Taps for bidirectional high-speed data on optical fibers

A system for monitoring data traversing a bidirectional optical fiber includes a network tap. The network tap includes first and second network ports for bidirectional data transmission over a first optical fiber. The device includes first and second tap ports respectively associated with the first and second network ports. The first network port receives data transmitted in a first direction over the first optical fiber and at a first wavelength and provides the data to the second network port and to the first tap port. The second network port receives data transmitted in a second direction opposite the first direction over the first optical fiber and at a second wavelength different from the first wavelength and provides the data to the first network port and to the second tap port. The first and second tap the first and second tap ports provide the data to one or more network monitoring devices.

BACKGROUND OF THE INVENTION

Digital data in the form of binary information has long been carried on optical fibers. Nowadays, the network of optical fibers spans the globe, forming the backbone of the Internet, the intranet, and extending all the way to the curb or even inside residences and businesses.

In the past, each optical fiber carries information unidirectionally (in only one direction such as in the transmit direction or in the receive direction), and a pair of optical fibers would be employed to implement a bidirectional flow of information between two communicating devices.

Bidirectional fibers carry data in both directions. Since each fiber carries both the transmit data and the receive data, the bandwidth capacity of each fiber is essentially doubled. Generally speaking, different wavelengths are employed for the two directions of information flow on each fiber. Multi-mode optical fiber technology has been employed to good effect to enable bidirectional traffic on optical fibers, for example.

Data monitoring using network taps has also been widely implemented. In network tapping, a portion of the information flow or the entire information flow on the fiber may be tapped, or duplicated, to be sent to a monitoring device. When data flow is only unidirectional on each fiber, tapping has been relatively straightforward. In an example, a splitter may be employed to receive data from the optical fiber (which data is sent from some transmitting equipment) and to provide two outputs. The first output provides the same data stream onward to the receiving equipment. The second output provides some or all of the same data stream to the monitoring equipment.

In this manner, the data is still transmitted from the transmitting equipment to the receiving equipment if desired. However, some or all of the data is duplicated and provided to the monitoring equipment. The tapped or duplicated data permits the monitoring equipment to perform tasks such as malware detection, network monitoring, access control, and the like. Optical network taps are available from vendors such as Ixia Corporation of Calabasas, Calif. and will not be further elaborated here.

Bidirectional traffic on each fiber, while increasing the bandwidth capacity of the fiber, complicates tapping. Tapping is particularly challenging when data is transmitted and received at high speeds, such as at 10 gigabits/second or above.

Embodiments of the subject matter described herein relate to methods and apparatus for efficiently tapping data on optical fibers that carry high speed bidirectional data traffic.

SUMMARY

A system for monitoring data traversing a bidirectional optical fiber includes a network tap720. The network tap720includes first and second network ports510A and510B or604A and606A for bidirectional data transmission over a first optical fiber706. The device includes first and second tap ports510C and510D or604B and606B respectively associated with the first and second network ports510A and510B or604A and606A. The first network port510A or604A receives data transmitted in a first direction over the first optical fiber706and at a first wavelength and provides the data to the second network port510B or606A and to the first tap port510C or604B. The second network port510B or606A receives data transmitted in a second direction opposite the first direction over the first optical fiber706and at a second wavelength different from the first wavelength and provides the data to the first network port510A or604A and to the second tap port510D or606B. The first and second tap ports510C and510D or604A and606B provide the data to one or more network monitoring devices.

DETAILED DESCRIPTION OF EMBODIMENTS

Embodiments of the subject matter described herein relate to methods and apparatus for tapping a bidirectional optical fiber that carries data in the full bidirectional mode to provide two unidirectional outputs to two monitoring ports. In an embodiment, a device comprising two sub-devices is provided. Each of the sub-devices functions as a splitter and has three ports, with one port of sub-device1being coupled to exchange data in a bidirectional mode with another port of sub-device2.

In this manner, two three-port splitters together function to provide the tapping function for a bidirectional optical fiber, enabling high speed bidirectional data to be passed back and forth between two bidirectional transceivers via the bidirectional optical fiber while also providing two unidirectional data streams to two monitoring ports.

In another embodiment of the subject matter described herein, single stage 4 port filter may be used to tap a bidirectional optical fiber.

The features and advantages of embodiments of the subject matter described herein may be better understood with reference to the figures and discussion that follow.

FIG. 1shows an example of a prior art arrangement wherein unidirectional fiber102is employed to transmit data between transceiver104and transceiver106. In the case ofFIG. 1, data only flows in one direction from transmitting transceiver104to receiving transceiver106.

