Author Archives: sven.tron

  • Meet Flexoptix @RIPE74 in Budapest Hungary 8.-12. May 2017


    RIPE 74 will take place in the InterContinental Budapest hotel in Hungary, 8-12 May 2017.
    Our FLEXOPTIX members Fearghas, Markus, Hubert, Esime, Thomas and Sven will welcome you
    there the whole week. We are hoping for some nice discussions and chats about fiber optic technology and of course to have some fun (&beer)

    What is a RIPE Meeting?

    A RIPE Meeting is a five-day event where Internet service providers, network operators and other interested parties from around the world gather to:

    • Participate in discussions about the policies and procedures used by the RIPE NCC to allocate Internet number resources
    • Participate in the RIPE Working Group sessions to discuss current technical and policy issues
    • Share experiences, latest developments and best common practices
    • Develop their network of peers in the Internet community
    • Meet at lunches, coffee breaks and informal social events


    Register yourself here:

  • Meet Flexoptix @CEE Peering Days in Ljubljana March 22nd & 23rd


    The CEE Peering Days are located in the beautiful city of Ljubljana in Slovenia.
    Take your chance and meet Fearghas & me (Sven) in person. We are open for some nice
    chats, talks and discussions and maybe some drinks ;-)

    There are still some seats available. Register now.

    About CEE Peering Days

    CEE Peering Days is an international conference of experts directed at network engineers, peering coordinators, internet providers, cloud administrators and data centre operators in the Central and Eastern European Region.

    The programme combines technical workshops with professional presentations and offers plenty of time and space for social networking and bilateral talks.

    The conference in 2017 is planned as a two-day event at the Austria Trend Hotel Ljubljana and will include a social evening in the centre of Ljubljana on 22nd March.



  • P.1596.A.R - Application & Design of using 100km CDR SFP+

    We already described the CDR feature in Why using CDR / 3R / Clock-Data Recovery.
    With our P.1596.A.R you are able to transmit up to 100km (26dB). Yes, I know: Why are you
    writing "up to 100km"? Is the question everyone has in mind while reading this sentence.
    That is exactly what this article is about. We need to define some technical parameters and I would like to tell you what we already tested.

    Additional technical parameters

    • Power Budget: 26 dB
    • Dispersion Tolerance: -500ps/nm to 1.600ps/nm
    • Transmitter Dispersion Penalty @1600ps/nm: 3.5 dB
    • Bit-error-ratio (BER): 10^-12 @10.3 Gbit/s with PRBS 2^31-1 and OSNR > 30dB


    This means, that the guaranteed power budget is 26dB but the dispersion tolerance is only 1.600ps/nm. Standard G.652 Singlemode Fibers have 18ps/km Chromatic Dispersion which leads to 88km with a dispersion tolerance of 1.600ps/nm. If you have a dispersion optimized fiber you might reach out longer.

    Our lab test under "field" conditions

    We used 100km of standard G.652 fiber and a P.1596.A.R. Our receive level was at -17,5 dBm and 10.3 Gbit/s (10G Ethernet). We did a BERT (bit-error-rate-test) with a Standard 2^31-1 PRBS and reached a BER of 10^-12. Reducing the light level lead to bit-errors.


    A Bit-Error-Rate of BER 10^-12 means 1 bit-error every 100 seconds. If the input power value is high enough you might reach the 100km. If the input power values will be lower there are just up to 88km possible.
    --> Calculated max. receiver sensitivity (dispersion penalty included): -21 dBm


  • Why using CDR / 3R / Clock-Data Recovery

    As already discussed in my blog post History / Technical details Tunable DWDM SFP+  there are transceivers with integrated CDR (e.g. XFPs) and without it (e.g. SFP+). Now you probably have the following questions in mind:

    • What does CDR stand for?
    • What do I use a CDR for?
    • When do I have to use a transceiver with CDR?
    • Which advantages come with a CDR?

    What does CDR stand for?

    CDR is the abbreviation for Clock-Data-Recovery.

    What do I use a CDR for?

    Physical impacts are influencing the optical signal during the transmission over fiber optic cables. Due to the length of an optical link the signal suffers a time delay deviation which leads to problems in synchronization. In addition an optical fiber attenuates the signal which leads to a degradation of the signal. The physical impacts are linear and non-linear effects which are leading to wave distortion.

    This is why a 3R-regeneration will be used:

    • Re-Amplification (regeneration of amplitude)
    • Re-Shaping (regeneration of signal waveform)
    • Re-Timing (regeneration of synchronization)

    The transceiver includes a Limiting Amplifier (*1), which compensates step 1 & 2 at receiver side. For step 3 (Re-Timing) there is an additional CDR chip set integrated in the transceiver.

