Question #195843 on rohc changed: https://answers.launchpad.net/rohc/+question/195843
Cedric Baudoin proposed the following answer: Yes for the user plane it has to be considered. Be careful however if you want toi group pk, since it Will have impacts on the perf (jitter and delay ) Br Cédric Le 5 mai 2012 13:55, "Didier Barvaux" <[email protected]> a écrit : > Question #195843 on rohc changed: > https://answers.launchpad.net/rohc/+question/195843 > > Didier Barvaux posted a new comment: > Cédric, > > > Using ROHC for that purpose implies that your 2 end points are able to > communicate using > > ROHC packets, that is not > straighforward (use of IP tunneling is not > really useful if your > > objective is to reduce overhead) . In addition, the main part of the > overhead is due to the > > rich text part (plain text XML) and not the header part. > > You're right for the modifications of the 2 end points and for the > overhead in the signalling packets (SIP). However, for data packets > (RTP), the overhead is still the header part. For those packets, ROHC > may be interesting even if IP tunneling is required. > > Gain for ROHC without tunneling: > - non-compressed IPv4/UDP/RTP packet = 20-byte IPv4 header + 8-byte UDP > header > + 12-byte RTP header + 40-byte audio data = 80 bytes > - ROHC-compressed IPv4/UDP/RTP packet = 1-byte ROHC header + 40-byte audio > data = 41 bytes > = 49% gain > > Gain for ROHC with IPv4 tunneling: > - non-compressed IPv4/UDP/RTP packet = 20-byte IPv4 header + 8-byte UDP > header > + 12-byte RTP header + 40-byte audio data = 80 bytes > - ROHC-compressed IPv4/UDP/RTP packet in IPv4 tunnel = 20-byte IPv4 > header for > tunnel + 1-byte ROHC header + 40-byte audio data = 61 bytes > = 24% gain > > A 24% gain is still interesting, but the IPv4 tunnel degrades the > compression gain. > > We may group several ROHC packets together (packing) to reduce the overhead > introduced by the IPv4 tunnel: > - 4 non-compressed IPv4/UDP/RTP packet = 4 * (20-byte IPv4 header + > 8-byte UDP header > + 12-byte RTP header + 40-byte audio data) = 320 bytes > - 4 ROHC-compressed IPv4/UDP/RTP packet in IPv4 tunnel = 20-byte IPv4 > header for > tunnel + 4 * (1-byte for packing + 1-byte ROHC header + 40-byte audio > data) = 188 bytes > = 41% gain > > A 41% gain is definitely interesting :) > > > Regards, > Didier > > -- > You received this question notification because you are a member of ROHC > Team, which is an answer contact for rohc. > > _______________________________________________ > Mailing list: https://launchpad.net/~rohc > Post to : [email protected] > Unsubscribe : https://launchpad.net/~rohc > More help : https://help.launchpad.net/ListHelp > -- You received this question notification because you are a member of ROHC Team, which is an answer contact for rohc. _______________________________________________ Mailing list: https://launchpad.net/~rohc Post to : [email protected] Unsubscribe : https://launchpad.net/~rohc More help : https://help.launchpad.net/ListHelp
