may include various network devices (not shown) other than multi-chassis router 4 and edge router 5, such as additional routers, switches, servers, or other devices.

In the example shown, edge router 5A is coupled to customer network 8A via access link 9A, while edge router 5B is coupled to customer networks 8B and 8C via access links 9B and 9C, respectively. Customer network 8 may be a network for geographically separated corporate sites. Client network 8 may include one or more computing devices (not shown), such as personal computers, laptops, palmtops, workstations, servers, switches, printers, client data centers, or other devices. The structure of the network environment 2 shown in FIG. 1 is merely exemplary. For example, service provider network 6 may be coupled to any number of customer networks 8 . However, for convenience of description, only customer networks 8A-8C are shown in FIG. 1 .

Consistent with the principles of the present invention, multi-chassis router 4 includes multiple routing nodes (not shown in FIG. 1 ) that are physically coupled and configured to operate as a single routing node. That is, to peer edge routers 5 of network environment 2, multi-chassis router 4 appears as a single routing device. For example, although multi-chassis router 4 includes multiple routing nodes, from the perspective of peer edge router 5, multi-chassis router 4 has a single network address and maintains a single peer routing session for use with each edge Each routing protocol for router 5's peer routing sessions.

As explained further below, the multiple routing nodes of the multi-chassis router 4 forward packets, ie, network traffic, on the data plane of the multi-chassis router 4 by using multi-way optical interconnection components. Control plane communication between the multiple routing nodes of the multi-chassis router 4 may also occur through the use of multi-way optical interconnects or by other means. The multi-chassis router 4 includes a multi-stage switch fabric, such as a 3-stage Clos switch fabric, which relays packets between these routing nodes via optical interconnection components by using multi-channel communication. The term packet is used herein to refer to both fixed-length and variable-length data units. In different configurations, only fixed-length data units, only variable-length data units, or both fixed-length and variable-length data units can be relayed between these routing nodes.

In an exemplary configuration, the stages of the switch fabric may be distributed among individual routing nodes of the multi-chassis router in a decentralized manner. For example, a multi-chassis router may include multiple line card chassis (LCCs) that cooperate to operate as a single router in the network without including a distinct, centralized switching fabric. The implementation of the multi-stage switch fabric can be distributed among the LCCs, and the LCCs can communicate by using multi-way communication. Additionally, one or more central switch fabric nodes, such as Switch Control Chassis (SCC), may be incorporated into a multi-chassis router. In either case, the use of multiway communication between these routing nodes may provide certain benefits. For example, the use of multiplex communication reduces the overall length of fiber optic cable required to implement a switch fabric interconnecting nodes. Additionally, multiplexing reduces the number of fiber optic interfaces required on each routing node. As a result, the multi-chassis router 4 can be more easily scaled to incorporate an increased number of routing nodes without reaching or exceeding any physical size limitations with respect to the environment in which the multi-chassis router will be deployed.

FIG. 2 is a block diagram illustrating an exemplary multi-chassis router 120 that routes data packets between network devices over a network. Multi-chassis router 120 may, for example, illustrate an instance of multi-chassis router 4 of FIG. 1 in more detail.

As shown in FIG. 2, multi-chassis router 120 includes a plurality of cooperating routing components that operate as a single node in the network. In this example, multi-chassis router 120 includes four substantially identical LCCs 128A-128D ("LCCs 128"). In other examples, a multi-chassis router may include more or fewer LCCs, and may also include a central routing node connecting the LCCs.

Each of the LCCs 128 can be constructed with a set of line cards 134A-134D ("LC134"), each of which includes a packet forwarding engine (PFE) and a set of one or more independent interface cards (IFC) ( not shown) for incoming and outgoing network communications. In this example, LCCs 128 each also include one of Routing Engines 130A-130D ("Routing Engines 130"), and a plurality of them for implementing Switch Fabrics 125A-125D ("Switch Fabrics 125"). part of the electronics.