FIG. 2shows an example of a prior art arrangement wherein a tap202is employed to tap unidirectional fiber102to provide a data stream out of port204of tap202. The data stream out of port204is a copy of the data traversing unidirectional fiber102and may be provided to monitoring equipment to permit monitoring of the data. As in the case ofFIG. 1, data is also from transmitting transceiver104to receiving transceiver106.

FIG. 3shows an example of a prior art arrangement wherein bidirectional fiber302is employed to transmit and receive data between transceivers304and306. In the case ofFIG. 3, data flows both in directions308from transceiver304to transceiver306and in direction310from transceiver306to transceiver304. By utilizing the optical fiber in the bidirectional (full duplex) mode instead of the unidirectional mode, the bandwidth capacity of optical fiber302is essentially doubled.

FIG. 4shows conceptually, in accordance with an embodiment of the subject matter described herein, a tapping arrangement for tapping the bidirectional data on bidirectional fiber302. A tap402is employed to tap bidirectional fiber302to provide a first data stream410out of port404of tap402and a second data stream412out of port406of tap402. The first data stream410may be a copy of the data flowing from transceiver304to transceiver306while the second data stream412may be a copy of the data flowing from transceiver306to transceiver304. The first data stream410and the second data stream412may be provided to respective monitoring devices to enabling monitoring the bidirectional data traversing bidirectional fiber302.

FIG. 5Ashows, in accordance with one embodiment of the subject matter described herein where tap402is implemented using a two stage filter. InFIG. 5A, a sub-device502for implementing one of two stages of the device employed for monitoring bidirectional data on a bidirectional optical fiber. In this embodiment, two of sub-devices502would be employed to enable monitoring of the bidirectional traffic as will be discussed later herein. In an embodiment, sub-device502represents a splitter having three ports502A,502B, and502C, Data input into bidirectional port502A will be reflected onto ports502B and502C. On the other hand, data input into port502C is sent only to bidirectional port502A. Thus, two sub-devices502may be connected together to implement a bidirectional tap402.

FIG. 5Billustrates an alternate embodiment of the subject matter described herein where a single stage four port filter may be used to implement bidirectional tap402. InFIG. 5B, single stage filter510includes network ports510A and510B and tap ports510C and510D. In the illustrated example, network port510A carries data of wavelength λ1, which in the illustrated example is 850 nm, in a first direction and data of wavelength λ2, which in the illustrated example is 900 nm, in a second direction opposite the first direction. Network port510B carries data of wavelength λ2in the second direction and data of wavelength λ1in the first direction. Tap port510C carries data of wavelength λ1reflected from network port510A. Tap port510D carries data of wavelength λ2reflected from port510B. In one embodiment, tap ports510C and510D may be unidirectional ports that carry monitored traffic to a monitoring device.

FIG. 6shows, in accordance with an embodiment of the subject matter described herein, a device602comprising two sub-devices or filter stages604and606. Sub-device604has three ports:604A,604B and604C. Sub-device606has three ports as well:606A,606B, and606C. Bidirectional ports604C and606C are coupled to each other to join the splitters or sub-devices together and exchange bidirectional data between the splitters or sub-devices. One of ports604A and604B is employed as a bidirectional port to transmit/receive data between the transceivers while the other of ports604A and604B is a unidirectional port outputting data to the monitoring equipment. Likewise, one of ports606A and606B is employed as a bidirectional port to transmit/receive data between the transceivers while the other of ports606A and606B is a unidirectional port outputting data to the monitoring equipment.

FIG. 7Ashows, in accordance with an embodiment of the subject matter described herein, an arrangement for monitoring bidirectional traffic traversing between two transceivers702and704on bidirectional fiber706. The bidirectional data comprises a first data flow706A in the direction from transceiver702to transceiver704and a second data flow706B in the direction from transceiver704to transceiver702.

As shown inFIG. 7A, bidirectional fiber706is coupled with a bidirectional port708of transceiver702and a bidirectional port710of transceiver704. A tap720is provided to tap bidirectional fiber706. Tap720includes connectors C1, C2, C3and C4for coupling with optical fibers. Four connectors are shown to facilitate monitoring of the two bidirectional optical fibers706and714in the manner discussed below.

For the purpose of explanation, the discussion below focuses on the tapping of data traversing bidirectional optical fiber706. The tapping operation for data traversing bidirectional optical fiber714operates similarly. Like fiber706, data flows in both directions in fiber714at different wavelengths. Thus, connector C1may receive data in one direction at one wavelength over fiber714and transmit data in the opposite direction at a different wavelength over fiber714. Similarly, connector C2may receive data in one direction at one wavelength over fiber714and transmit data in the opposite direction at a different wavelength over fiber714.