    When do I have to use a transceiver with CDR?

    This question was raised with the introduction of SFP+ modules.

    Short summary:
    XFP modules are built with CDR on-board as defined in the related MSA-Standard. To realize a cost effective and smaller form-factor this functionality doesn't become part of the SFP+ module. The idea was implementing CDR directly in the host-system of the SFP+ if needed. This would increase the price of the end-devices like switches and routers. A 2R-regeneration (Re-Amplification, Re-Shaping) is already part of the transceiver so it is not mandatory to implement a CDR function.
    To realize a standard link this is usually sufficient. Standard links are typically in-house wiring (Multimode), 10km, 20km and 40km point-to-point connections.

    But if you are planning to set up a wavelength multiplexing (DWDM), an optical amplifier or transmitting over long distances, you should consider a complete 3R-regeneration. This can be achieved with a CDR chip set either in your DWDM-transponder, host-system or transceiver. Most of the DWDM transponder-systems do have a CDR functionality on board.

    Which advantages come with a CDR?

    There are a lot of effects on an amplified DWDM link which have a lot of impact on the transmission signal. For an error-free detection parameters like:

    • ONSR (Optical signal-to-noise ratio)
    • BER (Bit-error-ratio)
    • Input power value
    • Data rate
    • Degradation of the signal

    have impact on each other. A stable reliable DWDM link can be achieved, if you take the first four points into consideration by planning an amplified DWDM link and in addition eliminating the last point by using a 3R-regeneration with CDR.

    Please find our important SFP+ modules in our shop:

    (*1) electrical component which amplifies and reshapes the incoming signal.

  • FLEXBOX: Distance Analyzer with microOTDR Transceiver

    Inspect the optical link loss or locate faults in your fiber with the Distance Analyzer of your FLEXBOX in combination with our microOTDR SFP Transceiver S.OB1612.40.OD. read more

  • DWDM OSNR values for X.1696.23.xT

    Data Rate (gbps) BER Dispersion (ps/nm) Rx Power Range (dBm) OSNR (dB)
    10.709 1E-4 0 -7 to -24 16.5
    10.709 1E-4 -400 to +1600 -7 to -24 18.5
    1E-4 0 -7 to -24 17
    1E-4 -400 to +1600 -7 to -24 19.5
    1E-12 0 -7 to -24 31
    1E-12 0 -7 to -19 26
    1E-12 -400 to +1600 -7 to -19 27

    (*) For all technology loving people: There is a balance or better a direct relation between Data Rate, BER (Bit-Error-Rate), Chromatic Dispersion (CD), Rx Power Range and OSNR (Optical-Signal-to-Noise-Ratio). A high gap between Signal-Level and Noise-Level results in a low BER. To achieve this big gap the input power needs to be higher than with lower BER and same OSNR. If you consider the Cromatic Disperion, too you need to have around 3-4dB more input power than without Chromatic Dispersion. This 3-4dB are known as Dispersion Penalty which has to be considered when CD is in given range. This is almost the same for all data-rates around 10G. (here 10.709-11.1 gbps) If you for example compare this with a 1G signal the OSNR can be much lower because of higher signal spacing.

  • FLEXBOX: How to tune DWDM Wavelength of your transceiver

    How to set the wavelength of your Universal XFP, SFP+ or CFP DWDM Tunable Transceiver?

    • Plug a transceiver into your FLEXBOX
    • Go to the "Your Transceiver" tab
    • Change the Wavelength in drop down to desired channel
    • Wait a few seconds while the FLEXBOX is tuning your transceiver
    Change Channel in Drop Down  Change Channel in Drop Down
    Tuning in Progress Tuning in Progress
    DWDM Wavelength changed DWDM Wavelength changed


  • FLEXBOX: Power Meter & (Light) Source Feature

    Without additional equipment/devices and expenses our FLEXBOX combines all the commonalities of a physical power meter and optical light source in an intuitive and reliable application, all you need is your FLEXBOX and a transceiver.
    read more

  • ArubaOS enables use of non HPE Transceivers & DACs (Software Version: 16.02)

    Flexoptix received an email from one of our customers (thanks for this) with the following information:
    New enterprise features*: Allow third-party transceiversFrom there on we looked for this new SW-Version but this was just a  advance notice.
    July 2016 started the roll out of the new SW-Version 16.02 with the ability to enable
    "unsupported transceiver" or the other way around all other optics than HPE/Aruba ones.
    We did some tests with Aruba 2920 and HPE / Aruba 54xx series. The Flexoptix optics and DACs are working fine now.First of all: Why is Aruba and Hewlett Packard creating a HPE ArubaOS for the HP switches?
    Hewlett Packard Networks acquired Aruba Networks and renamed the HP switching series from HP to Aruba, that's all.What does this mean for me as a HP user?
    You are now able to use FLEXOPTIX transceiver in you HP ProCurve / Aruba device. Just use the compatibility "Aruba Networks(ex. HP Network) SW > 16.02" with the transceiver hardware you need and follow the steps below.

