[asterisk-users] High delay from Asterisk as PSTN simulator

[Kevin P. Fleming]

On 09/15/2011 10:46 AM, Gustavo Santos wrote:
> I understand. I'm interested in simulate the real situation because I'm
> doing an academic comparative between algorithms, and is really
> interesting have all possible situations.
> In the real situation I use a E1 to connect a PBX through a R2 link, so
> I want to try change DAHDI to 10 ms... What should I modify?
> Any other sugestion to make it works?

Changing chan_dahdi to use 10ms packet size is *still* not going to 
solve your problem; when a 10ms packet is read from the incoming 
channel, the transmission of it on the outgoing channel will not 
overlap; it will begin as much as 10ms later, resulting in as much as 
20ms of latency.

The only way you are going to be able to use Asterisk in this scenario 
is what I outlined before; you will need to have Asterisk call back out 
over the same E1 to your test device, and let the DAHDI native bridging 
bridge the two channels on the E1 card itself; this will result in no 
more than 1ms of latency between the channels. Alternatively, it is 
conceivable that DAHDI could be modified to have a loopback mode, and a 
special dialplan application constructed to trigger it... and then a 
single channel could be looped back towards its source, on demand, with 
nearly zero latency.

-- 
Kevin P. Fleming
Digium, Inc. | Director of Software Technologies
Jabber: kfleming at digium.com | SIP: kpfleming at digium.com | Skype: kpfleming
445 Jan Davis Drive NW - Huntsville, AL 35806 - USA
Check us out at www.digium.com & www.asterisk.org