SFP super cage

An embodiment of the invention provides a super cage for receiving and providing a small form factor pluggable (SFP) communication module with a functionality, the super cage comprising: a sleeve dimensioned to receive an SFP communication module and be plugged into a conventional SFP cage having a socket for receiving an SFP connector of an SFP module; functionality circuitry housed in the sleeve; a cage connector electrically connected to the functionality circuitry and configured to be inserted into the conventional cage socket; and a coupling socket housed in the sleeve that receives an SFP connector of an SFP module and electrically connects the SFP connector to the functionality circuitry.

TECHNICAL FIELD

Embodiments of the invention relate to small form factor pluggable (SFP) communication modules and cages that receive these modules.

BACKGROUND

With the expansion of communication networks to connect ever more people to each other and to sources of entertainment and information, and to support autonomous communication between devices that support modern technology and culture, the networks have provided an enormous increase in communication connectivity and bandwidth. The physical infrastructures that support the networks have become increasingly more complex and have developed to enable an increasing variety of communication functionalities.

To provide for a greater variety of functionalities, optical fiber interfaces have, by practical necessity, been configured in small modules that are easily mounted onto communications equipment. By using such modules, communications equipment can be easily adapted to a large variety of optical fiber physical layers, such as single-mode or multi-mode fiber; short-range (less than 1 km), long range (10 km), or extended-range (80 km) coverage; different wavelengths of light such as 850, 1310, 1490, or 1550 nm (nanometer); and single wavelength, Coarse Wavelength Division Multiplexing (CWDM), or Dense Wavelength Division Multiplexing (DWDM). Without such modules communications equipment vendors would need to manufacture a wide variety of equipment, identical in communications functionality but differing in fiber optical interface characteristics.

Modern versions of these communications modules are pluggable, i.e. they may easily be inserted into and removed from matching receptacles, referred to as “cages” mounted on panels of communications equipment, such as switches and routers. The cages serve to mechanically and electronically connect the communication modules inserted into the cages to the communications equipment.

Standards for small communication modules, such as Small Form-factor Pluggable (SFP) modules, Enhanced Small Form-factor Pluggable (SFP+) modules, 10G Form-factor Pluggable (XFP) modules, 100G Form-factor Pluggable (CFP) modules, and Gigabit Interface Converter (GBIC) modules, have been specified by industry groups in agreements known as “multisource agreements (MSA)”. Multisource agreements specify electrical, optical, and physical features of the modules. Hereinafter the acronym “SFP” may be used generically to reference small communication modules, such as any of the exemplary small communication modules noted above.

Conventional small communications modules such as SFPs are limited in functionality to performing electric to optical and optical to electric conversions. Recently, additional functionalities have been implemented inside such modules, effectively turning these modules into sophisticated network elements in their own right. For example, U.S. Pat. No. 7,317,733 to Olsson and Salemi describes performing Ethernet to TDM protocol conversion inside an SFP. US patent application 2006/0209886 to Silberman and Stein further describes pseudowire encapsulation inside an SFP. U.S. Pat. No. 7,933,518 to Li et al describes performing optical loopback and dying gasp inside an SFP. U.S. Pat. No. 7,693,178 to Wojtowicz describes inserting Passive Optical Network ONU functionality into an SFP. SFPs and similar pluggable modules with such additional functionalities save rack space, power, and cabling, but suffer from the same deficiency as communications equipment before the introduction of SFPs, namely that vendors need to manufacture a wide variety of SFPs identical in communications functionality while differing only in fiber optical interface characteristics.

SUMMARY

An embodiment of the invention relates to providing a receptacle, referred to as a “super cage”, that can be plugged into a conventional SFP cage and into which an SFP module can be plugged and electrically connected to mechanically and electrically connect the SFP module to the conventional cage. The super cage comprises circuitry and/or devices, hereinafter also referred to as “functionality circuitry”, that provides the SFP module with an additional functionality and/or services, hereinafter generically referred to as a “functionality”. A “conventional cage” hereinafter refers to a receptacle that conforms to an MSA standard.

In accordance with an embodiment of the invention, the functionality circuitry provides a processing functionality, such as by way of example, protocol translation and/or a dying gasp alarm, for the SFP module. Optionally, the functionality circuitry comprises a mini-fan that generates air flow through the super cage and the SFP module to enhance dissipation of heat from the module.

DETAILED DESCRIPTION

In the following detailed description, conventional SFPs and SFP cages are discussed with reference toFIGS. 1A-1C.FIGS. 2A-2Dschematically show a super cage being inserted into a conventional SFP cage and how it accommodates an SFP module.FIGS. 3A-3Hshow parts of a super cage and their features and illustrate how they are assembled in a super cage, in accordance with an embodiment of the invention. Various functionalities that may be provided by a super cage in accordance with embodiments of the invention are discussed with reference toFIGS. 4A-4D.

