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DP83849IF as GPON Media Converter

Mike Brown24
Prodigy 170 points
Other Parts Discussed in Thread: DP83849IF

Hi all,

I am currently working on a design for using DP83849IF as a media converter for a GPON network. I have already asked a question about the configuration of the circuit and got my answer.

The important point is that we need to use an "GPON ONU" as our fiber interface and convert it to copper signal. is it OK to do that? I'm wondering that if any compatibility issues may happen to prevent the circuit from working.

My main concern is about the Rx/Tx  timings and the I2C interface as I want to leave the I2C signals floating.

  • 0
    TI__Mastermind 19780 points
    Hi Mike,

    If you are looking to implement a GPON ONU that is ITU-T G.984.1 compliant, the PMD of that ONU is defined by G.984.2. See figure I.11 in G.984.1 as an example of Ethernet in GPON ONT/U. This is not the same as a PMD that is implemented in the DP83849IF.

    The SFPs I have found are compliant to G.984.2 which would then interface to G.984.3 TC layer before being sent to an IEEE 802.3 MAC layer for Ethernet service.

    The DP83849IF implements the IEEE 802.3 PCS and PHY layer which do not appear in the ITU G.984.1 definition of an ONT/ONU.

    If you'd like to share the SFP part number you have in mind, I'd be happy to take a look at it.

    Best Regards,
  • 0 in reply to Rob Rodrigues
    Prodigy 170 points

    Thank you Rob for your reply,

    The specific SFP that we are working on is Ligent LTB-3468 (www.ligentphotonics.com/.../product-detail-046.shtml)

    however, we need our final product to be compatible with as many standard SFPs as possible (even non-GPON).

    is DP83849IF compatible with the before-mentioned SFP from Ligent? if not, can you offer another solution for this purpose?

    Also please tell me which type of SFPs can we use with the DP83849IF working as a media converter.

    Thank you.

  • 0 in reply to Mike Brown24
    TI__Mastermind 19780 points
    Hi Mike,

    The DP83849IF will not work directly with the GPON SFP from Ligent, or any other manufacturer.

    Finding a single PHY that works with numerous SFPs is going to be difficult as SFP is used for multiple comms standards: Gigabit Ethernet, GPON, SONET, 100base-fx, etc.

    The DP83849IF is designed to work with 100base-fx SFPs only. Examples can be found from Cisco and other manufacturers.

    Best Regards,
  • 0 in reply to Rob Rodrigues
    Prodigy 170 points

    Rob,

    It was a little sad for me to hear that as I have almost finished the schematic of our design based on DP83849IF.

    Does TI have a solution to work as a media converter in GPON (i.e. ITU-G.984.x) networks?  or would you please help me choosing another solution.

    Thank you.

  • 0 in reply to Mike Brown24
    TI__Mastermind 19780 points
    Hi Mike,

    I am also sad to hear I could not help with the GPON SFP. From the G.984.1 it seems like you need a GPON TC layer that conforms to G.984.3. I do not have guidance on where to get a module that performs this function.

    By the ITU standards, your Ethernet frames need to be recovered from the GEM packet format before they can be passed to a standard Ethernet PHY for media conversion.

    Best Regards,