[sldev] Uh... what was with the sudden voice release?

Matthew Dowd matthew.dowd at hotmail.co.uk
Sat Aug 4 02:31:06 PDT 2007


Mmmm, quite a complex stack - there's a little irony that the foundational code for the voice components are open source, whilst the actual implementation used by SL is not only closed source but non-redistrible either!

The SIP part I think is fine (it just uses UDP ports 5060 and 5062), there's also some STUN traffic (NAT traversal) on UDP Port 3478.

It is the outgoing UDP ports used for the RTP part which appears to be the problem (if I understand all this correctly).

As far as I can tell the underlying stacks allow you to specify the ports used in the RTP communication (or specify 0 for a random select). So I suspect the ports in use are being determined by Vivox's managed service. Your testing seems to support that it is the servers determining the ports to be used (or at least a range of them). Which comes back down to the fact that we and LL are reliant on technical information from Vivox here.

What worries me is that it really is essentially a randomly selected port in a range of thousands of possibles - which is really going to limit any use on corporate and quite a few academic networks. Asking the firewall team to open half a dozen outgoing ports on a firewall is one thing, but asking them to open thousands is quite another.

Matthew




----------------------------------------
> Date: Fri, 3 Aug 2007 16:24:20 -0700
> From: jhurliman at wsu.edu
> To: sldev at lists.secondlife.com
> Subject: Re: [sldev] Uh... what was with the sudden voice release?
> 
> One reason might be because they didn't write the SIP (or RTP) 
> implementation themselves. They use the SIP stack from 
> http://www.antisip.com/ (a mixture of all three; osip, eXosip, and 
> amsip), and the oRTP library originally designed for linphone 
> (http://www.linphone.org/index.php/eng/code_review/ortp). You might fall 
> back on those for technical details as the Vivox SDK is just mashing a 
> lot of components together and tying it in with their SIP gateways. For 
> a full list of components used by vivoxsdk check here: 
> http://wiki.secondlife.com/wiki/Voice#Technical
> 
> John Hurliman
> 
> 
> Matthew Dowd wrote:
> > Nope!
> >
> > So far I've seen on my network logs UDP ports in the 12000s, 15000s and occasionally 13000s. I must confess I haven't seen anything in the 14000s yet. 12000-16000 was therefore a best guess based on what I've seen.
> >
> > UDP port 3478 also comes into play somewhere as well. I think this port is NAT related. 
> >
> > However, the Vivox website is somewhat light on any technical information about how VOIP works!
> >
> > Matthew
> >
> >
> >
> >
> > ----------------------------------------
> >   
> >> Date: Fri, 3 Aug 2007 09:07:32 -0700
> >> From: jhurliman at wsu.edu
> >> To: sldev at lists.secondlife.com
> >> Subject: Re: [sldev] Uh... what was with the sudden voice release?
> >>
> >> Are you sure the range is always 12000-16000? I got this reply from the 
> >> Vivox gateway during testing:
> >>
> >> 2286022892
> >>
> >> Not sure if that port range is for the server or the client or both, or 
> >> if it is even used, but SIP/RTP are definitely going to be using a 
> >> couple different ports here and there.
> >>
> >> John
> >>
> >> Soft Linden wrote:
> >>     
> >>> I passed the previous notes on firewall ports in the knowledgebase to
> >>> bHear - I'll get this additional information out their way as well.
> >>> Thanks for posting this
> >>>
> >>> On 8/3/07, Matthew Dowd  wrote:
> >>>   
> >>>       
> >>>> It seems rather rushed - apart from the chatterbox issues, there are also firewall issues (the FAQ is wrong - it implies that if you are firewall router you only need to enable 5060 and possible 5062. This is incorrect. It looks like the SLVoice.exe does the initial handshake over 5060/5062 but then establishes the voip connections themselves over UDP ports which afaict are picked at random within the 12000-16000 range. If you firewall does not have this range open by default for outgoing messages, not only does VOIP not work but you get spammed with "Connecting to inworld voice..." every few minutes in the chat history log).
> >>>>
> >>>> Anyway, looks like this weekend, I'll be looking at the new chatterbox source code...
> >>>>
> >>>> Matthew
> >>>>     
> >>>>         
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