Without RoHC, the only 'cheap' way to save on bandwidth is to increase the packetization time, which leads to delays. Also, if a packet is dropped, a big chunk of media is lost. With RoHC, packetization time doesn't really matter. Choosing a low value for packetization (10-20ms) reduce the latency a lot and if a packet is discarded, the effect is negligible.
RoHC makes a lot of sense in scenarios where bandwidth is expesive (wireless transmissions). It can save a lot of bandwidth and it can improve the voice quality (low delay by choosing a low value for packetization and better tolerance for packet loss). Regards, Ovidiu Sas On Tue, May 18, 2010 at 4:00 PM, Jeff Brower <jbro...@signalogic.com> wrote: > Alex- > >> It is not supported by rtpproxy. But you could run all that traffic >> inside a high-compression IP-in-IP UDP tunnel, though there would be >> an overhead penalty there too. > > We've already extended rtpproxy for transcoding and encryption, we're > thinking to continue with that approach for > header compression. > >> Doesn't seem to me like this stuff really saves a lot of bandwidth, >> especially in a way that has meaningful network oversubscription >> returns. You might be better off just using a low-bandwidth codec >> than worrying about all this. > > Yes we're wondering also. The main customer concern seems to be physically > slow networks rather than > oversubscription. I.e. geographical regions and/or equipment where voice > channels are well under 50 kbps. But you > make a good point, and we're trying to evaluate this carefully. > > It does seem valuable if we can get down (and stay down) to a few bytes for > all headers instead of 40. Also it seems > a lot of work has gone in the area over the last few years. For example, > initial RFCs were sensitive to packet loss, > later revisions have improved this. > > -Jeff > >> On May 18, 2010, at 3:10 PM, Vikram Ragukumar >> <vraguku...@signalogic.com> wrote: >> >>> Hello, >>> >>> We are looking into bandwidth conservation by implementing RTP/UDP/ >>> IP header compression. >>> >>> Has anybody implemented ROHC or another header compression scheme in >>> combination with kamailio + rtpproxy ? Could you please point us to >>> online documentation or other useful resources ? >>> >>> Thanks and Regards, >>> Vikram. > > > _______________________________________________ > SIP Express Router (SER) and Kamailio (OpenSER) - sr-users mailing list > sr-users@lists.sip-router.org > http://lists.sip-router.org/cgi-bin/mailman/listinfo/sr-users > _______________________________________________ SIP Express Router (SER) and Kamailio (OpenSER) - sr-users mailing list sr-users@lists.sip-router.org http://lists.sip-router.org/cgi-bin/mailman/listinfo/sr-users