Switch fabric 125 provides multiple stages of switches that forward packets between LCCs 128 . As described herein, the switch fabric 125 includes a multi-way optical interconnection unit 136 that interconnects those portions of the switch fabric 125A- 125D distributed among the individual LCCs 128 . In this example, the multi-lane optical interconnection unit 136 consists of two sets of N optical cables interconnecting the LCCs 128, where N represents the number of LCCs, ie, N=4 in this example. That is to say, in this example, each group of optical cables includes four optical cables, one of which is connected to the multi-channel optical output on each LCC 128 . In one example, switch fabric 125 is a three-level switch fabric, and each LCC 128 includes a portion of each of the three levels. A first set of fiber optic cables in multi-chassis router 120 connects stage 1 of each LCC 128A to stage 2 of each LCC. A second set of fiber optic cables used in multi-chassis router 120 connects stage 2 of each LCC 128 to stage 3 of each LCC. As further explained below, for each stage of the switch fabric, a given LCC 128, such as LCC 128A, can communicate with each of the other LCCs (e.g., LCCs 128B-128D) by using a single fiber optic cable to output multiplexed communications. Both communicate. In this way, instead of 2N ² fiber optic cables, only 2N fiber optic cables can be used to provide a 3-level switch fabric interconnecting N routing nodes (LCC 128 ) in multi-chassis router 120 . In other embodiments, more or less fiber optic cables may be used to connect different parts of the switch fabric 125 .

Continuing with the example of FIG. 2, the multi-way optical interconnection assembly 136 includes a total of eight optical cables. For example, each of the eight optical cables may be substantially similar to optical interconnection component 136A in FIG. 3 . The switch fabric 125 for each LCC 128 includes two multiplexed optical outputs, that is, one output is for communication from the first stage of the switch fabric to the second stage, and the other output is for communication from the second level to tertiary communication. Each of the eight multiplexed optical outputs for the four LCCs 128 is connected to a different one of the eight optical interconnects 136. The LCCs 128 each also have six inputs to receive signals from other LCCs 128. Each fiber optic cable includes three optical splitters that distribute optical signals to the inputs of other LCCs 128. In some embodiments, the optical splitter of the fiber optic cable is configured to output a substantially equal share of the optical signal among all the optical splitters connected to the fiber optic cable. In one embodiment, LCC 128 outputs multiplexed communications by transmitting different wavelength channels of the same optical signal. The wavelength channels destined for a particular one of the LCCs 128 are optically isolated at that one LCC 128 to separate the relevant channels from the optical channels used for the other LCCs 128. Other forms of multiplexing, such as time division multiplexing (TDM), may also be used.

Routing engines 130A- 130D (“routing engines 130 ”) control the forwarding of packets through multi-chassis router 120 . A separate fiber optic cable 137 may be used to share control plane information between Routing Engines 130 . For example, routing engines may communicate with each other via fiber optic cable 137 to exchange routing information, status information, configuration data, and other information. For example, the routing information may include routing data describing the various routes through the network, and next hop data indicating suitable neighbors in the network for each route. Routing engine 130 updates routing information to accurately reflect the current network topology. Similar to optical interconnect 136, which is used to relay data plane traffic between LCCs 128, fiber optic cable 137 may also be a multi-lane optical interconnect.

Routing engine 130 also uses the routing information to derive forwarding information bases (FIB for short). Routing Engine 130 installs a FIB in each LCC 128 . The FIB for one of the LCCs 128 may be the same or different from the FIBs of the other LCCs 128. Routing engine 130 may communicate via fiber optic cable 137 to coordinate FIB installation. Because fiber optic cable 137 provides a dedicated connection, i.e., a connection separate from the packet forwarding connection provided between LCCs 128 by multi-way optical interconnect 136, the FIBs in Routing Engine 130 need not interrupt execution of the multi-chassis The packet forwarding of router 120 can be updated.

The following example illustrates the packet forwarding operation of multi-chassis router 120 . Incoming packets are first received from the network by an IFC of LC 134, such as LC 134B, which directs it to one of its PFEs, hereinafter referred to as the received PFE. The received PFE then determines the next hop for the packet by using the FIB provided by a routing engine such as routing engine 130B on the LCC. If the packet is sent to an outgoing link on the same LCC 128 as the IFC that initially received the packet, the receiving PFE forwards the packet to the outgoing link. In this way, packets sent out on the same PFE that were already received by the network bypass switch fabric 125 .

