Re: [tcpm] WG status update

[Bruno Mongazon-Cazavet <[e-mail]>]

  Hey Joe ;-)

Please see inline

Le 17/11/2010 00:39, Joe Touch a écrit :
>
> On 11/15/2010 4:54 AM, Lars Eggert wrote:
>> Hi,
>>
>> On 2010-11-15, at 12:27, Bruno Mongazon-Cazavet wrote:
>>> Please let me know, if from the design point of view, the WG would consider the opportunity to have a lightweight MPTCP that would look like TCP-Rehash.
>> given that the IETF is already working on MPTCP, it's a bit
>> difficult to see why we should work on another extension to TCP that
>> does some of what MPTCP does, but not all of it, and in a way that is
>> not interoperable with it.
> I had argued that MPTCP was trying to solve two separate issues (perhaps
> three):
>
> 1) use of more than one *path* between two endpoints at the same time
>
> 2) use of multiple endpoint IP addresses between two pairs at the same time
>
> (3) shifting the addresses in #2 dynamically, i.e., not so much
> concurrent use as a sequence of uses
>
> My concern, FWIW, remains that inferring #1 from #2 is just wrong.
> Beyond that concern, however, I didn't like the idea of bundling two
> separately useful features in a single system, since I didn't see the
> two as necessarily related anyway.
>
> TCP-Rehash - good or bad, I don't know (I haven't looked in detail, but
> see below) - at least admits that there's utility to #3 independent of
> #1 and #2.


[bm] correct.


> So I don't see this as related to MPTCP at all.

[bm] In fact, it is not.


> That said, I have other concerns, e.g., as to TCP-Rehash replicating
> work that has already been done in HIP, SHIM6, or just over tunnels in
> general.

[bm] i tried to make it different from HIP and SHIM6.
It is not like HIP because TCP-Rehash does not deal at all with 
"Identity" but only end-point addresses.
It is not like SHIM6 nor tunnel approaches because TCP-Rehash is not an 
intermediate or inner layer.
It is more like MIT's TCP-Migrate or kind of approaches.

> FWIW, I'm also concerned about the fact that TCP *defines* its
> connections in terms of endpoint addresses, so the *semantics* needs to
> be updated if there's a corresponding redefinition of how the connection
> is now dissociated from those addresses.

[bm] TCP-Rehash does not introduce new semantics. It is based on 
endpoint addresses and ports as regular TCP.
There is no dissociation and this is a major constraint of its design.

> But, again, this is not at all related to MPTCP to me.
>
> Joe
>