Re: tcp option added by driver

[Christoph Paasch <christoph.paasch@uclouvain.be>]

Hello,

On 22/04/14 - 05:27:55, Madhan wrote:
> hi ,
> Is it possible to update the option field of the tcp header dynamically by the driver rather than the change in tcp/ip stack .
> i.e Can i add a driver to implement mptcp rather than building entire kernel again ?

in principle it seems possible to do this at a driver-level. Alcatel-Lucent
implemented something similar using netfilter-hooks:
https://open-innovation.alcatel-lucent.com/projects/mptcp-proxy

Regular TCP was running on top, and the netfilter hooks allowed to
rewrite the TCP/IP header.


However, I think that doing it that way will be huge implementation effort
(considering that there exists already an open-source implementation at 
multipath-tcp.org) and it might be hard to achieve good performance and make it
scale properly.

You basically have to reimplement a full TCP-stack at the driver as each
TCP-subflow has to behave as regular TCP (3-way handshake, retransmissions,...)


Cheers,
Christoph