Otherwise, the received PFE sends the packet to the switch fabric 125, where it is distributed among the correct outgoing LCCs, namely one of the LCCs 128. In the LCC from which the LCC 128 departs, the packet is forwarded to the departing PFE. In some embodiments, the data packet is divided into smaller fixed-length data units at the received PFE. These fixed-length data units can then be sent individually to the outgoing PFE, where they are reassembled into the original, larger data packets. These smaller fixed-length data units do not each follow the same path between the received PFE and the outgoing PFE. These embodiments may provide more efficient utilization of switch fabric 125 than embodiments in which larger data packets are not fragmented prior to forwarding on switch fabric 125 . The outgoing PFE outputs the packet to the appropriate next hop via one of the IFCs on one of the LCs 134. Thus, an incoming packet received by one of the LCCs 128 may be routed to the next hop by the other LCC 128 along the route of the packet's ultimate destination. Other multi-chassis routers operating in a manner consistent with the principles of the invention may use different switching and routing mechanisms.

Multi-chassis router 120, and in particular LCC 128, may include hardware, firmware, and/or software, and may include a processor, control unit, discrete hardware circuits, or other logic for executing instructions retrieved from a computer-readable medium circuit. Examples of these media include: hard disks, flash memory, random access memory (RAM), read only memory (ROM), nonvolatile random access memory (NVRAM), electrically erasable programmable read only memory (EEPROM), etc. wait.

While multi-chassis router 120 is described as having four nodes each having a portion of a three-level switch fabric, other embodiments may include more or fewer nodes, and/or have more than one About three levels of switch fabric above the nodes. In either of these embodiments, groups of fiber optic cables can be used to connect different stages of the switch fabric among different nodes of the multi-chassis router. For example, in a multi-chassis router with N nodes, a first set of N fiber optic cables including one cable for each of the N nodes can be used to couple the first stage of the switch fabric to the second stage of the switch fabric. class. A second set of N fiber optic cables, including one for each of the N nodes, can be used to couple the second stage of the switch fabric to the third stage, such that 2N fiber optic cables in the multi-chassis router 120 A three-level switching fabric is implemented in the data plane. Each of the N optical cables may include a single input for receiving an optical signal from the first of the N nodes, and N-1 optical signals for outputting the optical signal to the remaining nodes Splitter. Extending this structure to any switch fabric comprising M stages, where M is at least 2, provides M-1 sets of cables or, more specifically, a total of N*(M-1) cables.

FIG. 3 is a schematic diagram illustrating a portion of FIG. 2 in greater detail and shows switch fabric 125A outputting multiplexed signal 240 to switch fabrics 125B-125D on optical interconnect 136A. Optical interconnect component 136A distributes the multiplexed signals to switch fabrics 125B- 125D via optical splitters 283A- 283C ("optical splitters 283").

Switch fabric 125A includes optical signal transmitter 281 . The optical signal transmitter 281 transmits an optical signal including a plurality of channels with different wavelengths. For example, the optical signal transmitter 281 may use laser light for each different wavelength. In the example shown in FIG. 3 , optical signal transmitter 281 is capable of transmitting optical signals including up to three wavelengths—one corresponding to each switch fabric 125B- 125D.

Multiple wavelengths are physically combined into a single optical signal 240 in multiplexer 282 . From multiplexer 282 , optical signal 240 enters fiber optic cable 236 via fiber optic cable connector 237 . The optical signal 240 passes through the optical fiber 239 without hindrance until the optical signal 240 reaches the optical splitter 283A. To allow unhindered passage, the optical fiber 239 may be made, for example, of glass or plastic with suitable optical communication characteristics.

Optical splitter 283A re-directs first portion 241A of optical signal 240 from optical fiber 239 . First portion 241A of optical signal 240 is identical to original optical signal 240 except that first portion 241A of optical signal 240 has a lower density than initial optical signal 240 . First portion 241A of optical signal 240 passes through wavelength filter 284A, which filters out wavelengths corresponding to communication channels but not directed to switch fabric 125B to isolate optical channels containing information intended for switch fabric 125B. The wavelength containing information intended for switch fabric 125B may remain the same so that filter 284A always blocks the same wavelength regardless of the content of optical signal 240 .

Detector 285A detects first portion 241A of filtered optical signal 240 . For example, the detector 285A can be: p-channel, intrinsic, n-channel detector (PIN detector), avalanche photodiode (APD for short), or other detectors. Detector 285A converts filtered first portion 241A of optical signal 240 into an electrical signal, which detector 285A communicates with switch fabric 125B.

