Fwd: RE: [Asterisk-Users] SIP / IAX over satellite

[John Todd]

>Date: Sat, 11 Oct 2003 22:07:49 -0700
>To: asterisk-users at lists.digium.com
>From: John Todd <jtodd at loligo.com>
>Subject: RE: [Asterisk-Users] SIP / IAX over satellite
>
>[post re-ordered chronologically]
>
>>-----Original Message-----
>>From: asterisk-users-admin at lists.digium.com
>>[mailto:asterisk-users-admin at lists.digium.com] On Behalf Of Tilghman
>>Lesher
>>Sent: Saturday, October 11, 2003 4:03 PM
>>To: asterisk-users at lists.digium.com
>>Subject: Re: [Asterisk-Users] SIP / IAX over satellite
>>
>>
>>On Saturday, Oct 11, 2003, at 17:04 America/Chicago, Paul Mahler wrote:
>>
>>>  Which satellite system?
>>>
>>>  I think you need some specialized support, even special hardware. 
>>>  Check
>>>  out
>>>
>>>  http://www.groundcontrol.com/igvoip_001.htm
>>>
>>>  You may need to replace TCP/IP
>>>
>>  > http://www.mentat.com/skyx/skyx-gateway.html
>>
>>I don't know why he'd need to replace TCP/IP when both SIP as well as
>>IAX use UDP/IP.  There may be substantial latency, however.
>>
>>-Tilghman
>
>
>>Well, it's that stack that needs to go. Check out the link.
>>
>>Paul
>>
>>
>>Paul Mahler
>>pmahler at signate.com
>>phone: 650-207-9855
>>fax: 877-408-0105
>
>
>It's unlikely that the TCP/IP stack "needs to go".  IP applications 
>work quite well over satellite, no matter what people tell you. 
>They just get really, really slow if they're TCP due to ACK response 
>delay, and UDP has the aforementioned 500ms lag as well.
>
>The skyx stuff is just a forward-ACKing spoofer for TCP, and 
>probably some smart squid derivatives to boost HTTP transfer speeds. 
>Not useful for VoIP, but probably useful if you're doing anything 
>that's not UDP based.
>
>For VoIP with IAX, there may be application layer issues that are 
>smudging your results.  I would suggest that you try to get SIP 
>working over satellite, as I have had that working with no 
>difficulty in the past (excepting the delay issues, of course.)  If 
>you can get "raw" RTP working with SIP, but not IAX2, then perhaps 
>the issue needs to be patched in the IAX source code if there is 
>some timer that is expiring inside the IAX protocol.  Let us know 
>how your results with SIP work.
>
>Again: VoIP works JUST FINE over satellite, at least as far as the 
>voice quality goes, as long as you have decent bandwidth available. 
>Latency is another issue, but there's nothing  you're going to be 
>able to do when you're pushing a radio wave 33,000 miles out and 
>33,000 miles back - physics doesn't allow for better QoS.  :-)
>
>JT


Of course, I meant 22,237 and not 33,000 miles.  Bad typing day.

JT