Urgent Software Upgrade for Servers

Affected Products

XR1000, XR2000, XR3000 units with pre-installed Elastix shipped between 12-Apr-09 and 18-May-09.

Problem Overview

Under certain circumstances, while speaking via a DAHDI channel, the voice is distorted or the "one way" voice phenomenon occurs. At times it is impossible to connect to the server via SSH due to the authentication failure.

Technical Description

Xorcom Asterisk appliances with pre-installed Elastix include the OSLEC echo canceller compiled with MMX optimization. This significantly improves the echo canceller performance and increases the ability to support many more concurrent calls via DAHDI channels. However, it requires a special patch for DAHDI that provides correct saving/restoring of the Floating Point Unit (FPU) registers during the OSLEC echo canceller activity. Unfortunately, this patch was not applied and as a result other Linux applications that use MMX/SSE CPU facilities, as well as the OSLEC functionality, cannot operate normally.

Suggested Resolution

Upgrade the currently installed DAHDI packages as described below: 

1. Connect to the server via SSH.
2. Update the DAHDI packages using the following command:
   yum update dahdi kernel-module-dahdi
3. Reboot the server in order to reset the FPU.