FIG. 1Aschematically shows a conventional SFP cage20mounted on printed circuit board (PCB)41of a communication device40housed in a chassis schematically represented by dashed lines42. The figure also shows an SFP module50that may be inserted into the conventional SFP cage to connect the SFP module to circuitry in PCB41. The conventional SFP cage and SFP module are partially cutaway to show details of their features discussed below. By way of example, SFP module50is assumed to be an optical transceiver configured having two optical connectors51that mate with optical fibers over which optical signals are received and transmitted by the transceiver.

SFP module50comprises an edge connector52, which has conductive contacts53that are electrically connected to circuitry (not shown) in the SFP. Whereas conductive contacts53are shown only on the upper side of the connector, they may be on the upper and/or the lower of the connector. SFP cage20comprises a cage socket22having conducting contacts24that match conducting contacts53and are electrically connected to conductive traces (not shown) in host PCB41. The conductive races in host PCB41connect the conducting contacts of the socket to circuitry (not shown) in communications device40. Cage socket22is configured to receive connector52and connect conductive contacts53of the connector to matching conductive contacts24in cage socket22, and thereby to electrically connect the transceiver to circuitry in communication device40.

Conventional SFP cage20optionally comprises a spring latch25formed having a hole26that receives and engages a matching “latch button” (not shown) in SFP transceiver50to lock the SFP transceiver in the cage when it is fully inserted into the cage. A release lever54is pulled downward to push a slider55(only a portion of which is shown inFIG. 1A) in the SFP transceiver so that it contacts and depresses spring latch25to disengage the spring latch from the latch button. With the latch button disengaged, the SFP may be extracted from conventional SFP cage20.FIG. 1Bschematically shows SFP transceiver50fully inserted into conventional SFP cage20and connector52plugged into cage socket22.

Generally, a communication device, such as a switch or router, comprises a bank of conventional SFP cages and is configured to receive and process signals from a plurality of different SFP modules.FIG. 1Cschematically shows a communication device44comprising a bank28of conventional SFP cages20. Often it is desired to provide given SFP modules plugged into cages in a communication device such as communication devices40and44with additional functionalities that are not provided by the communication device. Typically, this requires adding additional communication devices, providing them with rack-space and electrical power, connecting these additional devices to existing devices with optical fibers and/or electrical wires, and configuring/managing these devices via a network management system.

Super cages, in accordance with embodiments of the invention conveniently provide additional functionalities for SFP modules generally without need for re-cabling and reconfiguring physical communication equipment.FIGS. 2A and 2Bschematically show a super cage100before and after being inserted into a conventional SFP cage20respectively, in accordance with an embodiment of the invention.

Super cage110optionally comprises a sleeve101housing a “functionality” printed circuit board (PCB)120and a coupling socket140. The sleeve is shown in dashed lines inFIG. 2Ato indicate that internal features of the super cage are shown as if the sleeve is transparent.

In an embodiment, the super cage further comprises a latch button (not shown) similar to a latch button in an SFP module that is engaged by spring latch25of SFP cage20to lock the super cage in the SFP cage when the super cage is fully inserted into the SFP cage. A release slider110, only an edge of which is shown inFIG. 2AandFIG. 2B, is pushed to depress spring latch25of SFP cage20and disengage the super cage latch button from the spring latch to release the super cage from SFP cage20.

Coupling socket140is configured to receive an SFP connector of a conventional SFP module, hereinafter assumed by way of example to be SFP transceiver50(FIG. 1A), inserted into super cage100. The coupling socket140electrically connects the conventional SFP module to functionality PCB120when the module is inserted into the super cage. Functionality PCB120may comprise any of various functionality circuitries for providing the super cage and thereby SFP transceiver50, when inserted into the super cage, with an additional functionality.

Functionality PCB120comprises a cage connector121having conductive contacts122that are electrically connected to the functionality circuitry (not shown inFIG. 2A) it comprises. The cage connector and its conductive contacts are configured to be inserted into cage socket22of conventional SFP cage20and electrically connect the functionality circuitry and SFP transceiver50with the conventional SFP cage. Super cage100is formed having a spring latch103similar to spring latch25in conventional SFP cage20. Spring latch103locks SFP transceiver50in the super cage when the SFP transceiver is fully inserted into the super cage.FIGS. 2C and 2Dschematically show SFP transceiver50respectively before and after insertion into super cage100shown after the super cage is plugged into conventional cage20, as shown inFIG. 2B.

Features and details of super cage100are discussed below with reference toFIGS. 3A-3H. Exemplary functionalities that may be included in functionality PCB120in accordance with embodiments of the invention are discussed below with reference to variations of functionality PCB120shownFIG. 4A-4C.

