Asterisk and Xen
Posted by Greg on 17 Jul 2006 at 05:50 pm | Tagged as: asterisk, planetosl
One of the things we need to build for the OVSD project is a voice over IP (VoIP) tool for teachers and students to communicate with each other. Being familiar with Asterisk already, I immediately thought of it when this project came along. Mostly we plan on using it for conference calls and the like, but there are all sorts of interesting things we can do with it for podcasting and faxing as well. Regardless how we end up using Asterisk in the OVSD project, it’s an interesting use of the product.
Except for one slight problem. In order to use the MeetMe conferencing features within Asterisk, you need to install the zapel module for the clock. OK, that’s no problem, except that my development box is a Xen virtual machine. Xen virtual machines do not have access to the hardware clock. Zaptel appears to be rather unhappy about that lack of access to the hardware clock and tends to kernel panic.
Ouch. So now I need to either use a separate conference bridge application within Asterisk, or find a way to get Zaptel and Xen to play nice.
App_conference doesn’t use zaptel timing for it’s conference implimentation in Asterisk. Also a fork of Asterisk has been working on using POSIX system timing vs Zaptel. Heard some people have success with either option. Voip-info.org has some info on app_conference which is kept in the iaxclient src tree on SF.
Yeah. I was just working with the built-in conferences because I was more familiar with them and too lazy to look at other implementations. I´m debating on how much work I´m going to put into it, since only the dev server is on a Xen slice (the production system will be on dedicated hardware).
Hi there, search for ztxen… it’s a clone of the ztdummy module that uses the kernel 2.6 tick timer (1000Hz) instead of RTP
This means you can run a pseudo zap chan for meetme inside a domU (i am doing so successfully!)
Aha! That’s good to know. I have since migrated onto dedicated hardware so I can install a PRI card, so the issue is academic at this point. But it is useful to know should I ever decide to migrate to a cluster environment.
This is good stuff. I’ve known that this was possible for a while now, but I’ve never had a specific answer for people when it comes up in FreeNode #asterisk . I do now. Cheers!
Greg, I am using app_conference in my xen voip servers since last year with really good results, i did even change 2 lines in the freepbx code to make it work with it, being able of create/remove conferences from the admin site.
Nevertheless, i did not test it under asterisk 1.4.
cheers!
Matt,
That’s good to know. Thanks for sharing!
[...] ya no es solo posible evitar el problema de la señal de clock del ztdummy en sistemas virtuales, sino incluso poder acceder directamente a hardware Asterisk. Dado que [...]