As can be seen inFIG. 7A, tap720includes a device726that comprises two sub-devices S1and S2. Device726may be the same as device602illustrated inFIG. 6. Sub-device S1has three ports S1A, S1B, and S1C as shown. Sub-device S2also has three ports S2A, S2B, and S2C, with ports S2C of sub-device S2coupled to port S1C of sub-device S1using an appropriate connector (such as a piece of optical fiber) to exchange bidirectional data. In an embodiment and not by way of limitation, device726is implemented by a dual splitter that comprises two splitters S1and S2.

A first data flow706A from port708of transceiver702is inputted into port S1A of sub-device S1(via a coupler730on connector C1and an appropriate bidirectional optical fiber732between coupler730and port S1A). This first data flow706A is copied onto port S1B and port S1C of sub-device S1. Port S1B provides this first data flow706A in a half-duplex manner to coupler740of connector C3. A monitoring device may receive this first data flow706A from coupler740for monitoring purpose. The first data flow706A that is provided to port S1C of sub-device S1is received by port S2C of sub-device S2. This first data flow706A is then provided to port S2B of sub-device S2, and is subsequently provided to coupler742of connector C2. From coupler742of connector C2, this first data flow706A continues on to port710of transceiver706. A second data flow706B in the reverse direction from flow706A originates from port710of transceiver704and is inputted into port S2B of sub-device S2(via a coupler742on connector C2and an appropriate bidirectional optical fiber744between coupler742and port S2B). This second data flow706B is copied onto port S2A and port S2C of sub-device S2. Port S2A provides this second data flow706B in a half-duplex manner to coupler750of connector C4. A monitoring device may receive this second data flow706B from coupler750for monitoring purpose. The second data flow706B that is provided to port S2C of sub-device S2is received by port S1C of sub-device S1. This second data flow706B is then provided to port S1A of sub-device S1, and is subsequently provided to coupler730of connector C1via fiber732. From coupler730of connector C1, this second data flow706B continues on to port708of transceiver702. Since the first data flow706A and the second data flow706B employ different wavelengths, they can co-exist on for example port S1A, on port S2B, on fiber706, on fiber732, on fiber744, on coupler730of connector C1, and on coupler742of connector C2.

Thus, bidirectional data (comprising data flow706A and data flow706B) on bidirectional fiber706is tapped and copies of data flow706A and706B are provided to respective coupler740of connector C3and coupler750of connector C4.

A similar arrangement exists with respect to the bidirectional data flowing on bidirectional fiber714and tapped by the device760comprising sub-devices S3and S4. Like device726, device760may be the same as device602illustrated inFIG. 6.

For example, the data inputted into coupler762of connector C1is received by port S3A of sub-device S3(via fiber784) and copied onto port S3B and S3C. Port S3B provides the copy of this data in a half-duplex manner to monitoring equipment (via coupler766of connector C3). Port S3C of sub-device S3is coupled to port S4C of sub-device S4to exchange bidirectional data. Thus the data is received by port S4C from port S3C. From port S4C, this data flows out of port S4B to proceed onward on bidirectional fiber714(via coupler768of connector C2and optical fiber782) after being tapped.

In the reverse direction from the data from optical fiber714inputted into coupler762, the data inputted into coupler768of connector C2is received by port S4B and copied onto port S4A and S4C. Port S4A provides the copy of this data in a half-duplex manner to monitoring equipment (via coupler770of connector C4). Port S4C of sub-device S4is coupled to port S3C of sub-device S3to exchange bidirectional data. Thus the data is received by port S3C from port S4C. From port S3C, this data flows out of port S3A to proceed onward on bidirectional fiber714(via coupler762of connector C1and fiber784) after being tapped.

FIG. 7Arepresents an example showing a pair of bidirectional optical fibers (706and714) coupled to couplers730and762of connector C1on one side of tap720. Data on this pair of optical fibers (706and714) is provided on the other side of tap720via respective couplers742and768of connector C2. Monitoring is enabled by unidirectional output data from couplers766,740,750, and770of connectors C3and C4as discussed above.

It should be understood, however, that although coupler742is disposed on connector C2, it is possible to pair up coupler742with coupler730on connector C1if desired. In this case, one side of bidirectional fiber706would be coupled to coupler730of connector C1while the other side of bidirectional fiber706would be coupled to coupler742which would be now moved to connector C1.