    This feature can be enabled via the CLI on a supported switch. Please find the needed instructions to activate this feature on your HPE / Aruba device with SW-Version > 16.02

    Please type this command before plugging the optics:

    # config
    # allow-unsupported-transceiver

    DDM information are available with:

    # show interface transceiver detail

    For more details about the plugged transceiver, please type:

    # show tech transceiver

    FLEXOPTIX Transceiver will be shown as:

    # show interface transceiver detail
    Transceiver in A1*
       Interface Index    : 49
       Type               : SFP+SR
       Model              :   ??
       Connector Type     : LC
       Wavelength         : 850nm
       Transfer Distance  : 80m (50um), 20m (62.5um), 300m (50um OM3),
       Diagnostic Support : DOM
       Serial Number      : unsupported
       Temperature : 55.375C
       Voltage     : 3.2902V
       Tx Bias     : 5.782mA
       Tx Power    : 0.5198mW, -2.842dBm
       Rx Power    : 0.4740mW, -3.242dBm
      Time Stamp    : Mon Aug 15 13:24:15 2016
    * third-party transceiver

    An original HP J9150A will be shown as:

    # show interface transceiver detail
    Transceiver in A2
       Interface Index    : 50
       Type               : SFP+SR
       Model              : J9150A
       Connector Type     : LC
       Wavelength         : 850nm
       Transfer Distance  : 80m (50um), 30m (62.5um), 300m (50um OM3),
       Diagnostic Support : DOM
       Serial Number      : CN63G625CT
       Temperature : 45.628C
       Voltage     : 3.3024V
       Tx Bias     : 5.500mA
       Tx Power    : 0.6340mW, -1.979dBm
       Rx Power    : 0.5435mW, -2.648dBm
      Time Stamp    : Mon Aug 15 13:24:15 2016

    All devices which can be upgraded to SW-Version > 16.02.000x:

    2530 Starting YA.16.02.xxxx
    2920*** Starting WB.16.02.xxxx
    2930F Starting WC.16.02.xxxx
    3810***/5400R Starting KB.16.02.xxxx
    *** tested and confirmed


    Needs to be tested:
    3500/5400 Starting K.16.02.xxxx
    3800 Starting KA.16.02.xxxx

    We are happy to hear back about the experience with FLEXOPTIX
    transceivers and other devices. Just drop us a short line


  • The 10G copper / fiber comparison

    There are three solutions connecting two devices:

    1. SFP+ Direct Attach Cable (DAC)
    2. SFP+ Optical Transceiver Module
    3. Fix 10GBase-T RJ45 ports

    1. SFP+ DAC

    Beside low power consumption and low latency DACs became popular in datacenter cabling between server and switches or storage for short distances. Pricing is quite low compared to optical modules and complexity is less. But this cable ends typically in 7m – so for distances above you have to chose active DACs which are not that price sensitve any more. And cabling across several racks with SFP+ transceiver at each side becomes a bit awkward.

    2. SFP+ optical Transceiver

    Multimode 850nm transceivers - like our SFP+ SR (P.8596.02) - are typically used for short distances um to 300m at 10G data-rates. In comparison to Cat6a cabling multimode is quite expensive. And not every technician has knowledge regarding optical communication. So the operational costs might increase.

    3. 10GBase-T RJ-45 Ports

    10GBase-T ports became more popular while it was possible to cut down the power consumption for these ports. But using only fixed ports resulty in less flexibility. For optical transceiver ports there are different optics which lets you decide the application or link length. In addition fixed unused ports are not shut-down in contrast they are consuming at much power as a used port.

    To fill the gap in between a 10G SFP+ transceiver is available now (T.C96.02.KF).
    There are several advantages using this type of transceiver:

    • Link length: Up to 30m using Cat6a/7
    • Backwards-compatible to 100/1000Base-T
    • MDI/MDIX crossover
    • Auto-negotiation with other 10Gbase-T PHYs
    • Hot-pluggable
    • The RJ45 connector is well known and proven technology
    • FLEXBOX ready: Universal 10G SFP+ RJ45 – flexible use over different platforms


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