Re: [tcpm] Extending TCP option space

["SCHARF, Michael" <[e-mail]>]

Hi Pasi,

> TCP's option space has been under increasing demand recently, with new

> option-space hungry extensions such as MPTCP, and some recent ideas in

> the research domain. In the past there have been some discussion about

> mechanisms to extend the option space, and an extension option was 
> proposed in draft-eddy-tcp-loo, but since then these efforts have died

> down. I'm wondering if there would be any interest in the tcpm 
> community to resume this work.
> 
> I recall that re-segmenting middleboxes were mentioned as one 
> potential problem for such extension, and there might be other 
> problems. Nevertheless, I would find it useful, if there was an RFC 
> that a) documented the known problems with option space extension; and

> b) defined an option format and assigned the needed type codes, to 
> enable experimentations with larger than 40-byte option space.
> 
> Thoughts?

actually, I happened to argue in favor of a) in hallway discussions
during the last IETF meetings. Maybe someone should just start to put
together some text, at least for a)... (And I think it would really make
sense to raise awareness among researchers that TCP option space in SYNs
is a really scarce resource.)

Michael