Likewise on the monitoring side, although coupler750is disposed on connector C4, it is possible to pair coupler750with coupler740on connector C3. In this case, the two couplers on connector C3provide the two unidirectional data flows for monitoring purposes for the bidirectional data flows on bidirectional fiber706.

Furthermore, although each connector is shown inFIG. 7Ato have only two couplers, it is possible to employ connectors having only a single coupler each, or 3 couplers each, or 4 couplers each, or any arbitrary number of couplers in each connector. These are only examples of the mixing-and-matching that may be made between the couplers and the connectors.

FIG. 7Bis a simplified version of the bi-directional tap illustrated inFIG. 7A. InFIG. 7B, the center wavelength for which each fiber is designed is shown for illustrative purposes. It is understood that different fibers structured to carry different center wavelengths may be used without departing from the scope of the subject matter described herein. It is also understood that the fibers corresponding to the network ports on each tap may be structured to carry one center wavelength in one direction and a different center wavelength in the opposite direction.FIG. 7Balso shows cross sectional views of connectors C1-C4. Connectors C1-C4are illustrated outside of bi-directional tap720inFIG. 7B. However, it is understood that bi-directional tap720and connectors C1-C4would be integrated into a single package.

In an alternate embodiment, the four sub-devices to implement the bidirectional filter illustrated inFIG. 7Acan be replaced by two dual splitters as illustrated inFIG. 8.FIG. 8is similar toFIG. 7Aexcept that devices726and760respectively comprised of subdevices S1and S2and S3and S4are replaced by single stage four port network tap devices5101and5102, each of which may be the same as device510illustrated inFIG. 5B. Devices5101and5102can be considered dual splitters since they split the transmitted wavelengths in both directions. InFIG. 8, tap720includes a device5101that comprises a single stage four port device with bidirectional network ports510A1and510B1and tap ports510C1and510D1. Tap720further includes a device5102that comprises a single stage four port device with bidirectional network ports510A2and510B2and tap ports510C2and510D2.

A first data flow706A in the reverse direction from flow706A originates from port708of transceiver702and is inputted into port510B1of device5101(via a coupler730on connector C1and an appropriate bidirectional optical fiber732between coupler730and port510B1). This first data flow706A is copied onto tap port510D1and network port510A1of device5101. Tap port510D1provides this first data flow706A in a half-duplex manner to coupler740of connector C3. A monitoring device may receive this first data flow706A from coupler740for monitoring purpose. The first data flow706A that is provided to network port510A1of device5101is provided to coupler742of connector C2. From coupler742of connector C2, this first data flow706A continues on to port710of transceiver706.

A second data flow706B from port710of transceiver704is inputted into network port510A1of device5101(via a coupler742on connector C2and an appropriate bidirectional optical fiber744between coupler742and network port510A1). This second data flow706B is copied onto tap port510C1and network port510B1of device5101. Tap port510C1provides this second data flow706B in a half-duplex manner to coupler750of connector C4. A monitoring device may receive this second data flow706B from coupler750for monitoring purposes. The second data flow706B that is provided to network port510B1of device5101, and is subsequently provided to coupler730of connector C1via fiber732. From coupler730of connector C1, this second data flow706B continues on to port708of transceiver702. Since the first data flow706A and the second data flow706B employ different wavelengths, they can co-exist on for example network port510B1, on network port510A1, on fiber706, on fiber732, on fiber744, on coupler730of connector C1, and on coupler742of connector C2.

Thus bidirectional data (comprising data flow706A and data flow706B) on bidirectional fiber706is tapped and copies of data flow706A and706B are provided to respective coupler740of connector C3and coupler750of connector C4.

A similar arrangement exists with respect to the bidirectional data flowing on bidirectional fiber714and tapped by the device5102.

For example, data flowing in a first direction on optical fiber714and having a first wavelength may be inputted into coupler762of connector C1, received by network port510B2of device5102(via fiber784), and copied onto tap port510D2and network port510A2. Tap port510D2provides the copy of this data in a half-duplex manner to monitoring equipment (via coupler766of connector C3). Network port510B2of device5102is coupled to network port510A2of device5102to exchange bidirectional data. Thus, inbound data received on network port510B2flows out of port network port510A2to proceed onward on bidirectional fiber714(via coupler768of connector C2and optical fiber782) after being tapped.