FIGS. 3A and 3Bschematically show sleeve101and coupling socket140, shown inFIG. 2Aand referred to above, of super cage100before assembly and after assembly respectively, in accordance with an embodiment of the invention. Sleeve101has external dimensions matched to internal dimensions of a conventional SFP cage, such as conventional SFP cage20shown inFIGS. 2A-2Dso that the sleeve can be inserted into the conventional SFP cage. Optionally, the sleeve is formed by stamping and bending from a thin sheet of steel optionally about 0.1 mm thick.

In an embodiment of the invention sleeve101is formed having snap tabs104, a stop catch105, side lock openings106, and guide fins107. Coupling socket140is optionally injection molded from a suitable polymer and is formed having a socket cavity141and catch nub142. Upper and lower walls143and144of socket cavity141are formed having conductive contacts145, which are shown in the perspective of the figure only on bottom wall144.FIG. 3Bschematically shows coupling socket140assembled into sleeve101with the coupling socket catch nub142seated in stop catch105.

FIG. 3Cschematically shows functionality PCB120and a back-end cowling150that is configured to receive the functionality PCB and lock it into sleeve101. Functionality PCB120comprises in addition to cage connector121noted above, a PCB coupling connector123having conductive contacts124. The cage and PCB coupling connectors121and123straddle a region125, hereinafter a functionality region125. Functionality region125may comprise any of various functionality circuitries for providing SFP transceiver50with an additional functionality. Coupling connector123is configured to be inserted into coupling socket140and electrically connect functionality PCB and its functionality circuitry to the coupling connector and SFP transceiver50when the transceiver is plugged into super cage100.

In an embodiment of the invention functionality PCB120comprises protruding sidebars126that provide the functionality PCB with shoulders127. Optionally, back-end cowling150is formed having slots151, shown in the perspective ofFIG. 3Don only side of the cowling, for receiving sidebars126as schematically shown inFIG. 3D, and recesses152for receiving snap tabs104(FIGS. 3A,3B). Back-end cowling150and functionality PCB120are mounted to sleeve101by inserting the back-end cowling and functionality PCB into sleeve101so that PCB coupling connector123is inserted into coupling socket140and snap tabs104snap into snap recesses152as schematically shown inFIG. 3E. With the snap tabs snapped into the snap recesses, coupling socket140, functionality PCB120, and back-end cowling150are securely locked in place in sleeve101.

FIG. 3Fschematically shows release slider110and a front-end cowling160that receives the release slider and mounts the slider to sleeve101in accordance with an embodiment of the invention. Front-end cowling160is optionally formed by stamping and bending from a thin steel plate optionally having thickness of about 0.1 mm. In an embodiment of the invention, front-end cowling160is formed having top and side lock openings161and162respectively, spring latch103referred to above, and guide tabs164.

Release slider110comprises a depressor tongue111for depressing spring latch25(FIG. 2A) of conventional SFP cage20and unlocking and releasing super cage100from the conventional SFP cage after it has been inserted and locked into the conventional SFP cage. The release slider is formed having a bay112and seats on a bottom166of front-end cowling160with spring latch103positioned in the bay so that the release slider may slide back and forth between guide tabs164. The release slider is formed having shoulders113that limit the sliding motion of the slider between guide tabs164.

FIG. 3Gschematically shows front-end cowling160and release slider110mounted to sleeve101with side lock openings106of sleeve101and side lock openings162of front-end cowling160aligned but the cowling not locked into place in the sleeve. Front-end cowling160and release slider110are locked to sleeve101by a locking panel170. Locking panel170is optionally formed from an injection-molded polymer and comprises top locking nubs171and side locking nubs172. When pushed into place, as schematically shows inFIG. 3H, top locking nubs171seat into top lock openings161of front-end cowling160and side locking nubs172seat into aligned side lock openings106and162of sleeve101and front-end cowling160. When properly seated, the locking nubs lock front-end cowling160, release slider110and locking panel170in place in an assembled super cage100shown inFIG. 3HandFIG. 2A, in accordance with an embodiment of the invention.

In an embodiment of the invention, functionality region125contains electric circuitry and/or a Field Programmable Gate Array (FPGA) and/or an Application Specific Integrated Circuit and/or a Central Processing Unit (CPU), in order to provide an additional functionality. Such functionality may include packet inspection, statistics collection, packet header editing, packet insertion and removal, and traffic conditioning.

Packet inspection, including Deep Packet Inspection, may be employed in order to detect anomalous or potentially malicious packets, or to classify packets and collect statistics regarding applications in use, or to monitor and optionally police/shape traffic flows.

Packet header editing may be used for packet marking (e.g., drop eligibility marking), manipulation of Ethernet VLAN tags (insertion of a tag, deletion of a tag, swapping a tag value), manipulation of MPLS label stacks (pushing a label(s), swapping a label, popping a label), or protocol conversion (Rate Interface Conversion, TDM to packet conversion, pseudowire encapsulation, etc.).

