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4651 Views 6 Replies Latest reply: May 10, 2010 7:43 AM by Anthony Holloway RSS

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DSP Question

May 5, 2010 9:58 PM

Abu Hadee 19 posts since
Jun 16, 2009

Hi All,


Hope everybody is doing fine. As a group leader of this group, I'm going to pose some question to start some discussion.


Here is one for today.


If I need 10 g729 call, 5 transcoding session along with 3 conference.


How many DSP do I need?


Thank you

- abu

  • Anthony Holloway 5 posts since
    Mar 3, 2009
    Currently Being Moderated
    1. May 6, 2010 7:17 AM (in response to Abu Hadee)
    Re: DSP Question

    I don't know the answer to this, I just wanted to say thank you for getting this going.  I have been monitoring this forum for quite some time now, and have found very little value in it thus far.


    I hope to see some good discussion around this question, and not just the correct answer.


    Thanks again for the push in the right direction, this community needed that.

  • Janice 2 posts since
    Aug 20, 2008
    Currently Being Moderated
    2. May 6, 2010 6:15 PM (in response to Abu Hadee)
    Re: DSP Question

    I agree with Anthony, this is a nice way to start participation and look forward to learning more.  Don't know the answer either but will do some research to gain a better understanding.

  • Cindy 1 posts since
    Jul 2, 2008
    Currently Being Moderated
    3. May 7, 2010 11:20 AM (in response to Abu Hadee)
    Re: DSP Question

    The DSP calulator (on the cisco webpage) requires the router model and OS verision. Depending on what onboard DSP's the router has already, additional DSP's may not need to be added. If I choose : Cisco 3725 Router and Cisco IOS Release 12.4. the results are listed below. Link to the calculator is also listed.





    Onboard/NM SlotsG.711/ Fax passthrough/ Modem passthroughG.729a/ G.726/ Fax Relay/ T.37 FaxG.729b/ G.723.1/ G.728/ Modem Relay
    AIM Slot0
    WIC Slot 0VWIC2-1MFT-T1/E1(T1 voice)0100
    NM Slot 1NM-HDV2-1T1/E1One Onboard T10100
    VWIC2-1MFT-T1/E1(T1 voice)000


    Number of transcoding sessions
    G.711 a-law to/from u-lawG.711 to G.729aG.711 to G.729(b)
    NM Slot 1NM-HDV2-1T1/E1050
    Transcoding Type : CCM


    Number of conferences
    G.711 modeG.711 - G.729a/ G.729 mode
    NM Slot 1NM-HDV2-1T1/E103


    Analog reservation and Media Encryption
    Onboard/NM SlotsAnalog ReservationMedia Encryption




    DSP Calculator Result


    The AIM card(s) provide sufficient DSPs for the onboard Configuration.
    Minimum number of DSPs required to support the NM configuration is 4.


    DSP Requirements
    NM1CLI Information
    Optimized Result(Default)4 DSP(s).
    one PVDM2-48 + one PVDM2-8
    one PVDM2-16 + one PVDM2-32 + one PVDM2-8
    CLI Info
    Normal Result4 DSP(s).
    one PVDM2-48 + one PVDM2-8
    one PVDM2-16 + one PVDM2-32 + one PVDM2-8
    CLI Info
    Worst Case ResultN/AN/A
  • mickelmads 2 posts since
    Oct 29, 2008
    Currently Being Moderated
    4. May 7, 2010 1:44 PM (in response to Abu Hadee)
    Re: DSP Question

    Hi Abu

    Thanks for posing the question, I passed CCNA Voice this week so was keen to answer this, but looks like Cindy has done a fine job and answered this via the calculator. But I suppose this is not the full answer. I suppose it all depends on the model of Router in use. I understand that there are also two types of DSP C549 and C5510. I don't know the difference between these, I suppose this depends on router models too. Perhaps someone can advise?

  • Anthony Holloway 5 posts since
    Mar 3, 2009
    Currently Being Moderated
    6. May 10, 2010 7:43 AM (in response to Abu Hadee)
    Re: DSP Question

    This is a disappointing end to what could have been a great discussion on DSP resources.


    I was really looking forward to a discussion on DSP resources, to the core of why they even exist.  Not just a link to a calculator, and a dump of the output.


    I'm not saying we need a discussion on micro controllers, and circuit boards, but let's at least be able to configure a solution if the web is down.  Are these calculators available in the CCIE voice lab?


    An analogy:  I've seen many engineers use a subnet calculator, and have no idea how it arrived at a solution, to a problem they should really understand.


    Let's get this discussion going again.  What does a DSP actually do?  It takes a digital voice stream as input, does something to it (what?), and output a copy of the original digital voice stream?  Is that right?  What are the operations it can perform on a voice stream?  Encode?  Decode?  Make me sound like T-Pain?


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