After the tap point 241A, the optical signal 240 continues along the optical fiber 239 until the optical signal 240 reaches the optical splitter 283B. Optical splitter 283B diverts second portion 241B from optical signal 240 . The second portion 241B is filtered by a wavelength filter 284B. Similar to wavelength filter 284A, wavelength filter 284B isolates channels containing information intended for switch fabric 125C. In general, wavelength filter 284B isolates different channels than wavelength filters 284A and 284C. Filtered second portion 241B is detected by detector 285B, which then forwards a corresponding electrical signal to switch fabric 125C.

After optical splitter 283B, portion 241C is all remaining portion of optical signal 240 in optical fiber 239 . The entire 241C portion is collected by optical tap 283C and filtered by wavelength filter 284C. Filtered second portion 241C is detected by detector 285C, which then forwards a corresponding electrical signal to switch fabric 125D.

In an exemplary embodiment, optical splitter 283 is configured to split optical signal 240 substantially equally. In this example, the optical splitter 283A removes one-third of the optical signal 240 and the optical splitter 283B removes half of the remaining two-thirds of the optical signal 240 . This leaves one third of optical signal 240 to optical splitter 283C, which consumes the remaining third of optical signal 240 as part of 241C in its entirety.

Filters 284A-284C and detectors 285A-285C may be either part of optical interconnect 136A or part of switch fabric 125, or a combination of both. Similarly, multiplexer 282 may be part of either optical interconnect 136A or switch fabric 125A, or a combination of both.

4 is a block diagram illustrating an exemplary multi-chassis router 320 including a detailed view of a line card chassis (LCC) 328A, which represents one routing node of the multi-chassis router. The other routing nodes, namely, LCC 328B-LCC 328D are generally similar to LCC 328A. Further, the multi-chassis router 320 may be similar or identical to the multi-chassis router 120 of FIG. 2 . Details described with respect to multi-chassis router 320 that are the same as multi-chassis router 120 are not detailed in FIG. 4 for the sake of brevity.

In this example, LCC 328A includes routing engine 330A and four line cards (LCs) 334A ₁ -334A ₄ ("LC 334A"). Each LC 334A in LCC 328A includes a Packet Forwarding Engine (PFE) 332A. Each LC 334A further includes a set of interface cards (IFCs) 368A that provide the physical interface for receiving packets and sending packets to external networks. Each LC 334A also includes an LC controller 366A that performs control functions within the LC 334A in accordance with instructions from the routing engine 330A.

When one of the IFCs 368A ₁ on LC 334A ₁ receives an incoming data packet, IFC 368A ₁ forwards the incoming data packet to PFE 332A ₁ . The PFE _332A1 determines whether the incoming packet has a purpose that requires the packet to be forwarded to one of the IFCs _368A1 of the LCC 328A, or requires the packet to be forwarded to the multi-chassis router 320 according to the FIB provided by the routing engine 330A. Another IFC in . If an incoming data packet is to be output by any one of the IFCs 368A ₁ of the LCC 328A, the PFE 332A ₁ forwards the data packet to the appropriate one of the IFCs 368A ₁ . If not, PFE 332A ₁ forwards the packet to switch fabric portion 325A for relay to a different LCC 328 via a multi-way optical interconnect.

Switch fabric portion 325A and its like switch fabric portions residing in LCCs 328B-328D form a three-level switch fabric. For example, the three-stage switch fabric may be a Clos network including multiple crossbar switches in each stage. Each of LCCs 328A-328D (LCC 328) includes a portion of each of these three levels. As shown in switch fabric portion 325A, packets to be associated from LC 334A ₁ are first sent to stage 1 switch 372A for transmission to stage 2 switch. Level 1 switch 372A may be a crossbar switch or other switch. In other embodiments, a portion of Stage 1 on LCC 328A may include more than one crossbar switch. The other N-1 portions of stage 1 of the switch fabric are similarly located in LCCs 328B-328D.

Once received by stage 1 switch 372A, the packet is directed to the second stage of the switch fabric in one of the LCCs 328 of the multi-chassis router 320. For example, the packet may be directed to stage 2 switch 374A, which is located inside switch fabric portion 325A of LCC 328A, in which case the packet is not relayed to a different part of LCC 328 via multiplexed optical communications. one. Otherwise, the packet is encrypted as an optical signal by transmitter 381A and transmitted by multiplexer 382A to the stage 2 switch fabric portion in one of LCCs 328B-328D. Transmitter 381A is controlled to use the wavelength corresponding to the downstream wavelength filter on one of the LCCs 328B-328D to which the packet is intended.

