I am running Asterisk on a linux box in the DMZ of a D-Link 504g modem/router and am experiencing huge latency. The delay is about 5-10 seconds and results in an unusable service.
I’m sure its a D-Link thing because previously I used the linux server running asterisk for pppoe and dhcp so it was open completely to the net, and this worked fine.
I have changed my network arrangement due to over-dependance on the linux server in an effort to increase security and manageability.
I expected to have problems like this, but i’m not sure how to trouble shoot as the server is in the DMZ so it should be fine. I’m thinking perhaps its a problem with the phone with is a budgetone plugged into the D-Link so this device is not in the dmz…
Any ideas?
I’d say you’re probably right about your problems being caused by the modem/router. I’m using a Netcomm modem/router and i’ve had nothing but trouble with VOIP since i’ve had this setup
Previously i had an ADSL connection through a Speedtouch USB modem and i never had any trouble with asterisk/VOIP at all. Admittedly, this was with a different ISP and on the opposite side of the planet, but that shouldn’t make any difference really. I’m planning to change my connection back to the Speedtouch, as soon as i get time, and see if this fixes the problems.
Another thing that i’m certain is causing me problems is the ethernet switch between my laptop and the asterisk box - that’s definitely going to have to get replaced by something better.
Neither of these units produce any noticeable effect on other type of network traffic. Downloads, ping times, ssh, etc. And there never seems to be dropped packets or errors on the ethernet interface. I think there’s just something about the way these switches handle packets that plays havoc with VOIP traffic.
Have you read this? :
voip-info.org/wiki-QoS
Damn my dodgy tactics for troubleshooting…
I managed to fix the call quality back to what it should be, but I did a few different things and i’m not sure what exactly did the trick. Anyway, this is what i did:
1: Reset my modem, and set it up again changing only the areas needed. Basically just defining the * server as DMZ.
2: Fixed iax.conf which had a few minor errors and errant letters.
I think it was probably more to do with the iax.conf, as most problems can be fixed through the conf files, but I have this mental thing with regards to starting from the ground up when I am stumped with an issue like this 
.
Latency is now fantastic, the echo test through my provider is almost instant, about 32ms latency. Still, in future I will probably go with VoIP friendly hardware, if only to make me feel better.