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[Didier Barvaux <question228645@xxxxxxxxxxxxxxxxxxxxx>]

Question #228645 on rohc changed:
https://answers.launchpad.net/rohc/+question/228645

    Status: Open => Answered

Didier Barvaux proposed the following answer:
> Hello Teacher:

Hello young padawan :)

> firstly, In the rohc-1.5.1.tar.bz2,is there no compression and
> decompression codes for TCP protocol, if so,can I get it from
> yours?

The 1.5.1 release can compress TCP streams, but it is not as efficient
as one could expect: it compresses only the IPv4/IPv6 header. For best
compression, you need the TCP profile. It is available in a separate dev
branch: https://code.launchpad.net/~didier-barvaux/+junk/rohc-tcp . Use
with some caution, it is still beta quality.

> secondly, after unzipping rohc-1.5.1.tar.bz2, there is folder
> "examples" with a simple_rohc_program.c, the main function
> in it compress only one IP packet, yes,the size of IP packet
> become bigger than before, however,I use a lot of IP packets
> as input,the codes in the .c file still can not make the sizes of
> IP packets smaller after compression. is it right?

Probably not, but difficult to say without additional information about
the additional IP packets. Do they belong to the same stream as the
first one? Belonging to the same stream means: same source IP address,
same destination IP address, and same protocol field for IPv4-only
streams. If they do, there is probably a problem; if they don't that's
expected, they are all compressed in an independent fashion.

> thirdly,is there test codes for UDP/IP compression and
> decompression in the rohc-1.5.1.tar.bz2,if so,which foder and file?

Please read the documentation! There are many information about this everywhere:
 - in sources:
     - README file: http://bazaar.launchpad.net/~didier-barvaux/rohc/main/view/head:/README#L34
     - INSTALL file: http://bazaar.launchpad.net/~didier-barvaux/rohc/main/view/head:/INSTALL#L57
 - on wiki:
    - install instructions on wiki:
       http://rohc-lib.org/wiki/doku.php?id=library-install-sources#native_build_on_unix-like_systems
    - ROHC tunnel over UDP: http://rohc-lib.org/wiki/doku.php#rohc_over_udp_tunnel
    - ROHC sniffer: http://rohc-lib.org/wiki/doku.php#rohc_sniffer

'make check' builds plenty of small test programs, and runs them with
input data, checking in an automated way the results. For tests with
real world streams,  the ROHC tunnel over UDP and the ROHC sniffer are
possible options. The code of all thoses tests and applications are
useful sources of information too.

Regards,
Didier

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