As shown in FIG. 4, stage 2 switch 374A receives packets not only from switch 372A, but also from similar stage 1 switches located above LCCs 328B-328D. Inputs 384A-384C ("inputs 384") receive packets via fiber optic cables from Level 1 sections located above LCCs 328B-328D. Each input 384 is coupled to an optical splitter of a different fiber optic cable and receives an optical signal from a different one of the LCCs 328B-328D. The optical signal is filtered at input 384 to isolate wavelengths corresponding to packets intended for stage 2 switch 374A. Packets received at stage 2 switch 374A are either forwarded directly to stage 3 switch 376A or relayed via transmitter 381B and multiplexer 382B to stage 3 switches located at LCCs 328B-328D.

Inputs 385A-385C ("Inputs 385") receive packets via fiber optic cables from Tier 2 switches located at LCCs 328B-328D. Similar to input 384, each input 385 is coupled to an optical splitter of a different fiber optic cable and receives an optical signal from a different one of LCCs 328B-328D. These optical signals are filtered at input 385 to isolate wavelengths corresponding to packets intended for stage 3 switch 376A.

Stage 3 switch 376A includes discrete outputs (not shown) connected to each PFE 332A on LC 334A. Packets received by stage 3 switch 376A are directed to PFE 332A corresponding to the set of IFCs 368A required for the packet's purpose. For example, if a packet is received by PFE 332A ₁ , PFE 332A ₁ forwards the packet to one of the set of IFCs 368A according to the packet's purpose.

FIG. 5 is a block diagram showing a logical representation of a three-level switching network 470 . For example, tertiary network 470 may logically represent switch fabric 125 of FIG. 2 . As represented by dashed lines 425A-425N, these three stages of network 470 are distributed through the routing nodes of the multi-chassis router ("routing nodes 425"). The three stages of network 470 include: stage 1 consisting of crossbar switches 472A-472N (collectively "switches 472"), stage 2 consisting of crossbar switches 474A-474N (collectively "switches 474"), and stage 2 consisting of crossbar switches 474A-474N (collectively "switches 474") Level 3 is composed of crossbar switches 476A-476N (collectively "switches 476"). Switch 472 receives data packets via inputs 478A-478N (collectively "inputs 478"). Switch 476 relays the packet via outputs 480A-480N (collectively "outputs 480"). As shown in FIG. 5, each level of the three-level network 470 includes the same number of crossbar switches. In other embodiments, the stages may include different numbers of crossbar switches. For example, stage 2 may include more crossbar switches than stage 1 or stage 3 to reduce or eliminate the possibility that an open input in input 478 can be blocked by an open output in output 480 . These additional crossbar switches in stage 2 may be located in switch fabric 425 or elsewhere.

To establish a path through the network 470 from one of the inputs 478 to the desired output 480, one of the switches 472 associated with the received input 478 determines an available stage 2 switch that allows the path to connect to the stage that includes the desired output 480 3 switches 476. For example, assume that a packet received by switch 472A is relayed to one of outputs 480 on switch 476A. Switch 472A selects either switch 474 with an open connection to both switch 472A and switch 476A. Assume switch 472A selects switch 474B. Once switch 474B receives the packet, switch 474B determines an available path to switch 476A and forwards the packet to switch 476A. For example, switch 474B may have more than one open path to switch 476A.

As described herein, these connections between stages utilize optical multiplexing, and multiple (e.g., N-1 paths originating from switch 472A) to stage 2 switches 474A-N originate from the same switch. path, representing N-1 channels defined by different wavelengths carried by the same optical interconnection component. Each switch in network 470 can determine the paths available for packets. In this way, a packet received by switch 472 in stage 1 can pass through any switch 474 in stage 2 to be received by the desired switch 476 in stage 3 .

While the switch fabric is described as including a three-level switching network, the switch fabric in other embodiments may also include different switch fabrics. For example, the second level in a three-level network can be replaced by another three-level network, thereby forming a five-level network. Other configured switch fabrics are also possible.

