Today has been the day for satellite questions, apparently, so I'll proxy one out to the rest of the community... I asked this tangentially a month or two ago, but I'll put it in a more blunt way: If you have IAX2 trunking mode experience over satellite, please let us know your experiences with that protocol/transport combination. I've got several people asking about IAX2 and trunk mode over satellite. I have not experimented with IAX2 over satellite (though I have used IAX1 over satellite) and I'm wondering if anyone has direct experiences with IAX2's jitter buffer control over such long-latency connections. I've had SIP working very well over satellite (despite what some people have found to the contrary on this list) and other than the lag there have been no issues that have come up on a reasonably-managed satellite segment. However, the IP overhead really starts to cost significant amounts of pennies when you add it up on multiple SIP RTP sessions over the same link. Plus, packet contention and buffering may (_may_) be an issue when pushing multiple simultaneous streams out the same transponder. It would seem to me that IAX2 in trunk mode would be optimal for people on very expensive satellite bandwidth, as a G.729 9.6kbps channel starts to actually look like 9.6kbps instead of 24kbps. However, I have had mixed success with IAX2 in certain circumstances. Before I start to ask for favors and get satellite time for testing, I'd like to see if anyone else has performed this experiment. If you'd wish to remain anonymous, please mail me directly and I'll appropriately trim identity information and re-distribute, or re-write as appropriate. Other hints I have heard/used on VoIP over satellite: - use small transmit cell (packet) sizes on your satellite gear - turn off error correction (why use it for VoIP?) - turn off compression (G.729 is already compressed; you ARE using G.729, right?) - ensure minimal latency on the terrestrial portions of the call - tell your users to suck it up and deal with the half-second lag JT
clive18@webmail.co.za
2004-Mar-30 23:27 UTC
[Asterisk-Users] IAX2 trunk mode over satellite
Hi I have even used H323 over satelite, and beside the lagg, no trouble. My only issue is the jitter buffer on IAX2 seems to be broken. On a very jittery connection, I can hardly make a decent call on IAX2. Good luck! regards Clive On Tue, 30 Mar 2004 10:15:52 -0800 John Todd <jtodd@loligo.com> wrote:> > Today has been the day for satellite questions, > apparently, so I'll proxy one out to the rest of the > community... I asked this tangentially a month or two > ago, but I'll put it in a more blunt way: > > If you have IAX2 trunking mode experience over satellite, > please let us know your experiences with that > protocol/transport combination. > > I've got several people asking about IAX2 and trunk mode > over satellite. I have not experimented with IAX2 over > satellite (though I have used IAX1 over satellite) and > I'm wondering if anyone has direct experiences with > IAX2's jitter buffer control over such long-latency > connections. > > I've had SIP working very well over satellite (despite > what some people have found to the contrary on this list) > and other than the lag there have been no issues that > have come up on a reasonably-managed satellite segment. > However, the IP overhead really starts to cost > significant amounts of pennies when you add it up on > multiple SIP RTP sessions over the same link. Plus, > packet contention and buffering may (_may_) be an issue > when pushing multiple simultaneous streams out the same > transponder. > > It would seem to me that IAX2 in trunk mode would be > optimal for people on very expensive satellite bandwidth, > as a G.729 9.6kbps channel starts to actually look like > 9.6kbps instead of 24kbps. However, I have had mixed > success with IAX2 in certain circumstances. Before I > start to ask for favors and get satellite time for > testing, I'd like to see if anyone else has performed > this experiment. If you'd wish to remain anonymous, > please mail me directly and I'll appropriately trim > identity information and re-distribute, or re-write as > appropriate. > > Other hints I have heard/used on VoIP over satellite: > - use small transmit cell (packet) sizes on your > satellite gear > - turn off error correction (why use it for VoIP?) > - turn off compression (G.729 is already compressed; > you ARE using > G.729, right?) > - ensure minimal latency on the terrestrial portions > of the call > - tell your users to suck it up and deal with the > half-second lag > > JT > _______________________________________________ > Asterisk-Users mailing list > Asterisk-Users@lists.digium.com > http://lists.digium.com/mailman/listinfo/asterisk-users > To UNSUBSCRIBE or update options visit: >http://lists.digium.com/mailman/listinfo/asterisk-users __________________________________________________________________________ http://www.webmail.co.za/dialup Webmail ISP - Cool Connection, Cool Price