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Linux guest operating systems are greatly affected by the System clock of the kernel. Linux 2.6 defaults to a 1000Hz clock tick rate, and that will put a strain on the virtual environment, and can cause problems with system time keeping. Linux 2.4 does not have this problem as the clock runs at 100Hz. If running Linux 2.6 based virtual machines, re-compile the kernel to run at 100Hz, or use one of the newer kernels which use the No HZ dynamic clock. Centos offers community developed VMware Kernels with the 100Hz option already compiled in.

Clock drift related to VMware can cause major issues with Yate, but there are a couple of workarounds for this that don't require compiling a custom kernel. Which workaround you use depends on if you need virtual SMP (multi CPU) or not. It is not recommended to run Yate virtualized, but it is acceptable in most cases where Yate is not fowarding (not proxying) RTP traffic and is only doing the signaling work.


Single CPU Virtual Machines

  1. Insure VMware Tools is installed and running
  2. Insure that you have enabled "Synchronize guest time with host" from vmware-config-tools.pl or from "Edit Settings" and then "Options" for the Guest (in VCenter/VMWare Server)
  3. Add: "clock=pit nosmp noapic nolapic apci=off clocksource=acpi_pm elevator=noop" as kernel boot options
  4. Re-run grub-install or lilo after you have modified the grub/lilo config file
  5. Reboot

Multi CPU (SMP) Virtual Machines

  1. Insure VMware Tools is installed and running
  2. Insure that you have enabled "Synchronize guest time with host" from vmware-config-tools.pl or from "Edit Settings" and then "Options" for the Guest (in VCenter/VMWare Server)
  3. Add: "clock=pit clocksource=acpi_pm elevator=noop" as kernel boot options
  4. Re-run grub-install or lilo after you have modified the grub/lilo config file
  5. Reboot

APCI/APIC support must be enabled if you plan on using SMP virtualization in the guest, setting the clock to PIT has shown to have better time keeping than other clock sources, your mileage may vary. Setting elevator to noop will enable the host operating system to better schedule I/O as it has an overview of the whole system as opposed to just one virtual machine.


    * Sample Syntax for LILO:
      image=/boot/vmlinuz
      label="linux"
      root=/dev/hda1
      initrd=/boot/initrd.img
      append="resume=/dev/hda6 splash=silent clock=clock=pit nosmp noapic nolapic apci=off clocksource=acpi_pm elevator=noop"
      read-only

    * Sample Syntax for Grub:
      title Red Hat Linux (2.4.20-28.9)
      root (hd0,0)
      kernel /vmlinuz-2.4.20-28.9 ro root=/dev/hda2 clock=pit nosmp noapic nolapic apci=off clocksource=acpi_pm elevator=noop

Tickless Kernels

Since Linux 2.6.21 the NOHz option can be configured at build time. Recent distributions enable by default this option, especially for laptop and desktop systems.

These tickless kernels are supposed to reduce the power consumption by having a variable clock interrupt. Unfortunately this also results in:

  • Jitter in delay functions (affects time critical protocols)
  • Miscalculation of load average (makes Yate appear to consume excessive CPU)

To check if the kernel has this feature configured and active:

 # dmesg | grep -i nohz
 Switched to NOHz mode on CPU #0

This feature can be disabled from the kernel's boot options by adding nohz=off

March 2014:
YateBTS 2.0 launched. Added authentication and WebGUI. Added USSD support in commercial version.

March 2014:
Yate 5.2 launched. Better JavaScript support and a fixed memory leak.

Jan 2014:
YateBTS 1.0 launched. The first GSM Basestation which works with an IMS/VoLTE core network.

Jan 2014:
Yate 5.1 launched. Better JavaScript support and added libygsm. Elisa chatbot added in RManager

Oct 2013:
OpenHSS is the Yate based HLR/HSS solution for MVNO and LTE carriers.

Oct 2013:
Yate 5 released. Added IPv6 support in SIP for LTE. Improved JavaScript support. Download NOW

Jan 2013:
Yate 4.3 released: Added XML support in Javascript. SCCP - GTT routing between different networks. Stability improvements.
Download NOW

Aug 2012:
Yate 4.2 released: SIP flood protection. Better Jabber/Google Voice support. Usable Javascript. Fixed SIGTRAN links fluctuations.
Download NOW

Apr 2012:
YateClient was accepted in the Mac Store.

Yate 4.1 released: better Gvoice support, iSAC codec, support for new Wanpipe drivers. Fixes T.38 and Mac client issues.

Mar 2012:
SS7Cloud is launched today, 1st March, 2012, by NullTeam, Yate creators. Having all you need to be a US CLEC, it brings SS7 services in a cloud.

Feb 2012:
Yate 4.0 released.
SCCP, TCAP, MAP and CAMEL, TCP and TLS in SIP, Javascript fast prototyping of telephony applications and brand new face for YateClient.

Nov 2011:
Here is a video that, quote "demonstrates the truly awesome power of the YATE engine, as it easily handles 3 simultaneous calls to an audio player application including dtmf (button press) handling "(from PaintedRockComm).

Nov 2011:
Yate will attend ORR - OPENRHEINRUHR (November 12 - 13).

04 May 2011:
sipgate chooses open source project Yate for core infrastructure.

12 Apr 2011:
Yate 3.3.2 released.
Fix for Jingle calls to Google Voice dropping after 5 minutes.
4 Apr 2011:
Yate 3.3 released.
Support for GMail chat conference, fixes for internal microphone in MacOS. Minor fixes in SS7 M2PA and ANSI. Fixes in H.323, SIP and RTP.

9 Mar 2011:
Yate 3.2 released.
Bug fixes in SIGTRAN/MGCP/SS7 and added support for CNAM/LNP lookup by SIP INVITE/3xx.

Feb 2011:
Yate will attend FOSDEM and XMPP summit.

31 Jan 2011:
Yate 3.1 released.
Yate client support for Google Voice. Support for any country tones in tonegen.

20 Dec 2010:
Yate 3.0 released.
SS7 ITU certified. SS7 STP added. Client supports Jabber IM (Google Talk + Facebook).

3 May 2010:
Yate 3.0.0 alpha 3 released. Featuring the new Jabber server and wideband audio.

8 March 2010:
Yate 2.2 released. Mostly bug fixes. Dahdi compatible. Latest 2 release before 3.0.

6-7 February 2010:
Yate booth at FOSDEM 2010. Free CD with Freesentral available.

2 Nov 2009:
Yate 2.1 launched. Can replace a Cisco PGW2200 to control a Cisco AS54xx.

6 Aug 2008:
Yate and OpenSIPS (former OpenSER) join to build IP based clusters.

4 Aug 2008:
Yate 2 launched.


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