Packet insertion and deletion may be used for Operations, Administration, and Maintenance functionality (e.g., Ethernet OAM according to ITU-T Recommendation Y.1731 and or IEEE 802.3 Clause 57, IP performance measurement via One-Way or Two-Way Active Measurement Protocol (OWAMP/TWAMP), and for terminating control or management protocols. In an embodiment, the functionality region is configured to pass most packets transparently from the conventional SFP to the cage socket, but to be responsive to specific OAM or performance measurement packets. In an embodiment, the functionality region may be configured as a reflector or responder that reflects packets with specific characteristics back to their source, or selective responds to packets with specific characteristics.

Traffic conditioning may be used to match traffic parameters to configured levels, such as Ethernet bandwidth profiles as defined in Metro Ethernet Forum Technical Specification MEF-10.2. In an embodiment of the invention, packet inspection, header editing, and OAM functionalities are combined with traffic conditioning to implement an Ethernet Network Interface Device (NID) or Ethernet Network Termination Unit (NTU).

FIG. 4Aschematically shows a variation of functionality PCB120referred to as functionality PCB200, having cage connector121, coupling connector123and a functionality region125, for incorporation in super cage100, in accordance with an embodiment of the invention. Functionality PCB200comprises a mini-fan202mounted in functionality region125for improving ventilation and thereby improved heat dissipation for an SFP module inserted into the super cage. Functionality region125of functionality PCB200may comprise functionality circuitry (not shown) that measures temperature in the super cage and controls mini-fan202responsive to the measured temperature. For example, below a given predetermined threshold temperature the functionality circuitry may maintain mini-fan202turned off. Above the threshold temperature, the functionality circuitry turns on the min-fan to generate airflow in directions indicated by arrows204. Optionally, the functionality circuitry is located on a side of functionality PCB200opposite to that on which mini-fan202is located.

FIG. 4Bschematically shows a functionality PCB210comprising a rechargeable button battery212that may be included in super cage100, in accordance with an embodiment of the invention. In an embodiment of the invention, functionality PCB210includes functionality circuitry (not shown) that provides power to an SFP module plugged into the super cage when the SFP loses power. The functionality circuitry is located optionally on a side of the functionality PCB opposite to the side on which disc battery210is located. In an embodiment of the invention, the functionality circuitry is configured to control the SFP module to transmit a “dying gasp” alarm to alert a communication network that includes the SFP module that the SFP module is about to lose power.

In some embodiments of the invention, functionality circuitry to be included in a functionality PCB is not conveniently included in a functionality PCB having a size and construction shown inFIGS. 3C,4A, and4B.FIG. 4Cschematically shows a functionality PCB220for inclusion in super cage100that has increased area for functionality circuitry.

Functionality PCB220comprises upper and lower sub-PCBs221and222respectively. The portions are electrically and physically connected by a flexible neck223comprising conductive traces (not shown) that connect functionality circuitry components (not shown) located on bottom portion222with functionality circuitry components (not shown) located on top portion221. In an embodiment of the invention functionality PCB220is formed by slotting a PCB to form the two PCB portions connected by the neck region. The neck region is thinned, for example by etching or abrading, to make it sufficiently flexible so that it can be bent to position the PCB portions one over the other, as shown inFIG. 4C.

By way of example, functionality PCB220may have functionality circuitry similar to functionality circuitry250schematically shown inFIG. 4D. Functionality circuitry250optionally comprises a central processor unit (CPU)254, a communications processing unit255, a power monitor251, a temperature sensor252and a dying gasp mechanism253. Voltage monitor251monitors voltage provided to super cage100and an SFP module, such as SFP transceiver50, (FIG. 2D) plugged into the super cage. If the voltage supply to the super cage and its SFP module50drops below a desired operating voltage, the voltage monitor informs data processing unit255and CPU254. Optionally, CPU254generates a dying gasp message to inform the network management system of the loss of voltage. When voltage to super cage100returns to a level sufficient for proper operation, voltage monitor251awakens CPU254and processing unit255. Temperature sensor252acquires readings of ambient temperature and transmits the readings to CPU254. The CPU uses the readings to report status of the super cage100transceiver to a network management system (not shown) and optionally to turn on a mini-fan (not shown).

Descriptions of embodiments of the invention in the present application are provided by way of example and are not intended to limit the scope of the invention. The described embodiments comprise different features, not all of which are required in all embodiments of the invention. Some embodiments utilize only some of the features or possible combinations of the features. Variations of embodiments of the invention that are described, and embodiments of the invention comprising different combinations of features noted in the described embodiments, will occur to persons of the art. The scope of the invention is limited only by the claims.