How can we enable header compression for RTP/UDP packets sent over a PPP interface in linux?

Hints for any of the various header compression mechanisms (ROHC, IPHC, CRTP, etc.) are highly appreciated.

Note1: I prefer the compression to be done at the interface (not requiring the application to be modified)

Note2: I have a low BW serial link established in my linux box using pppd (named ppp0).

Note3) A similar question (with no answers) pointing out the different compression mechanisms can be found here

  • Not an answer, but besides van-Jacobson, pppd has multiple other compression options that may or may not help. AFAIK the header compression mechanisms you mentioned are not implemented in pppd. I wouldn't know any other place to implement them except in pppd. If you really need the header compression, adding it to the pppd code should be doable. – dirkt Sep 3 '18 at 7:30
  • @dirkt, thanks for your input; does any of the pppd compression options support UDP or RTP compression? – qwa Sep 3 '18 at 9:55
  • As I wrote: "AFAIK the header compression mechanisms you mentioned are not implemented in pppd". But I'd expect both deflate and bsdcompress to work on the whole packet, which includes RTP over UDP. Of course the question is if that actually saves something, so you'll have to try. There are also various link-level compression options. PPP by default also does a lot of control character escaping (it assumes they might not be properly transferred over serial), so it's worth looking into that, too. – dirkt Sep 3 '18 at 10:25

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