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Re: [Question #253104]: Reg ROHC implementation in Linux , Android

 

Question #253104 on rohc changed:
https://answers.launchpad.net/rohc/+question/253104

    Status: Open => Answered

Didier Barvaux proposed the following answer:
Hello,

> 1) Generally ubuntu kernel adds the udp, IP, ethernet headers to the
> packet ? like we will use sendto(), receivefrom() APIs the the reamining
> things like udp , IP Ethenet headers are added and parsed by the linux
> kernel ? Hence where we will get the control to compress these
> headers ? Is there any way we can specify to kernel don't add any these
> kind of headers ?

Yes, the Linux kernel (Ubuntu uses the Linux kernel) is in charge of
adding (resp. removing) the protocol headers when sending (resp.
receiving) data over Ethernet/IP/UDP or Ethernet/IP/TCP.

You may bypass this by using RAW sockets to send or receive packets
without adding/removing headers: see 'man 7 raw' or
http://man.cx/raw%287%29


> 2) If we suppose used this and compressed , how to send these IP compressed
> packets to the remote machine (which is having static IP remotely)?

This is entirely up to your application. The ROHC protocol does not
define how ROHC packets are transmitted to the remove node. For example,
the IP/ROHC tunnel application transmits the ROHC packets encapsulated
in IPv4 packets, see http://rohc-lib.org/wiki/doku.php?id=iprohc-
overview


Regards,
Didier

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