rohc team mailing list archive

[Ahmed Fathy <eng.afathy@xxxxxxxxx>]

Thanks for the quick reply,

To summarize my understanding:

*To send IP packets with the no compression profile, I must activate have
"no compression" profile activated and "IP profile" not activated, because
if IP profile is active, the compressor will use it for compression because
it matches the packet header (IP packet). and the same rule applies for
other headers/ profiles.*

Thanks,
Ahmed

On Mon, Jul 12, 2010 at 5:10 PM, Didier Barvaux <didier@xxxxxxxxxxx> wrote:

> Hi,
>
> > I have a general question about the no compression profile (0).
> >
> > How does the compressor decide on using it? should there be some kind
> > of indication from upper layers telling the compressor to use profile
> > 0 to compress the packet? or the other profiles must be deactivated
> > on the channel before sending the packet, so the compressor finds
> > only profile 0 to use?
>
> There are 2 possibilities in the ROHC library:
>  - If no other compression profile matches the packet, then the
>   uncompressed profile is selected.
>  - If the compression of the packet fails with the selected compression
>   profile, then the compressor tries again with the uncompressed
>   profile.
>
>
> > I know that some packets that are rarely appear on the link, get sent
> > with profile 0 to save memory resources needed for a new context,
>
> The ROHC library does not handle such case.
>
>
> > but my question is for normal IP packets, if i want to test rohc
> > without doing any compression, only CRC in IR packets and CID octet
> > (if cid != 0) and the optional feedback to trigger transition to
> > bidirectional mode,...etc.
>
> If you want to use only the uncompressed profile, then enable only the
> uncompressed profile with the rohc_activate_profile() function.
>
> See the API description:
>
> http://www.tech.viveris.com/docs/rohc/group__rohc__comp.html#g1a444eb91681521f726712a60a4df867
>
> See an example here:
>
> http://bazaar.launchpad.net/~didier-barvaux/rohc/main/annotate/head:/examples/simple_rohc_program.c#L102<http://bazaar.launchpad.net/%7Edidier-barvaux/rohc/main/annotate/head:/examples/simple_rohc_program.c#L102>
>
>
> Regards,
> Didier Barvaux
>
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-- 
Ahmed Abdelrazek
Embedded Software Developer,
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