Re: [tcpm] WG status update

[Joe Touch <[e-mail]>]

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.

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

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.

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.

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

Joe