Data flowing in a second direction opposite the first direction on optical fiber714and having a second wavelength different from the first wavelength may be inputted into coupler768of connector C2, received by network port510A2, and copied by network port510A2onto tap port510C2and network port510B2. Tap port510C2provides the copy of this data in a half-duplex manner to monitoring equipment (via coupler770of connector C4). Network port510A2of device5102is coupled to network port510B2of device5102to exchange bidirectional data. Thus, the data received by port510A2flows out of port510B2to proceed onward on bidirectional fiber714(via coupler762of connector C1and fiber784) after being tapped.

FIG. 8represents an example showing a pair of bidirectional optical fibers (706and714) coupled to couplers730and762of connector C1on one side of tap720. Data on this pair of optical fibers (706and714) is provided on the other side of tap720via respective couplers742and768of connector C2. Monitoring is enabled by unidirectional output data from couplers766,740,750, and770of connectors C3and C4as discussed above.

It should be understood, however, that although coupler742is disposed on connector C2, it is possible to pair up coupler742with coupler730on connector C1if desired. In this case, one side of bidirectional fiber706would be coupled to coupler730of connector C1while the other side of bidirectional fiber706would be coupled to coupler742which would be now moved to connector C1.

Likewise on the monitoring side, although coupler750is disposed on connector C4, it is possible to pair coupler750with coupler740on connector C3. In this case, the two couplers on connector C3provide the two unidirectional data flows for monitoring purposes for the bidirectional data flows on bidirectional fiber706.

Furthermore, although each connector is shown inFIG. 8to have only two couplers, it is possible to employ connectors having only a single coupler each, or 3 couplers each, or 4 couplers each, or any arbitrary number of couplers in each connector. These are only examples of the mixing-and-matching that may be made between the couplers and the connectors.

An important advantage of the subject matter described herein is the small form factor that results. This is due to, in one embodiment, the use of highly compact splitters that can handle high speed data to form a dual splitter for the purpose of tapping. The small form factor of the bidirectional tap enables a higher tap density (e.g., more taps per server rack or per chassis). This small form factor is extremely important in today's cramped server racks and over-populated data centers.

As can be appreciated from the foregoing, embodiments of the invention enable monitoring of high-speed (e.g., 10 gigabits/second and above) data that traverses bidirectionally on a bidirectional optical fiber. Embodiments of the invention result in a highly compact tap form factor, which is highly advantageous in today's market. As a result, more taps can be provided in a given chassis or server rack, enabling greater monitoring capacity than possible previously.

FIG. 9is a flow chart illustrating an exemplary process for monitoring data on a bidirectional optical fiber according to an embodiment of the subject matter described herein. Referring toFIG. 9, in step900, the method includes connecting a network tap including first and second network ports and first and second tap ports to a bidirectional optical fiber. For example a network tap720may be connected to a bidirectional optical fiber706or714, as illustrated inFIG. 7orFIG. 8.

In step902, the method includes receiving, using the first network port, data transmitted in a first direction over the first optical fiber and at a first wavelength. For example, data may be received on network port S1A of sub-device S1illustrated inFIG. 7or on network port510B1of device5101illustrated inFIG. 8.

In step904, the method includes providing the data received by the first network port to the second network port and to the first tap port. For example, data received on network port S1A illustrated inFIG. 7may be provided to tap port S1B and to network port S2B or data received on network port510B1illustrated inFIG. 8may be provided to tap port510D1and to network port510A1.

In step906, the method further includes receiving, using the second network port, data transmitted in a second direction opposite the first direction over the first optical fiber and at a second wavelength different from the first wavelength. For example, data may be received by network port S2B of sub-device S2illustrated inFIG. 7or at network port510A1of device5101illustrated inFIG. 8.

In step908, the method includes providing the data received by the second network port to the first network port and to the second tap port. For example, the data received on network port S2B inFIG. 7may be provided to tap port S2A and network port S1A. InFIG. 8, the data received on network port510A1may be provided to network port510B1and to tap port510C1.

In step910, the method includes providing the data form the first and second tap ports to one or more network monitoring devices. InFIG. 7, the data from tap ports S1B and S2B may be provided to network monitoring devices via connectors C3and C4, respectively. InFIG. 8, data provided from tap ports510D1and510C1may be provided to network monitoring devices via connectors C3and C4respectively. Examples of network monitoring devices include intrusion detection systems, intrusion protection systems, performance monitoring systems, etc.

While the subject matter described herein has been described in terms of several preferred embodiments, there are alterations, permutations, and equivalents, which fall within the scope of this invention. The invention should be understood to also encompass these alterations, permutations, and equivalents. It should also be noted that there are many alternative ways of implementing the methods and apparatuses of the present invention. Although various examples are provided herein, it is intended that these examples be illustrative and not limiting with respect to the invention.