[Xen-users] AsteriskNOW on Xen Choppiness

[Ian Murray <murrayie@xxxxxxxxxxx>]

Hi,

I have installed AsteriskNOW 1.5 as a paravirt DomU. Xen set-up is 3.3.1 fro 
GitCo on CentOS 5.4 with the current kernel for that distribution. Apart from a 
minimal glitch with the DAHDI drivers which I fixed post install, all went 
smoothly. I noticed there was some issues with the voicemail announcement being 
highly choppy. I was mainly trying it with X-Lite on windows (no issues), 
SipDroid on my phone (quite a few issues), Twinkle on Ubuntu (excessive issues 
- sounds like a Dalek in some instances) and incoming voiptalk.org IAX2 trunk 
(variable). SipDroid has handy feature that reports number of lost and late 
packeds while in a call. This indicated brief missing and tardy packets to the 
tune of up to 5% (mainly late) while the choppiness was happening, otherwise 
zero in both cases. This particularly seemed to happen at the start of the 
message, or after a period of silence (which sipdroid reports as "no data")

A bit of googling revealed that this kind of thing has been common in the past 
in virtual environments, but I got the feeling shouldn't be an issue these 
days. Seems like work has been done at the kernel/Asterisk(/Xen?) level to 
improve things. There seems to be special comments relating to timing issues 
and this could be solved in a bare metal environment by adding a piece of 
Digium hardware that would provide a timer. I happened to have one so, I added 
one to the DomU via pass-through. Card was seen by the DomU and the driver 
loaded okay. Start-up message about using DAHDI_Dummy for timing was also gone. 
However, the choppiness remains.

I realise all these issues could be exclusively AsteriskNOW and not Xen, and if 
I can eliminate Xen, I will approach it from a AsteriskNOW point of view.

Are people successfully running AsteriskNOW on Xen, and if so can anyone 
suggest anything that might help?

Am I right in thinking the timing issues of the past should now not be an issue?

Is there any mileage in upgrading Xen to the latest 3.3.x or 3.4.x? 

My current approach is to go with the Xen upgrade, try an HVM instance 
(although no good for production because I wanted a 4 port FXO on passthrough 
and finally try a bare metal install on another machine to compare, in that 
order.

I realise there has been much talk of Asterisk on Xen on the internet, but it 
is hard to work out what is current and what is irrelevant.

Thanks in advance for any help I receive,

Ian.





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