With a recent version of asterisk, the only thing that will not work without a zt device (including ztdummy) is conference calling. Early versions also required the zt device for music on hold, etc. I have run without a zt device and not had any stability issues running asterisk on xen for about 16 months.
Dave's comments on the performance risks of a virtual asterisk server are spot on. Introducing virtualization to the already complex cpu/resource scheduling requirements for any voice application is not a trivial matter. Of course, depending on the needs of a given implementation, neither is it impossible to mix asterisk and virtualization. Sent from my BlackBerry device on the Rogers Wireless Network -----Original Message----- From: David Cook <[EMAIL PROTECTED]> Date: Sun, 1 Apr 2007 08:14:05 To:Chriswlan2 <[EMAIL PROTECTED]> Cc:[email protected] Subject: Re: [on-asterisk] Linode vs Asterisk??? VPS with ztdummy??? ztdummy can replace a hardware timing source, but it still is required to be stable. As Linux is not a real-time operating system (the scheduler determines which apps get time slices and how oftern) you will _always_ have an issue of how often/accurately you get your time slices and therefor processing anything. Extrapolate that from the TDM vs. VoIP comments earlier - where do you want to be on the curve - The more accurate these timing "ticks" that your application gets, the smoother your voice is. The smoother your voice is, the less echo and more usable the reconstruction of your voice from packets is. Asterisk running as an application on a non-RTOS (Real Time Operating System) is a compromise AT BEST although we can make the results quite acceptable. Running the non-RTOS itself in a virtual machine where the machine itself competes with other virtual machines for clock cycles even before it can parse out clock cycles to Asterisk is an environment that is not likely to succeed unless you are in control over the entire machine (real) and all virtual machines and architect it _very_ well. This however is the antithesis of what hosting is all about. dbc. -- David Cook Quoting Chriswlan2 <[EMAIL PROTECTED]>: > > Tks Leif and Ian, > > aren't these TWO separate issues: > > ===international calls may well have more jitter, and we have to put > up with > it > > ===As for lo-quality timing on a virtual machine, I seem to have read > somewhere in my research that some software (was it ztdummy?) can > replace > proper hardware timing? And even then timing was only an issue for > music-on-hold and a couple of things? > > Tks > > Christian > > > ----- Original Message ----- > From: "Ian Howard" <[EMAIL PROTECTED]> > To: "Leif Madsen" <[EMAIL PROTECTED]> > Cc: "Chriswlan2" <[EMAIL PROTECTED]>; <[email protected]> > Sent: Saturday, March 31, 2007 8:53 PM > Subject: Re: [on-asterisk] Linode vs Asterisk??? > > > > All, > > > > I ran asterisk on a virtual server (UML and then XEN) for some time > -- > > the quality was awful, comparatively, but given that my bandwidth > was > > already constrained where I was (West Africa) I was ok with it -- > Indeed > > as Leif mentions there are certainly timing issues. There was > > substantial jitter. I would not recommend it to someone making > calls > > within Canada (our tolerance for jitter is low). It worked well > enough > > to play with though. > > > > Ian > > > > > > Leif Madsen wrote: > > > On 3/31/07, Chriswlan2 <[EMAIL PROTECTED]> wrote: > > >> I had never heard of "User Mode Linux" for Linux VPSs... Is > their > > >> "Platform > > >> Manager" (never heard of it either...) powerful enough for > everything > > >> Asterisk? > > > > > > The issue you're going to run into is an exact timing source > inside > > > the virtual machine. Asterisk is very sensitive to this kind of > thing. > > > Asterisk may be more forgiving on this kind of thing now, but it > seems > > > to be its a fundamental issue when you're virtualizing Asterisk > as to > > > the kind of call quality you're going to have (i.e. unusable). > > > > > > Anyone actually run Asterisk in a virtual server that was usable? > Xen > > > might be the best bet since its a bit closer to the hardware > other > > > than say, VMware. > > > > > > > > > > --------------------------------------------------------------------- > To unsubscribe, e-mail: [EMAIL PROTECTED] > For additional commands, e-mail: [EMAIL PROTECTED] > --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