FIG. 6 is a schematic diagram showing a single fiber optic cable 536 for a multi-chassis router with sixteen routing nodes (ie, N=16). In this example, fiber optic cable 536 has fifteen optical splitters 592A-592O ("optical splitters 592"), which are necessary for the cable as a whole. Optical splitter 592 is configured on fiber optic cable 536 to equally divide the optical energy of the optical signal received from transmitter 581 and multiplexer 582 . Fiber optic cable 536 is shown coupled to wavelength filter and detector assemblies 584A-584O ("assembly 584"). Assembly 584 isolates the lanes of data contained in the optical signal and forwards the isolated lanes to network devices such as nodes in a multi-chassis router. In this example, because there are fifteen optical splitters 592 to equally split the optical signal, each optical splitter 592 is designed to remove fifteen percent of the overall signal strength of the original optical signal transmitted by the transmitter 581. one-third.

The structure for realizing equal division of optical signals is as follows. Optical splitter 592A removes one-fifteenth of the signal it receives. However, because each remaining optical splitter 592 has a reduced signal strength, each subsequent optical splitter 592 removes a greater portion of the remaining signal strength. Specifically, each optical splitter 592 removes a certain percentage of the remaining signal strength according to Equation 1:

P=1/N _r , (Equation 1)

Wherein, P is equal to the proportion of light energy deflected to the optical splitter, and _Nr is equal to the number of remaining tap points of the optical cable.

Formula 1 shows that the upstream optical splitter does not need to be considered in the process of determining the proportion of the optical signal removed at any optical splitter. Instead, only focus on the number of remaining downstream optical splitters. This means that the optical splitter on the fiber optic cable 536 can be removed from the end of the fiber optic cable 536 closest to the transmitter 581 without disturbing the even distribution of the remaining optical splitters 592 . Similarly, additional optical splitters may be added to the end of fiber optic cable 536 closest to transmitter 581 while maintaining an even distribution between optical splitter 592 and any new optical splitters. As an example, a first optical splitter added to the end of fiber optic cable 536 closest to transmitter 581 would require removing one sixteenth of the signal strength with optical splitter 592 to have an even distribution.

Subsequently, the fiber optic cable 536 may be fabricated in smaller subsections as shown in the above example. This can be used for upgrades of multi-chassis routers, where new nodes are added to a pre-existing system. For example, a multi-chassis router including four nodes may use a fiber optic cable including only three optical splitters such as optical splitters 592M-592O of FIG. 6 . If the multi-chassis router is expanded to include eight nodes, fiber optic cables with seven optical splitters are required. Portions of the cable including four more optical splitters such as optical splitters 592I-592L would be added to the upstream side of the cable to create a cable with seven optical The average signal distribution of these optical splitters for ~592O. This technique can be used to extend a fiber optic cable to include any number of optical splitters, as long as the optical signal strength remains adequate, while maintaining an even distribution of optical signals between all optical splitters on the cable, thereby facilitating Scaling for multi-rack routers.

7 is a top view illustrating an embodiment of a multi-chassis router 640 including sixteen LCCs 628A-628P (LCCs 628) arranged therein in a circular layout. Multi-chassis router 640 operates in a manner substantially similar to multi-chassis router 120 of FIG. 2 . For brevity, details pertaining to the description of multi-chassis router 640 that are identical to multi-chassis router 120 are not discussed in detail in FIG. 7 .

The LCC 628 utilizes a three-level switch fabric with multiple optical interconnects. For example, the three-level switch fabric may be similar to the three-level network 470 of FIG. 5 . The tertiary switch fabric includes multiplex optical interconnects 636 for connecting different parts of the tertiary switch fabric on the LCC 628. In this example, each LCC 628 includes two transmitters: one transmitter transmits multiple optical signals to forward packets from stage 1 to stage 2, and the other transmitter transmits multiple optical signals to forward packets from stage 2 packet to level 3. Each LCC 628 also includes thirty optical signal inputs - one for each of the two transmitters on all the other fifteen LCCs 628.

Each LCC 628 has a trapezoidal frame so that the LCC 628 can be easily placed in a circular configuration. Multi-lane fiber optic cables produced as described herein may be arranged in the inner circle of the multi-chassis router 640 to interconnect the switch fabric of the LCC 628. The trapezoidal shape of the LCC 628 may also provide relatively greater surface area on the exposed sides 654A-654O of the LCC 628. The large surface area of exposed sides 654A-654O can be used to locate a large number of slots for insertion of interface cards with physical network interfaces. The trapezoidal shape of the LCC 628 in turn limits the overall contact area of the multi-rack router 640. Specifically, in this example, the trapezoidal shape of the LCCs 628 allows seventeen LCCs 628 to be placed tightly together in a circle. However, the multi-chassis router 640 utilizes only sixteen active LCCs 628. This less than a full circle configuration provides a clearance 660 that allows an administrator to facilitate central access to a multi-bay router 662 that may be required, for example, during maintenance service. Other configurations of multi-chassis routers with ladder-shaped nodes are also possible, for example a multi-chassis router may comprise two sets of nodes each arranged in a separate circular configuration and connected by fiber optic cables. As another example, multiple nodes may be superimposed on each other to form adjacent circular structures.

