Connecting two Asterisk boxes using Dynamic DNS

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mruane

420 posts

Ultimate Geek

#18946 30-Jan-2008 17:14

Hi

I have two Asterisk (Trixbox) PC's located in two seperate locations that are connected so that I can call extensions on Box B from Box A just by dialling the extension number on Box B. Box B extensions are formatted 2nn and Box A extensions are formatted 5nn. This works just fine until one or other of the ADSL routers needs to be restarted - then the system fails because the IP address has changed even though the dynamic DNS provider has been updated.

Whenever either ADSL router is rebooted, the new IP address is updated in the DDNS without any problems, but Asterisk (well Trixbox really) looses connection with the other device even though the "other" box is identified with the dynamic DNS name in the trunk definition.

The impression I get, is that Trixbox resolves the actual IP address for a trunk at Config Load time rather than when a connection is made.

Has anyone any experience joining two Asterisk boxes together in locations that use dynamic IP addressing and if so, how did you resolve this?

PS I connect the two boxes by creating an extension on Box A and a trunk on Box B that connects to the extension on Box A. I then duplicate that for the reverse connection. Sounds worse that it is but it works just fine.

Cheers Mike

ajobbins

5052 posts

Uber Geek

Trusted

#107767 31-Jan-2008 13:23

Why dont you get a Static IP for each connection? Who is the ISP?

Fraktul

836 posts

Ultimate Geek

Trusted

#107780 31-Jan-2008 14:38

Your OS and the DNS servers you are using for lookups will cache the domain record when doing a lookup, it may be that its (trixbox OS) default cache period is overwriting the TTL if the TTL with your dynamic DNS provider is set appropriately low.

mruane

420 posts

Ultimate Geek

#107796 31-Jan-2008 15:18

Adamj: I use WorldxChange as my ISP and Telecom for the other site, but I cannot justify the cost for fixed IP addresses and its probably a waste of their resources as well. It seemed to me that a dynamic DNS was a good solution and so far it has been - other than the caching of the ip address that Fraktul alludes to.

Fraktul: Thanks, your comment has given me something else to look into i.e. DNS caching on the linux box. I had not thought of trying to reduce the cache interval (nor do I know how to do that), but there's bound to be something to be found using our old mate Google.

Appreciate the help guys, thanks.

Cheers Mike

rphenix

985 posts

Ultimate Geek

Lifetime subscriber

#108176 2-Feb-2008 16:31

Since WXC nolonger offer free static ips to those that dont already havem. You could look at inspire.net.nz last time I had anything to do with them the helpdesk bods would happily give a static ip for free dont think thats changed (at least the person who I got a stic ip still has it free of charge)?

Ring them up and ask if they would do it, explain your not "hosting" just want it for voip stuff.

mruane

420 posts

Ultimate Geek

#108456 4-Feb-2008 12:28

Hi rphenix

To be honest, it would take a hell of a big crowbar to leverage me away from WXC, the ADSL (allbeit using Telecom infrastructure) and VFX service they provide are just too good to leave, even though some other provider could offer a fixed IP address. I can get around the problem (I think) by getting Asterisk to reload its configs on a regular basis.

Thanks for the feedback though.

Cheers Mike

rphenix

985 posts

Ultimate Geek

Lifetime subscriber

#108489 4-Feb-2008 14:10

Yep I understand completely :) There is another way:

You can get a dynamic dns clients that polls your router web interface (ie a cron job hits the web interface every minute) if it notices a change in the ip address it can then be told to do something (like update the dynamic dns ip address) ontop of this you could get it to reload the asterisk configuration file.

The good thing with hitting your router web interface instead of using a website to check if your ip is changed is you can check for updates a lot more often than is allowed by most dynamic DNS client providers without vioating any terms and conditions of the service.

I havent used dynamic DNS for ages now but http://ddclient.wiki.sourceforge.net/ was a good client back when I did. It's a perl script so easy to modify if it doesnt quite suit your needs it wouldnt take much to make it execute a bash script to reload both the local configuration and remote asterisk configuration (if needed?).

mruane

420 posts

Ultimate Geek

#108570 4-Feb-2008 22:14

Thanks for the link and the idea. That is worth pursing. I think that reloading the config files seems to be the easiest way to force Asterisk to redefine the DNS's IP address but only when it needs to. I will review the link you mentioned and see what I can find.

Really appreciate the suggestion.

Cheers Mike