The present disclosure relates to small form factor pluggable units, and more particularly to a small form factor pluggable unit having signal diagnostic capabilities.
Small Form-factor Pluggable (SFP) units are standardized units adapted to be inserted within a chassis. A suite of specifications, produced by the SFF (Small Form Factor) Committee, describe the size of the SFP unit, so as to ensure that all SFP compliant units may be inserted smoothly within one same chassis, i.e. inside cages, ganged cages, superposed cages and belly-to-belly cage. Specifications for SFP units are available at http://www.sffcommittee.com/ie/index.html.
Specification no SFF-8472 Rev 11.0, entitled “Diagnostic Monitoring Interface for Optical Transceivers”, dated Sep. 14, 2010, was produced by the SFF Committee. The specification defines a memory map with a digital diagnostic monitoring interface for optical transceivers that allows pseudo real time access to device operating parameters. It also defines options to previously defined two-wire interface ID memory map that accommodate new transceiver types that were not considered in earlier SFP Multi-Source Agreement (MSA) or Gigabit Interface Converter (GBIC) documents. The SFF Committee also produced specification no SFF-8431 Rev. 4.1, “Enhanced Small Form Factor Pluggable Module SFP+”, dated Jul. 6, 2010. This document defines, inter alia, high speed electrical interface specifications for 10 Gigabit per second SFP+ modules and hosts. The term “SFP+” designates an evolution of SFP specifications.
However, SFF-8472 and SFF-8431 do not address measurements of characteristics of electrical signals received at the SFP unit, or within the SFP unit. SFF-8431 only describes a test methodology for optical signals, in a context requiring use of test equipment that is external to a SFP unit under test.
In the appended drawings, provided for exemplary purposes only, similar references denote like parts:
The foregoing and other features of the present will become more apparent upon reading of the following non-restrictive description of examples of implementation thereof, given by way of illustration only with reference to the accompanying drawings. Like numerals represent like features on the various drawings.
The present disclosure relates to a small form-factor pluggable (SFP) unit having signal diagnostic capabilities. The expression ‘signal diagnostic’ is used throughout the present disclosure and claims, and is meant to be interpreted to encompass signal monitoring, signal measurement, and diagnostic of signal based on measured signal characteristics.
The SFP unit comprises a housing having a front panel, a back panel, a top, a bottom and two sides, and may be fully-compliant or partially compliant with standardized SFP dimensions, such as SFP, XFP (10 Gigabit SFP), Xenpak, or any other standardized small form factor pluggable unit.
In the context of the present SFP unit, the following terminology is used: “SFP” designates a Small Form Factor Pluggable Unit corresponding to SFP, SFP+, XFP or any other known standards related to small form factor pluggable units.
Reference is now made concurrently to
The SFP unit 10 further comprises a back panel 16 affixed to the housing 12. The back panel 16 may comprise one or more connectors 17, for example electrical or optical. In an example, the back panel comprises a connector suitable to connect the SFP unit to a backplane of a chassis (not shown for clarity purposes), as known to those skilled in the art.
The SFP unit 10 further comprises a front panel 18 affixed to the housing 12. The front panel may comprise one or more connectors, for example co-axial connectors 20 adapted to send and/or receive radio frequency (RF) signals, for connecting the SFP unit to external devices. The SFP unit 10 may further comprise an engagement mechanism such as for example a latch 26 as shown in a resting position on the bottom 24, for maintaining the SFP unit 10 in place within a chassis. Although not shown, the SFP unit further comprises at least one receiver, at least one transmitter and/or at least one transceiver. The SFP unit 10 may alternately comprise dual receivers and/or dual transmitters. Each connector of the SFP unit is directly connected to a transmitter, a transceiver or a transceiver.
Examples of connectors in the context of the present disclosure comprise electric and optic connectors such as: 8P8C connectors, Universal Serial Bus connectors, Radio Frequency (RF) connectors, Audio connectors, Video connectors, all types of coaxial cable connectors and all types of optic fiber connectors.
Reference is now made to
Diagnostic measurement points A, B, C, D illustrate exemplary locations on a signal path 620 within the SFP unit, located after the input module 602, where signal diagnostic measurements may be obtained. As shown on
Signal diagnostic measurements from the measurements points A, B, C, D, may be measured by a measuring unit such as an electric, optic or electronic components or group thereof, not shown for clarity purposes. Signal diagnostic measurements at diagnostic measurement points A, B, C and D may be directly outputted from the SFP unit 600 in the form of measurement signals on lines 632, 634, 636 and 638. Some or all of the lines 632, 634, 636 and 638 may be connected on one or more connectors 17 as shown on
Reference is now made to
In an exemplary implementation of the present SFP unit, the signal diagnostic unit 610 receives a signal diagnostic measurement from the diagnostic point A, i.e. between an equalizer 602 and a reclocker 604, indicating that amplitude of the signal at diagnostic point A is weak. The signal diagnostic unit 601 determines a required correction for the correction unit 612, indicating that the correction unit 612 must boost the signal.
In another exemplary implementation, the signal diagnostic unit 610 receives a signal measurement from the diagnostic point B, located before a reclocker 606. The signal diagnostic unit 610 determines that the signal at detection point B is closed in time, i.e. suffers from a lot of jitter, and that the amplitude is low. The signal diagnostic unit 610 instructs the correction unit 612 to retime the signal with the assistance of the reclocker 606, and amplifies the output power of the signal. By performing signal diagnosis of the signal along the signal path in the SFP unit, and correcting the signal based on the diagnosed information, it is possible to have an output signal at the crosspoint or crossbar 608 with better quality than at the entry of the SFP unit.
Although
Thus the present SFP unit 600 is not limited to receiving signal(s) from one or several connectors, but further performs signal diagnostic measurements at one or several diagnostic points of the signal path. Furthermore, the present SFP unit 600 may further use the signal diagnostic measurements to perform a signal diagnostic, and determine required correction. Also, the present SFP unit 600 may be adapted for correcting the signal based on the determined required correction.
As mechanical dimensions for SFP units are rather small, the present diagnostic measurement points A, B, C and D, signal diagnostic unit 610, correction unit 612 and output unit 614 may be implemented in dedicated hardware, made part of an integrated circuit, or comprise software components. Peut-on inclure XFP, et autre format de module pluggable? (Fait aux paragraphes 16 et 17)
The signal diagnostic measurements may comprise one or several types of signal measurements, such as for example: signal integrity, signal quality, signal strength, noise level, signal-to-noise ratio, distortion, jitter, bit rate, amplitude, wander, alignment jitter, timing jitter, (for example relative to an external signal, to a signal obtained at another measurement point, or to a reference clock), frequency, and the like. Information elements equivalent to those of typical eye diagrams may also be obtained for the signal diagnostic measurements obtained on the various diagnostic measurement points.
Diagnosticating of signal diagnostic measurement from the SFP unit 600 may provide similar information elements as those obtainable using an oscilloscope. As shown in
As can be appreciated by those skilled in the art, the present SFP unit with signal diagnostic capabilities adjusts the eye opening of the signal, based on the quality of the signal along the signal path. providing an output signal with better signal quality than the signal received.
Although the present SFP unit has been described in the foregoing description by way of illustrative embodiments thereof, these embodiments can be modified at will, within the scope of the appended claims without departing from the spirit and nature of the present SFP unit.