Various embodiments of the invention have been described. However, modifications to the described embodiments are still within the scope of the invention. For example, while the description has been made with reference to a non-centralized multi-chassis router utilizing multiplexed optical interconnect components through the use of wavelength division multiplexing, embodiments of the present invention also include single-headed or multi-headed multi-chassis router. In addition, other multiplexing techniques such as time division multiplexing (TDM) can also be used in the switching fabric of multi-chassis routers. Additionally, these techniques can be used for other point-to-point communication media besides optical, provided that the point-to-point communication medium has a bandwidth-delay product that substantially exceeds the bandwidth-delay of conventional copper conduction. The term "bandwidth latency" refers to the product of the connection capacity (in bits per second) multiplied by its end-to-end latency (in seconds). As a result, the amount of data measured in bits (or bytes) is equal to the amount of data "in the air" at any given moment, ie, the number of bytes that have been transmitted but not received. Optical bandwidth-delay products, for example, can be calculated from a 10 GHz bandwidth transmitted over hundreds of meters. These and other embodiments are within the scope of the following claims.

Claims (14)

1. A multi-rack router comprising: a plurality of routing nodes operating as a single router in the network; and A switch fabric that forwards packets between the plurality of routing nodes, wherein the switch fabric includes at least one multi-way optical interconnect for coupling the routing nodes. 2. The multi-chassis router of claim 1, wherein each routing node comprises: a first optical transmitter that transmits multiple optical signals to forward packets from a first stage to a second stage of the switch fabric; and a second optical transmitter that transmits multiplexed optical signals to forward packets from the second stage to the third stage of the switch fabric. 3. The multi-chassis router of claim 2, wherein the multi-way optical interconnection components are arranged within the interior of the multi-chassis router to interconnect the switch fabric in a circular shape. 4. The multi-chassis router of claim 1, wherein the plurality of routing nodes of the multi-chassis router are arranged in a substantially circular layout. 5. The multi-chassis router of claim 1, wherein each routing node has a substantially trapezoidal chassis. 6. The multi-chassis router of claim 1, wherein the plurality of nodes are configured such that the nodes form a substantially circular shape when interconnected. 7. The multi-chassis router of claim 1, wherein the plurality of nodes are positioned in a structure that is less than a full circle, the structure including a gap providing access to a center of the multi-chassis router. 8. A fiber optic cable for connecting multiple routing nodes in a multi-rack router, comprising: an optical cable input that receives an optical signal from a first routing node of the plurality of routing nodes; and a plurality of optical splitters outputting a portion of said optical signal to each of the remaining routing nodes, Wherein, the multiple optical splitters basically divide the optical energy of the optical signal into equal parts among the remaining routing nodes of the multiple routing nodes. 9. The optical cable according to claim 8, further comprising a plurality of wavelength filters for filtering the optical signals split by the plurality of optical splitters. 10. The fiber optic cable of claim 9, wherein each of the plurality of wavelength filters isolates a different wavelength. 11. A group of optical cables for interconnecting N network devices, the group of optical cables includes: N optical cables, where N is an integer greater than or equal to 2, Wherein, each of the N optical cables includes: an input for receiving an optical signal from the first of the N network devices, and an input for outputting the optical signal to the N-1 N-1 optical splitters of the remaining network devices, Wherein, the N-1 optical splitters split the optical signal to output a plurality of substantially equal parts of the optical signal to the N-1 remaining network devices. 12. A set of optical cables according to claim 11, wherein each of the N optical cables further comprises a plurality of wavelength filters for filtering the light split by the plurality of optical splitters Signal. 13. The set of optical cables of claim 12, wherein each of the plurality of wavelength filters in one of the N optical cables isolates a different wavelength. 14. A set of optical cables according to claim 11, wherein N is selected from the group of 4, 16 or 32.

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