Re: [Lwip] Constrained TCP draft

["Carles Gomez Montenegro" <[e-mail]>]

Hi Joe,

Thanks a lot for your feedback.

Please find below inline responses:

> Hi, all,
>
> Scanning this doc, I had expected to see some "success criteria" up front.
>
> In particular, I was expecting that this approach was intended to be
> some "minimal" variant of TCP,

The very first version of the document had an (admittedly tentative)
"intended status" of "Best Current Practice".

However, after discussion and feedback from many folks, it was clarified
that the best approach for this document would be "Informational", and its
home would be the LWIG working group. So the main purpose of the document
is to describe how TCP can be configured in a suitable way for constrained
devices. The main purpose is not to define new mechanisms or a new TCP
variant. If during the process we identify that any new mechanism has to
be defined or a TCP specification requires some special modification for
constrained devices, TCPM would probably be the best home for that.

> subject to the following constraint:
>     This variant of TCP is intended to be compatible with current TCP,
> albeit with lower performance.
>
> I.e.
>
> 1) a constrained TCP client would always be able to connect with a
> compliant TCP server
>
> 2) a constrained TCP server would always be able to connect with a
> compliant TCP cllient
>
> 3) #1 and #2 MAY result in reduced performance for that client-server
> connection
>
> 4) #1 and #2 MUST NOT interfere with other client-server connections any
> more than other compliant TCP connections (i.e., MUST be "TCP-friendly")
>
> Is there any analysis or summary of this in the current document? If
> not, that's a good place to start, IMO.

Currently there is not a summary/analysis of this in the document. In
fact,  as explained above, we don't intend to actually define a new TCP
variant.

Anyway, we may consider the possible impact of each of the TCP
features/mechanisms analyzed in the document (section 4) on your four
items above, and even we might analyze whether any of the existing TCP
implementations for constrained devices (section 7) would not comply with
any of the four items.

> As is discussing this work in TCPM or at least TSVWG.

Definitely.

By the way, Michael Scharf has joined as an author of the draft.

Once again, thanks for your comments.

Cheers,

Carles

> Joe