You have visited this page because your system is having performance issues (or you simply wish to optimize your system) by reducing system interrupt load from your Sangoma card for Asterisk.
The following page is only applicable for:
- Sangoam E1/T1 cards
- Sangoma cards with hardware echo cancellation
- systems that do no require any echo cancellation (hardware or software)
- E & M Wink (T1/E1)
- R2/ RBS
As seen in the diagram below, the default DAHDI signalling layer runs on 8 byte chunk size. This is because the DAHDI software echo cancellation (called 'mg2') is designed for 8 byte chunk size. This means that every 1ms the CPU is interrupted to process information from TDM hardware! This causes congestion on the PCI bus and overall creates a bottleneck.
Sangoma hardware is able to eliminate this limitation as we offer Hardware echo cancellation with more flexibility. See diagram below.
DAHDI chunk size can be configured for the following units:
- 8 bytes (default 1ms)
- 16 bytes (2ms)
- 40 bytes (5ms)
- 80 bytes (10ms)
How to take advantage of DAHDI chunk size adjustment
You must re-install the Wanpipe driver with a specific flag.
- navigate to the source directory of the Wanpipe driver
- i.e. cd /usr/src/wanpipe-7.0.6/ (or whichever directory you downloaded Wanpipe to)
Type the following:
./Setup install --dahdi-chunk=<CHUNK SIZE>
Where CHUNK SIZE: 8, 16 , 40 or 80
This will re-install the Wanpipe driver, and patch DAHDI sources for the chunk size you selected. It will remove the wct4xxx (Digium) driver Makefile because it does not support chunksize other than 8 bytes
Select YES to recompile DAHDI/Zaptel in the Setup process
- The rest of the ./Setup process is identical to the typical Wanpipe installation.
NOTE: For binary Distributions (i.e. Elastix or FreePBX Distro) you will need to download the Sources for both DAHDI and Wanpipe as they do not exist on your system.
Once completed, simply start Wanpipe, DAHDI + Asterisk:
- wanrouter start
- dahdi_cfg -vvv
To confirm that the DAHDI chunk size has been changed, type "ifconfig" and look at the MTU size for your Wanpipe ports.
MTU = configured chunk size (8, 16, 40, 80)