Elastix 1.6, redfone, outbound sound bad

Discussion in 'General' started by Nigel, Jul 1, 2010.

  1. Nigel

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    I have just completed my first production installation of Elastix and love it.

    I have a problem with sound quality, just for people external to the site and only the sound that the external party receives. The sound the external party transmits is received by the internal party perfectly. (Internal calls all work perfectly).

    I am running the latest version of Elastix 1.6 64 bit, updated to the latest version (Kernel was not updated and is currently kernel-2.6.18-164.el5. The machine is virtual running on ESX3.5i (I have read about people who have succeeded and failed however none of the posts I have read have been recent which makes me hopeful, also everything else is working well).

    The installation is in Australia and the ISDN is PRI 10 channel.

    Here are the config files I have been working with:

    /etc/redfone.conf
    -----------------

    [globals]
    fb=192.168.1.254
    port=1
    server=00:50:56:8F:6E:9F
    priorities=0,1,2,3

    [span1]
    framing=ccs
    encoding=hdb3
    crc4

    /etc/dahdi/system.conf
    ----------------------

    dynamic=ethmf,eth1/00:50:c2:65:da:b7/0,31,1
    bchan=1-15,17-31
    dchan=16
    alaw=1-15,17-31
    defaultzone = au
    loadzone = au

    /etc/asterisk/dahdi-channels.conf
    ---------------------------------

    group=1
    context=from-pstn
    switchtype = euroisdn
    signalling = pri_cpe
    language=en
    callerid=asreceived
    overlapdial=yes
    rxgain=-3.0
    txgain=-9.0
    channel => 1-10
    context = default
    group = 63

    /etc/asterisk/chan_dahdi.conf
    -----------------------------

    [trunkgroups]

    [channels]
    echocancel=no
    echocancelwhenbridged=no
    nationalprefix=0
    pridialplan=unknown
    prilocaldialplan=unknown
    priindication=outofband
    internationalprefix=0011
    overlapdial=yes
    context=from-pstn
    distinctiveringaftercid=yes
     
  2. Nigel

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    Running dahdi_tool shows that the Sync Source is Internally clocked.

    I have attached an image.

    Could this be part of the problem I am facing? [​IMG]
     
  3. dicko

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    I very much doubt that most VM's will work successfully with a layer two network attached device (redfone) If you read the redfone site, they SERIOUSLY advise against attempting sharing the NIC with anything else, (as do I, having tried it to see it miserably fail.) in your case your are sharing it with everything else :)

    You might get better success using a XEN kernel on decent paravirtualizing hardware with a dedicated NIC and with a well designed DOM0 in a well designed DOMU, but then again maybe not :)

    dicko

    p.s. with rx/txgains as high as you have them you might want to check the CSU settings on the Telco span, they indicate a mis-match somewhere.
     
  4. jgutierrez

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    Try setting longhaul=0 bellow your crc4 value at redfone.conf. Dont forget to restart the services before trying again.
     
  5. Nigel

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    Dicko you are all over this forum.

    Are the results that I am experiencing consistent with what you have experienced doing the same thing.

    If they are well I guess I am getting myself a physical server.

    It will be a shame because if I could have gotten this to work, I could have done it 60 more times :).

    Cheers
    Nige
     
  6. dicko

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    TDMOE is incredibly demanding, as is T1/E1 timing, VM's generally cut corners in network implementations as normally only much more forgiving layer three Traffic will be encountered, we have a user here called redfone, he posts occasionally, I take him as authoritative, but yes I have tried many things, your experience does not surprise me, and no, I would not recommend such a deploymnet.

    diko
     
  7. Nigel

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    Dicko,

    I wonder then if you or anyone has had any success tuning vmware.

    There are a lot of advanced tuning parameters that could do the trick.

    I also think vSphere will allow you to dedicate hardware to a virtual machine.

    Cheers
    Nige
     
  8. dicko

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    I'm happy with what I have achieved with my vmware based kernel .config file, but it does not include redfones. If you go that way you will have to compile your own kernel and resolve any Elastix yum repo based inconsistencies, almost certainly Asterisk and Dahdi.

    With the advent of Asterisk 1.6 and above, the strict requirements of an interrupt based dhadi_dummy timer is going away and there is a kernel based alternate timer source. as I stated before this is written with XEN in mind, but who knows maybe we'll be running on Vista some-time soon ;) , you will likely need to recompile Asterisk against your particular hardware to avail yourself of it though.

    With those strictures in mind, I believe that around here we have decided that anyone who wants to virtualize, will need to know what she is doing, and be so able to do it all on there own, there is never going to be a satisfactory recipe as right now there are too many choices, I guess you should choose one and suck it and see, if it tastes like s*&t move on and try another :)

    dicko
     
  9. Nigel

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    Haha,

    your a funny guy.

    I am not game compiling and then support a custom kernel.

    I looking at the virtual networking problem and was going to look at tweaking esx to try and get more performance.

    I did do some work to ensure that I got enough interrupts through to the virtual machine for the redfone.
     
  10. dicko

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  11. Nigel

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    I had read that negative non supported page.

    I am surprised that redfone have not found a resolve as this seems to be the perfect solution.

    Is there a product out there that will convert a pri isdn line to SIP? I have IAX and SIP trunks to virtual machines that work a treat.

    Cheers
    Nige
     
  12. dicko

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    There are many, look to adtrans, Cisco et al, be prepared to lay out 4-10k usd, per span.

    Even redfone have a software stack to do that for SIP based endpoints, (it wont work in a virtualized environment either for the same reason, it will likely work fine on a 250 dollar fanless atom boxette though, but so will Elastix which could do the same job cheaper and expose a SIP/IAX2 trunk to your massive and complicated but a little lagged VM machine)

    You seem to still miss the point though, TDM is TimeDivisionMultiplexing , if you can't divide the time by 1.54 (2.0) Megabitspersecond and pass it through your interface and reconstruct the 64k channels impeccably, then a traditional T(E)1 will just break, it always did and it always will, It just can't maintain the base clock, framing and encoding. TDM is intrinsically synchronous, networks are intrinsically asynchronous, any transitional layer through which it must pass justs make it worse, I rest my case QED, and please don't blame redfone, they do a very good product for a very good price.

    It for almostthe same reason that FAX often fails miserably over a mediocre VOIP link. Horses for courses and that course better be damn straight if you use TDM,

    Anyway keep on polishing that turd, if you can get it to work, you will get to be fanous.

    dicko
     
  13. Redfone

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    Nige,

    This is not a complete endorsement of fonebridge + VMWare but we are receiving some promising reports from other customers in the field that the latest VMWare ESXI 4.0 and vmware-tools installed on your Guest OS provides better and more reliable Ethernet communication which is key as Dicko has pointed out.

    There is a new virtualized network driver called VMXNET3 that appears to be highly optimized and much more efficient than the original drivers included in previous version of ESXi.

    We've done some preliminary testing in our labs as well and results do look very good. If you are able to test this out please update this thread to let us and the greater Elastix community know.

    thanks,
    Redfone
     
  14. Nigel

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    Thanks Redfone,

    That is very promising.

    I will see if I can swing it, and let everyone know if it works out.

    Cheers

    Nige
     

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